Criteria prioritization for sustainable development of second-generation bioethanol in Thailand with an 1 application of Delphi-AHP technique 2

9 Background: 10 The availability of underexploited agricultural residues in Thailand opens up the opportunity to supply second-generation 11 bioethanol production. The national implementation of residues-to-biofuel can potentially initiate the bioeconomy and 12 greenhouse gas mitigation, requiring engagement from the multi-stakeholders to develop effective policy recommendations. Thus, the study aims to optimize the implementation of the national strategy from a multi-criteria approach to evaluate the 14 concerned aspects and important indicators for second-generation bioethanol development through a participatory 15 prioritization by the actual stakeholders Methods: To analyze the relevance of the different dimensions regarding important levels of criteria, a Delphi-AHP technique was 18 applied. The evaluation process was conducted with different stakeholders and elaborated by using a pairwise comparison of 19 4 dimensions (main-criteria) and 12 indicators (sub-criteria). The evaluation was applied to the participants to share their 20 preferences evaluating the most important factors from the aspect of technical feasibility, environmental impacts, economic feasibility and social impacts. Results: Bioethanol stakeholders in Thailand from 5 different branches (industry/ business sectors, NPO/NGO, governmental sectors, academic/research institute and financial institution/bank) participated in the Delphi survey. The 20 expert’s evaluation of four 25 dimensions reveals the highest score from the economic feasibility (32.3%), followed by environmental impacts (25.6%), 26 technical feasibility (24.0%) and social impacts (18.1%). From the sub-criteria process of employing different associated backgrounds into account at the step of policy planning in addition to the consideration of affiliations. The stakeholder’s participatory evaluation indicated the importance of economic aspects, highlighting the necessity of the 4 governmental driven policy that needs to be considered. However, implementation scenarios have to be embedded in a 5 broader range of aspects because all the dimension were rated with high impacts. For the future sustainable bioenergy, 6 involvement from stakeholders’ opinions can imply multifaceted scenarios that may interconnect to the social acceptance and 7 benefits for all relevant players when considering the development of advanced bioenergy as a policy recommendation.


Introduction 1
The greenhouse gas (GHG) reduction goal is an urgent driver for Thailand to search for sustainable energy sources to pursue 2 effective mitigation. Thailand has committed to the Paris Agreement at the COP21 meeting to reduce 20-25% GHG intensity 3 from the business as usual by 2030 [1,2]. Constantly increasing energy demand leads to the requirement of a sustainable energy 4 transition to stay within the greenhouse gas emission budget. Taking an opportunity from agricultural products in the country,

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Thailand attempts to substitute the consumption of fossil fuels with bioenergy production from the agricultural crops. At 6 present, bioenergy production in Thailand comprises bioethanol and biodiesel. In particular, for bioethanol production, cassavas 7 and sugarcanes are cultivated to serve the biofuel supply in the transportation sector. According to the long-term promotion of

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This conventional bioethanol development thus far benefits on the abatement of dependency on fossil fuel. However, there 11 are challenges that need to pay attention to while biofuel production becomes intensified in proportions. The controversial 12 issues involve the production process, as the projected goal of ethanol production could associate with higher requirement of 13 crops cultivation. Due to a limit of yield per area up until now, the national policy to promote bioethanol for substitution of 14 fossil fuel is projected for a land use expansion [5][6][7], which also affects land use of food and other crops cultivation [6]. In 15 this sense, the conflict between the crops supply and increasing bioethanol demand needs to be taken into consideration to 16 achieve a sustainable long-term bioethanol policy in Thailand.

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Nowadays, sustainability for future bioenergy development has been scrutinized extensively. Although the conventional 18 production of biofuel has admittedly provided the benefits of fossil fuel replacement, the widespread commercialization of the 19 biofuel industry from the past decades has been inevitably associated with the environmental side-effects, involving conflicts 20 of land use for food-based crops cultivation [8][9][10]. The recent researchers and stakeholders have paid more attention to pursue 21 the transition of bio-based products or bioenergy systems towards sustainable direction by addressing indicators from holistic 22 points of view based on United Nations Sustainable Development Goals (SDGs) [11][12][13]. The exemplary framework can be 23 observed from the policy by European Union (EU), which has shown more concerns on sustainability and environmental 24 harmonization for biofuels and bioliquids implementation [8].

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Towards the direction of sustainability, one of the implementable concepts is the utilization of the regional biomass, such 26 as wood-based wastes, to supplying as bio-materials [14][15][16]. The strategy would not only provide the environmental and 27 economic advantages, but the investment in bio-based industries is also expected to contribute to social benefits, such as 28 increasing workforce from the local business, educational opportunities, and research projects for enhancing innovation [12, 29 17,18].

