R ENEWABLE E NERGY Chapter 18. S HIFT FROM O IL TO H YDROGEN F UEL Will be used to produce electricity, to run cars & appliances, heat water, heat/cool

RENEWABLE ENERGYChapter 18

SHIFT FROM OIL TO HYDROGEN FUEL

Will be used to produce electricity, to run cars & appliances, heat water, heat/cool buildings

Burning hydrogen (adds oxygen) = production of water (not carbon dioxide)

Eliminates air pollution = slows global warming

ENERGY EFFICIENCY

Measure of the useful energy produced by an energy conversion device compared to the energy that is converted to useless (low quality) heat

2nd Law of Thermodynamics- 41% of energy used is wasted

US wastes 43% unnecessarily (fuel-wasting, vehicles, furnace, poorly designed/insulated buildings)

FIGURE 18-2PAGE 380

Solutions

Reducing Energy Waste

Prolongs fossil fuel supplies

Reduces oil imports

Very high net energy

Low cost

Reduces pollution and environmentaldegradation

Buys time to phase in renewable energy

Less need for military protection of Middle East oil resources

Improves local economy by reducing flow of money out to pay for energy

Creates local jobs

Solutions

Reducing Energy Waste

LIFE CYCLE COST

Initial cost plus life-time operating costs

3 LEAST efficient devices: Incandescent light bulb Nuclear power plant Motor vehicle

NET ENERGY EFFICIENCY

Determine by efficiency of each step in energy conversion for entire system

Improved by: Keeping number of conversion steps low Strive for highest possible energy efficiency for

each step

COGENERATION

Combined heat & power system (CHP) 80-90% efficient 30-40% for coal/nuclear plants

Energy Savers: Replace energy-wasting electric motors Switch from incandescent light bulbs to

fluorescent lighting

SAVING ENERGY IN TRANSPORTATION

Increase fuel efficiency Encourage development of hybrid, fuel cell,

or other fuel-saving vehicles

Not in US because Inflation – adjusted price of gasoline = low price 2/3 of Americans prefer SUVs, pickup trucks,

minivans, & other large inefficient vehicles

CAFE standards have not been raised since 1985

HIDDEN COSTS OF GASOLINE

Subsidies & tax breaks for oil companies & road builders

Pollution cleanup Military protection for oil supplies in Middle

East Increased medical bills & insurance

premiums Harmful effects on habitats

HYBRID-ELECTRIC CARS

+ Super efficient (80-300 mpg)+ Recharged by internal combustion engine

ElectricityFuel

Combustion engineSmall, efficient internalcombustion engine powersvehicle with low emissions.

A

Fuel tankLiquid fuel such as gasoline, diesel, or ethanol runs small combustion engine.

B

Electric motorTraction drive provides additional power, recoversbreaking energy to recharge battery.

C

Battery bankHigh-density batteries power electricMotor for increased power.

D

RegulatorControls flow of power between electricMotor and battery pack.

E

TransmissionEfficient 5-speed automatic transmission.F

A

B

C

D

EF

FIGURE 18-9PAGE 385

HYDROGEN-FUEL CELL CARS

+ Abundant fuel (hydrogen)+ 2x efficient+ No moving engine parts+ Little maintenance+ Little or no pollution- Expense- Development needed

1

2

3

4

1

2

3

4

H2

O2

H2O

Hydrogen gas

Emits water (H2O) vapor.

Produce electrical energy (flow of electrons) to power car.

React with oxygen (O2).

Cell splits H2 into protonsand electrons. Protons flowacross catalyst membrane.

FIGURE 18-10APAGE 385

A

C

E

D

B

ElectricityFuel

AFuel cell stackHydrogen and oxygen combinechemically to produce electricity.

BFuel tankHydrogen gas or liquid or solid metalhydride stored on board or made fromgasoline or methanol.

CTurbo compressorSends pressurized air to fuel cell.

