Readings for the assignment: Renewables assignment: Questions. Amory Lovins. Environmental Issues & Problems ENV 150 Guillaume Mauger

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1 Environmental Issues & Problems ENV 150 Guillaume Mauger Today: Renewable Energy Assignment: Research your Renewable Energy topic: - Hydrokinetic: Waves - Hydrokinetic: Tidal Power - Hydroelectric - Passive Solar and solar water heating - Solar Thermal (also called concentrated solar ) - Photovoltaics - Wind - Geothermal - Biofuels - Biomass Readings for the assignment: 1. _energy_101/the-sources-of-energy.html! Click on the link entitled How Energy Works 2. The course textbook You may need to look up additional information elsewhere, such as: _101/the-sources-of-energy.html nd_impacts/energy_technologies/barriers-torenewable-energy.html etc. Renewables assignment: Questions 1. Describe your renewable energy resource 2. How is energy generated using this resource? (e.g., what are the technologies, and how do they work?) 3. What regions are best suited for using this resource? 4. Describe a working example of this energy resource that is in use today (if possible, in our region). 5. Describe one negative environmental impact. Are there alternatives or ways to fix this problem? 6. Can this technology be used today, or is more work needed? Why? 7. What do you think is the main barrier to its widespread use? Amory Lovins TED: Ending the Oil Endgame: g_the_oil_endgame.html

2 outline Contribution to total energy consumption (percent) Wood Coal Oil Today Nuclear Natural gas Solar, biofuels, etc Decentralization Renewable Energy sources Efficiency: cogeneration and passive solar Solar Hydro Wind Biomass Geothermal Year Hydrogen? Fig , p. 413 Decentralization of Energy Production Bioenergy power plants Wind farm Small solar-cell power plants Rooftop solar cell arrays Fuel cells Solar-cell rooftop systems Transmission and distribution system Residential Small wind turbine Commercial Industrial Microturbines Fig , p. 414

3 Renewable Energy: Sources Efficiency Solar Hydro Wind Biomass Geothermal Hydrogen? (not actually a source of energy) simply different forms of solar energy ( the same is true of fossil fuels) table: TOTAL COSTS OF ELECTRICITY Efficiency Efficiency Energy Inputs 85% System U.S. economy and lifestyles Outputs 9% 7% 41% Electricity Generation: Turbine Generator Waste heat Cooling tower transfers waste heat to atmosphere 43% 8% 4% 3% Nonrenewable fossil fuels Nonrenewable nuclear Hydropower, geothermal, wind, solar Biomass Useful energy Petrochemicals Unavoidable energy waste Unnecessary energy waste Boiler

4 Cogeneration! Make use of waste heat!! for heating bldgs (e.g., NYC, Scandinavia)! to heat water! desalination (proposed plant in San Diego)! Thermally Enhanced Oil Recovery (TEOR)! small scale, micro cogeneration :! cars already do it! (in winter)! heat and power a home at same time Efficiency: Reducing Unnecessary waste Examples: Incandescent bulbs really heat bulbs : 90-95% wasted. Motor vehicles 94% wasted (not including energy used to move weight of car) Nuclear power full nuclear fuel cycle is much more costly than plant operation Coal: 66% wasted Average fuel economy (miles per gallon, or mpg) Model year Cars Both Pickups, vans, and sport utility vehicles Regulator: Controls flow of power between electric motor and battery bank. Transmission: Efficient 5-speed automatic transmission. Combustion engine: Small, efficient internal combustion engine powers vehicle with low emmissions; shuts off at low speeds and stops. Fuel Fuel tank: Liquid fuel such as gasoline, diesel, or ethanol runs small combustion engine. Battery: High-density battery powers electric motor for increased power. Electric motor: Traction drive provides additional power for passing and acceleration; excess energy recovered during braking is used to help power motor. Electricity

5 US energy use: history Fig , p. 393 Fig. 17-9a, p. 392 Fig. 17-9b, p. 392

6 Why do we continue to waste Energy? Cheap energy Environmental / Health costs not included in the market price of fossil fuels. Lopsided incentives 2005: US federal funding for research and development in fossil fuels was six times greater than that for energy efficiency! Fig , p. 393 Solar Energy Heat to house (radiators or forced air duct) Summer sun Passive / Active Solar Use heat gained by absorbing sunlight to heat house / water Winter sun Superwindow Heavy insulation Pump Super window Superwindow Heat exchanger Stone floor and wall for heat storage PASSIVE Hot water tank ACTIVE