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Under the debate of sustainable resource use, the energy sector is considered as one of the potential cascading use of 31 agricultural residues to enhance values of agricultural industries in the form of bioenergy [19]. Particularly, the bioenergy from 32 Foreseeable constraints of the first-generation bioethanol implementation in Thailand -Literature review 1 The promotion of bioethanol development in Thailand contributed the benefits to the transport section since it provided the 2 self-sufficient sources of energy supply. Since 2004, commercialized bioethanol shows a constant growth according to fostering 3 policy for production and consumption sides. Nonetheless, the bioethanol development plan and policy of Thailand, namely 4 the Alternative Energy Development Plan (AEDP, 2015(AEDP, -2036, has barely integrated the socio-economic dimension since it 5 involves crossing-disciplinary fields and authority from governmental organizations. On the contrary of achievement in 6 replacing the fossil fuel, the long-term policy is prone to encounter with constraints occurred due to several aspects, which may 7 become the bottlenecks for the bioethanol development policy in Thailand in the future.  Thailand's bioethanol policy advocates energy security in the country, the biofuel promoting approach still lacks the concrete 11 strategy to improve the crops cultivating management for the long-term development goal. Due to the limited farm areas, there 12 is a bottleneck to stabilize the sources for biofuel supply to correspond to the production goal in the future. Along with that, 13 prices of raw material, as well as the production cost are considered significant influences. Since biofuel production mainly 14 varies on the crop price, the fluctuation of the feedstocks price is a worrying issue that the government needs to overcome.

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From the background of instability in raw materials price, the biofuel pricing mechanism in Thailand is structured by a 16 subsidization system [38]. The stakeholders of bioethanol business projected the opportunity that demand can still grow steadily, 17 as long as there are incentives for driving the demand in terms of blending mandatory, tax reduction or subsidization [37]. The 18 subsidy is collected from the non-bio-based fuel as oil funds. The oil funds are the instrument to stabilize the retail price of 19 bioethanol blended gasoline, which also encourages the consumption of biofuel by maintaining the discount for users of 20 bioethanol blended gasoline type, E20 and E85 (20% and 85% ethanol blending rates, respectively) [38]. Nonetheless, the 21 reliance on governmental subsidization has also been criticized as a cause of distortion of the actual price and a possible long 22 term negative effect to the market [39]. By controlling retail price for consumers, the lower price of gasoline is related to entail 23 the energy consumption to become higher [39,40].

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Apart from the issue concerning market mechanism of biofuel, it has been unclear from the policy making regarding the 25 sustainable strategy of bioethanol development. In the study by Lecksiwilai  yields, which was contemplated as one of possible solutions under the land use restriction, possibly demands higher input 32 6 fertilizers and pesticides. Consequently, the foreseen limited crops yields would decrease the GHG mitigation effect of the 1 biofuel, resulting in environmental tradeoffs from the life cycle GHG emission [6,41]. In addition to that, the cultivation of 2 cassavas and sugarcanes is associated with intensive water footprint per ton of crop production. It has been investigated that 3 the water footprint in the cassava plantation required double amount of water comparing to sugarcane plantation [46].

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The complications of current policy also involve a socio-economic aspect. Concerning the traditional practice of sugarcane 5 plantation, the agricultural residues management is executed by field burning [47,48]. At the end of each cultivating season 6 and before starting the new cultivating round, the preparation steps comprises the sugarcane trash burning. This procedure gives 7 impact to not only the environmental burden, but the health issues of the farm workers also are directly affected, giving 8 disadvantages to the farmers [49]. In particular for the agricultural laboring system, unguaranteed crop prices for stable incomes 9 of the farmers, and unequally protected by national labor law affect the quality of farming job. Thus, several dimensions take 10 part in the bioethanol policy, which are necessary to be evaluated for the long term sustainable development [50].

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The information from the mentioned studies reflected the existing issues and prospective barriers in the bioethanol policy 12 in Thailand particularly on the feedstocks supply. Exploring a substitution of the conventional feedstocks is recognized as a 13 promising option especially from the available agricultural residues. The utilization of lignocellulosic biomass for second-

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From the angle of current biofuel policy, there are many underlying opportunities for the bioethanol development to reach 19 the long-term goal. Towards the process of policy planning for advanced bioethanol development, aside from technical and 20 economic viability, the estimation of social and environmental impacts have become vital concerns to evaluate for the most 21 sustainable system [33]. It is irrefutable to say that to commercialize the advanced biofuel technology, it involves many 22 uncertainties, trans-disciplines, standards and measures as well as the related players, such as the crops growers, private firms, 23 governments and ending products users [35,56,57]. Therefore, the proposal of the alternative system of bioethanol should be 24 aware comprehensively from various backgrounds and based on the bottom-up opinions sharing by incorporating multi-25 disciplinary organizations in the bioethanol value-chain.

