Gino Baudry
email: gino.baudry@univ-nantes.fr

Florian Delrue
email: florian.delrue@cea.fr

Jack Legrand
email: jack.legrand@univ-nantes.fr

Jérémy Pruvost
email: jeremy.pruvost@univ-nantes.fr

Thomas Vallée
email: thomas.vallee@univ-nantes.fr

Lemna

The challenge of measuring biofuel sustainability: A stakeholder-driven approach applied to the French case

Keywords:

Measuring biofuel sustainability requires dealing with a wide variety of complex and conflicting values at stake. Consequently, the biofuel capacity to contribute to one specific value cannot lead to any absolute conclusion about the overall sustainability of biofuel. The scope of the sustainability concept may vary depending on individuals' preferences, the time scale and the geographical region. Based on the 5 pillars sustainability concept that includes social, economic, environmental, legal and cultural considerations, the present study proposes to assess several biofuel sustainability options for France by 2030 through a stakeholder-driven approach. Rather than seeking to reach a consensus, our approach allows us to capture the wide diversity of stakeholders' perspectives and preferences. French stakeholders perceive 22 different sustainability criteria for biofuels with a very low level of agreement between the different segments of professions (feedstock producers, biofuel producers, refining industry, fuel distributors, car manufacturers, end-users, government and NGOs). In order to operationalize the sustainability assessment, a set of indicators has been identified with stakeholders that allows us to measure the capacity of biofuels to fulfill each of their criteria. Seventeen biofuel options were assessed with regards to economic, social, environmental, cultural and legal considerations, allowing the identification of the strengths and weaknesses of each biofuel.

Introduction

In 1992, the European Common Agricultural Policy (CAP) introduced a set-aside measure to face the agricultural overproduction crisis but non-food usage crops were exempted. Since then, France has supported biofuel development in order to create new market opportunities for the agro-food industry. Relying on environmental sustainability considerations, especially for CO 2 emissions, the European parliament promoted a directive in 2003 (2003/30/EC) to support biofuel deployment. The directive required the Member States to ensure that renewable energy account for at least 5.75% of energy consumption in the transport sector by 2010. However, rising concerns about biofuel socio-environmental sustainability led to the addition of qualitative criteria to quantitative ones in 2009 through the Renewable Energy Directive (RED) [START_REF][END_REF]. The RED requires the Member States to reach a 10% share of renewable energy in the transport sector by 2020 with respect to several sustainability criteria. Three years later, the European Commission proposed limiting the contribution of food crop based biofuels to a level of 5% because of direct and indirect land use change impacts (ILUC). According to the European Commission, despite a 10 billion euro per year public subsidy, the 2010 objective was not reached. Furthermore, without a massive contribution of food crops based biofuels, the attainment of the objective by 2020 is also highly uncertain. Consequently, the limit was increased to 7% in 2015 after three other years of conflicting debates between the different stakeholders. In the same year, the promotion of renewable energy was intensified and now includes a 15% sub-target by 2030 within the transport sector.

Biofuels and sustainability

Over the last decade, biofuels were perceived as one of the most sustainable alternatives to fossil fuels for transportation but due to several socio-environmental issues, this positive image has dramati-cally changed [START_REF] Gnansounou | Assessing the sustainability of biofuels: a logic-based model[END_REF]. Although biofuel deployment creates and maintains jobs, diversifies fuels and promotes renewable energy consumption, several drawbacks have been highlighted such as rising food prices, the land grabbing phenomena and ILUC [START_REF] Scarlat | Recent developments of biofuels/bioenergy sustainability certification: a global overview[END_REF][START_REF] Bracco | Effectiveness of EU biofuels sustainability criteria in the context of land acquisitions in Africa[END_REF][START_REF] Gnansounou | Assessing the sustainability of biofuels: a logic-based model[END_REF][START_REF] Hamelinck | Land grabs for biofuels driven by EU biofuels policies[END_REF]. Indeed, biofuel deployment is not just about energy but also about agricultural sector support, global trade food impacts and land use issues [START_REF] Khanna | Handbook of bioenergy economics and policy and buisness media[END_REF]. The biofuel support means an overlapping of several policies and measures with complex interactions. The biofuel policy impacts are still highly uncertain being neither linear nor proportional while depending on local, national and international contexts [24]. The biofuel capacity to fulfill one specific objective cannot lead to any absolute conclusion about its overall sustainability and whether it has a positive or negative impact.

Focusing on the French context, biofuel deployment was successively an agricultural sector support, an energy independence objective and finally an environmental and a bioeconomy issue. Therefore, defining a set of relevant sustainability criteria is necessary for the planning of the stages for renewable energy deployment [START_REF] Galo | Criteria for smart grid deployment in Brazil by applying the Delphi method[END_REF], especially for biofuels [START_REF] Markevičius | Trends and sustainability criteria of the production and use of liquid biofuels[END_REF][START_REF] Wiesenthal | Biofuel support policies in Europe: lessons learnt for the long way ahead[END_REF]. Indeed, complex ecological and environmental problems such as biofuel systems are characterized by a diversity of conflicting values at stake associated with high uncertainties [START_REF] Cuppen | Q methodology to select participants for a stakeholder dialogue on energy options from biomass in the Netherlands[END_REF][START_REF] Van Dam | Striving to further harmonization of sustainability criteria for bioenergy in Europe: recommendations from a stakeholder questionnaire[END_REF]. According to Athanasios Angelis-Dimakis [START_REF] Angelis-Dimakis | Monitoring the sustainability of the Greek energy system. energy[END_REF], there is no standardized methodology that can be used to assess energy systems sustainability. Consequently, researchers have to design their approach depending on their specific objectives [START_REF]Sustainability assessment of electricity generation technologies using weighted multi-criteria decision analysis[END_REF].

Objectives

Literature provides a wide range of papers that aim at assessing the sustainability of biofuel [109,[START_REF] Upham | Governance and legitimacy aspects of the UK biofuel carbon and sustainability reporting system[END_REF][START_REF] Demirbas | Political, economic and environmental impacts of biofuels: a review[END_REF][START_REF] German | A review of social sustainability considerations among EU-approved voluntary schemes for biofuels, with implications for rural livelihoods. energy policy[END_REF][START_REF] Liew | Review of evolution, technology and sustainability assessments of biofuel production[END_REF]. Several papers focus on specific criteria such as GHG mitigation ( [START_REF]Biofuels Review: Greenhouse gas saving calculations[END_REF][START_REF] Haberl | Correcting a fundamental error in greenhouse gas accounting related to bioenergy[END_REF][START_REF] Hoefnagels | Greenhouse gas footprints of different biofuel production systems[END_REF][START_REF] Larson | A review of life-cycle analysis studies on liquid biofuel systems for the transport sector[END_REF][START_REF] Menten | A review of LCA greenhouse gas emissions results for advanced biofuels: The use of meta-regression analysis[END_REF][START_REF] Smeets | The impact of the rebound effect of the use of first generation biofuels in the EU on greenhouse gas emissions: A critical review[END_REF]), ILUC impact [START_REF] Wicke | Indirect land use change: review of existing models and strategies for mitigation[END_REF][START_REF] Broch | A review of variability in indirect land use change assessment and modeling in biofuel policy[END_REF][START_REF] De Cara | Revue critique des études évaluant l′effet des changements d′affectation des[END_REF][START_REF] Gawel | The iLUC dilemma: how to deal with indirect land use changes when governing energy crops?[END_REF][START_REF] Ahlgren | Indirect land use changes of biofuel productiona review of modelling efforts and policy developments in the European Union[END_REF][START_REF] Lapola | Indirect land-use changes can overcome carbon savings from biofuels in Brazil[END_REF], as well as the impact on food prices [START_REF] Zilberman | The impact of biofuels on commodity food prices: assessment of findings[END_REF][START_REF] Ignaciuk | Competition between biomass and food production in the presence of energy policies: a partial equilibrium analysis[END_REF][START_REF] Ajanovic | Biofuels versus food production: Does biofuels production increase food prices? Energy[END_REF][START_REF] Mueller | Impact of biofuel production and other supply and demand factors on food price increases in 2008[END_REF], etc. Other papers focus on a wider range of sustainability criteria, but for a particular biofuel option [START_REF] Yee | Life cycle assessment of palm biodiesel: revealing facts and benefits for sustainability[END_REF][START_REF] Delrue | An economic, sustainability, and energetic model of biodiesel production from microalgae[END_REF][START_REF] Mata | Microalgae for biodiesel production and other applications: a review[END_REF][START_REF] Murphy | Life cycle analysis of biochemical cellulosic ethanol under multiple scenarios[END_REF][START_REF] Pfromm | Sustainability of algae derived biodiesel: a mass balance approach[END_REF][START_REF] Von Blottnitz | A review of assessments conducted on bio-ethanol as a transportation fuel from a net energy, greenhouse gas, and environmental life cycle perspective[END_REF]. The sustainability assessment of biofuels requires dealing with a wide range of criteria, whether economic, social, environmental or legal issues [START_REF] Van Dam | Striving to further harmonization of sustainability criteria for bioenergy in Europe: recommendations from a stakeholder questionnaire[END_REF][START_REF] Gnansounou | Assessing the sustainability of biofuels: a logic-based model[END_REF][START_REF] Markevičius | Trends and sustainability criteria of the production and use of liquid biofuels[END_REF]. To our knowledge, there is currently no review that proposes bringing together in one paper the sustainability assessment of conventional and advanced biofuels (17 options) on the basis of a large range of criteria (22 criteria). Through a stakeholder-driven approach, we aim to propose such a review which furthermore is complemented by expert consultations. On the one hand, our paper relies on a wide range of literature that focuses on the identification of sustainability criteria within a bioenergy-system, which led us to deploy a stakeholder-driven approach [START_REF] Van Dam | Striving to further harmonization of sustainability criteria for bioenergy in Europe: recommendations from a stakeholder questionnaire[END_REF][START_REF] Buchholz | Sustainability criteria for bioenergy systems: results from an expert survey[END_REF][START_REF] Carrera | Sustainability assessment of energy technologies via social indicators: results of a survey among European energy experts[END_REF][START_REF] Markevičius | Trends and sustainability criteria of the production and use of liquid biofuels[END_REF]. On the other hand, given the large number of biofuels and criteria that were considered, we mobilized a wide range of literature concerning economic, social, environmental, legal and technical issues.

Through semi-structured interviews, the present study provides a basis to clearly identify criteria for inclusion in a sustainability assessment that reflect the whole biofuel system from the different perspectives of French stakeholders. The next section presents the theoretical background that led us to develop a stakeholder-driven approach to assess the biofuel system in France. Section 3 presents the identification of sets of biofuels, sustainability criteria and their associated indicators. Finally, Section 4 provides the sustainability assessment of the different identified biofuel options based on their capacity to fulfill the sustainability criteria of French stakeholders.

Theoretical background

The sustainability concept

The concept of sustainability was first defined in 1987 by the Brundtland Commission [START_REF] Brundtland | Our common future[END_REF] through the sustainable development definition: "a development that meets the needs of the present without compromising the ability of future generations to meet their own needs". To achieve and maintain sustainability objectives, policymakers require information to demonstrate whether the complex human system is becoming more or less sustainable [START_REF] Mayer | Strengths and weaknesses of common sustainability indices for multidimensional systems[END_REF]. Consequently, implementing sustainability policies requires the operationalization of the concept [START_REF] Rennings | Steps towards indicators of sustainable development: linking economic and ecological concepts[END_REF]. In order to operationalize sustainability measurement of the human-environment system, criteria have to be identified, long-term perspective and uncertainty have to be considered while keeping the whole framework manageable [START_REF] Buchholz | Sustainability criteria for bioenergy systems: results from an expert survey[END_REF].