7 Direct Gain Greenhouse, Sunspace, or Attached Solarium Ceiling and north wall heavily insulated Summer sun Hot air Summer cooling vent Warm air Warm air Insulated windows Winter sun Superinsulated windows Cool air Cool air Earth tubes Fig , p. 396 Fig , p. 396 Passive or Active Solar Heating Earth Sheltered Earth Reinforced concrete, carefully waterproofed walls and roof Energy is free Need access to sun 60% of time Net energy is moderate (active) to high (passive) Triple-paned or superwindows Quick installation No CO2 emissions Flagstone floor for heat storage Fig , p. 396 Sun blocked by other structures Need heat storage system Very low air and water pollution High cost (active) Very low land disturbance (built into roof or window) Active system needs maintenance and repair Moderate cost (passive) Active collectors unattractive

8 Solar Energy Solar thermal pic Solar Thermal Use mirrors to concentrate heat Convert heat to electricity using conventional methods for generation Solar Energy for High-Temperature Heat and Electricity Moderate net energy Low efficiency Moderate environmental impact No CO2 emissions Fast construction (1 2 years) Costs reduced with natural gas turbine backup Fig , p. 397 High costs Needs backup or storage system Need access to sun most of the time High land use May disturb desert areas

9 Solar Energy Single solar cell Solar-cell roof Photovoltaics MW, SunEdison, Alamosa, CO Semiconductors convert photons to electricity Step 1: Make a semiconductor sandwich Step 2: Sandwich creates an electric field Step 3: Add photons Step 4: Electrons (electric current) flow Boron enriched silicon Roof options Junction Phosphorus enriched silicon Panels of solar cells Solar shingles Fig , p. 398 Solar Cells Solar PV pic Fairly high net energy Need access to sun Work on cloudy days Low efficiency Quick installation Easily expanded or moved Need electricity storage system or backup No CO2 emissions Low environmental impact Last years Low land use (if on roof or built into walls or windows) Reduces dependence on fossil fuels High land use (solar-cell power plants) could disrupt desert areas High costs (but should be competitive in 5 15 years) DC current must be converted to AC

10 Hydropower Hydropower Two types: 1. Reservoir dam ex: Grand Coulee 2. Diversion (run-of-the-river) dam Turbine off to the side ex: Niagara Falls Hydropower s Future 1. Large dams: stable or declining 2. Growth in small dams Hydroelectric: rivers 1. Three Gorges Dam, China18.2 GW, 600 Fully operational (22.5 GW) by meters thick at the bottom, 40 m at the top 1 / 9 China s power (85 billion kwh/yr) $25 billion >1 million people relocated Hydroelectric: rivers Three Gorges Dam, China 18.2 GW, 600 Source: BBC Source: BBC

11 Hydroelectric: rivers Three Gorges Dam, China Hydroelectric: rivers 18.2 GW, 600 Three Gorges Dam, China 18.2 GW, 600 Source: BBC Hydroelectric: rivers Three Gorges Dam, China Source: BBC Hydroelectric: rivers 18.2 GW, 600 Grand Coulee Dam Source: BBC 6.5 GW, 550

12 Dams: Columbia River Basin Large-Scale Hydropower Moderate to high net energy High efficiency (80%) Large untapped potential Low-cost electricity Long life span No CO 2 emissions during operation in temperate areas May provide flood control below dam Provides water for year-round irrigation of cropland Reservoir is useful for fishing and recreation High construction costs High environmental impact from flooding land to form a reservoir High CO 2 emissions from biomass decay in shallow tropical reservoirs Floods natural areas behind dam Converts land habitat to lake habitat Danger of collapse Uproots people Decreases fish harvest below dam Decreases flow of natural fertilizer (silt) to land below dam Wind turbine Wind farm Wind s Future Electrical generator Gearbox could be 20% US energy by 2030 Power cable

13 Wild Horse Wind Farm Developed: Horizon Wind Energy 127 wind turbines, 8,600 acres 230 MW (70,000 homes) Electric Power Generation: 9% renewable (<1% wind) Horse Hollow, Taylor County, TX Developed: Florida Power & Light 291 wind turbines, 47,000 acres 735 MW (220,000 homes) AWEA Power management: wind variability At < 10% of electricity in any given hour: variable winds are not an issue Moderate to high net energy High efficiency Moderate capital cost Wind Power Steady winds needed Backup systems needed when winds are low Between 10-20%: variable winds needs to be addressed with wind forecasting and system software adjustments At > 20%: operator incurs significant additional expense for additional equipment related to wind variability AWEA Low electricity cost (and falling) Very low environmental impact No CO 2 emissions Quick construction Easily expanded Can be located at sea Land below turbines can be used to grow crops or graze livestock High land use for wind farm Visual pollution NIMBY Noise when located near populated areas May interfere in flights of migratory birds and kill birds of prey