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Objective of the study 28 Considering that drawbacks and projected constraints from the current first-generation bioethanol would inevitably occur 29 in the near future, transitioning from the conventional ethanol production to the second-generation technology is a promising 30 solution. For a future sustainable policy, it is necessary to construct the system based on the assessment from the multi-7 disciplinary aspects. In order to bridge the gap in the transdisciplinary assessment in regard to sustainable framework for policy 1 implications, socio-economic and environmental variables require to take part in the system analysis and decision-making.

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Thus, the objective of this study is to evaluate the level of importance of criteria from several relevant dimensions by 3 involving the stakeholders' perspectives. The outcomes of criteria prioritization are expected to reflect the most concerned 4 topics and preferences that bioethanol stakeholders encountered at the current stage, which could be beneficial for second-5 generation bioethanol policy recommendations. The results of criteria prioritization by the stakeholders in this study are planned 6 to be accommodated in the scenarios analysis as a further study step to determine the consensual sustainable strategy for second-7 generation bioethanol development.

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Consolidating the different viewpoints from the various branches of stakeholders with the application of Delphi-AHP 9 (Analytic Hierarchy Process) in the context of second-generation biofuel policy in Thailand is considered a novelty. With this 10 approach, the stakeholders are provided the opportunity to share their preferences and concerns which could become a 11 foundation for the second-generation ethanol policy development. In addition, the stakeholders are given chances to rethink the 12 preferences under the consideration of the first survey round. Following the Delphi-AHP procedures, it is expected to enable 13 the policymakers to objectively achieve the efficient and justified indicators in the policy design, since the technique could 14 eliminate the subjective opinions, which might lead to the bias decisions.

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Process of survey preparation and conduction 1 In this study, Delphi-AHP methods were deployed to prioritize the important aspects and criteria regarding 2 commercialization and policy implications of the second-generation bioethanol in Thailand. The evaluation of important levels 3 of the associated criteria was conducted by the relevant experts. The criteria were addressed from crossing dimensions of a 4 whole supply chain from farm to ethanol production, including technical, environmental, and socio-economic aspects from 5 diverse participants' perspectives.

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The process flow of the survey and data analysis is summarized in Figure 1.

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The research question was planned to pursue the objective of the study. The questionnaire was planned to inquire the 12 experts' opinions to vote for the preferable criteria to be considered in the second-generation ethanol development in Thailand.

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For the initial step, the aspects and criteria set were selected and categorized separately in technical, economic, environmental,   The principle of Delphi-survey for collecting opinions shall be taken place with diverse backgrounds of experts group 5 under the specific topic. Based on that, the selection of panel of participating experts was considered from experiences in the 6 field of bioethanol production and other topics in line with the bioethanol supply chain corresponding to the system boundary 7 of assessment in this study, covering biomass feedstock providers, ethanol producers and energy corporations as bioethanol 8 purchasers. Principally, each specialist does not acknowledge each other in order to avoid interference between respondents.

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Aiming to structure the panelists from the diverse points of views to obtain the outcomes from different opinions and 10 concerns, the experts were selected from 5 distinctive functionality of organizations, which are 1) governmental sectors, 2) 11 business sectors, 3) non-profit or non-governmental organizations, 4) academic or research institutes and 5) financial 12 institutions and banks. In this study, the systematic selection of the participants was carried out from each background to 13 represent the function of organization as well as the opinions towards bioethanol production in Thailand.
14 In a realistic practice, it is not possible to personally indicate the evaluator in every organization due to the fact that 15 some organizations have the delegation system to allocate the tasks, especially in large-sized enterprises. The delegated experts 16 were internally assigned to deliver the Delphi-survey, meaning that the evaluator was determined to be adequate for  In the first round, the Delphi survey questionnaires were distributed to potential targets. After gathering all evaluated 22 scores from the participants, AHP was applied to weight the criteria for prioritizing the level of importance. The hierarchical 23 structure of the variables in this study was determined based on the calculation procedures, as mentioned in section Analysis 24 of the survey data from AHP method. In the following step, the results from round one of Delphi-AHP were distributed to 25 the participants. The preliminary compilation of results was informed to the experts to provide the opportunity to participate in 26 the second-round survey. After each round of the survey, the participants were asked to consent to the results or re-evaluate the  The criteria in this study were selected from the publications related to the field of energy analysis, as summarized in Table   2 1. The goal is to prioritize the preferable criteria to be focused on the context of second-generation bioethanol. The derived 3 scores of criteria ranking are planned to be undertaken as parameters in the system analysis for proposing the second-generation 4 bioethanol as a policy recommendation.

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The criteria were selected based on the fundamental that they are independent of one another but eventually correspond to 6 the goal of the study. The scores of criteria evaluations are subjected to contribute in the scenarios study as the further step of 7 the research. The set of criteria relatively affects the results of multi-criteria decision-making outcomes. To achieve the goal in 8 this study, the set of criteria was constituted from technical, environmental, economic, and social aspects. The variables 9 introduced in this study refer to the scope cradle-to-gate, ranging from farm areas to ethanol production as a boundary in this 10 study.

