Chap 16 Energy Efficiency and Renewable Energy. Iceland ’ s Vision of Renewable Energy 3/4 of...
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Transcript of Chap 16 Energy Efficiency and Renewable Energy. Iceland ’ s Vision of Renewable Energy 3/4 of...
Iceland’s Vision of Renewable Energy
3/4 of island is covered by volcanoes, glaciers, & hot springs20 active volcanoes¾ of its energy from geothermal & hydroelectricImports oil for cars, factories & fishing boatsProposing using water- to power vehicles in future- hydrogen power Only bi-product is water vapor no CO2 2003- 1st commercial hydrogen refueling station
16-1 Energy Efficiency
Improving energy efficiency could save up to 43% of energy we useEnergy conservation- strategy to decrease energy use by reducing unnecessary waste of energyImprove energy efficiency is best way- how much we can get from each unit of energy 41% of energy loss is unavoidable because of Law
of Thermodynamics 43% of U.S energy loss due to inefficient lighting,
heating, cars, power plants
Energy Efficiency
Canada & developing countries less efficient than U.S, Japan & Germany 2-3 times more efficientAdvantages of reducing energy waste: Quick and clean Usually the cheapest to provide more
energy Reduce pollution and degradation Slow global warming Increase economic and national security
Fig. 16-3, p. 401
SOLUTIONS
Reducing Energy Waste
Prolongs fossil fuel supplies
Reduces oil imports and improves energy security
Very high net energy yield
Low cost
Reduces pollution and environmental degradation
Buys time to phase in renewable energy
Creates local jobs
Net Energy Efficiency
Net energy efficiency- determined by combining the efficiencies of all steps in energy conversion for a system
cumulative net efficiency=multiplying the percentage of energy available from source by the energy efficiency for that step. So 100 × 0.95 = 95%; 95 × 0.57 = 54%;.
16-2 Cut Energy Waste
Cutting Industry’s Energy Waste Cogeneration or combined heat and power
(CHP)- 2 useful forms of energy produced (steam & electricity) – electricity powers plant & steam heats it
Replace energy-wasting electric motors Recycling materials Switch from low-efficiency incandescent lighting
to higher-efficiency fluorescent and LED lighting Update- outdated & wasteful electrical grids Utility companies promote efficient use of
energy
Transportation Energy Waste
1973-1985 U.S fuel efficiency rose due to - Corporate average fuel standards (CAFE) standards Since 1985, Fuel economy standards lower U.S. vs. many other
countries mileage standards not update & SUVs & trucks efficiency not high 2008 U.S law sets fuel efficiency to 35 mpg by 2020
Fuel-efficient cars on market less than 1% of car salesHidden prices in the gasoline- not paid at pump- pollution control & monitoring, road construction, military protection of oil
Should there be tax breaks for buying fuel-efficient cars, or feebate?
Energy Efficient Vehicles
Superefficient and ultralight cars- lighter materialsGasoline-electric hybrid car- Prius (what to do with battery & smelter for Nickel-Cadmium battery damaging) Plug-in hybrid electric vehicle- issues with battery lifeEnergy-efficient diesel car-bodiesel (lower CO2 emissions)Electric vehicle with a fuel cell- use hydrogen gas (cost is factor)
Energy Efficient Buildings20% of energy savings if utilize Passive Solar Heating in Construction, 75% savings for airtight & well insulatedGreen architecture- use natural lighting, passive solar heating, geothermal heat pumps, solar hot water heaters, recycled building materials, etc.Living or green roofs-covered w/ soil & vegetation (used for decades in Europe)Straw bale houses- wall insides are straw plastered over with adobe-
LEED
U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED)Two buildings that were designed with energy in mind Georgia Power Company in Atlanta,
GA (U.S.) Ministry of Science and Technology
Building in Beijing, China
More Efficient Existing Buildings
Insulate and plug leaks Use energy-efficient windowsStop other heating and cooling losses-Heat houses more efficiently-geothermal or natural gas Heat water more efficiently-solar heating & tankless water heaterUse energy-efficient appliances-Use energy-efficient lighting
Fig. 16-9, p. 409
Attic• Hang reflective foil nearroof to reflect heat.• Use house fan.• Be sure attic insulation isat least 30 centimeters(12 inches).
