ABSTRACT. Keywords: Biofuel, biomass, gasification, efficiency, Life Cycle Analysis (LCA), techno-economic evaluation. 1.

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1 Selection of the best Biomass-to-Bioenergy route for its implementation in the European Energy sector. An Integrated Efficiency, Economic and Environmental Analysis Anna Sues, Hubert J. Veringa Chemical Engineering and Chemistry, Environmental Technology Group TU/e Eindhoven University of Technology Eindhoven, North Brabant 5600 MB, the Netherlands ABSTRACT Biomass availability is rather limited in Europe and, hence, it is of crucial importance to determine the optimal biomass-toenergy conversion pathway. This selection is somehow complex as there could be antagonistic motivations coming from industrial stake-holders, politicians, scientists or the society. Consequently, the aim of this paper is to present different biomass-to-biofuels alternatives that follows various economic, environmental and/or social drivers. Results are also compared with European Directives 2001/77/EC and 2009/28/EC. In General, maximizing bio-electricity over other biofuels turns out to be the best economical and environmental option. Combined with solar and wind energy, about 31% of the electricity production by 2020 could be renewable, i.e., 10 points higher than the target of Directive 2001/77/EC. If biomass is conducted to SNG production, fossil natural gas imports could be reduced by 1.63 EJ/yr in 2020, although this alternative implies higher costs and less CO 2 savings than the previous bio-electricity solution. In case of promoting Fischer- Tropsch fuels, the share of biofuels in transport will be 9.5%, which is slightly below the 10% share target of Directive 2009/28/EC. H 2 is disregarded as feasible option for transport due to several technological barriers, although it would lead to substantial CO 2 savings at a moderate price. Conversely, methanol results in the worst environmental solution as CO 2 emissions are larger than those of conventional fossil fuels. Keywords: Biofuel, biomass, gasification, efficiency, Life Cycle Analysis (LCA), techno-economic evaluation. 1. INTRODUCTION Among all renewable technologies, biomass is the only source that could be used to produce biofuels for the transport sector. However, unlike wind or solar energy, biomass availability is limited and, hence, it is of crucial importance to select the most convenient biomass-to-biofuel conversion route. Nowadays, 2 nd generation biofuels, and gasification technology in particular, are gaining interest for its implementation in the medium-term future due to its potentially higher efficiency and lower cost and CO 2 emissions. In this paper we present the evaluation of five biofuels (i.e., Syntethic Natural Gas (SNG), methanol (MeOH), Fischer-Trospch fuels (F-T), H 2 and electricity) for their introduction in the European Energy sector by The most convenient biomass-to-bioenergy technology will be selected following technological, economic and environmental drivers. In Europe, forest and agricultural residues are stochastically distributed, leading to definite areas where the concentration of biomass differs substantially among them. In some cases, those areas do not correspond with the established country borders and, hence, new bio-borders are suggested to maximize the amount of biofuels that can be later produced in Europe. This re-drawing is especially sensitive for the processes that require a relatively large scale in order to operate at a more competitive price (e.g., Fischer-Tropsch or methanol plants). SNG and hydrogen production are profitable at medium plant sizes, thus giving a combined national and bio-borders scenario. Similarly, since logistics costs have a major impact in electricity final price, borders follow also a combined scenario. Once the bio-border for different biofuels and biopower production is determined, the next step is to identify which alternative is the best for the European energy market. Answering this question is somehow complex as the society, the scientific community, industry, or the politicians have their own motivations. In this paper, biofuels or bioelectricity implementation within European countries is discussed under