Chap 16 Energy Efficiency and Renewable Energy

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to higher-efficiency fluorescent and LED lighting Update- outdated & wasteful electrical grids Utility companies promote efficient use of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

Solar-Cell Power Plant in Arizona, U.S., Is the Largest Solar-Cell Power Plant

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?

Wind Power

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?

Natural Capital: A Geothermal Heat Pump System Can Heat or Cool a House

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

What Can you Do? Shifting to Sustainable Energy Use