Abstract The Feasibility Study of Commercial Algal Fuel Production in China Pu Peng - Research Institute of Petroleum Processing, SINOPEC, Beijing 100083, China The shortage of feedstock such as rape, soybean and palm, etc. for 1st generation biodiesel (refer to FAME, fatty acid methyl ester) production is the main bottleneck impeding the development of sustainable liquid bio-fuel. There was eager for seeking the next generation bio-fuel based on the energy crops like Jatropha curcas Linnaeus (JCL) planting on marginal land and microalgae like Chlorella cultivating on the ponds located on the mudflat or desert. However, the prospective productivity of biomass, transport fuel and by-product derived from JCL/Chlorella are still unclear and even confused according to literature review. The content of protein and polysaccharide in microalgae are usually higher than those of oil-producing crops such as palm and JCL. But for the lipid fraction (solvent extraction), both include a large part of components which are difficult to be transesterified or esterified to form FAME. Therefore, it was strongly suggested that not only FAME but also Fischer-Tropsch ( FT ) fuel and bio-electricity all should be considered as the sustainable energy sources to maximizing the yield of algal energy. The whole algal biomass including lipids (extracts) and by-product (residues) could be processed to produce various forms of sustainable bio-energies such as bio-hydrogenated diesel (BHD), FT-fuel, bio-gas, bio-power and bio-heat instead of biodiesel (FAME) only. Otherwise, the net energy ratio (NER) and net energy balance (NEB) are hardly larger than one and positive, respectively, if the energy from by-product was not accounted according to the life cycle inventory (LCI) analysis of the algal energy producing process. On the other hand, an integrated anaerobic digestion (AD) and gas to liquid (GTL) process were also considered，in which 32% methane (purity: 96%) produced from AD stage using microalgae cake (moisture: 70%) was converted to FT-oil in GTL stage to replace pipeline natural gas (purity: 94%) as the bio-fuel feedstock. Comparative evaluation of AD-GTL combined process with other process such as direct biomass to liquid (BTL) process and EST-AD process (AD stage was added after esterification (EST) stage to treat the residues unable to be esterified in the microalgae) was also presented and discussed. The productivity of algal biomass and the yield of algal fuels were the most important two issues. The former is more difficult to be resolved in the near future. There is a long way to go for either Jatropha or Chlorella to become real next feedstock at the scale corresponding to 1st generation feedstock. China is located in subtropical zone so that much more land or pond would be established and used to produce same amount of algal fuel in Southeast Asia such as Thailand, Indonesia and Malaysia to get enough biomass. Productivity of algal biomass (10~20 ton per hectare) have to be improved dramatically by developing most promising algal species with high grow rate, pond or PBR with novel designing, effective harvesting and separating techniques with low energy consuming and finding more non-arable land, mudflat or desert suitable to algal cultivation so as to realize commercial algal fuel production in an economic viable and environmentally friendly way.
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