the several scenarios presented in Table 1. When co-firing is prioritized (i.e., scenarios I-A, II, VI), coal is replaced up to 10% in weight basis. In other scenarios, less coal is replaced as biomass is primarily consumed for biofuels production. Table 1: Biofuels and bioelectricity scenarios, which takes into account preferences from industry, politicians, scientists or the society. Code Preference Description I-A I-B II III IV V VI VII VIII Max. bioelectricity production (a) Potential biofuels introduction in the medium-term Max. biofuels (b) share in transport Max. FT-diesel (Oil companies) Max. SNG production Hypothetical (c) max CO 2 reduction Max. Hydrogen production Max. MeOH production A fraction of biomass is used for co-firing and the rest is send in new BIGCC (d) All biomass is used in new BIGCC A fraction of biomass is used for co-firing. The rest is consumed in new FT plants, and remainings for SNG production. Biomass is primarily consumed in new FT plants. The rest is used for SNG plants. Biomass is primarily consumed in new FT plants. The rest is used for cofiring. Biomass is primarily consumed in new SNG plants. The rest is used for cofiring. Our initial hypothesis is that maximal CO 2 reduction is obtained when a fraction of biomass is used for co-firing and the rest for SNG plants. However, later analyses will confront our initial hypothesis. Biomass is primarily consumed in new H 2 plants. The rest is used for cofiring. Biomass is primarily consumed in new MeOH plants. The rest is used for cofiring (a): According to the European Directive 2001/77/EC, about 21% of the electricity must be produced from renewable sources by 2010 in EU25. (b): According to the European Biofuels Directive (2003/30/EC), the share of biofuels in transport should achieve the target of 10% by (c): The EU countries have committed to reduce greenhouse gas emissions during the first Kyoto commitment period by 5% compared to the 1990 reference year (COM 2006). (d): New plants refers to new BIGCC (Biomass Integrated Combined Cycle) plants that will operate on 100% biomass (i.e., no co-firing). 1

2 Figure 1: Overview of the 5 biowaste-to-biofuels conversion routes (W and Q represent work and heat flows, respectively) [1]. 2. BIOFUELS TECHNOLOGY SELECTION The five different biomass-to-biofuels routes have been modeled in Aspen Plus. The corresponding diagram block of each process is depicted in Figure 1. In all cases, pre-treatment is required to adjust particles size and moisture content to 10%. Gasification is the core operation unit for the 5 biofuels chains although the working conditions, the oxidizing agent (i.e., steam, air or O 2 ) and its design are different among them. After gasification, biomass is converted into the so-called syngas, a mixture of mainly CO and H 2, although other gases such as CO 2, CH 4, C 2 H 6 or C 2 H 4 are also produced. In subsequent units, undesired by-products (mainly H 2 S, NH 3, and HCl) are removed in order to avoid deactivation of the catalysts used downstream, damage engines, boilers or turbines, as well as to minimize SO x and NO x formation when burning remaining unconverted gases. In all the production chains, H 2 S is removed at 55 o C and 1bar in a MDEA scrubber system, and the solution is regenerated in a stripping column working at 110 o C and 2 bar. MDEA is selected due to its low energy requirement for regeneration and higher selectivity over H 2 S compared to CO 2. In fact, at this stage of cleaning, CO 2 removal is not desired as this gas is a reactant for some downstream catalytic reactors. NH 3 is removed in a subsequent unit using a H 2 SO 4 solution. HCl and other halogens can be removed by injecting sodium or calciumbased powdered absorbents into the gas streams and by removing them in the de-dusting stage (e.g., cyclones). After the cleaning stages, the H 2 :CO ratio is adjusted in a WGS (watergas-shift) reactor by adding a specific amount of superheated steam. Outlet gases then undergo a series of catalytic reactions in a specific reactor for each biofuel. Later stages of the process comprise upgrading and final compression in order to achieve the specifications imposed by the market. For the electricity generation process, syngas leaving the