Bathroom • Install water-saving toilets, faucets, and shower heads.• Repair water leaks promptly.
Kitchen • Use microwave rather than stove or oven as much as possible.• Run only full loads indishwasher and use low- or no-heat drying.• Clean refrigerator coilsregularly.
Basement or utility room • Use front-loading clothes washer. If possible run only full loads with warm or cold water.• Hang clothes on racks for drying.• Run only full loads in clothes dryer and use lower heat setting.• Set water heater at 140° if dishwasher is used and 120° or lower if no dishwasher is used.• Use water heater thermal blanket.• Insulate exposed hot water pipes.• Regularly clean or replace furnace filters.
Outside Plant deciduous trees to block summer sun and let in winter sunlight.
Other rooms • Use compact fluorescentlightbulbs or LEDs and avoidusing incandescent bulbswherever possible.• Turn off lights, computers, TV,and other electronic deviceswhen they are not in use.• Use high efficiency windows;use insulating window coversand close them at night andon sunny, hot days.• Set thermostat as low as youcan in winter and as high asyou can in summer.• Weather-strip and caulk doors,windows, light fixtures, andwall sockets.• Keep heating and coolingvents free of obstructions.• Keep fireplace damper closedwhen not in use.• Use fans instead of, or alongwith, air conditioning.
Still wasting energy
Energy market price still lowFew large and lasting govt tax breaks for energy efficient homesRebound effect- save money due to improved efficiency = raise temp in winter lower in summer
16-3 Solar EnergyPassive solar heating system- absorbs & stores energy during direct sunlight w/o pumps & fansActive solar heating system- absorbs & stores energy from sun using fluids, air etc. that are pumped through collectors
Countries using solar energy to heat water
Fig. 16-10a, p. 411
Vent allows hot air to escape in summer
Summer sun
Heavy insulation
Winter sun
Superwindow
Superwindow
Stone floor and wall for heat storage
PASSIVE
Fig. 16-10b, p. 411
Solar collector Heat to house (radiators or forced air duct)
PumpHeavy insulation
Super- window
Hot water tank
Heat exchanger
ACTIVE
Fig. 16-11, p. 412
TRADE-OFFS
Passive or Active Solar Heating
Advantages Disadvantages
Energy is free Need access to sun 60% of time
Net energy is moderate (active) to high (passive)
Sun can be blocked by trees and other structures
Quick installation Environmental costs not included in market priceNo CO2 emissions
Very low air and water pollution
Need heat storage system
Very low land disturbance (built into roof or windows)
Active system needs maintenance and repair
High cost (active)
Active collectors unattractive
Moderate cost (passive)
We Can Cool Buildings Naturally
Technologies available Superinsulation and high-efficiency
windows Overhangs or awnings on windows Light-colored roof Reflective insulating foil in an attic Geothermal pumps Plastic earth tubes underground
Sunlight for High Temperature Electricity Generation
Solar thermal systems
Central receiver system
Other collecting systems
Unfeasible for widespread use
High cost Low new energy yields Limited suitable sites
Sunny, desert sites
Solar for Cooking
Use sunlight instead of wood, oil, gas, or electricity
Cooks just as well, sometimes in same amount of time, sometimes start in morning & finish by evening (solar crockpot)
Solar for ElectricityPhotovoltaic (PV) cells (solar cells) Convert solar energy to electric energy
Solar-cell power plants Near Tucson, AZ (U.S.) 2007: Portugal
Key problem High cost of producing electricity
Will the cost drop with Mass production New designs Nanotechnology
Fig. 16-17a, p. 415
Single solar cell
Boron- enriched silicon
Junction
Phosphorus- enriched silicon
Roof options
Solar shinglesPanels of solar cells
Solar Power is Expanding
Solar cells: 0.2% of the world’s electricity
2040: could solar cells produce 16%?
Nanosolar: California (U.S.)