According to Pope et al. [START_REF] Pope | Conceptualising sustainability assessment[END_REF], the scope of the concept depends on the characteristics of the dimensions incorporated which are the basis of the sustainability assessment. Single pillar concepts were the oldest and primarily focus on the ecological impacts while socio-economic ones are seen as secondary and should never take priority over ecological preservation [START_REF] Carrera | Sustainability assessment of energy technologies via social indicators: results of a survey among European energy experts[END_REF]. Two-pillar concepts focus on the balance between economic growth and ecological integrity regardless of social factors which are otherwise considered in the well-known three-pillar concepts [START_REF] Pope | Conceptualising sustainability assessment[END_REF]. By including cultural and institutional dimensions, four and five-pillar approaches have also been developed to broaden the scope of the sustainability concept [START_REF] Parris | Characterizing and measuring sustainable development[END_REF].

Fundamentally, the concept of sustainability implies defining: what is to be sustained? What is to be developed? How is it possible to balance present and future needs [START_REF] Brown | Developing an "Energy Sustainability Index[END_REF][START_REF] Parris | Characterizing and measuring sustainable development[END_REF]. However, due to the ambiguity of the scope of sustainable development, i.e. multiple and overlapping objectives, data availability, uncertainty and measurement methods, more than 500 concepts have been developed [START_REF] Parris | Characterizing and measuring sustainable development[END_REF]. Although no clear consensus has emerged about sustainability indicator sets, according to Mayer [START_REF] Mayer | Strengths and weaknesses of common sustainability indices for multidimensional systems[END_REF], the sustainability of the complex humanbased system is determined through both natural and anthropogenic resilience, desirability to human societies, as well as temporal and spatial scale boundaries. Both resilience and desirability determine sustainability objectives and the temporal and spatial scales define the extent of the system. The scope of the sustainability concept, objectives and indicators may vary depending on the expertise, the preferences of individuals and the geographical region [START_REF] Buchholz | Sustainability criteria for bioenergy systems: results from an expert survey[END_REF]. Consequently, stakeholder-based approaches may help in identifying and structuring the multiple and sometimes conflicting perspectives of actors for sustainability assessment with regard to the temporal and spatial scales [START_REF] Upham | Governance and legitimacy aspects of the UK biofuel carbon and sustainability reporting system[END_REF][START_REF] Buchholz | Sustainability criteria for bioenergy systems: results from an expert survey[END_REF][START_REF] Cuppen | Q methodology to select participants for a stakeholder dialogue on energy options from biomass in the Netherlands[END_REF][START_REF] Carrera | Sustainability assessment of energy technologies via social indicators: results of a survey among European energy experts[END_REF].

The Stakeholder-driven approach to measuring sustainability

Depending on the problem characteristics, stakeholder participation can take many forms and different degrees of involvement ranging from informing the public to co-producing knowledge and policy plans [START_REF] Van Dam | Striving to further harmonization of sustainability criteria for bioenergy in Europe: recommendations from a stakeholder questionnaire[END_REF][START_REF] Cuppen | Q methodology to select participants for a stakeholder dialogue on energy options from biomass in the Netherlands[END_REF][START_REF] Kerkhof M Van De | Debating climate change: a study of stakeholder participation in an integrated assessment of long-term climate policy in the Netherlands[END_REF]. When focusing on sustainability problems, participation helps structuring and improving understanding of both the problem and its potential solutions by considering, articulating and evaluating divergent perspectives [START_REF] Cuppen | Q methodology to select participants for a stakeholder dialogue on energy options from biomass in the Netherlands[END_REF][START_REF] Hisschemöller | Coping with intractable controversies: the case for problem structuring in policy design and analysis[END_REF]. Based on Brodbeck et al. [START_REF] Brodbeck | The dissemination of critical, unshared information in decision-making groups: the effects of pre-discussion dissent[END_REF], such an approach requires involving heterogeneous stakeholder groups with different backgrounds, knowledge and expertise to facilitate mutual learning and to produce new insights. Moreover, marginal perspectives and viewpoints of unorganized stakeholder groups also need to be considered, especially within sustainability problems [START_REF] Hoppe | Knowledge, power, and participation in environmental policy analysis[END_REF][START_REF] Munda | Social multi-criteria evaluation: methodological foundations and operational consequences[END_REF]. Consequently, rather than seeking to reach a consensus, stakeholder participation allows for the diversity of perspectives and preferences to be captured [START_REF] Gregory | Decision aiding, not dispute resolution: creating insights through structured environmental decisions[END_REF]. Indeed, stakeholder based methods that are aimed at reaching a consensus often fail in capturing the whole variety of viewpoints [START_REF] Cuppen | Q methodology to select participants for a stakeholder dialogue on energy options from biomass in the Netherlands[END_REF].

The literature provides a wide range of stakeholder-based approaches for addressing complex sustainability problems. Buchholz et al. [START_REF] Buchholz | Sustainability criteria for bioenergy systems: results from an expert survey[END_REF] proposed analyzing the level of agreement and uncertainty concerning 35 sustainability criteria for bioenergy through an international expert survey composed of government, industry, academia, consulting and NGO representatives. Only 2 of the 35 proposed criteria were perceived as critical by more than a half of the 137 respondents.

Considering the lack of consensus, they suggested further debate and exchange among experts. Van Dam and Junginger [START_REF] Van Dam | Striving to further harmonization of sustainability criteria for bioenergy in Europe: recommendations from a stakeholder questionnaire[END_REF] proposed analyzing the need to come to a harmonization of certification systems in the European Union through recommendations from a stakeholder questionnaire. The 473 respondents were from 34 countries and were represented by 6 stakeholder groups: NGOs, the policy sector, R & D, bioenergy producers, end-users and traders. Gallego Carrera and Mack [START_REF] Carrera | Sustainability assessment of energy technologies via social indicators: results of a survey among European energy experts[END_REF] proposed an expert-based set of social indicators for the sustainability assessment of energy systems. The 39 respondents were composed of energy industry, political and administrative institutions, end user and environmental associations, as well as trade unions. Kern and Smith [START_REF] Kern | Restructuring energy systems for sustainability? Energy transition policy in the Netherlands[END_REF] have analyzed 27 semi-structured personal interviews within the Netherlands energy transition project carried out by the Ministry of Economic Affairs. Four stakeholder groups were represented in the study: policy makers, NGOs, researchers and businesses, all being interviewed.

Through a stakeholder-driven approach that includes 8 different stakeholder groups, the next section provides a basis to clearly identify criteria and their associated indicators for inclusion in a sustainability assessment of several biofuel options by 2030.

Selection of the set of indicators for the assessment of biofuel sustainability

As mentioned previously, the relevance of sustainability criteria depends on the points of view and cultural background of the stakeholders [START_REF] Buchholz | Sustainability criteria for bioenergy systems: results from an expert survey[END_REF][START_REF] Lahdelma | Using multicriteria methods in environmental planning and management[END_REF]. Based on the elaboration of the corresponding evaluation criteria associated with measurement scales, i.e. indicators, biofuel sustainability can be appropriately assessed. By applying a participatory process, the sustainability indicator set is discussed and reviewed by relevant and representative stakeholders in order to satisfy social acceptance requirements, i.e. legitimizing and ensuring that indicators fit their sustainability conception [START_REF] Carrera | Sustainability assessment of energy technologies via social indicators: results of a survey among European energy experts[END_REF]. The stakeholder sustainability criteria can be revealed from the consequences of biofuels deployment, namely the bottom-up approach [START_REF] Roy | Méthodologie multicritère d′aide à la décision[END_REF], and through the decomposition of the sustainability biofuel goal in subobjectives, namely the top-down approach [START_REF] Keeney | Decisions with multiple objectives: preferences and value trade-offs[END_REF][START_REF] Saaty | A scaling method for priorities in hierarchical structures[END_REF]. Both methods are not mutually exclusive and can even be complementary [START_REF] Lahdelma | Using multicriteria methods in environmental planning and management[END_REF] such as in the present paper.

Questionnaire structure

Stakeholders were individually asked to respond to a questionnaire (Table 1) through face-to-face meetings or call conferences split between a 30-min structured questionnaire and an unlimited and unstructured discussion concerning biofuel sustainability.

Table 1 presents the questionnaire structure. Part I focuses on determining the background of stakeholders. Next, on the basis of the bottom-up approach proposed by Roy [START_REF] Roy | Méthodologie multicritère d′aide à la décision[END_REF], Part II consists of identifying the set of the relevant biofuel options to consider by 2030. Part III aims at identifying and formulating sustainability criteria starting from the impacts of biofuels while respecting methodological requirements (adapted from Buchholz et al. [START_REF] Buchholz | Sustainability criteria for bioenergy systems: results from an expert survey[END_REF]; Gallego Carrera and Mack [START_REF] Carrera | Sustainability assessment of energy technologies via social indicators: results of a survey among European energy experts[END_REF]; Keeney and Raiffa, [START_REF] Keeney | Decisions with multiple objectives: preferences and value trade-offs[END_REF]):

• Completeness: through the participatory process, completeness requires that all the relevant points of view be captured;

• Operationality: the set of criteria should be measured on an appropriate scale while ensuring both data and information availability;

• Non-redundancy: within each stakeholder group, sustainable cri- teria should not measure the same thing;

• Homogeneity: within each stakeholder group, an agreement about the set of criteria group can be reached.

According to Munda [START_REF] Munda | Social multi-criteria evaluation: methodological foundations and operational consequences[END_REF], researchers are the most relevant individuals for formulating sustainability criteria with respect to methodological requirements. Based on literature, a set of sustainability criteria were provided to stakeholders for review and discussion [START_REF] Buchholz | Sustainability criteria for bioenergy systems: results from an expert survey[END_REF]. Considering the participatory process, stakeholders were obviously allowed to suggest additional sustainability criteria, biofuel options and stakeholder groups as long as they were relevant.

Finally, given the above mentioned "completeness requirement", Part IV aims to define which relevant stakeholders to consider within the biofuel-system in order to adequately assess its sustainability. Based on the methodology proposed by Munda [START_REF] Munda | Social multi-criteria evaluation: methodological foundations and operational consequences[END_REF], an analysis of historical legislative, research and administrative documents complemented with in-depth interviews of relevant stakeholders were carried out. Based on Macharis et al. [START_REF] Macharis | The multi-actor, multi-criteria analysis methodology (MAMCA) for the evaluation of transport projects: theory and practice[END_REF], the present paper refers to relevant stakeholders as individuals or groups of individuals who might affect or might be affected by the consequences of biofuel deployment.

Study population

Based on literature review [START_REF] Turcksin | A multi-actor multi-criteria framework to assess the stakeholder support for different biofuel options: the case of Belgium[END_REF][START_REF] Van Dam | Striving to further harmonization of sustainability criteria for bioenergy in Europe: recommendations from a stakeholder questionnaire[END_REF][START_REF] Buchholz | Sustainability criteria for bioenergy systems: results from an expert survey[END_REF],24], 7 stakeholder groups were initially considered: feedstock producers, biofuel producers, fuel distributors, end users, car manufacturers, government and NGOs. However, by taking into account the suggestions of stakeholders (Part IV), the refining industry was added to cope with the completeness requirement. Moreover, 11 biofuel experts were consulted in order to assess the biofuel capacity to fulfill the stakeholder sustainability criteria.