gasifier is cleaned and then send to a combine Brayton-Rankine cycle. A single expansion turbine is used for the Brayton cycle where exhaust gases are expanded from 1200 o C and 15 bar to 1 bar and ~ 605 o C. This remaining hot stream is used to provide part of the heat required for the Rankine cycle, in which three steam turbines are operated with inter-heating. In this cycle, steam is expanded from 200 bar to ~ 0.07 bar. Moreover, for a better overall process efficiency, heat supply and demand are carefully matched so that more high quality heat is left to produced superheated steam that will be later used for electricity production (Rankine cycles), steam gasification, biowastes drying, and H 2 :CO adjustment in the WGS reactors. In particular, a considerable amount of heat is recovered after gasification as the syngas needs to be cooled down prior to cleaning and compression stages. Another source of heat is taken during cooling of methanation and Fischer-Trospch or methanol reactors. However, extra fuel is still needed to cover the energy demand of the biofuels plant. In previous studies, we have evaluated to burn either an extra amount of biomass or 2

3 natural gas to meet energy requirement of the plants. Our results show that the best configuration is to burn an extra amount of biomass and take electricity from the grid. 3. OWN MULTIDIMENSIONAL 3-E MODEL: INTEGRATION OF EFFICIENCY, ECONOMIC AND ENVIRONMENTAL PARAMETERS 3.1 Model definition Sustainability of a process is rather difficult to evaluate and quantify as many factors are involved and they are also given in different units. For instance, environmental impact is measured in ppm (or gco 2 eq/kg biofuel for the case of global warming evaluation), whereas production costs are given in /GJ biofuel, and efficiency is calculated as the ratio of energy output divided by the energy input (i.e., MW output /MW input ). Hence, conversion factors are required if we intend to give one unique parameter in order to be able to communicate with scientists, legislators and economists at once. In our model, mass and energy balances from Aspen Plus simulations are used to calculate exergetic and energy efficiency of the 5 biofuels conversion routes (i.e., SNG, MeOH, FT, H 2 and electricity), as shown in the left-hand sequence of Figure 2. Aspen Plus simulations are coupled to Aspen Icarus in order to calculate the biofuels production price ex-works. This price is determined by fixing and investor internal rate of return (IRR) of 12%, and with 50% of capital leverage (i.e., 50% of the TCI is borrowed from banks). Final end-user price is obtained by adding logistic and distribution costs. Those calculations are iterated for different plants sizes (i.e., from 1 to 5000 MW fuel ) and 24 European countries in order to determine the optimal plant scale and location for each biofuel. In the last stage, environmental impact of each configuration is integrated into the economic evaluation by calculating an ecotax value (i.e., /ton CO 2 that would equalize biofuels and conventional fossil fuel price). 3.2 Model application to Europe The multidimensional model of previous section 3.1 is applied to Europe to select the best scenario of Table 1. For that purpose, several stages are needed (see Figure 2, right-hand sequence). Firstly, forestry and straw residues availability within 24 European countries is calculated from different values found in literature [2-7]. Subsequently, total biofuel and/or bioelectricity generation in Europe is determined by applying efficiency values from our model. Produced biofuels can substitute part of the fossil fuels consumption by 2020, although their share will be different for each scenario in Table 1. In any case, fossil energy is still needed in order to meet the energy demand by 2020, whose values have been stipulated in the report of Mantzos et al [8]. In particular, we assume that biofuels and bioelectricity can be introduced in 3 sectors: Electricity production from coal (i.e., 3.77 EJ/year). This figure implies that about 8.34 EJ/yr of coal is consumed. Natural gas consumption for several uses (e.g., electricity, heating, or other industrial applications), which accounts for EJ/year Fossil fuel consumption in the road