Table 1 Characteristics of selected biofuel options and their development status[2],[5],[11]-[13]
From: Benchmarking biofuels—a comparison of technical, economic and environmental indicators
Raw materials | Main conversion steps/plant concept | By-productsa | R&D | Status of technical developmentb | Plant capacityc | Installed capacity | biofuel production worldwided | Installed capacity | biofuel production EUd | |
|---|---|---|---|---|---|---|---|---|
Liquid biofuels | ||||||||
Biodiesel (FAME) | Oil crops (e.g., rape, soya, palm), animal fats, waste oils (UCO, grease), algae and micro oils | Oil extraction (mechanical/solvent), oil refining, trans-/esterification, biodiesel cleaning and upgrading | Press cake/extraction meal, glycerine, salt fractions, fatty acids, oleochemicals | Process optimisation with regard to e.g., oil quality, catalysts, auxiliary substitutionj | Commercial TRL 9 | 2–350 MW | 1,835 mn GJ a−1 | 624 mn GJ a−1 | 823 mn GJ a−1 | 336 mn GJ a−1 |
Hydrotreated vegetable oils (HVO) or hydroprocessed esters and fatty acids (HEFA) | Oil extraction (mechanical/solvent), oil refining, hydrotreating of oil, isomerisation | Extraction meal, fractions like naphtha, propane/butane, waxes | Raw material diversification (e.g., algae, micro oils, hydrothermal oil), co-refiningk, process optimisation with regard to e.g., catalysts, H2 demand | Commercial TRL 9 | 255–265 MW (150–1,220 MW) | 102 mn GJ a−1 | n.a. | 65 mn GJ a−1 | 46 mn GJ a−1 (estimation) | |
Bioethanol (conventional) | Sugar (e.g., beets and cane) or starch (e.g., corn, wheat, rye) | Sugar extraction or hydrolysis/saccharification, C6 fermentation, distillation, final dehydration | From sugar based e.g., bagasse and vinasse From starch based e.g., gluten, DDGSf biogas/biomethane, technical CO2g | Process optimisation with regard to e.g., upgrading stillages and by-products | Commercial TRL 9 | 38–450 MW | 2,403 mn GJ a−1 | 1,869 mn GJ a−1 | 179 mn GJ a−1 | 123 mn GJ a−1 |
Bioethanol (lignocellulose) | Lignocelluloses (e.g., straw, bagasse, wood, switch grass) | Pretreatment (e.g., hydrolysis, thermal, acid), saccharification, C6/C5 fermentation, distillation, final dehydration | Intermediatesh like lignin, pentoses, fertiliser biogas (P&Hi), technical CO2 | Upscaling, applications for lignin (e.g., conversion to fuel, chemicals or for P&H), pentoses, enzyme use and efficiency increase | Demonstration TRL 7 | 0.5–5 MW (35–100 MW) | 2,96 mn GJ a−1 | n.a., often only test campaigns | 0,51 mn GJ a−1 | n.a., often only test campaigns |
Synthetic biomass-to-liquids (BTL) | Lignocelluloses (e.g., wood, straw, mischanthus), black liquor | Pretreatment (e.g., mechanical, drying, pyrolysis, hydrothermal), gasification, gas treatment, synthesis (e.g., Fischer-Tropsch, FT), hydrocracking, distillation, isomerisation | From FT: waxes, naphtha, P&H | Upscaling overall concepts but downscaling of synthesis and upgrading units Process optimisation with regard e.g., to syngas treatment, efficiency increase, final fuel treatment | Pilot for FT fuels TRL 6 | 0.8–5 MW (40–300 MW) | 1 mn GJ a−1 | n.a., often only test campaigns | No plants running |
Gaseous biofuels | ||||||||
Biomethane/biogas | Residuese (e.g., biowaste, manure, stillage) | Silaging, hydrolysis (optional), anaerobic digestion, gas treatment and upgrading | P&H, digestate, fertiliser fractions | Process optimisation with regard to e.g., methane yields, enzyme use, gas treatment | Commercial TRL 9 | 0.5–50 MW | 60 GJ a−1 | n.a. | 38 GJ a−1 | 36 GJ a−1 (estimation) |
Biomethane/synthetic natural gas (SNG) | Lignocelluloses (e.g., wood and straw) | Pretreatment (e.g., mechanical, drying, gasification, gas treatment, synthesis (methanation), gas upgrading | P&H | Upscaling, process optimisation: with regard to e.g., syngas treatment, efficiency increase, adaption to decentralised concepts | Demonstration TRL 7 | 1–10 MW (20–200 MW) | Not realised outside Europe | 0,092 mn GJ a−1 | n.a., often only test campaigns |