1. Feedstock producers included the biomass-based industry, French agricultural unions and feedstock traders; 2. The biofuel industry was represented by biotechnology companies and the unions of French biofuel producers; 3. The refining industry was represented by the oil-refining industry and the biorefinery industry; 4. Fuel distributors included the petroleum industry and large-scale retailers which share the French fuel distribution market (respectively 37.4% and 62.6%); 5. The end-users perspective was assessed through the French car users association. Other end-users associations were contacted but they mentioned a lack of knowledge as to why they did not contribute to the study; 6. Car manufacturers were represented by French car manufacturing union and a car manufacturer; 7. The government included specialized energy and environmental institutions and the French agricultural, energy, ecological and finance ministries; 8. NGOs were represented by socio-environmental and energy oriented non-governmental associations to capture the sustainability criteria of unorganized groups such as food security for the population of the South. 9. The biofuel experts who were consulted work in the field of academic research, research and development, consulting and the biofuel industry.

Validating the biofuel set

Based on a literature survey, a biofuel set was submitted for the stakeholder's review [START_REF]Technology Roadmap Biofuels for Transport[END_REF][START_REF] Iea-Estap | Production of Liquid Biofuels, technology brief[END_REF][START_REF] Ipcc | panel on climate change[END_REF][START_REF] Ribeiro | Prospects of using microalgae for biofuels production: results of a Delphi study[END_REF]. By considering their cultural background and expertise, stakeholders were asked to give their points of view on each biofuel option by explaining whether they agreed, disagreed or neither agreed nor disagreed with the hypothesis of a large scale production in France by 2030 (Table 2).

First generation biofuels, also called conventional biofuels, are produced from food-crops such as rapeseed, soybean and maize. By considering the increasing concerns about ILUC and food security issues, the representatives of NGOs consider that conventional biofuels will not be part of the biofuel mix by 2030 to the benefit of advanced biofuels, i.e. biofuels produced from lignocellulosic feedstocks, wastes and non-food crops. From the perspective of other stakeholder groups, conventional biofuels will still be the most produced in France by 2030.

Depending on the feedstock, Hydrotreated Vegetable Oil (HVO) can be defined as conventional (rapeseed and palm oils) or advanced biofuel (waste oil) based on the potential competition with food. In either case, stakeholders have highlighted their high production costs and consequently HVO deployment will depend on the European support scheme through "double counting policy", i.e. a legal mechanism that allows advanced biofuels to count twice towards European incorporation objectives. Opinions about the double counting mechanism are split depending on the stakeholder group: NGOs and government point out a higher support for advanced biofuels through the incentives for refining industry and fuel distribution, whereas feedstock and biofuel producers report there is an unfair competition.

From the overall stakeholder perspective, second generation biofuels, i.e. biofuels produced from lignocellulosic feedstocks, will be produced on a large scale by 2030. However, stakeholders have expressed several reserves about the availability of sustainable feedstock: biomass availability from energy crops is limited by land-use issues [START_REF] Popp | The effect of bioenergy expansion: food, energy, and environment[END_REF] and also by feedstock usage competition such as methanisation [START_REF] Ademe | Vision 2030-2050[END_REF]. Moreover, the collect of residues is limited by environmental sustainability concerns, i.e. preventing erosion, soil carbon loss and nutrients [START_REF] Searle | National case studies on potential waste and residue availability for cellulosic biofuel production in the EU[END_REF].

Third generation defines biofuels produced from photosynthetic micro-organisms such as microalgae. Opinions about microalgae biomass availability for energy-uses are split: based on the opinions of 55 worldwide microalgae experts [START_REF] Ribeiro | Prospects of using microalgae for biofuels production: results of a Delphi study[END_REF], microalgae biofuels will most probably reach a fully commercial scale between 2021 and 2030 while representing from 5% to 10% of the worldwide fuel consumption. According to Ademe [START_REF] Ademe | Vision 2030-2050[END_REF], because of the early stage of development, microalgae will not be part of the biofuel feedstock mix by 2030. According to most of the stakeholders, microalgae biofuels are considered as highly promising but opinions were split concerning the time horizon ranging in between 2030 and 2050. European and French fuel consumption in the transport sector is balanced in favor of diesel [START_REF] Turcksin | A multi-actor multi-criteria framework to assess the stakeholder support for different biofuel options: the case of Belgium[END_REF]. Consequently, only the hypothesis of large scale deployment for the biodiesel option was supported by more than 50% of the respondents. Finally, large scale deployment of biogas options in the transport sector were considered irrelevant by almost all the stakeholders because of end-user acceptability and much better efficiency through heating and power generation than liquid fuel production.

Validating sustainability criteria and its associated indicator set

Based on literature survey, a non-exhaustive list of sustainability criteria were submitted to stakeholder review [START_REF] Scarlat | Recent developments of biofuels/bioenergy sustainability certification: a global overview[END_REF][START_REF] Turcksin | A multi-actor multi-criteria framework to assess the stakeholder support for different biofuel options: the case of Belgium[END_REF][START_REF] Wiesenthal | Biofuel support policies in Europe: lessons learnt for the long way ahead[END_REF][START_REF] Ziolkowska | Optimizing biofuels production in an uncertain decision environment: conventional vs. advanced technologies[END_REF][START_REF][END_REF][START_REF] Gnansounou | Assessing the sustainability of biofuels: a logic-based model[END_REF][START_REF] Markevičius | Trends and sustainability criteria of the production and use of liquid biofuels[END_REF]. By considering their own group concerns regardless of others, stakeholders were asked to give their point of view about the most relevant biofuel sustainability criteria. In other words, the perspectives of stakeholders were captured without aiming to reach a consensus about biofuel sustainability criteria but rather by considering the specificities of each heterogeneous stakeholder group [START_REF] Cuppen | Q methodology to select participants for a stakeholder dialogue on energy options from biomass in the Netherlands[END_REF][START_REF] Gregory | Decision aiding, not dispute resolution: creating insights through structured environmental decisions[END_REF]. Presented in Table 3, stakeholder criteria for biofuel sustainability are split between economic (45%), environmental (29%) and social considerations (26%).

As mentioned by Buchholz et al. [START_REF] Buchholz | Sustainability criteria for bioenergy systems: results from an expert survey[END_REF], stakeholder consensus about sustainability criteria is very low among the different professions represented. In the present study, only 5 of the 22 sustainability criteria were identified with a consensus higher than 50%, namely the GHG mitigation, the ILUC impact, the biofuel production cost, the additional costs for end-users and the air quality. Such a result highlights the completeness requirement as one of the keystones of the sustainability assessment.

Although some sustainability criteria can be characterized by a unique dimension such as GHG emission, other criteria cannot be. For example, biofuel producer concern for biomass availability relies on legal aspects through land-use limitation and thus land productivity in order to limit food security, soil erosion and ILUC impacts, i.e. socioenvironmental aspects. For each criterion, stakeholders express their concerns about biofuel sustainability that needs to be assessed through adequate measurement scales. Consequently, the indicator set cannot be separated from the sustainability criteria set for meeting the acceptance requirements of stakeholders [START_REF] Carrera | Sustainability assessment of energy technologies via social indicators: results of a survey among European energy experts[END_REF].

Sustainability assessment of the biofuel set

The sustainability criteria set is associated with an indicator set in order to measure the performances of biofuel options, i.e. their capacity to fulfill each of the stakeholder criteria. The sustainability assessment of the biofuel set requires addressing multiple criteria characterized by a heterogeneous level of uncertainty, but also different time frames [START_REF] Greening | Design of coordinated energy and environmental policies: use of multi-criteria decision-making[END_REF]. Moreover, the evolving socio-economic and legal context can also impact several criteria such as biomass availability through land-use restriction as mentioned previously. Consequently, the next section presents a range of possible biofuel performances ranging between optimistic and pessimistic values and continuing through explicit measurement methods with regards to transparency and stakeholder acceptance considerations [START_REF] Carrera | Sustainability assessment of energy technologies via social indicators: results of a survey among European energy experts[END_REF][START_REF] Lahdelma | Using multicriteria methods in environmental planning and management[END_REF].

Economic indicator set

Economic considerations focus on biofuel market opportunities, including incorporation mandates, biofuel competitiveness, coproduction opportunities and the feedstock availability. NGOs are the only stakeholder group which does not consider any economic sustainability criteria.

Biomass and biofuel availability

Through the security of supply, biomass availability is a critical sustainability criterion for biofuel producers and fuel distributors. Biomass availability relies on both legal and social considerations: through food security issues, importation limitation and agricultural sector support for food crop based biofuels [START_REF] Ademe | Vision 2030-2050[END_REF]; through competition for different energy valorization for second generation biofuels feedstocks [START_REF] Ademe | Vision 2030-2050[END_REF]; and through site characteristics for microalgae biofuels [START_REF] Houdon | Evaluation du gisement potentiel de ressources algales pour l′énergie et la chimie en France à l′horizon[END_REF] such as climate, gradient and CO 2 availability, i.e. the proximity to industries that generate high volumes of CO 2 . Based on the expected land availability and productivity by 2030 (Table 4), Table 5 presents both biomass and biofuel availability.

On the one hand, Table 4 presents the expected biomass productivity per feedstock by 2030 [START_REF] Bonnet | Eau et biocarburants, impacts sur l'eau du développement des biocarburants en France à l'horizon[END_REF][START_REF] Departe | Étude prospective sur la seconde génération de biocarburants[END_REF][START_REF]Technology Roadmap Biofuels for Transport[END_REF][START_REF] Searle | National case studies on potential waste and residue availability for cellulosic biofuel production in the EU[END_REF]. On the other hand, based on both biomass energy content and process yields [START_REF] Sunde | Environmental impacts and costs of hydrotreated vegetable oils, transesterified lipids and woody BTL-a review[END_REF][START_REF] Departe | Étude prospective sur la seconde génération de biocarburants[END_REF][START_REF] Forslund | Etude complémentaire à l′analyse rétrospective des interactions du développement des biocarburants en France avec l′évolution des marchés français et mondiaux et les changements d′affectation des sols -La base de données du modèle MATSIM-LUCA[END_REF], Table 4 presents the expected biofuel land productivity by 2030. Food crop based biodiesels are assumed to be produced through transesterification with a typical mass yield of 97% for FAMEs and 80% for HVOs [START_REF] Forslund | Etude complémentaire à l′analyse rétrospective des interactions du développement des biocarburants en France avec l′évolution des marchés français et mondiaux et les changements d′affectation des sols -La base de données du modèle MATSIM-LUCA[END_REF][START_REF] Sunde | Environmental impacts and costs of hydrotreated vegetable oils, transesterified lipids and woody BTL-a review[END_REF].