transport, which sums EJ/year. This figure includes public road transport, private cars, motorcycles, and trucks. Optimal biofuels plant scales are deducted from the iteration of our model in section 3.1. This parameter, together with biomass availability across Europe, fixes the number of plants that could be built in each scenario in Table 1, which in turn, allows the calculation of total capital investment (TCI). Following the profitability analysis of our model (i.e., IRR equal to 12%), final end-user prices for each biofuels and country are obtained. However, since biofuels prices are always higher than conventional fossil fuel prices, governmental subsidies would be needed to equalize prices and do not charge the final consumer. An alternative to public assistance is to calculate an ecotax (i.e., /ton CO 2 ), which would notably penalize fossil fuels as their CO 2 emissions are notably higher. 4. RESULTS Results are presented following the structure of previous section 3. Hence, the first section of this paper is dedicated to the individual values for each biofuel, whereas the second part includes results of the different scenarios in Table 1. Figure 2: Schematic representation of our model. 4.1 Specific biofuels efficiency, final price and ecotax Figure 3 depicts the final biofuel end-user price for a specific country and at different plant sizes. However, it should be mentioned that the represented biofuels prices accounts only for Austria, which is in the average side together with Eastern countries. In effect, biofuels production turns out to be economically more competitive in Southern, Baltic countries and UK, biofuels, whereas it is notably more expensive in Northern and Scandinavian states. This Figure 3 is completed by representing the effect of scale on the efficiency of the processing plants (i.e., right y-axis). As observed, both parameters are intrinsically connected as higher efficiencies are translated into lower Total Production Costs (TPC). Moreover, according to the William s equation, TCI does not follow a straight line when increasing the plant size. On the contrary, it is represented by an exponential relationship with a scaling factor 3

4 in the range of 0.4 to 0.8. Conversely, logistics are directly dependent on the scale, whereas distribution costs are assumed to be constant (i.e., 3.61 /GJ SNG, 3.44 /GJ FT, 4.32 /GJ FT, 10 /GJ H2, 0.01 /GJ elec ). Figure 3 also identifies the optimal plant scale for each biofuel. As observed, electricity and SNG production is more profitable at lower sizes (i.e., 100 and 200 MW fuel respectively), followed by H 2 (i.e., 500 MW H2 ), whereas MeOH and FT-fuels generation require larger plants (i.e., 1000 MW fuel ). Comparison among biofuels reveals that SNG and electricity prices are on the lowest side (i.e., 19 and 23 /GJ respectively for Austria). Conversely, FT-fuel, MeOH and H 2 are more expensive and yield close values (i.e., 26, 27 and 28 /GJ). However, it should be mentioned that H 2 price is much higher than SNG due to its intensive distribution costs. Similar conclusions can be drawn in terms of exergetic efficiency. In effect, SNG and electricity production is more efficient (i.e., up to 45.5% for both biofuels), followed by MeOH and FT (i.e., up to 43.9%). Hydrogen efficiency (i.e., 42.5%) is notably penalized by the compression requirements of the pipelines distribution system. Results for the rest of European countries follow similar trends, although, as aforementioned, quantitative values are different for each country. Same analysis is done for straw residues in Figure 4, where it is observed that prices are always higher due to lower efficiencies and larger pre-treatment and logistics costs. Biofuel production price EX-WORKS 140 /GJ 120 /GJ 100 /GJ 80 /GJ 60 /GJ 40 /GJ 20 /GJ 0 /GJ 0 MW Effect of plant size on final END-USER price and exergetic efficiency 100 MW 200 MW 300 MW 400 MW Plant size 500 MW 600 MW 700 MW 800 MW 900 MW 1,000 MW Price-SNG Price-H2 Price-FT Price-MeOH Price-Elec Eff-SNG Eff-H2 Eff-FT Eff-MeOH Eff-Elec Figure 3: Final prices and exergy efficiency for wood-based biofuels. Biofuel production price EX-WORKS 140 /GJ 120 /GJ 100 /GJ 80 /GJ 60 /GJ 40 /GJ 20 /GJ 0 /GJ 0 MW Effect of plant size on final END-USER price and exergetic efficiency 100 MW 200 MW 300 MW 400 MW Plant size 500 MW 600 MW 700 MW 800 MW 900 MW 1,000 MW Price-SNG Price-H2 Price-FT Price-MeOH Price-Elec Eff-SNG Eff-H2 Eff-FT Eff-MeOH Eff-Elec Figure 4: Final prices and exergy efficiency for straw-based biofuels. 