DTraction inverterModule converts DC electricity from fuelcell to AC for use in electric motors.

E Electric motor/transaxleConverts electrical energy to mechanical energy to turn wheels.

FIGURE 18-10BPAGE 385

WAYS TO SAVE ENERGY IN BUILDINGS

Passive solar heating Superinsulation – like strawbales Ecoroof (green roof) – plants provide

insulation, absorb storm water, outlast conventional roofs

SUPERINSULATED HOMES

Heavily insulated & air tight Heat from direct sunlight, appliances, &

human bodies warm home with little or no need for backup heating system

Air-to-air heat exchanger prevents indoor air pollution

R-30 toR-43 insulation

Insulated glass,triple-paned orsuperwindows(passive solar gain)

R-30 to R-43insulation

Air-to-airheat exchanger

House nearly airtight

R-30 toR-43 insulation

Small or no north-facingwindows or superwindows

R-60 or higher insulation

FIGURE 18-12PAGE 387

STRAWBALE HOUSE

Walls made by stacking compacted bales of low-cost straw & covering with plaster or adobe


DO NOT POST TO INTERNET

ECO-ROOF

Covered with green plants Provides good insulation Absorbs stormwater & releases slowly Outlasts conventional roofs Increases efficiency

REDUCING ENERGY WASTE

Insulate & plug leaks Use energy-efficient windows Stop other heating & cooling losses (leaky

heating & cooling ducts in attics & unheated basements)

More efficient home heating More efficient water heating Use energy efficient appliances & lighting Turn off unused electrical devices Stricter energy-efficiency standards for new

buildings

FOUR EFFICIENT HOME HEATING METHODS

Superinsulation Geothermal heat pump Passive solar heating Conventional heat pump

EFFICIENT WAYS TO HEAT WATER

Tankless instant water heater Well-insulated, conventional natural gas or

LPG water heater

Electric water heaters are inefficient

NOT SAVING BECAUSE…

Glut of low-cost oil/gasoline Lack of sufficient government tax breaks or

economic incentives to improve energy efficiency

PASSIVE SOLAR HEATING

Absorbs & stores heat from sun directing with structure

+ No special equipment needed- Small backup heating system+ Cheap heating method- Cannot convert existing homes+ 3-7 years payback time

PASSIVE

Stone floor and wallfor heat storage

Superwindow

Wintersun

Summersun

Superwindow

Heavyinsulation


ACTIVE SOLAR HEATING

Absorbs energy from sun by pumping heat-absorbing fluid (like water) through collectors

- Collectors are expensive+ Some collected heat is used directly+ Can supply hot water- Maintenance required- Unappealing appearance

Hotwatertank

Pump

Heatexchanger

Super-window

Heat to house(radiators orforced air duct)

ACTIVE

Heavyinsulation


COOLING HOMES NATURALLY

Superinsulation & superinsulating windows Open windows for breezes Use fans to move air Block summer sun with deciduous trees or

window overhangs (awnings) Use light colored roof Suspend reflective insulating foil in attic to

block downward radiating heat

Direct GainCeiling and north wall heavily insulated

Hot air

Super insulated windows

Cool air

Warmair

Summersun

Wintersun

Earth tubes


Greenhouse, Sunspace, orAttached Solarium

Summer cooling vent

Warm air

Cool air

Insulatedwindows


Earth Sheltered

Earth Triple-paned or superwindows

Flagstone floorfor heat storage

Reinforced concrete,carefully waterproofedwalls and roof

FIGURE 18-17CPAGE 392

Moderate net energy

Moderate environmentalImpact

No CO2 emissions

Fast construction (1-2 years)