Germany: huge investment in solar cell technology
General Electric: entered the solar cell market
Fig. 16-20, p. 417
TRADE-OFFS
Solar Cells
Advantages Disadvantages
Fairly high net energy yield
Need access to sun
Work on cloudy days
Low efficiency
Easily expanded or moved
Need electricity storage system or backupQuick installation
Environmental costs not included in market priceNo CO2 emissions
Low environmental impact
High costs (but should be competitive in 5–15 years)
Low land use (if on roof or built into walls or windows)
High land use (solar-cell power plants) could disrupt desert areas
Last 20–40 years
Reduces dependence on fossil fuels
DC current must be converted to AC
16-4 Electricity from Water CycleHydropower World’s leading
renewable energy source used to produce electricity
Hydroelectric power: Iceland
Micro-hydropower generators
Tidal Energy
Produce electricity from flowing water
Ocean tides and waves
So far, power systems are limited
Norway New York City
Disadvantages Few suitable sites High costs Equipment damaged by
storms and corrosion
16-5 Wind EnergyWind: indirect form of solar energy Captured by turbines Converted into electrical energy
Second fastest-growing source of energyWind farms: on land and offshore“Saudi Arabia of wind power” North Dakota South Dakota Kansas Texas How much electricity is possible with wind farms in
those states?
Producing Electricity with Windpower
Countries with the highest total installed wind power capacity Germany United States Spain India Denmark
Installation is increasing in several other countries
Fig. 16-23, p. 421
TRADE-OFFSWind Power
Advantages DisadvantagesModerate to high net energy yield
Steady winds needed
High efficiencyBackup systems needed when winds are lowModerate capital
costLow electricity cost (and falling)
Plastic components produced from oil
Very low environmental impact
Environmental costs not included in market price
No CO2 emissions High land use for wind farm
Quick construction
Easily expandedVisual pollution
Can be located at seaNoise when located near populated areas
Land below turbines can be used to grow crops or graze livestock
Can kill birds and interfere with flights of migratory birds
16-5- Biomass as Energy Source
Biofuels
Production of solid mass fuel Plant fast-growing trees Biomass plantations Collect crop residues and animal
manure
Fig. 16-24, p. 422
TRADE-OFFSSolid Biomass
Advantages DisadvantagesLarge potential supply in some areas
Nonrenewable if harvested unsustainably
Moderate to high environmental impactModerate costs
No net CO2 increase if harvested, burned, and replanted sustainably
Environmental costs not included in market price
Increases CO2 emissions if harvested and burned unsustainably
Low photosynthetic efficiency
Plantation can be located on semiarid land not needed for crops Soil erosion, water
pollution, and loss of wildlife habitat
Can make use of agricultural, timber, and urban wastes
Often burned in inefficient and polluting open fires and stoves
Plantations could compete with cropland
Plantation can help restore degraded lands
Plants & Plant Wastes to Liquid
Liquid biofuels Biodiesel
Ethanol
Biggest producers of biofuel Brazil United States The European Union China
Liquid BioFuels
Major advantages over gasoline and diesel fuel produced from oil
Biofuel crops can be grown almost anywhere
No net increase in CO2 emissions if managed properly
Available now
Studies warn of problems: Decrease
biodiversity Increase soil
degrading, erosion, and nutrient leaching
Push farmers off their land
Raise food prices
Fig. 16-25, p. 424
TRADE-OFFS
Biodiesel
Advantages Disadvantages
Reduced CO emissions
Increased NOx emissions and more smog
Reduced CO2 emissions (78%)
Higher cost than regular diesel
High net energy yield for oil palm crops
Environmental costs not included in market price
Low net energy yield for soybean crops
Moderate net energy yield for rapeseed crops May compete with
growing food on cropland and raise food prices
Reduced hydrocarbon emissions
Loss and degradation of biodiversity from crop plantations
Better gas mileage (40%)
Potentially renewable
Can make engines hard to start in cold weather
Case Study: Is Ethanol the Answer?