11
The selection of required criteria in this study shares the common ground that they are the quantitative factors, which can 12 be processed in the MCDA. Criteria to be studied were categorized by 4 main aspects of main criteria, comprising 3 sub-criteria 13 under respective aspects, providing a total of 12 sub-criteria to be evaluated. A simple scheme of the hierarchical structure is  Second-generation bioethanol has been improved for its technical potential as commercialized production has developed 21 in these decades [28]. Nevertheless, the potential of this advanced technology in the context of Thailand has to be verified.

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First, biomass availability is a criterion for verifying if the capacity of generated agricultural residues is sufficient to be supplied 23 in production units. Moreover, the availability of input materials indicates the potential location for installing facilities and 1 determines the production capacities [68, 69].

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Next, to verify the potential of input material, ethanol conversion efficiency from the available feedstock needs to be 3 taken into consideration. The ethanol productivity from lignocellulosic materials plays a major part in evaluating cost-benefits 4 [70] since the ethanol conversion efficiency can be deficient due to the constraint from the complex structures of lignocellulosic 5 components [71]. Therefore, conversion process requires more operating cost and input energy compared to the conventional 6 production [53].

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In regard to the related elements in the production boundary, biomass logistics is one of the key factors for assessing 8 technical feasibility. This factor refers to distances and transferable amounts of biomass from supply area to the ethanol 9 production process and the end-use stations. Logistics work involves the terms of harvesting, collecting, baling, and handling

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The final selling price could be referred as the structure of minimum ethanol selling price. Principally, the final price of 23 biofuel is constructed from costs of raw material and production process under the condition of 10% internal rate of return 24 (IRR). The production cost of bioethanol from lignocellulosic feedstocks comprises the capital costs of the production plants

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In addition to the economic analysis from the production process, the possibility to extend the added values of input 1 materials is also a vital factor to consider. Conversion of biofuel from the residues has high potential in the value addition, 2 varying on the types of input materials and the output products. The value addition of the biomass from conventional production 3 can increase through the technological development [82,83]. Compared with the biofuel productions from crop farming, 4 utilizing lignocellulosic biomass as input materials for higher value-added was assessed to give more economic benefits and 5 socio-economic advantages such as expanding the employment rates [84]. In recent years, industrialized ethanol production 6 from lignocellulosic biomass has transformed from only ethanol production to value-added co-products. For example, from 7 fermentation process of the residual by-products, it is possible to derive lignin plastic composite material simultaneously as

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In the case that the production of food crops is associated with non-food purpose business, it is necessary to take the 23 factor of food security into account. The increase of biofuel demand has led to the rising price of maize, which affected the 24 contribution of grains production in the food industry became smaller due to the expansion of land use [89]. The parameters 25 related to food security imply the sufficiency of food for the inhabitants regarding physical, social, and economic possibilities.

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The indicators are associated with, for example, the sufficiency of food availability, changes in areas of food crops, food 27 accessibility, reasonable price, and sufficient calorie intake [89,90]. Nonetheless, utilizing agricultural residues is prospected 28 to lessen the conflicts on food price competition from land use with conventional counterparts [91].

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Another engaging variable in the study of the socio-economic aspect is the indicator of household income. This indicator 30 is used in monitoring economic growth as part of sustainable bioeconomy development [15]. Household income can be used

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The iLUC indicator has been widely applied in the evaluation of biofuels since it is an indicator that directly indicates 13 the consequence of alternating previous activity in the cropland into bioenergy targeted production. This indicator has been 14 remarked as more complicated than direct land use due to its definition since the evaluating method includes the outside areas

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In terms of energy analysis, net energy balance is a parameter for assessing environmental impacts, indicating how the 20 efficiency of the bioenergy production process is. Accordingly, it can be applied with a life cycle assessment to evaluate CO2

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Net energy yield has also been analyzed in terms of gross energy yield per area as evaluated by Vries et al. The 26 assessment helps select adequate bioenergy production resources, which gives the highest net energy yield [101]. However, the 27 value is not limited to energy per area, but it also involves required energy factors during the production process, such as farm production from wheat straw resulted in net energy ratio (NER) >1. Nonetheless, the study remarked that the NER would be 30 offset depending on the types of consuming energy in the process.
The GHG balance refers to the GHG reduction comparing to the emission throughout the production phases, which 1 relies on various factors, such as types of fossil fuel and fertilizers in crops plantation [102]. GHG balance has been attracted 2 to researchers in the study of conventional bioenergy since it showed the negative balance (input > output) from energy crops 3 cultivation and the soil carbon sequestration [103]. In addition to the GHG emission from land use change, the life cycle CO2 4 from farm to end-products is the factor to compare CO2 mitigation with the conventional biofuel production and fossil fuel

