4/4/20131 Sustainable energy sources 6 CO2 + 6 H2O + energy ? C6H12O6 + 6O2 Incident solar energy = 178,000 Twatts = 15,000 times global energy demand Photosynthetic efficiency = 11%, theoretical = 3 6%, actual Plants fix 2E11 tons CO2/year and store 70E3 MTEP, which is 10 times global energy needs. Document Preview: 4/4/20131 Sustainable energy sources 6 CO2 + 6 H2O + energy ? C6H12O6 + 6O2 Incident solar energy = 178,000 Twatts = 15,000 times global energy demand Photosynthetic efficiency = 11%, theoretical = 3 6%, actual Plants fix 2E11 tons CO2/year and store 70E3 MTEP, which is 10 times global energy needs. Biomass Sustainable energy sources Biomass for bioenergy production: -Wood -Agricultural crops -Crop wastes -Animal wastes -Solid wastes Technologies for conversion of biomass to bioenergy: -Combustion to heat/electricity -Fermentation to fuels -Anaerobic digestion to biogas -Chemical conversion to fuels US biomass energy consumption, 2010 Biomass to Bioenergy 4/4/20132 Sustainable energy sources Direct combustion-Cooking, heating, steam-to-electricity (Rankine cycle) Thermochemical conversion-Heating at 5 atm. without O2 to produce CO + H2 (syngas) for further conversion to ethanol or hydrogen Biochemical conversion-1) Fermentation to produce alcohols, ethanol 2) Anaerobic digestion to produce CO2 + CH4 (biogas) 3) Anaerobic digestion to produce CO2 + H2 (biohydrogen) Transesterification-Conversion of bio-oils (triglycerides) to methyl or ethyl esters of fatty acids (biodiesel) Biomass to Bioenergy Sustainable energy sources First generation of biofuels -Use of food crops (corn, sugar beet, oil seeds etc) -mature technology, drop-in fuel Second generation of biofuels -Use of non-food (straw, bagasse, crop wastes etc) -near-mature technology, drop-in fuel Third generation of biofuels -Algal biodiesel -emerging technology Fourth generation of biofuels -Genetically modified crops, advanced bioconversion processes, energy-efficient cultivation/processing Biomass to Bioenergy 4/4/20133 Sustainable energy sources Biofuel pathways Sustainable energy sources Biofuel pathways 4/4/20134 Sustainable energy sources Biomass to Bioenergy 1. Net energy value NEV = energy contained in the fuel + energy contained in the co-products -energy consumed in the cultivation Attachments: Refrences.pdf