Costs reduced with natural gasturbine backup

Low efficiency

High costs

Needs backup or storage system

Need access to sunmost of the time

High land use

May disturb desert areas

Advantages Disadvantages

Trade-Offs

Solar Energy for High-TemperatureHeat and Electricity


SOLAR CELL

Photovoltaic (PV) cell- converts solar energy directly into electrical energy

Fairly high net energy Work on cloudy days Quick installation Easily expanded or moved No CO2 emissions Low environmental impact Last 20-40 years Low land use (if on roof or built into walls or windows)

Reduce dependence on fossil fuels

Need access to sun Low efficiency Need electricity storage system or backup

High land use (solar cell power plants) could disrupt desert areas High costs (but should becompetitive in 5-15 years) DC current must be converted to AC

FIGURE 18-21PAGE 395 Advantages Disadvantages

Trade-Offs

Solar Cells

HYDROPOWER

Large-scale hydropower- high dam built across a large river to create reservoir; water is stored or allowed to flow through huge pipes at controlled rate; spinning turbines & producing electricity

Small-scale hydropower- low dam with little or no reservoir; small high-efficiency turbine in stream without impeding stream navigation or fish movements

Pumped-storage hydropower- pumps use surplus electricity from conventional plant to pump water to lake or reservoir at higher elevation

Moderate to high net energy High efficiency (80%)

Large untapped potential

Low-cost electricity

Long life span

No CO2 emissions during operation May provide flood control below dam

Provides water for year-roundirrigation of crop land

Reservoir is useful for fishing and recreation

High construction costs

High environmental impact from flooding land to form a reservoir

High CO2 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


Trade-Offs

Large-Scale Hydropower

Figure 18-22Page 396

WIND POWER

Winds turn turbine to generate electricity

Wind Turbine

Power cable

Electricalgenerator

GearboxFIGURE 18-23APAGE 396

Wind Farm


Moderate to highnet energy High efficiency

Moderate capital cost

Low electricity cost(and falling)

Very low environmentalimpact

No CO2 emissions Quick construction Easily expanded

Land below turbinescan be used to growcrops or graze livestock

Steady winds needed

Backup systems whenneeded winds are low

High land use for wind farm

Visual pollution

Noise when locatednear populated areas

May interfere in flights of migratory birds and killbirds of prey

FIGURE 18-24PAGE 397Advantages Disadvantages

Trade-Offs

Wind Power

Large potential supply in some areas

Moderate costs

No net CO2 increase if harvested and burnedsustainably

Plantation can be located on semiarid land not needed for crops

Plantation can help restoredegraded lands

Can make use of agricultural,timber, and urban wastes

Nonrenewable if harvested unsustainably Moderate to high environmental impact CO2 emissions if harvested and burned unsustainably Low photosynthetic efficiency Soil erosion, water pollution, and loss of wildlife habitat Plantations could compete withcropland Often burned in inefficientand polluting open fires and stoves


Trade-Offs

Solid Biomass

High octane

Some reduction in CO2 emission

Reduced CO emissions

Can be sold as gasohol

Potentially renewable

Large fuel tank needed

Lower driving range

Net energy loss

Much higher cost

Corn supply limited

May compete with growingfood on cropland

Higher NO emission

Corrosive

Hard to start incolder weather


Trade-Offs

Ethanol Fuel

GEOTHERMAL ENERGY

Consists of heat stored in soil, underground rocks, & fluids in earth’s mantle

Reservoirs (other than near surface) Molten rock Hot dry-rock zones- magma penetrates crust &

heats subsurface rock (8-10km down) Warm-water rock

Very high efficiency

Moderate net energy at accessible sites

Lower CO2 emissions than fossil fuels

Low cost at favorable sites

Low land use

Low land disturbance

Moderate environmental impact

Scarcity of suitable sites

Depleted if used too rapidly

CO2 emissions

Moderate to high local air pollution

Noise and odor (H2S)

Cost too high except at the most concentrated and accessible source



Trade-Offs

Geothermal Fuel

FIGURE 18-30PAGE 401Can be produced from plentiful

water

Low environmental impact

Renewable if producedFrom renewable energyresources

No CO2 emissions if produced from water Good substitute for oil Competitive price if environmental and social costs are included incost comparisons Easier to store than electricity Safer than gasoline and natural gas