Lignocellulosic (LC) ethanols are assumed to be produced through a biochemical pathway with a typical mass yield of 30% when Biomass to Liquid (BtL) biodiesels are assumed to be produced through a thermochemical pathway with a typical mass yield of 40% [START_REF] Ademe | Feuille de route des biocarburants avancés[END_REF]. For both agricultural and forestry residues, the collection rate is assumed to be limited for preventing the risks of erosion, soil carbon loss and nutrients. By considering land slope and climate and soil characteristics in France, Searle and Malins [START_REF] Searle | National case studies on potential waste and residue availability for cellulosic biofuel production in the EU[END_REF] considered biomass retention constraints of 80% for forestry residues while Ademe [START_REF] Ademe | Feuille de route des biocarburants avancés[END_REF] recommended 67% for agricultural residues. Forestry residue availability also depends on both the wine and wood industries which allow higher biomass availability without increasing land requirement. Data about microalgae biomass productivity is based on expert consultation whereas data about the lipid content, the efficiency of lipid extraction and transesterification are based on Subhadra and Edwards [START_REF] Subhadra Bobban | Coproduct market analysis and water footprint of simulated commercial algal biorefineries[END_REF]. Two different production pathways are considered, through raceways and photobioreactors (PBR) [START_REF] Delrue | An economic, sustainability, and energetic model of biodiesel production from microalgae[END_REF]. By considering social, environmental, economic, legal and technical constraints, Table 5 presents the expected biomass and biofuel availability in France by 2030.

Table 5 provides the biofuel availability that relies on the land availability [START_REF] Ademe | Vision 2030-2050[END_REF]24] and the expected yield by 2030 [START_REF] Bonnet | Eau et biocarburants, impacts sur l'eau du développement des biocarburants en France à l'horizon[END_REF][START_REF] Forslund | Etude complémentaire à l′analyse rétrospective des interactions du développement des biocarburants en France avec l′évolution des marchés français et mondiaux et les changements d′affectation des sols -La base de données du modèle MATSIM-LUCA[END_REF][START_REF]Technology Roadmap Biofuels for Transport[END_REF]. Based on Ademe [START_REF] Ademe | Vision 2030-2050[END_REF], land dedicated to food crop biofuels production will be limited to the level of 2010 with regards to food security concerns, i.e. 1, 677 kha split between 1, 450 kha for biodiesel and 277 kha for ethanol [24]. Expected yield improvement may imply a potential of 3 Mtoe by 2030 compared to 2.5 Mtoe in 2010 by considering equivalent feedstock mix. However, the land allocation for different feedstocks could also depend on policy arbitrage by 2030. Through sustainability concerns such as GHG, ILUC and food security, both biomass and biofuel availability related to imported biofuels are expected to be limited for all types of feedstocks at an overall level of 1 Mtoe [START_REF] Ademe | Vision 2030-2050[END_REF].

Concerning biofuels produced from agricultural and forestry residues, biomass availability depends on both environmental and legal considerations. From the feedstock and biofuel producer points of view, competition between the different energy-uses of biomass resource might hamper their security of supply [START_REF] Departe | Étude prospective sur la seconde génération de biocarburants[END_REF]. Biofuel producers and academic experts have even pointed out the risk of fossil energyuse such as coal and petroleum coke, in order to ensure that biofuel production units run at full capacity and to ensure their economic viability. For environmental sustainability concerns, the availability of residues is limited by retention rates but also by feedstock use competition, namely livestock feeds, mushroom cultivation, horticulture for agricultural residues and other energy uses for agricultural and forestry residues [START_REF] Ademe | Feuille de route des biocarburants avancés[END_REF][START_REF] Searle | National case studies on potential waste and residue availability for cellulosic biofuel production in the EU[END_REF]. Consequently, Table 5 presents the biomass availability for energy-usage ranging from optimistic to pessimistic values depending on whether biofuel, heat, biogas and electricity is considered the relative higher priority [START_REF] Ademe | Vision 2030-2050[END_REF][START_REF] Searle | National case studies on potential waste and residue availability for cellulosic biofuel production in the EU[END_REF].

Microalgae biomass availability rely on land availability which depends on economic, social, environmental, technical and legal constraints such as slope gradient, land-use, and climate characteristics. Finally, between 0.27% and 0.45% of French lands are adequate for deploying microalgae for biofuel production [START_REF] Houdon | Evaluation du gisement potentiel de ressources algales pour l′énergie et la chimie en France à l′horizon[END_REF]. Consequently, depending on the technology and regardless of economic considerations, biomass availability for microalgae could reach from 2.2 to 3.4 Mtoe.

Market opportunities

Relying on the set aside policy, France has started to support biofuel deployment for creating new market opportunities for the agrofood industry while hedging its exposure to risks related to international competition through market diversification (Table 6).

Food crop based feedstock price assessment depends on land productivity [START_REF] Forslund | Etude complémentaire à l′analyse rétrospective des interactions du développement des biocarburants en France avec l′évolution des marchés français et mondiaux et les changements d′affectation des sols -La base de données du modèle MATSIM-LUCA[END_REF], expected yield improvement [START_REF] Bonnet | Eau et biocarburants, impacts sur l'eau du développement des biocarburants en France à l'horizon[END_REF][START_REF] Departe | Étude prospective sur la seconde génération de biocarburants[END_REF][START_REF] Iea-Estap | Production of Liquid Biofuels, technology brief[END_REF][START_REF] Quinn | The potentials and challenges of algae based biofuels: a review of the techno-economic, life cycle, and resource assessment modeling[END_REF], oil price scenarios [START_REF] Iea-Estap | Production of Liquid Biofuels, technology brief[END_REF] and both commodity prices and prospective production costs [START_REF] Departe | Étude prospective sur la seconde génération de biocarburants[END_REF][START_REF] Festel | Modelling production cost scenarios for biofuels and fossil fuels in Europe[END_REF][START_REF] Hugues | Stratégies technologique et réglementaire de déploiement des filières bioénergies françaises[END_REF][START_REF] Kumar | Biomass power cost and optimum plant size in western Canada[END_REF]120].

Unlike food crop feedstocks, there is currently no global market for residues and there is a high degree of uncertainty concerning the cost curve for residues [START_REF] Gregg | Global and regional potential for bioenergy from agricultural and forestry residue biomass[END_REF]. The expected incomes for residues were assessed through both the expected biomass price by 2030 [START_REF] Departe | Étude prospective sur la seconde génération de biocarburants[END_REF][START_REF] Iea-Estap | Production of Liquid Biofuels, technology brief[END_REF] and the residue collection costs [START_REF] Kumar | Biomass power cost and optimum plant size in western Canada[END_REF]. Focusing on the third generation, valorizing microalgae as biofuel implies moving from a high value niche market toward a low value but large market one [START_REF] Houdon | Evaluation du gisement potentiel de ressources algales pour l′énergie et la chimie en France à l′horizon[END_REF].

Based on expert consultation, reaching the biofuel market implies lowering the microalgae biomass production costs to around a threshold of € 1000 per ton while the production cost is generally expected to be higher [START_REF] Delrue | An economic, sustainability, and energetic model of biodiesel production from microalgae[END_REF][START_REF] Quinn | The potentials and challenges of algae based biofuels: a review of the techno-economic, life cycle, and resource assessment modeling[END_REF]. Based on Delrue et al. [START_REF] Delrue | An economic, sustainability, and energetic model of biodiesel production from microalgae[END_REF] and regardless of the valorization of byproducts, biomass production costs are assumed to respectively represent 76% and 93% of the overall biofuel production costs for raceway and PBR (including operating, cultivation, harvesting and drying costs). The biorefinery approach allows for the valorization of by-products and thus higher incomes, especially for microalgae feedstocks [START_REF] Yee | Life cycle assessment of palm biodiesel: revealing facts and benefits for sustainability[END_REF]. For example, the price of omega-3 fatty acids (O3FA) exceeds $100, 000 per ton but large-scale deployment of microalgae biofuels may quickly saturate the high-value product markets [START_REF] Subhadra Bobban | Coproduct market analysis and water footprint of simulated commercial algal biorefineries[END_REF]. Indeed, the O3FA market currently represents between 0.2 and 0.4Mton compared with 100Mton for the biofuel one [START_REF] Subhadra Bobban | Coproduct market analysis and water footprint of simulated commercial algal biorefineries[END_REF][START_REF] Patel | Biofuels from biomass[END_REF]. Market diversification is also an opportunity to lower the risks related to international competition (Table 7):

Depending on both biofuel feedstock and production processes, biofuel production allows for the valorization of different byproducts [START_REF] Subhadra Bobban | Coproduct market analysis and water footprint of simulated commercial algal biorefineries[END_REF][START_REF] Iea-Estap | Production of Liquid Biofuels, technology brief[END_REF]. Food crop and microalgae based biofuels allow the production of food and feed coproducts, namely dried distillers' grain with solubles (DDGS) for cereal based ethanols; respectively bagasse and pulp for sugar cane and sugar beet ethanols and protein meals for biodiesels [START_REF] Iea-Estap | Production of Liquid Biofuels, technology brief[END_REF]. CO 2 for food-use can also be generated through the production process of both sugar and lignocellulosic based ethanols [START_REF] Agpm Agdespdem | AlcoolA, FOP Ffrançaisedesproducteursd'oléagineuxetdeprotéagineux, Esterifrance Sfrançaisdesesterificateurs. Livre blanc: Biocarburants: une énergie renouvelable produite en France[END_REF]. Both food crop and microalgae based oils require an esterification process which generates glycerin for chemical markets [START_REF] Hugues | Stratégies technologique et réglementaire de déploiement des filières bioénergies françaises[END_REF].

Second generation biofuels production processes generate biowastes such as fibers and lignin that can be valorized in energy through electricity, heat and biogas generation. HVO produced from food crop based oils allows feed by-products valorization upstream contrary to waste oil feedstock. Unlike biofuels produced through the transesterification process, the HVO process generates liquefied petroleum gas which is valorized on site to meet heat and energy requirements [START_REF] Aatola | Hydrotreated Vegetable Oil (HVO) as a Renewable Diesel Fuel: Trade-off between NOx, Particulate Emission, and Fuel Consumption of a Heavy Duty Engine[END_REF]. Although Table 7 presents the main market diversification opportunities for coproducts valorization, other possibilities exist such as cosmetic and medicine markets for microalgae biodiesel [START_REF] Zhu | Biorefinery as a promising approach to promote microalgae industry: an innovative framework[END_REF]. Focusing on BtL biodiesel and by assuming additional costs, naphtha can be generated through an additional refining process but the potential of the naphtha market is highly uncertain [START_REF] Departe | Étude prospective sur la seconde génération de biocarburants[END_REF].

Competitiveness of biofuels

Through the consideration of competitiveness, biofuels production cost compared with oil based fuels represents the main economic concern for all stakeholder groups, with the exception of NGOs which focus on socio-environmental criteria. From the perspective of biofuel producers, French biofuel production has to be competitive compared with fossil based fuels but also with imported biofuels. Consequently, promoting international fair competition requires preventing potential social and environmental dumping through legal measures. In order to assess the additional shipping costs of imported biofuels (adapted from MCRIT [START_REF] Mcrit | Mobility scenarios toward a post-carbon society[END_REF] and Wolfgang, [START_REF]iTREN-2030 Integrated transport and energy baseline until 2030[END_REF]), sugar cane ethanol, soybean and palm are respectively assumed to be produced in Brazil, Argentina and Indonesia; transported by water to Rotterdam and finally delivered in France by road. Based on both freight cost trends [START_REF]iTREN-2030 Integrated transport and energy baseline until 2030[END_REF] and biofuel/ feedstock origin, additional costs for imported biofuels range from €0.02 to €0.137 per liter. The refining industry, fuel distributors, end-users and car manufacturers focus on biofuel costs compared with those of oil based fuels which rely on expected crude oil prices [START_REF]Technology Roadmap Biofuels for Transport[END_REF] and French refining costs (adapted from both UFIP [START_REF] Ufip Ufdesip | Les biocarburants en France[END_REF] and expert consultation).

