RENEWABLE ENERGY SOURCES

Our power, our future

Residential Solar PowerUsing the sun to heat your home

Photovoltaics

In PV cells, sun’s energy powers a chemical reaction -> electricityCommercial residential PV modules anywhere from 10 to 300 wattsCan be used en masse to create power plantsDirect current generated must be inverted into alternating current energy

Pollution Reduction

Over 20 years, a 100-megawatt plant avoids 3 million tons of carbon dioxide.

1000 kWh of solar power saves:

8 pounds of sulfur dioxide

5 pounds of nitrogen oxide

1,400 pounds of carbon dioxide

Expensive!

5-kW systems can cost up to $40,000!

Power costs up to $9/watt!

Over 30 states offer incentivesCalifornia is the leader in encouraging solar power use

Biomass Fuels

Solid Fuel Combustion

Combustion of biomass instead of coal tends to be cleaner and helps eliminate waste efficiently

Products burned are usually wood matter, vegetation, waste from lumber yards, etc (cellulosic)

Digestion

Occurs naturally - bacteria feed on decomposing wasteReleases gases like methane, hydrogen, CO, etcPipelines running thru waste collect gases (landfills, feedlots, zoos)Synthesis gases can become any kind of hydrocarbon fuel.

Pyrolysis

Intense heat (above 800° F) and pressure makes a product like charcoal, doubling the energy density

Highly transportable and efficient

Ethanol

A.k.a. alcohol; chemical formula CH3CH2OH.

Produced using the dry mill method.

81 plants in 20 states can produce 4.4 billion gallons each year

Any cellulosic biomass can be converted into ethanol.

Ethanol in Cars

Mixed with gasoline to form either E10 or E85

Number is percentage of ethanol in mixture

Increases octane rating and decreases emissions

Ethanol is favored oxygenate under Clean Air Acts Amendments of 1990Many incentives encourage its use

Wind EnergyFastest Growing Source of

Renewable Energy

History and DefinitionFirst use as early as 5000 B.C.First used to generate electricity in Denmark as early as 1890.Now, wind-generated electricity is very close in cost to the power from conventional utility generation in some locations.

•Wind is a form of solar energy.•Caused by uneven heating of atmosphere by the Sun, irregularities of the Earth’s surface, and rotation of the Earth.

•The amount and speed of wind depends on the Earth’s terrain and other factors.

Horizontal-Axis Wind Turbine

Vertical-Axis Wind Turbine

Advantages and DisadvantagesWind is free, wind farms need no fuel. Produces no waste or greenhouse gases. The land beneath can usually still be used for farming. Wind farms can be tourist attractions. A good method of supplying energy to remote areas.

•Not always predictable. •Price of land.•Changing landscape.•Can kill birds - migrating flocks tend to like strong winds. •Can affect television reception if you live nearby. •Noisy. A wind generator makes a constant, low, "swooshing" noise day and night.

Hydroelectric PowerAmerica’s leading renewable

energy source

History and BasicsThe earliest reference from 4th century BC Greek literature. “hydro” comes from the Greek word for “water.” By 1980, accounted for 25% of global electricity and 5% of total world energy use, totalling 2,044 billion kilowatt hours (kW h).

•Water flows from a high potential energy (high ground) to lower potential energy (lower ground), the potential energy difference is partially converted into electric energy through the use of a generator. •There are two major designs in use that utilize water to produce electricity

Hydroelectric DamAdvantages:

The energy is virtually free. No waste or pollutionReliableCan cope with peaks in demand. Can increase to full power very quickly, unlike other power stations. Electricity can be generated constantly.

•Disadvantages:–Expensive to build. –Environmental concerns upstream and downstream–Siting

Pumped-Storage PlantAdvantages:

Without some means of storing energy for quick release, we'd be in trouble. Little effect on the landscape.No pollution or waste.

DisadvantagesExpensive to build. Once it's used, you can't use it again until you've pumped the water back up. Good planning can get around this problem.

Important Concept:These plants are not really power stations, but a means of storing energy from other power stations.