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[104], since types of fuel as an input energy influence the total GHG balance. Meanwhile, it is possible to save output GHGs 6 with the generated co-products in the biofuel production system [105]. 10 Analysis of the survey data from AHP method 11 After retrieving quantitative and qualitative opinions from the participatory Delphi survey conduction in this study, AHP is 12 applied to interpret the subjective opinions and systematically transform them into objective information. AHP is a tool that 13 helps make decisions from complex sets of alternatives to reach the goal of multi-attributes decision-making [122]. The complexity from a variety of quantitative data is able to be reduced and become one-dimensional figures. According to Saaty, 1 the AHP method is mainly performed by two steps comprising the hierarchical structure and rating the scales on elements in 2 pairwise comparisons [58].

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The criteria were reviewed via pairwise comparisons using the provided rating scores, as the intensity of importance and 4 definition are shown in Table 2. Since the format of criteria weighting was designed for the participants to rate by selecting a 5 level of intensity from multiple choices (Supplementary information), in order to process the data according to AHP, it is 6 necessary to convert the reviewed criteria and intensities into the matrix form. If the respondents vote for the left column 7 criteria, the scales of 1-9 shall be filled out in the matrix for specifying that the row was more important than criteria from the 8 column. In the reverse case, if the variables were located towards the right side, then criteria on the row were intended to be 9 less important. Thus, the reciprocal numbers; 1/3, 1/5, 1/7, 1/9, or 1/2, 1/4, 1/6, 1/8 have to be placed for restructuring.

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In addition to the calculation of relative weights, the calculated results ought to be examined for consistency to verify the 3 reliability of the data. The following steps are described to verify the AHP consistency.

Eq. 4 9
When n indicates the size of the matrix, in this study, n = 4 and 3 for the main criteria and sub-criteria, respectively.

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Consistency index (C.I.) and consistency ratio (C.R.) can be determined, as shown in Eq. 3 and 4, respectively. This value can 11 be calculated from the random index (R.I.), as clarified in Table 3, identified by Saaty vary on the matrix size (N). An acceptable     Due to only few feedbacks were returned in the second round in this performed survey, the survey interval stopped until 10 round two. As a process of round two, after informing the round one results, the surveys were sent to the participants, while 4 11 respondents (20%) returned their responses, and only 2 participants made a modification of the answers from the first round.

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Regarding the marginal number of feedback in the second round, we terminated the further rounds of the survey. The numbers 13 of round have been reported to be varied but found average at two to three rounds [126]. Many studies stopped at the second-

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During the time of survey conduction, engagement with the organizations was the most challenging part. The regular 17 organizational system limited the access to connect with the experts directly, but it needed to be delegated from the executive 18 levels to responsible for survey answering. In this way, there was the circumstance that the persons neglected to reply since 19 they did not feel their prominent role as a decision-maker to the topic. Nonetheless, according to the institutional system, the 20 delegation could guarantee that the participants are well qualified to responsible for the task. Meanwhile, regarding the 21 limitation, we managed the lack of engagement by constantly revising the approach, such as attempts to communicating more 22 frequently, providing insightful information, and searching for alternative ways of personal connection. In some cases, 23 especially from the private firms, the decision to attend the survey were taken based on their core business of the institutes.

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This means that the enterprise's background is one of the explainable reasons for not being able to commit to every contacted 25 respondent.

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The result from round one and round two did not significantly differentiate results since only small numbers of the returning 27 responses in round two. The participated organizations with numbers of the respondent are summarized in Table 4. As 28 categorized by branches of expertise, proportions of participants are shown in Figure 3, elaborating that the structure of expert 29 panels comprises of 6 experts from governmental sectors, 5 experts from private sectors, and 3 experts from each Non-Profit

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Organization NPO/NGO, academic and financial institute.  Results of the relative weights of the main criteria from round one to round two showed slight changes. However, the 3 ranking of preferable main criteria remained the same. The result of relative weights from the second round is shown in Figure   4 4. Based on the scores of pairwise comparison from every respondent, the Consistency Index (C.I.) was ranging from 0.000 -5 0.074, whereas the calculation of Consistency Ratio (C.R.) resulted in between 0.000 -0.083. According to Saaty, if the C.R. 6 is <0.1, the answers of evaluation by all participants were verified to be consistent. Among the four main criteria as the overall 7 weight presented in Figure 4, 'Economic feasibility' gained the highest priority (32.3%). Following that, the second and third 8 ranks were resulted in 'Environmental impacts' (25.6%) and 'Technical feasibility' (24.0%), respectively. Lastly, the criteria 9 weights for 'Social impacts' resulted in the least important (18.1%).

