Bioenergy_1 - Climate Change Energy Needs and Biofuels Where are the biofuel feedstocks going to come from The Problem We need to meet the

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Unformatted text preview: Climate Change, Energy Needs and Biofuels Where are the biofuel feedstocks going to come from? The Problem: We need to meet the world’s increasing demand for energy while simultaneously reducing the trend of global warming due to the release of CO 2 The world is warming From: Anders Röj (Volvo Inc.) Agenda 2020 Technology Summit (2004) Carbon dioxide remains in atmosphere for long periods of time after emission – continued effect on climate How urgent is climate change? Science 318:1230 (2007) CO 2 release rises with per capita GDP M Hoeffert Some figures: • The total amount of energy humans use annually is delivered to the earth in one hour from the sun • Biomass serves only 11% of human energy needs, 2/3 of which is gathered unsustainably • 80-85% of our energy comes from fossil fuels • 70% of petroleum use is for transportation Source: Crabtree and Lewis, March 2007 Physics Today Worldwide Oil Reserves Source: Long-Term World Oil Supply Scenarios , Energy Information Association eia.doe.gov Peak Oil: The point in time when the maximum rate of global petroleum extraction is reached, after which the rate of production enters terminal decline Potential of underused renewable energy sources Hydro Tides & currents Wind Geothermal Solar Current use 0.1 1 10 100 1000 10000 100000 1000000 TW ? Nuclear From: Basic Research Needs for Solar Energy Utilization, DOE 2005 How much would every roof contribute if photovoltaic? • 7x10 7 detached single family homes in U.S. • ≈2000 sq ft/roof = 180 m 2 /home • = 1.2x10 10 m 2 total roof area • Hence can (only) supply 0.25 TW, ≈7.5% U.S. Primary Energy Consumption Nate Lewis, Caltech ~160,000 km 2 of photovoltaic devices would meet US energy needs N. Lewis, Caltech 3 . 3 T w 3.3 TW Biofuels: Combustion of biomass provides carbon neutral energy CO 2 Polysaccharides Photosynthesis “Combustion” Work Sunlight (Storage) Ideal: Solar collector that is: 1) Self-assembling 2) Self-repairing/replacing 3) Provides stored chemical energy. Starch vs. Lignocellulose starchy grains sugar Ethanol sugar cellulosic biomass (Other Products) Oils Biodiesel Fuel from crops Ethanol production from starch not very energetically favorable compared to cellulose Liquid Fuel Market (E15, E85) • Corn ethanol (4:5) • Cellulosic ethanol (1:5)-If all corn grain today were converted to EtOH it would provide only...
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This note was uploaded on 01/19/2011 for the course ESPM 192 taught by Professor Lindow during the Fall '10 term at University of California, Berkeley.

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Bioenergy_1 - Climate Change Energy Needs and Biofuels Where are the biofuel feedstocks going to come from The Problem We need to meet the

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