Ethanol converted to gasoholBrazil: “Saudi Arabia of sugarcane” Saved $50 billion in oil import costs since the 1970s
United States: ethanol from corn Reduce the need for oil imports? Slow global warming? Reduce air pollution?
Cellulosic ethanol: alternative to corn ethanolSources Switchgrass Crop residues Municipal wastes
Fig. 16-27, p. 426
TRADE-OFFS
Ethanol Fuel
Advantages DisadvantagesHigh octane Lower driving range
Low net energy yield (corn)
Some reduction in CO2 emissions (sugarcane bagasse)
Higher CO2 emissions (corn)Much higher cost
High net energy yield (bagasse and switchgrass)
Environmental costs not included in market price
May compete with growing food and raise food prices
Reduced CO emissions
Higher NOx emissions and more smog
Can be sold as E85 or pure ethanol
Corrosive
Can make engines hard to start in cold weather
Potentially renewable
16-7 Geothermal Energy
Geothermal energy: heat stored in Soil Underground rocks Fluids in the earth’s mantle
Geothermal heat pump system Energy efficient and reliable Environmentally clean Cost effective to heat or cool a space
Geothermal Energy
Hydrothermal reservoirs Iceland
Geothermal energy: two problems High cost of tapping large-scale hydrothermal
reservoirs Dry- or wet-steam geothermal reservoirs could
be depleted
Hot, dry rock: another potential source of geothermal energy?
Fig. 16-29, p. 428
TRADE-OFFS
Advantages Disadvantages
Geothermal Energy
Very high efficiency Scarcity of suitable sites
Moderate net energy at accessible sites
Can be depleted if used too rapidly
Environmental costs not included in market priceLower CO2 emissions
than fossil fuelsCO2 emissions
Low cost at favorable sites
Moderate to high local air pollution
Low land use and disturbance Noise and odor (H2S)
Moderate environmental impact
High cost except at the most concentrated and accessible sources
16-8 Hydrogen as Energy Source
Hydrogen as a fuel Eliminate most of the air pollution problems Reduce threats of global warming
Some challenges Chemically locked in water and organic
compounds Fuel cells are the best way to use hydrogen CO2 levels dependent on method of
hydrogen production
Challenges to Hydrogen
Production and storage of H2
Hydrogen-powered vehicles: prototypes available
Can we produce hydrogen on demand?
Larger fuel cells
Fig. 16-31, p. 430
TRADE-OFFSHydrogen
AdvantagesFuel cell
DisadvantagesCan be produced from plentiful water
Not found as H2 in natureEnergy is needed to produce fuelLow environmental
impact Negative net energyRenewable if produced from renewable energy resources
CO2 emissions if produced from carbon-containing compounds
No CO2 emissions if produced from water
Environmental costs not included in market price
Good substitute for oil Nonrenewable if
generated by fossil fuels or nuclear powerCompetitive price if
environmental and social costs are included in cost comparisons
High costs (that may eventually come down)
Easier to store than electricity
Will take 25 to 50 years to phase inShort driving range for current fuel-cell carsSafer than gasoline
and natural gas No fuel distribution system in place
Nontoxic
High efficiency (45–65%) in fuel cells
Excessive H2 leaks may deplete ozone in the atmosphere
Fig. 16-33, p. 432
SOLUTIONSMaking the Transition to a More Sustainable Energy Future
Improve Energy Efficiency More Renewable Energy
Increase fuel-efficiency standards for vehicles, buildings, and appliances
Greatly increase use of renewable energyProvide large subsidies and tax credits for use of renewable energy
Mandate government purchases of efficient vehicles and other devices
Include environmental costs in prices for all energy resourcesEncourage government purchase of renewable energy devices
Provide large tax credits or feebates for buying efficient cars, houses, and appliances
Greatly increase renewable energy research and development
Reduce Pollution and Health RiskOffer large tax credits for investments in energy efficiency
Cut coal use 50% by 2020
Phase out coal subsidiesReward utilities for reducing demand for electricity Levy taxes on coal and oil use
Greatly increase energy efficiency research and development
Phase out nuclear power subsidies, tax breaks, and loan guarantees