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When considering the scores of preferable criteria by categorizing based on expert panels, it is noticeable that the results 11 could be divided into two groups. First, the group of governmental organizations, industry/business sectors, and financial 12 institutes, where the 'Economic feasibility' showed noteworthy high scores. The other was the expert groups that prioritized 13 'Technical feasibility' as the most preferable, as found in NPO/NGO and academic or research institutes. 14 Comparing 'Environmental impacts' and 'Social impacts', except for the group academic/ research institute, most of 15 the experts rated the 'Environmental impact' as more important than the latter. Interestingly, NPO/NGO showed more attention 16 to the technical aspects, as it can be seen the merely higher scores than those from economic and environmental criteria. On   The results of normalized evaluations of overall sub-criteria are shown in Figure 5. The top three priorities were occupied 9 by the sub-criteria from 'Economic feasibility' and 'Environmental impacts'. The highest priority was voted from 'Final price 10 per liter of ethanol' (12.8%), following by 'Added value of input materials' (11.7%) and 'Net energy balance' (11.3%). On the 11 other hand, the sub-criteria 'Food security' (6.2%) and 'Job creation' (4.5%) from 'Social impacts' were prioritized at the 12 lowest two criteria.  Table 5 presented the relative weights in respective main-criteria and overall relative weights of sub-criteria. The  In the dimension of economic feasibility, the experts prioritized 'Final price per liter of ethanol' as the most important 10 criteria (39.6%). This outcome identified the concern regarding the production cost of biofuel prices from agricultural residues.

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The concern was considered to be logical from the current status due to the fact that it is an under-commercialized technology 12 in Thailand, implying the lack of referenced market prices.   1 Besides the overall criteria prioritization, the sub-criteria weights were categorized separately into types of organizations 2 and branches of backgrounds (see Figure 6). In Figure 6, the relative weights of 12 sub-criteria were classified in the 5 groups

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Following that, for the academic and research institutes, the factor 'Biomass availability and collectability' was voted 10 for the highest priority (13.3%). Surprisingly, even though the representatives from academic institutes were allocated from the Unlike the other organizations, the governmental sector showed similar proportions in each criterion in terms of relative 1 weights allocation. There was no significantly high proportion among 12 attributes; however, the highest score was the 'Final 2 price per liter of ethanol' (13.7%). The retail price of biofuel affects governmental subsidization since Thailand uses the 3 mechanism to maintain the price gap between biofuel type and fossil fuel to promote consumption of renewable energy [133].

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Therefore, this criterion resulted in being attractive for policy-makers to consider cost-benefits at the national level.

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Interestingly, despite the results that the respondents from the governmental and academic sectors did not hold the points or requirements. For instance, this parameter could be interpreted as the profitable rate for the ethanol manufacturers, 1 whereas the ethanol price can indicate the necessary incentive to persuade consumers from the governmental perspectives.

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Looking at the connection between the highest voted criteria under each organization ( Figure 6) and the relationship 3 with their backgrounds (Figure 7), most of the participants from Academic/research hold the background of 'Technology and 4 project management' -voted for 'biomass availability and collectability' to be the most important. A similar result can be seen 5 from NPO/NGO, with the majority of backgrounds in 'Environmental impacts analysis' gave the highest priority to the same 6 criteria. The NPO/NGO were the organizations that engaged significantly with broad topics, including environmental, 7 bioethanol, energy policy, agriculture, and socio-economic aspects. The output from the NPO/NGO is motivating to involve 8 their perceptions in the early stage of policy-making process in order to avoid a possible disagreement towards public policy 9 implementation.

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Meanwhile, the experts from Industry and business sectors are associated mostly with 'Bioethanol and biofuel 11 production' as well as 'Energy policy'. Their prioritized criteria went to 'Net energy balance' from the environmental aspect.

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Following that, the most voted variable from the experts in the governmental sectors was 'Added value of input materials',

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although it can be seen that the related backgrounds were mainly located in 'Energy policy' and 'Agricultural production',

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The summary of further remarks is summarized in Table 6. It is remarkable that the most frequently selected criterion 9 by all participants was 'Dependence on subsidy'. The most attention receiving factor emphasized the perceptions towards the 10 role of government in the policy recommendation. Unsurprisingly, the technology readiness level resulted in the second most 11 votes. Regarding the current status that the second generation bioethanol progressed at the pilot scale-production, the result 12 suggested that it might still be too early for projection from their perceptions.