Nontoxic

High efficiency (65-95%) in fuel cells

Not found in nature

Energy is needed to produce fuel

Negative net energy

CO2 emissions if produced fromcarbon-containing compounds

Nonrenewable if generated byfossil fuels or nuclear power

High costs (but expected to come down)

Will take 25 to 50 years to phase in

Short driving range for current fuel cell cars

No distribution system in place

Excessive H2 leaks may deplete ozone


Trade-Offs

Hydrogen

MICROPOWER

Decentralized, dispersed small-scale power plants

Small modular units

Fast factory production

Fast installation (hours to days)

Can add or remove modules as needed

High energy efficiency (60–80%)

Low or no CO2 emissions

Low air pollution emissions

Reliable

Easy to repair

Much less vulnerable to power outages

Increase national security by dispersal of targets

Useful anywhere

Especially useful in rural areas in developing countries with no power

Can use locally available renewable energy resources

Easily financed (costs included in mortgage and commercial loan)


BioenergyPowerplants

Wind farm Small solar cellpower plants

Fuel cells

Solar cellrooftop systems

Commercial

MicroturbinesIndustrial

Transmissionand distributionsystem

Residential

Smallwindturbine

Rooftop solarcell arrays


ECONOMIC APPROACHES TO CHANGING ENERGY SOURCES

Keep energy prices artificially low to encourage use of selected energy resources- Encourages energy waste- Rapid depletion of nonrenewable energy resources- Discourages development of other energy alternatives- Discourages improvements in energy efficiency

Keep energy prices artificially high to discourage use of resource+ Increases government revenue+ Encourages improvements in energy efficiency+ Reduces dependence on imported energy+ Decreases use of energy resource with limited

future supply Increasing taxes on fossil fuels

+ Reduce air & water pollution+ Slows greenhouse gas emissions+ Encourages improvements in energy efficiency+ Greater use of renewable energy

Improve Energy Efficiency

Increase fuel-efficiencystandards for vehicles,buildings, and appliances

Mandate governmentpurchases of efficient vehicles and other devices

Provide large tax credits for buying efficient cars, houses, and appliances

Offer large tax credits for investments in efficiency

Reward utilities forreducing demand

Encourage independentpower producers

Greatly increase efficiencyresearch and development

More Renewable Energy

Increase renewable energy to 20% by 2020 and 50% by 2050

Provide large subsidies and tax credits for renewable energy

Use full-cost accounting and life cycle cost for comparing all energy alternatives

Encourage government purchase of renewable energy devices

Greatly increase renewableenergy research and development

Reduce Pollution andHealth Risk

Cut coal use 50% by 2020

Phase out coal subsidies

Levy taxes on coal and oil use

Phase out nuclear power or put it on hold until 2020

Phase out nuclear power subsidies


Figure 18-36 Page 408

•Drive a car that gets at least 15 kilometers per liter (35 miles per gallon) and join a carpool.

•Use mass transit, walking, and bicycling.

•Superinsulate your house and plug all air leaks.

•Turn off lights, TV sets, computers, and other electronic equipment when they are not in use.

•Wash laundry in warm or cold water.

•Use passive solar heating.

•For cooling, open windows and use ceiling fans or whole-house attic or window fans.

•Turn thermostats down in winter and up in summer.

•Buy the most energy-efficient homes, lights, cars, and appliances available.

•Turn down the thermostat on water heaters to 43-49ºC (110-120ºF) and insulate hot water heaters and pipes.

What Can You Do?

Energy Use ad Waste

Documents

R ENEWABLE E NERGY Chapter 18. S HIFT FROM O IL TO H YDROGEN F UEL Will be used to produce electricity, to run cars & appliances, heat water, heat/cool