Fig. 1 presents the expected biofuel costs in France by 2030. Regardless of socio-environmental concerns, both gasoline and diesel fuels should be competitive by 2030 with an expected price ranging from €0.32 to €1.11/lge (i.e. from $50 to $180 per barrel). Sugarcane ethanol imported from Brazil is the most competitive biofuel, followed by the other food crop based ethanols and second generation biofuels. Food crop based biodiesels require higher oil prices to be competitive with an average cost of €0.85/lge. Expected demand for palm oil for both food and energy uses is expected to rise by 2030 which should hamper palm based biodiesels relative competitiveness compared with other food crop based biodiesels. Finally, by assuming a large scale deployment, microalgae biodiesel should reach costs ranging from €1.34 to €4.47/lde depending on the process pathway [START_REF] Delrue | An economic, sustainability, and energetic model of biodiesel production from microalgae[END_REF]. Technological and biological breakthroughs are needed, expected and even on-going for microalgae biofuel [START_REF] Hognon | Energetic and economic evaluation of Chlamydomonas reinhardtii hydrothermal liquefaction and pyrolysis through thermochemical models[END_REF].

Biofuel competitiveness is also about logistics for the refining industry and fuel distributors. Considering that the French fuel consumption in the transport sector is balanced in favor of diesel [START_REF] Ufip Ufdesip | Les biocarburants en France[END_REF], refiners have to import diesel and export gasoline. Consequently, biodiesel importation allows refiners to reduce the amount of diesel importation and thus freight costs ($15/ton). Ethanol incorporation implies higher gasoline exportation which generates additional freight costs ($20/ton). Moreover, an additional cost is also induced by the lack of competitiveness of French refineries compared to European ones [34,[START_REF] Ufip Ufdesip | Les biocarburants en France[END_REF]. From a fuel distributor's point of view, biofuel incorporation could imply the development of the range of fuels which means additional costs though pumps, tanks and logistics. Based on Turcksin et al. [START_REF] Turcksin | A multi-actor multi-criteria framework to assess the stakeholder support for different biofuel options: the case of Belgium[END_REF], costs for additional pumps range from €16 000 for liquid fuels to €250 000 for natural gas fuels.

Social indicator set

Government and feedstock producer social sustainability criteria are partly linked to economic concerns for fuel poverty and job creation whereas NGOs mainly focus on food security issues regardless of any economic considerations. Transparency about feedstock origin was also mentioned by NGOs. Based on France AgriMer and Biomass Biofuels Sustainability Association (2BS), waste oil is currently the only feedstock that is not clearly and easily traceable, especially imported waste oil based biofuels.

Food security

From the government and NGOs points of view, threats to food security can eventually hamper biofuels social sustainability through food price increases. Literature provides a wide variety of studies that assess the impacts of biofuel in both food supply and prices (for a review, see Serra and Zilberman, [START_REF] Serra | Biofuel-related price transmission literature: a review[END_REF]). According to Mueller et al. [START_REF] Mueller | Impact of biofuel production and other supply and demand factors on food price increases in 2008[END_REF], literature provides assessment of the biofuel contribution in increasing food prices that ranges from 3% to 75%. From perspectives of biofuel and feedstock producers, food security impact is limited by feed byproducts. In the present paper, considering the uncertainty about biofuel impact on food security and with regards to stakeholder perspectives, the food security criterion is assessed through land requirement that competes with food production. In other words, the lower the land requirement, the lower the risk to food security. Table 8 presents the arable land requirement to produce a ton of oil equivalent (toe) depending on the crop yield [START_REF] Bonnet | Eau et biocarburants, impacts sur l'eau du développement des biocarburants en France à l'horizon[END_REF][START_REF] Forslund | Etude complémentaire à l′analyse rétrospective des interactions du développement des biocarburants en France avec l′évolution des marchés français et mondiaux et les changements d′affectation des sols -La base de données du modèle MATSIM-LUCA[END_REF][START_REF]Technology Roadmap Biofuels for Transport[END_REF] and processes yields [START_REF] Subhadra Bobban | Coproduct market analysis and water footprint of simulated commercial algal biorefineries[END_REF][START_REF] Departe | Étude prospective sur la seconde génération de biocarburants[END_REF][START_REF] Forslund | Etude complémentaire à l′analyse rétrospective des interactions du développement des biocarburants en France avec l′évolution des marchés français et mondiaux et les changements d′affectation des sols -La base de données du modèle MATSIM-LUCA[END_REF] expected by 2030. Ethanol biofuels have better yield and thus lower impacts on land requirement than biodiesels (Table 8). The most land-intensive biofuel is soybean biodiesel that requires from 3 to 10 times more surface compared with other food crop based biofuels at equivalent energy content. From the point of view of feedstock producers, domestic feed by-products particularly limit food security impact by the substitution of imported soybean by rapeseed meals which have lower socio-environmental impacts while generating employment in France (nearly 1.6 of direct job creation per kton according to Raes et al. Moreover, biofuels by-products for feed usage allow a higher protein independence which is considered as sustainability criterion by feedstock producers and the government. Biofuels produced from residues, waste oil and microalgae do not require feedstocks that compete with food, thus their impact on food security is considered null.

Direct job creation

From feedstock producers and government perspective, job creation through biofuel deployment is a key sustainability criterion. Based on Raes et al. [START_REF] Raes | Évaluation du poids socio-économique et environnemental de la filière biodiesel en France[END_REF] and expert consultation, direct job creation relies on the fertilizer and seed industry; feedstock production, transport storage; biofuel production, transport and storage.

Fig. 2 presents the potential job creation per type of biofuel in France by 2030. For imported biofuels, employment ranges from 0.05 to 0.35 jobs per kton depending on whether biofuel (transport related job) and feedstock is imported (transport and processing operation related jobs). Land availability for first generation biofuel production by 2030 is expected to be legally limited to the 2010 level for socioenvironmental concerns [START_REF] Ademe | Vision 2030-2050[END_REF]. Based on expert consultation, with respect to a 20% margin of error, job creation related to first generation biofuel production is assumed to be constant, i.e. nearly 5 jobs per thousand tons. Food crop biofuels are intensive in agricultural jobs which represent more than 85% of the overall employment [START_REF] Raes | Évaluation du poids socio-économique et environnemental de la filière biodiesel en France[END_REF].

Job creation related to LC-ethanol and BtL biodiesel depends on employment related to feedstock production and collection, biorefinery processing jobs [START_REF] Searle | National case studies on potential waste and residue availability for cellulosic biofuel production in the EU[END_REF] and biofuel storage and transportation [START_REF] Raes | Évaluation du poids socio-économique et environnemental de la filière biodiesel en France[END_REF]. Based on Searle and Malins [START_REF] Searle | National case studies on potential waste and residue availability for cellulosic biofuel production in the EU[END_REF], feedstock production and collection should employ between 0.85 and 1.70 jobs per thousand tons depending on the feedstock, i.e. energy crops, agricultural and forestry residues; operational processing should generate from 30 to 48 jobs per biorefinery. Job creation related to biofuel transport and storage are assumed to be the same for advanced and conventional biofuels. Although construction should represent 600 jobs per facility, they are not included in Fig. 2 because they are not permanent, lasting only 2 years [START_REF] Searle | National case studies on potential waste and residue availability for cellulosic biofuel production in the EU[END_REF].

PBR facilities are expected to generate 43 jobs for 1 000 ha whereas raceway facilities should generate from 10 to 13 jobs for 100 ha [START_REF] Richardson | The economics of microalgae oil[END_REF][START_REF] Lundquist | A realistic technology and engineering assessment of algae biofuel production[END_REF]. Based on expert consultation, the esterification process of microalgae oil is assumed to generate as many jobs per kilo ton as food crop based oil, i.e. 0.22 jobs per kilo ton [START_REF] Raes | Évaluation du poids socio-économique et environnemental de la filière biodiesel en France[END_REF]. According to the Algae Biomass Association, the construction phase should respectively represent 2000 and 600 non-permanent jobs for PBR and raceway facilities. According to Bio-era [START_REF] Bio-Era | economic impact of advanced biofuels production: perspective to[END_REF], the research and development sector associated with the deployment of advanced biofuels may account for 3% of the overall job creation. Considering the lack of available data for France, Fig. 2 does not include either construction or research and development jobs.

Fuel-poverty and government budget

Fuel poverty is defined when household budget spending is higher than 8% for heat, including domestic hot water, and 4.5% for transport. In 2015, around 22% of French households were in fuel poverty [START_REF] Cochez | La précaritéénergétique: avoir froid ou dépenser trop pour se chauffer[END_REF]. Consequently, additional costs for end-users implied by biofuel deployment are important to fuel distributors, the government and obviously end-users. Additional costs for end-users can be characterized by the relative competitiveness of biofuels and fossil fuels, including overconsumption, car purchasing price, biofuel and fuel taxes. Based on consultation with car manufacturers, additional costs for high blending engines are very low for ethanol options which require less than €100 per car for flex-fuel technology. By considering a slightly higher cost because of a more regular maintenance, French diesel engines already allow a blending rate up to 30%. However, according to car manufacturers, neither biofuel policy nor the demand of end users currently justifies a deployment of high blending engines such as flex-fuel cars.

From the point of view of the government, the budget impact relies on revenues and spending, i.e. tax revenues and subsidies to support the biofuel deployment. In the present section, the budget spending is assumed to cover the additional cost for end-users for fuel poverty concerns. The budget impact has been assessed through the average tax revenues generated from job creation [START_REF] Onidol | Evaluation du poids socio-économique et environnemental de la filière biodiesel en France[END_REF][START_REF] Searle | National case studies on potential waste and residue availability for cellulosic biofuel production in the EU[END_REF], TICPE and VAT (Value Added Tax) surplus while considering both low and high oil price scenarios [START_REF] Iea-Estap | Production of Liquid Biofuels, technology brief[END_REF]. TICPE is applied with regard to energy volume, considering both ethanol and biodiesel lower energy contents compared with oil based-fuels [START_REF] Departe | Étude prospective sur la seconde génération de biocarburants[END_REF][START_REF] Ademe | Analyses de Cycle de Vie appliquées aux biocarburants de première génération consommés en France[END_REF][START_REF] Quinn | The potentials and challenges of algae based biofuels: a review of the techno-economic, life cycle, and resource assessment modeling[END_REF] and the tax surplus is mechanically generated at equivalent energy consumption. Moreover, regardless of tax exemption, the higher the biofuel cost compared with oil based fuels, the higher the VAT revenues.