48% 46% 44% 42% 40% 38% 36% 34% 32% 30% 48% 46% 44% 42% 40% 38% 36% 34% 32% 30% Exergetic efficiency Exergetic efficiency When biomass availability is taken into account, it is observed that few countries have enough biomass to feed any biofuel plant at its optimal production scale. This assertion is especially sensitive for FT and MeOH production as both biofuels require large amount of biomass to run plant scales of 1000 MW fuel. In effect only Spain, France, Italy, Austria, Germany, Poland, Sweden, Finland, UK, Hungary and Romania can feed either wood or straw-based biofuels plants using own biomass sources (see Figure 5 and 6). Alternatively, biomass could be also imported from nearby regions, as done in next section 4.2. However, in some cases, CO 2 emissions could exceed the threshold of fossil fuels. Figure 5. The colors identify that at least 1 plant can be fed with national forest residues. Figure 6. The colors identify that at least 1 plant can be fed with national straw residues. For the case that biomass is not imported, relative ecotax (i.e., /ton CO 2 ) are found in the range presented in Table 2. This ecotax does not correspond to the Carbon taxes that are levied from companies exceeding the limits of CO 2 emissions. In fact, is a virtual value that we have calculated in order to charge CO 2 emissions and equalize biofuels and fossil fuels prices. Hence, it should be added in top of production costs. Calculated ecotax values are notably high as biofuels and fossil fuels price difference is rather substantial. Bio-electricity production turns out to be an exception as, for some countries, bio-based price is cheaper than coal-based power price (i.e., all countries except Austria, Bulgary, Baltic states, Sweden, Finland and France). Concerning SNG production, Sweden is the only country where bio-based SNG is cheaper than fossil natural gas. Table 2: Ecotax ranges for wood and straw-based biofuels ( /ton CO 2). Biofuel / Feedstock Forest wastes Straw Electricity 0 to 53 0 to 32 SNG 51 (*) to (*) to 373 FT-fuels 152 to to 640 MeOH 198 to to 900 H 2 9 to to 233 (*) Ecotax for Sweden is 0 as SNG is cheaper than fossil gas. On the other hand, the LCA analysis reveals that less CO 2 is emitted (in terms of kg-eq CO 2 /GJ fuel ) during SNG production, followed by electricity and H 2 generation. Notably higher CO 2 emissions are released for FT and MeOH mainly because a larger amount of biomass needs to be transported and biofuel distribution is done by means of trucks, which consume fossil diesel. In countries where biomass availability density is (i.e., kton/km 2 ) is scarce, CO 2 emissions exceed those of the corresponding fossil fuel. In effect, wood-based MeOH and/or FT production in Sweden and Finland release more CO 2 than fossil diesel as biomass collection distances are considerable. 4

5 Same observation applies for straw-based MeOH and FT generation in Poland, Germany and Spain. This fact could be minimized by importing biomass from nearby regions, as suggested in section Biofuels introduction into the European Energy market The model of Figure 2 is applied in this section to determine maximum bioenergy production when all available forest and straw residues are consumed, and following the scenarios of Table 1. However, values of each scenario correspond to the maximum theoretical production that could be achieved if all available biomass could be purchased. In effect, unlike solar and wind energy, biomass is normally owned by individuals or holdings, which ultimately decide its final application and price. For an optimal utilization of biomass sources in electricity generation, two short-terms scenarios are analyzed. In the first case (i.e., scenario I-A), it is assumed that 10 wt% of the coal consumed in power plants is substituted by the corresponding amount of straw, and the remaining part together with forestry residues are used in potentially new BIGCC plants operating at the optimal scale of