14 Biofuels: uses Biofuels Two types: 1. Solid ex: cow dung, wood 2. Conversion to liquid / gaseous fuels Solid Biomass Fuels!!!!!!!! Wood logs and pellets Charcoal Agricultural waste (stalks and other plant debris) Timbering wastes (branches, treetops, and wood chips) Animal wastes (dung) Aquatic plants (kelp and water hyacinths) Urban wastes (paper, cardboard), And other combustible materials Conversion to gaseous and liquid biofuels Direct burning ex: ethanol, biodiesel Gaseous Biofuels Synthetic natural gas (biogas) Wood gas Liquid Biofuels Ethanol Methanol Gasonol Biodiesel Solid Biomass Large potential supply in some areas Nonrenewable if harvested unsustainably Moderate costs Moderate to high environmental impact No net CO2 increase if harvested and burned sustainably CO2 emissions if harvested and burned unsustainably Plantation can be located on semiarid land not needed for crops Low photosynthetic efficiency Soil erosion, water pollution, and loss of wildlife habitat Plantation can help restore degraded lands Plantations could compete with cropland Can make use of agricultural, timber, and urban wastes Often burned in inefficient and polluting open fires and stoves

15 Main idea: Use a high-carbohydrate biomass that is (ideally) not used for food. Ethanol Corn-based vs. Cellulosic Fig , p. 406 Ethanol Fuel Biodiesel vs. Ethanol High octane Some reduction in CO2 emissions High net energy (bagasse and switchgrass) Reduced CO emissions Large fuel tank needed Lower driving range Low net energy (corn) Much higher cost Corn supply limited May compete with growing food on cropland Higher NO emissions Can be sold as gasohol Potentially renewable Corrosive Hard to start in cold weather

16 Biodiesel Reduced CO emissions Reduced CO2 emissions (78%) Reduced hydrocarbon emissions Slightly increased emissions of nitrogen oxides Higher cost than regular diesel Geothermal Energy Two types: 1. Near-surface hotspots Low yield for soybean crops Harvest heat from below-ground sources Better gas mileage (40%) High yield for oil palm crops Moderate yield for rapeseed crops Potentially renewable May compete with growing food on cropland Loss and degradation of biodiversity from crop plantations 2. Use moderating effect of belowground tempeartures Hard to start in cold weather Near-surface hotspots Underground heat produces steam Steam used to turn turbines Basement heat pump Fig , p. 409

17 Very high efficiency Moderate net energy at accessible sites Lower CO 2 emissions than fossil fuels Low cost at favorable sites Low land use Low land disturbance Moderate environmental impact Geothermal Energy Scarcity of suitable sites Depleted if used too rapidly CO 2 emissions Moderate to high local air pollution Noise and odor (H 2 S) Cost too high except at the most concentrated and accessible sources Fig , p. 410 Hydrogen? H 2 + 2O 2 " 2H 2 O + energy Hydrogen? H 2 + 2O 2 " 2H 2 O + energy NOT AN ENERGY SOURCE!!!!! energy needed to make H 2 gas INSTEAD: energy storage. Air system management Fuel-cell stack Converts hydrogen fuel into electricity Front crush zone Absorbs crash energy Electric wheel motors Provide four-wheel drive; have built-in brakes Body attachments Universal docking connection Mechanical locks that secure Connects the chassis with the the body to the chassis drive-by-wire system in the body Hydrogen fuel tanks Rear crush zone Absorbs crash energy Drive-by-wire system controls Cabin heating unit Side-mounted radiators Release heat generated by the fuel cell, vehicle electronics, and wheel motors Fig. 17-8, p. 390

18 Can be produced from plentiful water Low environmental impact Renewable if from renewable resources No CO 2 emissions if produced from water Good substitute for oil Competitive price if environmental & social costs are included in cost comparisons Easier to store than electricity Safer than gasoline and natural gas Nontoxic High efficiency (45 65%) in fuel cells Hydrogen Not found in nature Energy is needed to produce fuel Negative net energy CO 2 emissions if produced from carbon-containing compounds Nonrenewable if generated by fossil fuels or nuclear power High costs (but may eventually come down) Will take 25 to 50 years to phase in Short driving range for current fuel-cell cars No fuel distribution system in place Excessive H 2 leaks may deplete ozone in the atmosphere Fig , p. 412 Can be produced from plentiful water Low environmental impact Renewable if from renewable resources No CO 2 emissions if produced from water Good substitute for oil Competitive price if environmental & social costs are included in cost comparisons Easier to store than electricity Safer than gasoline and natural gas Nontoxic High efficiency (45 65%) in fuel cells Hydrogen Not found in nature Energy is needed to produce fuel Negative net energy CO 2 emissions if produced from carbon-containing compounds Nonrenewable if generated by fossil fuels or nuclear power High costs (but may eventually come down) Will take 25 to 50 years to phase in Short driving range for current fuel-cell cars No fuel distribution system in place Not in terms of safety! Only in terms of energy density. Excessive H 2 leaks may deplete ozone in the atmosphere Fig , p. 412