Tham khảo tài liệu 'biofuels, solar and wind as renewable energy systems_benefits and risks episode 2 part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 390 D. Pimentel T Patzek Table Inputs per 1 000 kg of biodiesel oil from canola Inputs Quantity kcal X 1000 Costs Canola 3 333 kga 9 355a 1 Electricity 270kWhb 697c Methanol 120Li 1 248i Steam 1 350 000 kcalb 1 350b Cleanup water 160 000 kcalb 160b Space heat 152 000 kcalb 152b Direct heat 440 000 kcalb 440b Losses 300 000 kcalb 300b Stainless steel 11kgf 158g Steel 21 kgf 246g Cement 56kgf 106g TOTAL 14 212 1 The 1 000 kg of biodiesel produced has an energy value of 9 million kcal. With an energy input requirement of million kcal there is a net loss of energy of 58 . If a credit of million kcal is given for the canola meal produced then the net loss is less. The cost per kg of biodiesel is . a Data from Table . b Data from Singh 1986. c An estimated 3 kWh thermal is needed to produce a kWh of electricity. d Cost per kWh is 7 c e Calculated cost of producing heat energy using coal. f Calculated inputs. g Calculated from Newton 2001. h Calculated. i Hekkert et al. 2005. are 40 greater than contained in the biodiesel fuel produced. Giving credit for the byproducts produced can reduce the fossil energy inputs only from 10 to 20 . An extremely low fraction of the sunlight reaching a hectare of cropland is captured by green plant biomass. On average only of the sunlight is captured by plants. This value is in sharp contrast to photovoltaics that capture more than 10 of the sunlight or approximately 100-fold more sunlight than the green plant biomass. The environmental impacts of producing either ethanol or biodiesel from biomass are enormous. These include severe soil erosion heavy use of nitrogen fertilizer and use of large quantities of pesticides insecticides and herbicides . In addition to a significant contribution to global warming there is the use of 1 000-2 000 liters of water required for the production of each liter of either ethanol or biodiesel. .