about ~100 MW el. Electrical efficiency (η el ) of co-firing plants is negatively affected by 4% when introducing 10 wt% of straw. Efficiencies of new bio-based BIGCC stations attain lower values, i..e, 42% and 36% for wood and straw (see Figure 3 and 4). In the second case (scenario I-B ), biomass sources are fully consumed in potential new BIGCC plants. Hence, in this case, no co-firing is envisaged and energy efficiencies of coal plants are not affected (i.e., 45.2% [8]). Table 3 presents the share of renewable electricity generated in these 2 scenarios. In both tables, x and y represent the wood and straw fraction that is used in cofiring plants. By definition, in scenario I-B, x and y fractions are both 0%. In all cases, final electricity outcome (renewable + fossil) should at least equal 3.77 EJ/yr, which accounts for the predicted coal-based electricity generation by 2020 [8]. Table 3: Share of renewable energy (i.e., bio-electricity or biofuel production divided per total energy (a) ) for the each scenarios of Table 1. Scenarios % renewable energy in Biomass in co-firing natural road electricity total gas fuel I-A x=0,y=26% 28.9 % 0.0% 0.0% 3.0% I-B x=0,y= % 0.0% 0.0% 3.0% II x=0,y=26% 5.1% 0.4% 8.1% 3.4% III x=0,y=0 0.0% 0.3% 9.5% 3.3% IV x+y=5.7% 1.2 % 0.0% 9.5% 3.3% V x+y=1.9% 0.1 % 6.3% 0.0% 3.7% VI x=0,y=26% 5.1 % 5.5% 0.0% 3.7% VII x+y=4.6% 0.3 % 0.0% 10.3% 3.5% VIII x+y=6.3% 1.1 % 0.0% 5.6% 2.0% (a) Total energy equals to 3.77 EJ/yr of coal-based electricity, 25.9EJ/yr of natural gas and 15.1 of fossil road fuels by 2020 in Europe. According to results from Table 3, the share of renewable electricity produced from biomass (i.e., 34.3%) is the largest for the second scenario I-B, in which no co-firing is planned. In effect, notably less coal is needed to fulfill total power outcome of 3.77 EJ/yr. Conversely direct co-firing (i.e., I-A ) has the limitation of 10% coal substitution by biomass. Combined with solar and wind energy, about 31% of the electricity production by 2020 could be renewable, i.e., 10 points higher than the target of Directive 2001/77/EC. The third scenario II refers to maximizing the introduction of biomass into the energy market with minor changes in the actual infrastructure. In this case, about 10 wt% of coal consumed in existing coal-fired power plants is replaced by the corresponding straw amount. The remaining biomass fraction is then used for new bio-based FT-plants which would operate at the optimal scale of 1000 MW fuel. In scenarios III and IV FT-fuels production is prioritized and biomass leftovers are used for either SNG or cofiring respectively. As expected, higher biofuel share is obtained in the III and IV (i.e., 9.5%) as more biomass is available for FT-production. The 9.5% biofuels share is slightly behind the 10% European target established in the Directive 2009/28/EC. Maximal SNG production, at the optimal scale of 200 MW SNG, is obtained in scenario VI (i.e., SNG share of 6.3%). For this analysis, all available wood and straw residues are primarily converted into SNG plants, whereas the leftovers are used in co-firing stations. In the scenario V, preferences are exchanged and, thus, less biomass is ready for SNG production (i.e., SNG share of 5.5%). If H 2 and MeOH (i.e., scenario VII and VIII ) are produced for road transport, the corresponding biofuels shares attain 10.3 and 5.6 % respectively. The share of H 2 is notably high due to the expected better efficiencies of fuel cell cars (FCV). However, it should be mentioned that the introduction of H 2 in the energy market is predicted for a long-term future. Therefore, is highly probable that biomass would be already consumed in other processes, thus, reducing the possibility of producing bio-h 2. When comparing the share of renewable energy in the total energy (see last column in table 3), it is observed that MeOH, followed by maximal electricity (i.e., I-A and I-B ) and FTfuels production (i.e., II to IV ) lead to the lowest total renewable share, whereas SNG attain the highest value. However, when taking into account that a diesel-fuelled car has an efficiency of about 22%, and natural gas-fuelled power plants work at less than 60% efficiency, the conclusion is then different, as more useful renewable energy is produced in the I-A and I-B cases. On the other hand, a LCA analysis reveals that the maximal renewable share in scenario V does not correspond to the maximal CO 2 savings. I-A I-B II III IV V VI VII VIII REF-fossil 4,300 Comparison of CO 2 Emissions & Savings of each scenario 4, , , , ,139 Mton CO2 / year CO2 Emissions from fossil fuels CO2 Emissions from bioenergy CO2 Savings 4,800 4, , ,100 Figure 6: CO 2 emissions (from fossil & biofuels) and savings ,200 5