Table 9 presents the additional cost for end-users implied by a 10% blend of biofuel and the overall budget impact for government. A lowprice oil scenario implies an additional cost for end-users ranging from €0.03 to €0.06 per liter (except for microalgae). Considering new tax revenues generated from TICPE, VAT and professional taxes, the overall budget impact is positive for the biofuel options that are produced in France except for microalgae biodiesel because of its high expected cost. The budget impact for ethanol options is also higher compared with biodiesels because of its lower energy content which generates additional taxes. Considering a high-cost oil scenario, biofuels are more competitive compared with fossil fuels, except for HVO, palm oil and microalgae biodiesels because of their expected higher costs [START_REF] Delrue | An economic, sustainability, and energetic model of biodiesel production from microalgae[END_REF][START_REF]Technology Roadmap Biofuels for Transport[END_REF][START_REF] Ipcc | panel on climate change[END_REF]. In this scenario, even imported biofuels allow the government budget to be positive, except for HVO and microalgae biodiesels.

Environmental indicator set

Environmental sustainability of biofuels is considered by all stakeholder groups but by different criteria. From the points of view of both NGOs and feedstock producers, environmental sustainability of agriculture is a common criterion through the water footprint (Fig. 3) soil eutrophication (Table 10), and GHG emissions considerations (Fig. 4). Although direct GHG emission is the only criterion common to all stakeholder groups, opinions are split concerning ILUC impacts (Fig. 5). Car manufacturers, the government and end-users also point out air quality as an environmental sustainability criterion (Table 12).

Environmental sustainability of agriculture

The environmental sustainability of agriculture includes water requirement [START_REF] Fraiture | Biofuels and implications for agricultural water use: blue impacts of green energy[END_REF][START_REF] Yang | Land and water requirements of biofuel and implications for food supply and the environment in China[END_REF] and eutrophication potential [START_REF] Ademe | Analyses de Cycle de Vie appliquées aux biocarburants de première génération consommés en France[END_REF][START_REF] Hugues | Stratégies technologique et réglementaire de déploiement des filières bioénergies françaises[END_REF]. Based on Gerbens-Leenes and Hoekstra [START_REF] Gerbens-Leenes | The water footprint of sweeteners and bioethanol[END_REF] and Gerbens-Leenes et al. [START_REF] Gerbens-Leenes | The blue water footprint and land use of biofuels from algae[END_REF], France is one of the most effective countries concerning the water footprint (WF). According to Berndes [START_REF] Berndes | Bioenergy and water-the implications of large-scale bioenergy production for water use and supply[END_REF] and Gerbens-Leenes et al. [START_REF] Gerbens-Leenes | Biofuel scenarios in a water perspective: the global blue and green water footprint of road transport in 2030[END_REF], water requirement and evapo-transpiration will increase but especially from 2030 to 2100. Consequently, Fig. 3 presents the expected WF of biofuels in 2030 based on Gerbens-Leenes et al. [START_REF] Gerbens-Leenes | The water footprint of bioenergy[END_REF], [START_REF] Bulsink | The water footprint of Indonesian provinces related to the consumption of crop products[END_REF] [START_REF] Bulsink | The water footprint of Indonesian provinces related to the consumption of crop products[END_REF], Wu et al. [120] and Gerbens-Leenes et al. [START_REF] Gerbens-Leenes | The blue water footprint and land use of biofuels from algae[END_REF].

A blue WF refers to surface and groundwater volumes consumed while a green WF refers to the rainwater consumed [START_REF] Gerbens-Leenes | Biofuel scenarios in a water perspective: the global blue and green water footprint of road transport in 2030[END_REF]. First generation ethanol production usually requires a lower amount of water with an average consumption of 120 m 3 per GJ, i.e. 2, 500 l water per liter of biofuel produced, compared with biodiesels (537 m 3 per GJ i.e. 16, 800 l water per liter biofuel produced). Based on Bulsnik [START_REF] Bulsink | The water footprint of Indonesian provinces related to the consumption of crop products[END_REF], palm crops in Indonesia require the greatest amount of water because of climate issues, namely high evapo-transpiration and low effective rain falls (i.e. no green water). Advanced biofuels produced from wood, miscanthus and microalgae have the lower blue WF impact [START_REF] Wu | Life-cycle water quantity and water quality implications of biofuels[END_REF].

Due to fertilizer-use, large nitrogen and phosphorus-related environmental burdens are released from the soil during cultivation [START_REF] Kim | Life cycle assessment of various cropping systems utilized for producing biofuels: bioethanol and biodiesel[END_REF] which induce eutrophication. Eutrophication generates several negative environmental impacts such as the decrease of plant and animal biodiversity, the increase of water and soil toxicity and the increase of algae at the expense of other biomass [START_REF] Ademe | Analyses de Cycle de Vie appliquées aux biocarburants de première génération consommés en France[END_REF].

Table 10 presents the biofuel potential of eutrophication [START_REF] Ademe | Analyses de Cycle de Vie appliquées aux biocarburants de première génération consommés en France[END_REF][START_REF] Hugues | Stratégies technologique et réglementaire de déploiement des filières bioénergies françaises[END_REF][START_REF] Arvidsson | Life cycle assessment of hydrotreated vegetable oil from rape, oil palm and Jatropha[END_REF]. Compared with fossil fuels, first generation biofuels have a 10-20 times higher potential of eutrophication because of fertilizer usage [START_REF] Ademe | Analyses de Cycle de Vie appliquées aux biocarburants de première génération consommés en France[END_REF]. Advanced biofuels have a lower eutrophication potential than foodcrop based biofuels but still higher than fossil fuels.

GHG emissions

Concerns about GHG emissions are common to all the stakeholder groups. Depending on the process and the way feedstock is produced and byproducts are valorized, Fig. 4 presents the potential of GHG mitigation of different biofuel options regardless of ILUC effects [START_REF] Ademe | Feuille de route des biocarburants avancés[END_REF][START_REF] Delrue | An economic, sustainability, and energetic model of biodiesel production from microalgae[END_REF][START_REF]Technology Roadmap Biofuels for Transport[END_REF][START_REF] Ipcc | panel on climate change[END_REF].

Advanced biofuels have a higher GHG mitigation potential than conventional ones except for microalgae biodiesel which still suffers high uncertainty concerning their process and performance [START_REF] Davis | Integrated evaluation of cost, emissions, and resource potential for algal biofuels at the national scale[END_REF]. Maize and wheat ethanols can also have a worse GHG balance than fossil fuels (Fig. 4, based on IAE [START_REF]Technology Roadmap Biofuels for Transport[END_REF]) because of direct land use change issues such as deforestation. Focusing on the French context, a respective mitigation of -42% and -35% are the most probable values for maize and wheat ethanols [START_REF] Ademe | Analyses de Cycle de Vie appliquées aux biocarburants de première génération consommés en France[END_REF]. Additional GHG emissions may stem from ILUC, especially for food and energy crop biofuels. Indeed, producing biofuels while leaving the food supply unchanged may imply turning new lands into agricultural lands. For example, turning forest that is a natural carbon sink into agricultural land may imply additional GHG release. However, the assessment of ILUC impacts is highly uncertain [START_REF] De Cara | Revue critique des études évaluant l′effet des changements d′affectation des[END_REF].

Fig. 5 presents the potential GHG emissions associated with ILUC impact caused by the expansion of crops that are dedicated to biofuels [START_REF] De Cara | Revue critique des études évaluant l′effet des changements d′affectation des[END_REF][START_REF]Technology Roadmap Biofuels for Transport[END_REF][START_REF] Ipcc | panel on climate change[END_REF]. Biofuels based on wastes (including waste oil based HVO), residues and microalgae are assumed to have no ILUC impact as they are not competing with food and feed crops [START_REF][END_REF]. Imported biodiesels, namely soybean, palm and HVO have the greater potential for ILUC impacts because of deforestation issues [START_REF] Gao | Assessing deforestation from biofuels: methodological challenges[END_REF][START_REF] Janssen | Sustainability of biofuels in Latin America: risks and opportunities[END_REF]. According to Lapola et al. [START_REF] Lapola | Indirect land-use changes can overcome carbon savings from biofuels in Brazil[END_REF], ILUC impacts in Brazil can also exhaust the sugarcane ethanol GHG savings because of the deforestation of Amazonian forests.

Environmental sustainability of energy consumption

Through energy independency, renewable energy consumption [START_REF] Arvidsson | Life cycle assessment of hydrotreated vegetable oil from rape, oil palm and Jatropha[END_REF][START_REF] Beal | The energy return on investment for algal biocrude: results for a research production facility[END_REF] and air quality criteria [START_REF] Smith | air pollution, and health: a global review[END_REF][START_REF] Tsao | Increased estimates of air-pollution emissions from Brazilian sugar-cane ethanol[END_REF][START_REF] Magara-Gomez | Sensitivity of hazardous air pollutant emissions to the combustion of blends of petroleum diesel and biodiesel fuel[END_REF], government, end-users and car-manufacturers express their preferences for more sustainable energy consumption.

Table 11 presents the reduction of fossil energy consumption associated with the substitution of fossil based fuels by biofuels. Based on expert consultation and Ademe [START_REF] Ademe | Analyses de Cycle de Vie appliquées aux biocarburants de première génération consommés en France[END_REF], first generation biofuels allow fossil fuel consumption reduction ranging from 34-81% for ethanol and from 59-90% for biodiesels. Despite their transport, imported biofuels have a higher renewable energy consumption ratio than first generation biofuels produced in France [START_REF] Ademe | Analyses de Cycle de Vie appliquées aux biocarburants de première génération consommés en France[END_REF][START_REF] Kalnes | Green diesel production by hydrorefining renewable feedstocks[END_REF]. Depending on the process and byproducts valorization (see the market opportunities section), LC-ethanol and BtL-biodiesel allow a high reduction of fossil fuel consumption [START_REF] Ballerini | Les biocarburants -Répondre aux défis énergétiques et environnementaux des transports[END_REF][START_REF] Edwards | Well-to-wheels Analysis of Future Automotive Fuels and Powertrains in the European Context[END_REF], of about 71% and 93% respectively. The literature provides a wide variety of studies concerning microalgae energy balance depending on the process pathways (for a review, see Quinn and Davis [START_REF] Quinn | The potentials and challenges of algae based biofuels: a review of the techno-economic, life cycle, and resource assessment modeling[END_REF]) but based on Delrue et al. [START_REF] Delrue | An economic, sustainability, and energetic model of biodiesel production from microalgae[END_REF], the reduction of fossil fuel consumption may range between 20% and 70%.

Renewable energy consumption also allows air pollutant emissions to be reduced compared with fossil based fuels.

Table 12 presents the air quality impacts depending on biofuel type while considering different blending rates [START_REF] Ballerini | Les biocarburants -Répondre aux défis énergétiques et environnementaux des transports[END_REF][START_REF] Edwards | Well-to-wheels Analysis of Future Automotive Fuels and Powertrains in the European Context[END_REF][START_REF] Ademe | Analyses de Cycle de Vie appliquées aux biocarburants de première génération consommés en France[END_REF][START_REF] Mercier | Mobilité durable: qu'en pensent les Français[END_REF]91]. According to these studies, emission scaling factors for different blends of biofuels are only linear for low blending rates. In France, ethanol is used as an additive up to a limit of 5% in conventional gasoline, up to 10% in E10 gasoline and up to 85% in E85 for flex-fuel cars. In the present study, ethanols are produced from wheat, maize, sugar beet, sugar and lignocellulosic feedstocks. First generation biodiesel are used as diesel additives which can be blended up to 7% according to the European Committee for Standardization (8% in France since 2015). B10 assumes a 10% biodiesel blend while B100 assumes direct use of biodiesel without a fossil diesel additive. B100 is already marginally used by public captive fleets. In order to compare the different biofuels,

The Biofuel image from end-user perspective

From the perspectives of fuel distributors and car manufacturers, the green image of biofuel concerning the end-users viewpoints is a critical criterion. Green image is assumed to include GHG emissions, ILUC, renewable energy consumption and the air quality impact [START_REF] Menten | A review of LCA greenhouse gas emissions results for advanced biofuels: The use of meta-regression analysis[END_REF]. Moreover, engine compatibility and overconsumption implied by the difference of energy content compared to fossil fuels were highlighted (Table 13, based on Ademe [START_REF] Ademe | Analyses de Cycle de Vie appliquées aux biocarburants de première génération consommés en France[END_REF], and Gehrer et al. [START_REF] Gehrer | Life Cycle Assessment of BtL as Compared to HVO Paths in Alternative Aviation Fuel Production[END_REF]).