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The second and third most voted additional criteria were derived from technological feasibility, namely 'Technology 14 readiness level' and 'Co-products'. On the other hand, it is noticeable that the environment related criteria gained rather limited 15 priority, such as output wastes, forest areas, and fertilizers/ pesticides. In addition, the social aspect criterion, 'Job quality', was  Land prices -----0 1 Supplementary comments were compiled from the participants' opinions simultaneously in the surveying process. The 2 comments were summarized and elaborated by groups of experts in Table 7. It is noticeable that the raised-up viewpoints 3 reflected the insights based on their experiences. Some comments hinted at the underlying issues that should be properly 4 discussed across multi-sectors. As it can be noticed from the comments, the governmental role is crucial for endorsing the 5 strategic development of bioenergy. This involves governance-related elements, including laws and regulations that can support 6 the upcoming advanced technology and, more importantly, the incentivized system structure. Meanwhile, the participants also 7 emphasized the importance of competitiveness in the biofuel market from economic perspectives, which needs to be approached 8 for biofuel producers and market expansion for bioenergy. Moreover, several have mentioned factors, which have not been 9 provided in the current study, such as risk management and ethanol quality. Nonetheless, due to the concerns regarding under 10 commercialized status, the technical feasibility would need to be verified as a transformation threshold. These retrieved 11 comments were deemed to be valuable for creating future scenarios and evaluating for further study.
12 Table 7 Supplementary remarks from the participants categorized in branch of experts

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Group of experts Supplementary comments Government "Appropriate fuel price structure needs to be clarified." "Incentive by the government to promote project initiation." "Ethanol quality to be blended with the gasoline needs to be controlled for the reliability." Industry / Business sectors "The role of governmental policy is critical to take part in." "Mechanism analysis to drive the expansion of the biofuel market." "Products from the agricultural residues should not limit to only biofuel production, but the technology for value-added products should be integrated into the value chain." NPO / NGO "Other indicators for the analysis of environmental impacts can be specified by several indicators, such as conversion of GHG emissions per farming area, total GHGs from all production cycle by comparing the scenarios of fossil fuel and biofuels, and impact assessment on biodiversity." "Wastewater treatment should be concerned in the process." Academic/ Research Institute "There is a possibility that the weights of the criteria will change over time. The weights I provided are the opinions based on the assumption that the 2nd generation bioethanol is not a market-ready technology." "Even though the viability in the financial terms could be confirmed, technological feasibility is the imperative issue that has to be achieved." "The comprehensive study on risk management for commercialization of the secondgeneration bioethanol technology." Financial institution/ Bank "The criteria evaluation in the study is mainly focused on the supply side; however, the criteria evaluation from the demand side, which can influence ethanol consumption, should also be taken into consideration." "It is still questionable regarding the possibility for the advanced bioethanol to complying with the current law and regulations." "Is the level of competitiveness between the bioethanol producing corporates high  Regarding the most attentive aspect that was voted for economic feasibility, the reflection from the respondents to economic 9 viability could be contemplated from the supply and demand side. The supply side was likely inferred to the concerns towards 10 investment cost and financial attractiveness due to new emerging technology. A similar result was also remarked in the literature 11 studies that the investment cost is the most critical criterion for the economic aspect [111]. For the demand side, fuel price 12 instability could be a matter of concern for consumers. Belonging to the economic aspect, the biofuel price was the most focused 13 factor from overall relative weights.
14 When considering the cost structure of bioethanol, the raw material price can influence 40 -60% of the minimum selling   because of the concern regarding an effect on increasing commodity price that would become a burden for the consumers. This 15 has been a significant bottleneck to promote economic instruments for GHG mitigation [140].

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Considered to be the second-highest relative weights, the factor of added value in biomass emphasized the stakeholders'

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Regardless of the preferred aspect that the environmental impacts were highly ranked as the second priority, the factors 1 of land use change and GHG balance did not stand out at the top ranking of overall sub-criteria scores. Significantly, the criteria 2 regarding indirect land use change gained relatively low recognition from the governmental sectors, which are the key players 3 in the policy-making process. Currently, deforestation still has been remarked as a constant issue [144]. Despite the fact that 4 there is a forest preservation law in Thailand, namely Forest Act, B.E. 2484 [145], the land use for the agricultural industry still

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Meanwhile, the technical feasibility was voted as the third-ranked dimension. The scores for this criterion were mostly 12 given by experts from academic/research institutes who hold background knowledge mainly in technology and project 13 management, and from NGO/NPO with backgrounds in energy policy and agricultural production. Among the studied criteria,

14
the biomass availability was ranked at the fourth important of overall relative weights. However, this criterion is also a critical 15 factor for bioenergy promotion in Thailand, along with the importance of economic feasibility and environmental impacts 16 because it refers to the capacity and potential to develop productions from a stable supply [147]. Spatial data with the density 17 of available biomass would indicate the potential areas and optimal production scale [148], which also influences the economic 18 analysis. This factor is considered to be a key driver in decision-making for project implementation [149].

19
The surprising outcome was the weight of social impacts as ranked at the fourth concerning dimension. Based on this, it 20 is possible to illustrate that the awareness for the local benefits has not yet risen enough in the stakeholder's perspectives.