6 35 /GJ Average biofuel price as a function of the scenario 5. CONCLUSION & DISCUSSION 30 /GJ 25 /GJ 20 /GJ 15 /GJ 10 /GJ 5 /GJ I-A I-B II III IV V VI VII VIII Road fuel Electricity Natural gas / SNG Average REF-fossil-electricity REF-fossil-N.gas REF-fossil-road fuel REF-fossil-average Figure 7: Average fossil/biofuel prices for each scenario. Extra payment (Billion /year) Comparison based on biofuels/fossil fuels price difference (left-axis) & ecotax (right-axis) Extra payment ( /yr) Ecotax I-A I-B II III IV V VI VII VIII Figure 8: Annual extra payment (grey bars) due to biofuels and fossil price differences. Calculated ecotax ( /ton CO 2) is given by black bars. In effect, as shown in Figure 6, bio-electricity production is a better alternative from an environmental point of view as ~ 361 to 491 Mton CO 2 are avoided annually. The V scenario is now the third best candidate with CO 2 savings of 145 Mton/yr. Average scenarios biofuels/fossil fuel prices are also compared in Figure 7, where biofuel prices are assumed to be free from taxation. Annual extra payment, which is due to difference in biofuels and fossil prices, is given by grey bars in Figure 8. As observed, average electricity price difference is notably higher in the I-B than in the I-A scenario. This extra costs account for 3-4 Billion annually for the 24 European countries. In effect, bio-based electricity generation, especially when produced in new BIGCC plants, is more expensive than conventional coal power production. Black bars of Figure 8 represent the ecotax that would equalize fossil and biofuels prices (in /ton CO 2 ). In this case, the I-B scenario implies the lowest ecotax (i.e., 7 /ton CO 2 ), closely followed by the I- A case (i.e., 8 /ton CO 2 ). H 2 would be the subsequent second best alternative although, as aforementioned, H 2 -fuelled FCV will not be commercialized in the coming years. Moreover, prioritizing co-firing over extra biofuels production is a better solution (i.e., II versus III and IV scenarios for FT, and VI versus V for SNG). Methanol (i.e., VIII ) is completely disregarded as not only its price is high, but also it pollutes more than fossil diesel due to the low efficiency of MeOH-fuelled FCV Ecotax ( /ton CO2) Individual biofuels evaluation reveals that SNG and electricity yield the highest exergetic efficiencies when using wood as feedstock (i.e., ~ 45.5%). This statement is translated into the lowest biofuel prices (i.e., and /GJ for SNG and electricity respectively in Austria) and required ecotax. However, when the analysis is extended to consume all available forest and straw residues in Europe for energy purposes, bioelectricity production turns out to be the best alternative from an economic and environmental point of view. In effect, about 391 to 461 Mton CO 2 are saved each year when biomass is used in either co-firing or new BIGCC plants (i.e., I-A scenario) or all biomass for new BIGCC plants (i.e., I- B ) respectively. The corresponding biofuels and fossil prices differences are also the lowest for both scenario, i.e., 3-4 Billion /year respectively, with ecotax lying in the range of 7-8 /ton CO 2. It is also observed that co-firing is preferred over extra biofuels production when the aim is to increase CO 2 savings. On the other hand, if bioelectricity is summed to solar and wind energy, about 31% of the electricity production by 2020 could be renewable, i.e., 10% points higher than the target of Directive 2001/77/EC. In case of prioritizing FT-fuels production (i.e., scenarios III or IV ), the share of biofuels in transport will be 9.5%, which is slightly below the 10% share target of Directive 2009/28/EC. REFERENCES 1. Sues, A., M. Jurascik, and K.J. 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