Ethanol represents 62% of the energy content of the gasoline reference which induces overconsumption in volume. For example, E10 implies nearly 5% of overconsumption. First generation biodiesels and microalgae biodiesel energy content are close to diesel reference (88%). For example, a 10% blend of biodiesel implies a slight overconsumption of nearly 1.5%. On the other hand, HVO and BtL biodiesels energy content are higher than the references of fossil-fuels which allow the consumption in volume to be reduced.

Conclusion and discussions

Sustainable biofuel deployment is characterized by a diversity of complex and conflicting values at stake associated with high uncertainties [START_REF] Cuppen | Q methodology to select participants for a stakeholder dialogue on energy options from biomass in the Netherlands[END_REF][START_REF] Van Dam | Striving to further harmonization of sustainability criteria for bioenergy in Europe: recommendations from a stakeholder questionnaire[END_REF]. Based on the 5 pillars sustainability concept [START_REF] Parris | Characterizing and measuring sustainable development[END_REF], i.e. social, economic, environmental, legal and cultural the present study proposes to assess the sustainability of several biofuel options for France by 2030 through a stakeholder-driven approach. Based on the methodology proposed by Munda, [START_REF] Munda | Social multi-criteria evaluation: methodological foundations and operational consequences[END_REF], 34 stakeholder representatives were identified and interviewed, including feedstock producers, biofuel producers, the refining industry, fuel distributors, car manufacturers, end-users, the government and NGOs which has led to identify sets of 22 sustainability criteria and 17 biofuel options. As mentioned by Buchholz et al. [START_REF] Buchholz | Sustainability criteria for bioenergy systems: results from an expert survey[END_REF], stakeholder consensus concerning sustainability criteria is very low among the different professions. Indeed, only 5 of the 22 sustainability criteria were identified with a consensus greater than 50%. Consequently, the study highlights the importance of including all the stakeholder groups have an interest, financial and otherwise, in the sustainability assessment process. Moreover, the involvement of stakeholders in the identification of other groups is critical and it has led us to identify a new group which was not mentioned in other biofuel sustainability studies [START_REF] Turcksin | A multi-actor multi-criteria framework to assess the stakeholder support for different biofuel options: the case of Belgium[END_REF][START_REF] Van Dam | Striving to further harmonization of sustainability criteria for bioenergy in Europe: recommendations from a stakeholder questionnaire[END_REF][START_REF] Buchholz | Sustainability criteria for bioenergy systems: results from an expert survey[END_REF], namely the refining industry.

Based on the average data regardless of the overlaps induced by the uncertainty, Table 14 presents the ranking of the biofuel options according to their expected performance by 2030 for each sustainability criterion identified by the French stakeholders. Biofuels are ranked from 1 to 18 with 1 being the most suited to fulfill a criterion and 18 the least which allows for the identification of the strengths and the weaknesses of each biofuel. When options equally contribute to a criterion, the same ranking was assigned. For example, wheat and maize ethanol have the potential to contribute equally to job creation.

As an illustration, let us consider biodiesel produced from microalgae through the PBR process. Based on Table 14, microalgae biodiesel is the option that contributes least to meeting the stakeholders' economic criteria because of a high production cost. Moreover, their potential for GHG mitigation is rather low compared to other advanced biofuels such as BtL biodiesel. However, the present study proves that sustainability is not just about GHG and economic considerations. Considering impacts associated with land requirement such as food security, ILUC and feedstock availability, microalgae biodiesel is by far the most suited option with regards to several stakeholders' sustainability criteria. For example, compared with other advanced biofuels, microalgae biodiesel allows for the production of feed byproducts which is a critical issue for the government and feedstock producers through the protein independence criterion. Biofuel sustainability assessment requires considering a wide range of heterogeneous opinions to cope with their multidimensional impacts. Consequently, the biofuel capacity to fulfill one specific objective cannot lead to any absolute conclusion about biofuel overall sustainability, policy efficiency and whether it has a positive or negative impact. The present study proposes assessing biofuel sustainability, criterion by criterion, but regardless of the stakeholders' priorities concerning each one. Our further research will focus on developing a participatory multi-criteria analysis to incorporate the different stakeholder perspectives and priorities while taking into account the uncertainty about biofuel sustainability.

Annexure

See Table A1.

Fig. 3 .

 3 Fig. 3. Blue and green water footprints of biofuel (m 3 per GJ).

Fig. 5 .

 5 Fig. 5. Ranges GHG emission associated with indirect land-use change (gCO 2 eq/MJ). *Imported biofuels.

Table 1

 1 Questionnaire structure.

	Part	Questions / From your perspective…
	Part I	About you, your organization
		Name, organization, job title, organizational position on biofuels in
		France
	Part II	Review and definition of the set of biofuel options
		Scoring biofuel options from not at all to large-scale deployment
	Part III	Review and definition of the set of biofuel options
		Including economic, social, environmental, technical, and legal
		issues
	Part IV	Stakeholder group identification
		Individuals or group of individuals who might affect or might be
		affected by the consequences of biofuel deployment

Table 2

 2 Biofuel set submitted to stakeholders' review.

	Biofuel options by	Feedstocks	Stakeholders' opinions
	2030
	First generation biofuels (conventional	Agree	Neither	Disagree
	biofuels)
	Biodiesel	Rapeseed	88,5%	3,8%	7,7%
		Sunflower	84,6%	3,8%	11,5%
		Soybean (imported)	84,6%	7,7%	7,7%
		Palm (imported)	84,6%	7,7%	7,7%
	Ethanol	Wheat	88,5%	3,8%	7,7%
		Corn	88,5%	3,8%	7,7%
		Sugar beet	84,6%	7,7%	7,7%
		Sugar cane	84,6%	7,7%	7,7%
		(imported)
	Hydrotreated	Rapeseed (imported)	65,4%	19,2%	15,4%
	Vegetable Oil
	(HVO)	Palm (imported)	65,4%	19,2%	15,4%
		Waste oils (imported) 69,2%	23,1%	7,7%
	Second generation biofuels (advanced	Agree	Neither	Disagree
	biofuels)
	Biodiesel	Agricultural residues	69,2%	15,4%	15,4%
		Forestry residues	69,2%	11,5%	19,2%
		Energy crops	53,8%	19,2%	26,9%
	Lignocellulosic	Agricultural residues	69,2%	15,4%	15,4%
	Ethanol
		Forestry residues	69,2%	11,5%	19,2%
		Energy crops	53,8%	19,2%	26,9%
	Bio-methane	Farm effluents,	23,1%	7,7%	69,2%
		industrial wastes
	Third generation biofuels (advanced	Agree	Neither	Disagree
	biofuels)
	Biodiesel	Microalgae	53,8%	26,9%	19,2%
	Ethanol	Microalgae	46,2%	26,9%	26,9%
	Bio-methane	Microalgae	15,4%	19,2%	65,4%

Table 3

 3 Sustainability criteria identified by the stakeholders.

	Sustainability criteria	Consensus (%)	Stakeholder groups a	Economic concerns	Social concerns	Environmental concerns
	GHG mitigation	100,0%	1,2,3,4,5,6,7,8				x
	ILUC	75,0%	3,4,5,6,7,8				x
	Biofuel production cost	75,0%	2,3,4,5,6,7	x
	Additional cost for end-users	50,0%	4,5,6,7	x		x
	Air quality	50,0%	4,5,6,7				x
	Renewable energy ratio	37,5%	4,5,6				x
	Land productivity -Energy yield	25,0%	1,7	x
	Land productivity -Protein yield	25,0%	1,7	x
	Food security	25,0%	7,8			x
	Eutrophication	25,0%	1,8				x
	Water footprint	25,0%	1,8				x
	Job creation	25,0%	1,7	x		x
	Biomass availability	12,5%	2			x	x
	Biofuel availability	12,5%	4			x	x
	Incomes from feedstock	12,5%	1	x
	Biofuel international competition	12,5%	2	x		x	x
	Market opportunities	12,5%	1	x
	Biofuel incorporation costs	12,5%	3	x
	Existing logistics (fuel distributors)	12,5%	4	x
	Overconsumption	12,5%	5	x		x
	Budget impact	12,5%	7	x
	Transparency	12,5%	8			x
	Repartition			45%		29%	26%
				Table 4
				Expected land productivity by 2030.
				Biomass / Biofuel	Biomass (ton per hectare)	Biofuel (toe per hectare)
				Scenario	Pessimistic	Optimistic	Pessimistic	Optimistic
				Wheat ethanol	7,95		9,51	1,44	1,72
				Maize ethanol	11,13		13,62	2,66	3,25
				Sugar beet ethanol	12,04		13,94	6,21	7,19
				Sugar cane ethanol	8,97		9,31	4,63	4,80
				LC ethanol a	10,00		12,00	1,28	1,54
				(agricultural
				residues)
				LC ethanol (forestry	8,00		18,00	1,04	2,35
				residues)
				LC ethanol (energy	13,00		20,00	1,67	2,57
				crops)
				Rapeseed biodiesel	4,06		4,59	1,53	1,73
				Soybean biodiesel	3,09		3,50	0,53	0,60
				Palm biodiesel	5,31		5,54	4,46	4,65
				HVO (rapeseed)	4,06		4,59	1,50	1,70
				HVO (palm)	5,31		5,54	4,46	4,65
				BtL b biodiesel	10,00		12,00	1,71	2,05
				(agricultural
				residues)
				BtL biodiesel	8,00		18,00	1,39	3,13
				(forestry
				residues)
				BtL biodiesel	13,00		20,00	2,23	3,42
				(energy crops)
				Microalgae biodiesel	20,00		50,00	4,51	11,27
				(raceway)
				Microalgae biodiesel	40,00		60,00	9,02	13,53
				(PBR)

a Stakeholder group numbers refers to Section 3.1.

a LC: lignocellulosic. b BtL: Biomass to Liquid.

