Presentation Transcript

1. Energy Efficiency and Renewable Energy G. Tyler Miller’s Living in the Environment 13th Edition Chapter 16
2. Key Concepts Improving energy efficiency Types and uses of solar energy Types and uses of flowing water Uses of wind energy Types and uses of biomass Use of hydrogen as a fuel Use of geothermal energy Decentralized power systems
3. Case Study Rocky Mountain Institute in Colorado 99% of space and 95% water heating, daytime lighting from sun Uses 1/10 the electricity of other facilities its size Energy saved paid for energy saving features in 10 months Components of energy-efficiency and renewable energy revolution Smart walls: absorb or release heat to a room at certain temperatures Solar-hydrogen revolution: electricity produced by solar cells passed through water to make hydrogen gas Fuel cells: burn hydrogen to produce electricity Best Option: cut out unnecessary energy waste by improving energy efficiency Next best: renewable or nonrenewable resources
4. 16-1 The Importance of Improving Energy Efficiency What is energy efficiency? The % of total energy input into an energy conversion device or system the (1) does useful work and (2) is not converted to low quality essentially useless heat. (2nd Law of Thermodynamics) 84% of all commercial energy used in the US is wasted. 43% wasted by thermodynamics rest is wasted unnecessarily. US wastes as much as 2/3 as rest of world just consumes Costs US about 300billion/yr
5. Net Energy Efficiency Includes the entire energy delivery process 2 principles for saving energy Keep the number of steps in an energy conversion process as low as possible Attain the highest possible energy efficiency for each step in an energy conversion process
6. Importance of Improving E-Efficiency Net useful energy Life cycle cost - U.S. wastes 84% of commercial E (43% unnecessarily) Need to reduce consumption by: lifestyle changes (easiest and fastest way): walk, bike, mass transit, turnoff lights, buy energy efficient systems for heating, cars, air conditioners, etc. …cost more initially save money in long run by lower life cycle cost (initial cost plus lifetime operating costs)
7. Importance of reducing energy waste nonrenewable fossil fuels last longer more time to phase in renewable energy resources decreases dependence on oil imports lessens the need for military intervention in Middle East reduces local and global environmental damage cheapest and quickest way to slow projected global warming more money, more jobs, improved productivity, and more economic growth per unit of energy than alternatives improves competitiveness in international market place *Could save $1 trillion per year so why not do? Primary reason: plenty of low cost, under-priced fossil fuels (environmental damage not figured in cost) so energy wasted and no motivation for improving energy efficiency
8. 16.2 Ways to Improve Energy Efficiency 1. How we can use waste heat - we cannot recycle energy but we can slow the rate at which waste heat flows into the environment when high quality energy is degraded. Insulate homes thoroughly Vent collected heat outdoors in hot weather to reduce cooling bills 2. Saving in Industry - co-generation(CHP) : producing 2 useful forms of energy from the same fuel source. These are 80% efficient and emit less C02 per unit of energy than coal burners - replacing energy wasting electric motors with adjustable running motors
9. Efficiencies (fig. 16-4 p. 382)
10. Electric and Hybrid Cars Fig. 16-10 p. 365 Rechargeable battery systems Hybrid electric-internal combustion engine Fuel cells
11. Renewable Energy Sources 92% of known reserves and potentially available energy resources in U.S. are renewable from sun, wind, flowing, water, biomass, and geothermal 8% are coal (5%), oil (2.5%), and uranium (0.5%) *Advantages of renewable energy sources save money, create 2-5 times more jobs per unit of electricity, eliminate the need for oil imports, cause much less pollution and environmental damage per unit increase military, economic, and environmental security some renewables already produce electricity more cheaply than nuclear power plants
12. 3. Saving Energy in Transportation - increase fuel efficiency in MV - good news: fuel efficiency in MV did get better between 1973 and 1985. Bad news : since 1985 fuel efficiency leveled off or declined because of desire for SUV and political failures toe raise standards. - increasing fuel economy of new vehicles in US just 5% a year for 10yrs would save10-20 times more oil then the projected supply from the Arctic Hybrid Cars the Answer? Runs on gas, diesel fuels or NG. Small battery is recharged by internal combustion engine Fuel Cell Cars? Burns hydrogen fuel to produce the electric. H2 in cell combines with O2 in air
13. Saving Energy in Buildings? Georgia Power Co. – south facing windows, energy efficient lighting- uses 60% less energy than conventional Superinsulate house- more upfront cost but paid back in energy savings Strawbale house Eco roofs Energy efficient heating of homes using passive solar, heat pumps in warm climates not cold, high efficient nat. gas furnace Add insulation Energy saving windows Tankless instant water heaters Cut off lights, computers, appliances when not in use Set high efficiency standards for new buildings
14. 16-3 Using Solar Energy to Provide Heat and Electricity Advantages/Disadvantages? Advantages: reduce air pollution, CO2 emissions, dependence on oil, long lasting Disadvantages: solar cells produce toxic chem. last only 30-40 yrs, need night time backup system, costly  Despite the positives of using this renewable resource, solar and wind still only provide 1% of the worlds commercial energy because they have received much lower tax breaks, and R&D money.