21
According to the study of conventional ethanol production from sugarcane, the socio-economic advantage was elucidated for

28
Not only the issue concerning fewer farmers working in agriculture, but unimproved production yields of sugarcane and 29 cassavas could also be reflective feedbacks from the bottom-up assessment, which could draw awareness from the policymakers.

30
Projecting for long-term sustainable development, it is necessary to address the investment of infrastructures, adequate 31 irrigation systems, and technology for mechanizing agriculture to achieve higher value-added products. These are essential 32 30 elements to transform the agricultural sector to the higher-level industry, as advised by the stakeholders in the supplementary 1 remarks, and could also, in turn, endorse employment in this sector.

2
From the additional indicators, as voted in this study, the governmental subsidy was the most additionally selected criteria.

3
This implied that energy policy or energy-related initiation relied heavily on the economic aspect, as the subsidization or price 4 incentive is the driver to be launched by the nation. In a sense, this result emphasized an essential role of government to 5 incentivize biofuel system promotion. Thus far, the government incentive has been located at only the retail level by inducing 6 the cross-subsidization scheme, subsidizing the biofuel selling price from non-blended fossil fuel selling [133, 151].

7
Nevertheless, considering the farmers' benefits, the price guarantee system for feedstocks providers or crops growers has 8 remained concerned [147].

9
The utilization of cellulosic residues in the biorefinery for further products is a possible option to increase alternative 10 incomes for the farmers and more channels to develop the higher-skilled labors in the agricultural sector [152]. One of the 11 potential scenarios is the promotion of utilizing regional biomass, which could encourage mixed feedstocks, providing the 12 possibilities to facilitate biomass handling and logistics [72]. Furthermore, as of the technological development corresponding 13 to added-value and co-products, the end-products could be extensively recommended for biochemical production. One of the 14 backgrounds is that the bioeconomy market is transforming over time, encouraging the biomass conversion technology to be 15 established for a broad range of biorefinery products, which can be a plus for the industries to have more flexibility [153].

16
Even though the commercialization of second-generation bioethanol as an emerging technology still needs advancement

23
The findings highlighted the importance of financial feasibility and environmental impacts from the overall results of the 24 prioritization. However, with respect to the results, it is also likely to determine that there are no significant differences between 25 the four main-criteria. The priority would not be equal, but the evaluation should not focus on only one dimension. Regarding 26 the fact that there is no perfect bioenergy strategy that would fit all requirements [55], the results as obtained from this study 27 might be used as the initial step to developing second-generation bioethanol. Particularly, due to a long term field burn severity 28 as seen in Thailand, the first focus that needs to be dealt with is the environmental aspects regarding the pollution from field 29 burning, which could be promoted to deploy the unutilized agricultural residues. This perspective scenario is believed to be an 30 opportunity for developing lignocellulosic biomass to promote the bioeconomy and mitigate environmental impacts.

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Conclusions 1 A development plan of bioethanol in Thailand has been promoted initially to substitute the imported fossil fuel and 2 encourage agricultural crop production in the energy sector. However, biofuel production has focused very little on the aspects 3 of socio-economic impacts and environmental side effects. In order to create a sustainable framework to meet the goal of 4 bioethanol production and ensure the long-term benefits for related stakeholders, the multidisciplinary dimensions and criteria 5 have become more necessary to be incorporated in the policy-making.

6
The participatory evaluation through the Delphi-AHP approach has accomplished the main objective of the study to 7 prioritize the criteria for second-generation bioethanol development. The Delphi survey process verifies the advantage of 8 anonymity in the survey conduction, which encourages the respondents to share their opinions openly. At the same time, the 9 AHP technique has proved a convincing performance in transforming the subjective opinions into multi-criteria prioritization, 10 which enables the present study to obtain the most reflective indicators representing transdisciplinary perceptions of experts.

11
Even though the scattered perceptions from different backgrounds are commonly noticeable, the Delphi-AHP technique could 12 reduce conflicts and provide agreeable results by the consenting process.

13
The findings from the study of criteria prioritization demonstrate the stakeholder's priority towards new generation 14 bioethanol, suggesting the key indicators to be taken into consideration when putting the advanced technology forward to policy 15 implementation. As a result, it is confirmed that the economic feasibility is the essential aspect of project analysis. Especially,

20
The application of AHP did its work to reflect the perceptions regarding current concerns and the prospect of scenarios 21 suggestion, which can be compatible with the future biofuel development in Thailand. The outcomes from the current analysis 22 are believed to be references for creating a second-generation bioethanol analysis framework as a future step. With the 23 integration of multi-dimensional perspectives from stakeholders, it is possible to construct an effective process for bioenergy 24 policy to be consented by the stakeholders and attain the GHG mitigation goals, while the tradeoffs could be minimized.