Table 5

 5 Expected biomass (and biofuel) availability in France by 2030 (ktoe).

	Biomass / Biofuel	Biomass (kton)	Biofuel (ktoe)
	Scenario	Pessimistic Optimistic Pessimistic Optimistic
	Imported biofuels	-	-	1050	1050
	Wheat ethanol	2202	2634	398	476
	Maize ethanol	3084	3772	736	900
	Sugar beet ethanol	26038	30146	1344	1556
	LC ethanol (agricultural	5329	11872	684	1524
	residues)
	LC ethanol (forestry	6500	9170	848	1197
	residues)
	LC ethanol (energy crops)	2300	12000	295	1541
	Rapeseed biodiesel	6245	7063	2356	2665
	BtL biodiesel (agricultural	5329	11872	912	2032
	residues)
	BtL biodiesel (forestry	6500	9170	1131	1596
	residues)
	BtL biodiesel (energy crops) 2300	12000	394	2054
	Microalgae biodiesel	2966	7416	669	1672
	(raceway)
	Microalgae biodiesel (PBR)	9994	14991	2253	3379

Table 6

 6 Expected income from feedstock by 2030 (€ per ton).

	Feedstock	Pessimistic	Optimistic
	Imported feedstocks/biofuels *	-€	-€
	Wheat	11 €	79 €
	Maize	-€	58 €
	Sugar beat	11 €	12 €
	Rapeseed	327 €	707 €
	Agricultural residues	90 €	108 €
	Forestry residues	42 €	117 €
	Energy crops	104 €	85 €
	Microalgae biodiesel (raceway)	-184 €	-1 304 €
	Microalgae biodiesel (PBR)	-1 500 €	-3 800 €

* Imported feedstocks/biofuels generate incomes from feedstock abroad but none in France.

Table 7

 7 Main market opportunities / market diversification criterion.

	Feedstocks	Biofuels	Feed	Food	Chemical	Energy
	Wheat	Ethanol	x	x		x
	Maize	Ethanol	x	x		x
	Sugar beet	Ethanol	x	x		x
	Sugar cane *	Ethanol	x	x		x
	Rapeseed	Biodiesel	x		x	x
	Soybean *	Biodiesel	x		x	x
	Palm *	Biodiesel	x		x	x
	HVO * (rapeseed/palm)	Biodiesel	x			x
	HVO * (waste oil)	Biodiesel				x
	Agricultural residues	Both		x		x
	Forestry residues	Both		x		x
	Energy crops	Both		x		x
	Microalgae	Biodiesel	x	x	x	x

* Imported biofuels. Fig. 1. Range of expected biofuel costs France by 2030 (€/ lde, €/ lge). *Imported biofuels.

Table 8

 8 Arable land requirement per energy produced (ha per toe).

	Biomass / Biofuel	Arable land requirement	Feed-byproduct yield
		(hectare per toe)	(ton per hectare)
	Scenario	Pessimistic	Optimistic	Pessimistic Optimistic
	Wheat ethanol	0,70	0,58	2,39	2,85
	Maize ethanol	0,38	0,31	4,12	5,04
	Sugar beet ethanol	0,21	0,18	4,70	5,44
	Sugar cane ethanol	0,27	0,26	13,33	13,84
	LC ethanol (agricultural	0,00	0,00	0,00	0,00
	residues)
	LC ethanol (forestry	0,00	0,00	0,00	0,00
	residues)
	LC ethanol (energy	0,60	0,39	0,00	0,00
	crops)
	Rapeseed oil	0,65	0,58	1,95	2,20
	Soybean	1,88	1,67	2,41	2,73
	Palm oil	0,22	0,22	0,59	0,62
	HVO (rapeseed)	0,67	0,59	1,95	2,20
	HVO (palm)	0,22	0,22	0,59	0,62
	BtL biodiesel	0,00	0,00	0,00	0,00
	(agricultural
	residues)
	BtL biodiesel (forestry	0,00	0,00	0,00	0,00
	residues)
	BtL biodiesel (energy	0,45	0,29	0,00	0,00
	crops)
	Microalgae biodiesel	0,22	0,09	12,00	30,00
	(raceway)
	Microalgae biodiesel	0,00	0,00	24,00	36,00
	(PBR)

Fig. 2. Potential job creation related to production (job per

Table 9

 9 Additional cost for consumers (€/T) and overall government budget impact (c€/lde, c€/ lge).

	Indicators	Cost for end-users	Budget impact
		(c€ per lde/lge)	(c€ per lde/lge)
	Oil price scenario	50$ per	180$ per	50$ per	180$ per
		barrel	barrel	barrel	barrel
	Wheat ethanol	0,04 €	-0,02 €	0,09 €	0,14 €
	Maize ethanol	0,03 €	-0,03 €	0,10 €	0,15 €
	Sugar beet ethanol	0,03 €	-0,03 €	0,10 €	0,15 €
	Sugar cane ethanol *	0,04 €	-0,01 €	-0,02 €	0,04 €
	Lignocellulosic ethanol	0,04 €	-0,02 €	0,10 €	0,14 €
	(average)
	Rapeseed biodiesel	0,04 €	-0,02 €	0,03 €	0,08 €
	Soybean biodiesel *	0,03 €	-0,01 €	-0,02 €	0,01 €
	Palm oil biodiesel *	0,03 €	0,03 €	-0,02 €	0,04 €
	HVO *	0,06 €	0,09 €	-0,00 €	-0,03 €
	BtL-biodiesel (average)	0,04 €	-0,03 €	0,01 €	0,07 €
	Microalgae biodiesel	0,29 €	0,18 €	-0,18 €	-0,08 €
	(average)

* Imported biofuels.

Table 10

 10

	Biofuels potential of eutrophication (kg PO 4	3-/MJ).
	Biofuel	Eutrophication (kg PO43-/MJ)
	Wheat ethanol	4,11E-04
	Maize ethanol	3,79E-04
	Sugar beet ethanol	1,95E-04
	Sugar cane ethanol	2,19E-04
	Lignocellulosic ethanol	8,40E-05
	Rapeseed biodiesel	3,64E-04
	Soybean biodiesel	1,79E-04
	Palm oil biodiesel	1,84E-04
	HVO	5,00E-05
	BtL biodiesel	1,00E-04
	Microalgae	1,21E-04

Fig.

[START_REF] Ademe | Analyses de Cycle de Vie appliquées aux biocarburants de première génération consommés en France[END_REF]

. Life cycle balance of biofuel (% emission reductions compared to fossil fuels). *Imported biofuels.

Table 12

 12

	considers a 10% biofuel blend. Ethanol allows a greater
	improvement of air quality compared with biodiesel with the exception
	of HVO.

Table 11

 11 Reduction of fossil energy consumption.

	Feedstock	Pessimistic	Optimistic
	Wheat ethanol	34%	42%
	Maize ethanol	38%	46%
	Sugar beet ethanol	37%	45%
	Sugar cane ethanol	67%	81%
	Lignocellulosic ethanol	68%	74%
	Rapeseed biodiesel	59%	72%
	Soybean biodiesel	62%	76%
	Palm oil biodiesel	70%	86%
	HVO	74%	90%
	BtL-biodiesel	92%	94%
	Microalgae biodiesel	20%	70%

Table 12

 12 Air quality (% reduction compared with of fossil energy use).

					Table 13
					Biofuel energy content (MJ/kg).
					Biofuel	Energy Content
					Unit	MJ/kg
					Gasoline reference	43,1
					Diesel reference	42,8
					Ethanol	26,90
					Biodiesel	37,50
					HVO	44,00
					BtL biodiesel	42,50
	Biofuel	HC ( a )	C O	N O x	PM
	Ethanol E10	-5%	-20%	0%	-40%
	Ethanol E85	0%	0%	0%	-20%
	Biodiesel B10	-5%	-2%	0%	-9%
	Biodiesel B100	-69%	-34%	8%	-38%
	HVO (10%)	-9,5%	-15,7%	-8,3%	0,7%
	HVO (85%)	-27,7%	-44,0%	-12,0%	6,0%
	BtL-biodiesel (100%)	-49%	-60%	2%	-16%

a HC: Hydrocarbons; CO: carbon monoxide; NO x: oxides of nitrogen; PM: particulate matter.

Table 14

 14 Ranking of the different biofuel options per sustainability criteria.

	Food crop ethanols Lignocellulosic ethanols Food crop biodiesels HVOs BtL biodiesels Algae biodiesels	Wheat Maize S. beet S. cane A. residue F. residue E. crops Rape-seed Soybean Palm Rape-seed Palm Waste oil A. residue F. residue E. crops Raceway PBR
	Biofuels	Feedstocks	Land productivity -Energy yield

Table A1

 A1 List of the stakeholders who contributed to the study. Association Générale des Producteurs de Maïs France's General Association of Maize Growers Luis DA SILVA E SERRA Association 2BSvs Biomass and Biofuels sustainability volontary scheme Sylvain DEMOURES SNPAA -Syndicat National des Producteurs d′Alcool Agricole French syndicate of agricultural alcohol producers Valérie DERMAUX Ministère de l′Agriculture de l′Agroalimentaire et de la Forêt Ministery of Agriculture, Agro-food and Forest Bertrand DUFRENOY INEOS / Estérifrance INEOS / French Syndicate of biodiesel producers Bruno GAGNEPAIN ADEME French agency for the energy efficiency and for the environment Institut Français du Pétrole et des énergies nouvelles French Petroleum Institute Nicolas LE BIGOT CCFA -Comité des Constructeurs Français d′Automobiles Syndicate of French car manufacturers Jack LEGRAND GEPEA -Génie des Procédés Environnement et Agroalimentaire Research laboratory Génie des Procédés Environnement et Agroalimentaire Research laboratory Caroline RANTIEN ADEME French agency for the energy efficiency and for the environment Caroline RAYOL IAR pôle de compétitivité Industires et Agro-Ressources Pole of competitivness for agro-ressources Ronan ROCLE Global Bioénergies Global Bioénergies Nicolas RIALLAND CGB -Confédération Générale des planteurs de Betteraves Agricultural syndicate for sugar beet producers Sylvain SOURISSEAU ADEME French agency for the energy efficiency and for the environment

	First name	Name	Organization
	Maud	ANJUERE	Direction Générale du Trésor Ministry of Economy and Finances
	Jean-Michel	ASPAR	Synacomex French association for cereals and oilseeds trading
	Antonio	BISPO	ADEME French agency for the energy efficiency and for the environment
	Christophe	BLAVOT	Ecologie Industriel Ecological Industry
	Frank	BOUHERET	BP France British Petroleum France
	Matthieu	CALAME	Fondation pour le progès de l′homme (fph) Fondation Charles Léopold Mayer for human progress
	Pierre	CHASSERAY	40 millions d′automobilistes French car users association
	Gildas AGPM -Marc COTTEN GILLMAN Total Total
	Kristell	GUIZOUARN	Sofiprotéol / Esterifrance Sofiprotéol / French Syndicate of biodiesel producers
	Vivien	ISOARD	Diréction Générale de l′Énergie et du Climat Ministry of Ecology, Sustainable devlopment and Energy
	Géry	LAGRANGE	PétroInéos PétroInéos
	Frédéric IFPEN -Olivier LANTZ LEPINE Algosource Algosource
	Tarek	MHIRI	FranceAgriMer Establishment for agricultural and sea products
	Béatrice	PERRIER	PSA -Peugeot Citroën PSA -Peugeot Citroën
	Stéphane	POUFFARY	Energies 2050 NGO Energies 2050
	Jérémy GEPEA -Isabelle PRUVOST SPIEGEL PWC PWC
	Bernard	TICOT	ONIDOL -Organization Nationale Interprofessionnelle des Graines et Fruits Oléagineux French interprofessional organization for
			oleaginous seeds and fruits
	Alex	TRUCHETTO	Intermarché Intermarché
	Hugo	VALIN	IIASA International Institute for Applied Systems Analysis