15. How Solar Energy is used in homes. Passive solar: system absorbs and stores heat directly with a structure. Use windows that face sun, walls, timber collect heat and release throughout day. Cannot be used in exiting homes or building blocked by sunlight. Active solar: collectors absorb energy and pumps force it into air and water heating systems. Some used, rest is stored. Not widely used do to high cost, maintenance, appearance Producing Electricity with Solar Cells Using photovoltaic (PV) cells or solar cells
16. Using Solar Energy to Provide Heat and Electricity Passive solar heating - captures sunlight directly within a structure/ converts to low-temperature heat for space heating Active solar heating - specially designed collectors absorb solar energy
17. Using Solar Energy to Provide High-Temperature Heat and Electricity Fig. 16-23 p. 398 Solar thermal systems Photovoltaic (PV) cells convert solar energy directly into electrical energy, transparent paper-thin silicon wafer
18. Producing Electricity from Moving Water Large-scale hydropower - high dam built across river to create a large reservoir, controlled water flow through huge pipes spins turbines & creates electricity (advantages/disadvantages, current China project) Small-scale hydropower - low dam (no reservoir) built across stream, varying electrical output Pumped-storage hydropower Tidal power plant – Rance River in France Currently supplies about 20% of world’s electricity (95% in Norway and 50% in developing countries) Major producers: Canada, U.S., and Brazil (U.S. use dropping, importing from Canada)
19. Producing Electricity from Heat Stored in Water Ocean thermal energy conversion (OTEC): technology is still in research and development Saline and Freshwater solar ponds:use heat stored in water, need no energy storage and backup systems, have moderate costs, may be useful in supplying U.S. electricity needs within 10 years
20. Producing Electricity from Wind - Growing rapidly since 1980 - Wind turbines are turned by wind, usually in clusters in U.S. (called wind farms, ex: California produces 1% of its electricity needs this way) - Areas of potential use, wind-farms are now being planned in 12 other states  Global potential of wind power is about 5 times current world electricity use No CO2 or other air pollution production, no water for cooling, little water pollution in manufacture, land under turbines used for cattle grazing or farming, currently cheaper than nuclear Negatives: Need steady winds, Visual pollution and noise (would need 1% of U.S. land to produce 1/3 of country’s electricity, could be in remote areas), Interfere with flight patterns of migratory birds and kill large birds of prey
21. Producing Electricity from Wind Fig. 16-28 p. 402 Fig. 16-29 p. 402
22. Producing Energy from Biomass Biomass: organic matter in plants produced through photosynthesis, can be burned directly as a solid fuel or converted into gaseous or liquid biofuels Supplies 13% of world’s energy (about 35% in developing countries) Renewable if trees and plants not harvested faster than used Current supplies of wood and agricultural wastes could supply 30% of world’s electricity needs, currently potentially renewable biomass used in nonrenewable and unsustainable ways
23. Burning Agricultural and Urban Wastes Crop residues and animal manure can be collected and burned or converted into biofuels Bagasse: residue left after sugarcane harvesting (supplies about 10% of Hawaii’s electricity) Biomass ash can sometimes be used as fertilizer Trash burning increasing in Japan, W. Europe, and U.S. Negatives: concern about emissions of toxic gases, disposal of toxic ash, recycling paper saves twice as much energy as burning it produces
24. The Solar Hydrogen Revolution Hydrogen gas can be produced by splitting water Pros: Easy to store and transport, Readily available, No CO2 Vehicle will not explode if gas tank ruptured in accident End products are water vapor and some nitrogen oxides so little AP Cons: Takes energy to split water, Use fossil fuels to split, Expensive Solar-hydrogen revolution - If use sun to split water, solve energy problem BUT now too costly Use natural gas to produce hydrogen gas and gradually phase in solar production as technology increases -Politics and Economics are the main factors holding up the transition to solar-hydrogen gas -opposition by oil companies, electric utilities, auto manufacturers governments must put up development and research monies
25. The Solar-Hydrogen Revolution Fig. 16-33 p. 386
26. Fuel cell :hydrogen and oxygen gas combine to produce electric current no air pollution no moving parts high energy efficiencies of up to 65% don’t have to be recharged cost little more to build than gasoline vehicles prototypes are being tested and evaluated, 3 busses operating in Chicago currently expensive and heavy Advantages/Disadvantages? Advantages: prod. From water, low environmental impact, safer than gas, highly efficient, no CO2 Disadvantages: no found in nature, needs energy to prod., neg net energy, high cost, no distribution in place
27. Geothermal Energy Geothermal energy: heat contained in underground rocks and fluids Three types: 1. dry steam: steam with no water droplets 2. wet steam: mixture of steam and water droplets 3. hot water trapped in fractured or porous rock - Near surface can drill wells and use for heating, electricity, etc. - Can be depleted if steam removed faster than replaced naturally - Used by about 20 countries (U.S. produces 44% of energy produced worldwide)
28. Geothermal Reservoirs Fig. 16-37 p. 410 Pros vast, reliable, and sometimes renewable supply of energy, about 96% fewer emissions per unit of energy than fossil fuels, competitive with electricity production Cons scarcity of easily accessible sites destroy or degrade ecosystems possibility of land sinking (removal or water) noise, odor, and local climate changes Economics is main barrier
29. 16-10 Solutions: A Sustainable Energy Strategy Best Practices A more sustainable energy policy would improve energy efficiency, rely more on renewable energy, and reduce the harmful effects of using fossil fuels and nuclear energy. Governments can use a combination of subsidies, tax breaks and taxes to promote or discourage us of various energy alternatives
30. Toward a Sustainable Energy Future Increase fuel efficiency standards for vehicle, appliances, buildings Tax and other financial incentives for energy efficiency Subsidize renewable energy use, research and development By 2050: renewable energy=50% cut coal use by 50% phase out nuclear altogether
31. Entering the Age of Decentralized Micropower Fig. 16-40 p. 411 Fig. 16-39 p. 411 Centralized power systems Decentralized power systems Micropower systems
32. Solutions: A Sustainable Energy Strategy Fig. 16-44 p. 414 Between 1800 and 1970 shift from dependence on solid fuels (wood and coal) to liquid (oil). May now see shift to cleaner gaseous fuels (methane and solar-produced hydrogen)