1 A Sustainable Energy Future Lester B. Lave Carnegie Mellon University October 24, 2006

2 Is Energy Important? The average American uses 350 giga-joules of energy per year Equivalent to having 45 horses/working hour Or 450 workers per working hour Energy makes modern civilization possible Until 1850 use of fossil fuels negligible Burning fossil fuels emits CO 2 & pollution

3 How much Emissions Reduction? Kyoto calls for 10% decrease from 1990 World needs 40%? 60% to stop carbon concentrations at 3 times preindustrial levels If CO2 emissions per person equal over the world, US emissions have to decline % over 1990 levels Need to appreciate the scale of our problem

4 2 Views of Our Future Optimistic View: We have faced shortages of wood, whale oil, latex, tin, & many other materials: We found new technology & substitutes every time - & will in the future Precautionary View: Some civilizations have not been so fortunate: Easter Island. If we poison our world & squander its resources, we have nowhere else to go: Don’t jump off the cliff!

5 Implications of 2 views Optimistic: No need to sacrifice today, technology will solve the problems. We don’t even know what we would sacrifice. Precautionary: Exponential growth cannot persist forever. Blind faith in technology? Our quality of life is already suffering from too many people & “toys” that use resources & give us no pleasure. 40,000 square feet houses for two …

6 What Are Our Options? 1.Conservation: Use energy much more efficiently 2.Carbon capture and sequestration 3.Switch to renewable energy

7 A Tale of Two Nations 2002 BTU/GDP BTU/pop GDP/pop Denmark USA About half the difference is efficiency & half is lifestyle An automobile is less than 1% efficient: 20% of energy in the gas tank moves the wheels & 4% of weight moved is the passenger Driving a Hummer to a McMansion MORE TOYS! vs. sufficient

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9 Conservation Without Pain Improve car fuel economy 30-50% by hybrids and new diesels Improve building efficiency by 80% Improve lighting, AC, etc. by 50% With no perceptible drop in quality & some improvements Why don’t we do it: Energy is too cheap

10 Conservation: Some Pain Double fuel economy: Some downsizing of vehicles, light trucks for commercial use We can end oil imports by going to cellulosic ethanol & plug-in hybrids What are the costs & benefits?

11 Carbon-Free Fossil Fuels The world has abundant fossil fuels: Oil, coal, natural gas: We will run out of atmosphere before we run out of carbon We have technology to capture & store 90%+ of carbon: Coal gasification, amine scrubbing, oxyfuel Electricity production with carbon capture or using nuclear power raises generation costs 30-40% or delivered costs 15-20% Costs affordable

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13 Confidence in Carbon Storage? Commercially proven carbon separation Use CO 2 for secondary oil recovery Geologists confident CO 2 pumped deep underground would stay for 1,000+ years No social institutions to manage this Need to solve problems of mining & transporting coal: Acid mine drainage, subsidence, transportation deaths

14 Renewable Options Wind, photovoltaic (PV) (solar cells), solar thermal, dams, tides, waves, geothermal, biomass (energy crops) Wind cheapest in good locations, but not dependable and supply limited: Local climate effects & global climate effects PV is the largest resource, but expensive – sun may not shine when you need power Efficient, cheap energy storage critical

15 Renewable Resources At best US Sites, electricity is generated 1/3 of the time: Need 3 times the wind capacity even with free storage At best US sites, PV generates electricity 22% of the time – need 5 times capacity Or we can modify demand to take power only when it is available – Regulate our activities by the sun and wind?

16 Other Renewables In addition to wind and photovoltaic cell, there are river dams, tides, waves, geothermal, & biomass All, except solar, have limited capacity – they can contribute, but not satisfy our demand All have adverse environmental effects

17 Energy for Transportation Cars, trucks, aircraft, ships, trains major energy users & CO 2 emitters No way to capture CO 2 – don’t produce it! Biofuels is the short-term answer Hydrogen economy?: Energy source?: H 2 is an energy carrier, like electricity H 2 difficult to transport & store – dangerous H 2 unlikely to be commercial for yrs H 2 advantage: Water (H 2 O) is only emission

18 A Primer on Biofuels Plants 1-2% efficient in using sunlight (solar cells about 10% efficient now) Oil yield per acre from soybeans, corn rape seed, etc. is low Bio-diesel from cooking fat, animal parts is great, but growing crops less attractive – thus supply is limited

19 Corn or Switchgrass? The export market for corn is disappearing Stop soil loss & pesticide & fertilizer runoff Switchgrass improves soil quality Potentially greater profit from farming switchgrass – no subsidies Return much of Great Plains to prairie grass Annual harvest (mowing hay) Let herds of bison & elk roam More diverse, natural ecology

20 Switchgrass Production Limits How much farmland is available? US can produce billion gal/yr Switchgrass farming potentially profitable Going to lower quality land raises harvesting & shipping costs Brazil, Argentina, & many nations would produce ethanol from switchgrass, bagasse, trees and other biomass

21 Biomass Ethanol Advantages No net CO2 to atmosphere – plants grab CO2 for cellulose – which is returned when ethanol is burned During fermentation, a pure stream of CO2 can be captured & sequestered – a carbon pump taking O2 from the atmosphere Sustainable fuel supply that eliminates many current farming problems & produces better soil for the future & biodiversity

22 Eliminating Gasoline from USA USA uses 140 billion gallons of gasoline/yr Equivalent to 200 billion gallons of ethanol Hybrid electric vehicle can get 40% more miles per gallon of fuel – need 120 B gal 90% of trips less than 30 miles 75% of fuel Plug-in hybrids use electricity for 30 miles Need only 40 B gallons of ethanol! PHEVs can eliminate need for gas in cars Or Smaller, less powerful hybrids: 60 B gal

23 Conclusion 90-95% reduction in CO2 is our goal For factories & homes, use electricity from fossil fuels with carbon separation & storage, or nuclear, or renewables For transportation, biomass ethanol: Plug- in hybrids or smaller hybrids Costs & inconvenience modest Barriers: Lethargy & low fossil fuel prices – need a CO 2 or oil tax

24 Importance of Life Cycle Analysis Carnegie Mellon Green Design Institute: Input-Output Life Cycle Assessment: Book: Environmental Life Cycle Assessment of Goods & Services: An Input-Output Approach, Available at Resources for the Future or Amazon