Ocean EnergiesWaves, tides, ocean currents,

ocean thermal energy

General Information70% of Earth’s surface is covered by oceansHuge potential: “a mere .1% of total energy potential in oceans would satisfy all of mankind’s energy needs five times over.”United States faces siting challenges and economic obstaclesEurope: leader in ocean energiesExploiting Location and natural geography

Winds blown across Atlantic (West -> East) create bigger waves -> more energy potential

Areas for underwater currents and tides

Wave Power vs. Ocean Currents

Waves push high-pressure oil through hydraulic motors to generate electricity; fed to grid via underwater cableWave farms: 30 MW / sq. km; enough to power 20,000 homesAll systems manipulate wave motions to power hydraulic pumps or spin turbinesEuropean power costs roughly 9 cents/kWh

•Britain’s example

•Turbines anchored to ocean floor, currents spin blades, generate electricity. •More efficient than wind: 8 mph ocean current vs. 230 mph wind

•10 cents/kWh estimate

•Verdant Power company plans to build 5-10 MW field in East River in New York

Tidal Power

Damming estuaries, water flows through turbinesOne method: ebb generation

High and low tides are very predictable

Can only produce electricity at certain times

Not many places in the world where it’s efficient5-10 meter difference between high and low tides

High costs to build deters private investors

Negative impact on estuarine ecosystems

Ocean Thermal Energy Conversion (OTEC)

Hawaii can exploit this technology because of its location near the equator

Sun heats water to depths of 100 meters to temperatures around 24-30 degrees Celsius

Flashing into steam

Cold water from deeper in ocean condenses the steam, produces desalinated water!

OTEC can serve much of Hawaii’s energy needs, but not really any of the contiguous United States

Geothermal

Exploiting Earth’s temperatures to produce electricity and heat our homes.

Direct Heating vs Generating ElectricityImmediate, usable energyCan heat buildings or entire areas

Relatively warm air in winterWarm water piped under streets in Klamath Falls, OR melts snow

Same principle of relative temperatures allows for cooling of buildings in summer

•Different types of plants depending on geothermal area

–Hot water/steam–Not-so-hot water

•Using steam directly to spin turbine•“Flashing” steam to spin turbine

Advantages

Reliability – the Earth’s heat provides a constant source of energy

Low impact on environment

Room for improvement: 2,300 MW in 2004, D.O.E. estimates could be 15,000 MW by 2014

Hot Dry RockHow does it work?

If the technology works, we could tap geothermal energy ANYWHERE!

Disadvantages

Depletion of waterRe-injecting water

Earthquakes…should plants be responsible?

Heat depletionNatural cooling of Earth’s crust cannot be avoided

Plants become less and less efficient

EconomicsBuilding costs: $1175-1750 per kW installed capacity

Geothermal areas aren’t always near electricity grids…

Projections for Geothermal

National Commission on Energy Policy estimates 4-6 cents per kWhCompares favorably with other renewables (solar: 20-25 cents per kWh)Compares favorably with coal and NG: 4-5 cents per kWhEstimates depend on availability of geothermal resources and success of HDR technology

Encouraging Development Through Government

PoliciesEnergy Policy Act of 2005, Tradable Permits, State Renewable Portfolio

Standards (RPS)

National LevelCongress passed Energy Policy Act of 2005To expand renewables so they become economically competitive energy sources

Increase US consumption of renewable energyAt least 3% from 2007-09

Developing existing renewable sourcesHydroelectric: $10,000,000 budget for incentives to plants

Up to $750,000 to any particular plantGoal: increase efficiency by at least 3%

Biomass: synergy between forest-clearing and biomass facilities; expand markets for products of forest clearing

National Commission on Energy Policy Tradable permits system

State Level

State Renewable Portfolio Standards (RPS)

AZ, CA, CO, CT, IA, ME, MD, MA, NJ, NM, NY, NV, PA, RI, TX, WIStates with ample renewable resources

Hawaii, Illinois, Minnesota shifting towards adopting themMost have adopted them in the past five years, more will catch on as conventional energy sources run out.

The Future…Energy Policy Act means we will see more renewables in the next ten years; efficiency will increase Tradable-permits system, if passed, will provide huge economic boost to renewables

consumption of renewables will increase by up to 60%depends on solving problems of initial allocation of permits, and other countries’ cooperation

Action at the state level will increase as the nation seeks to find alternatives to fossil fuelsMore renewables legislation will undoubtedly be put into effect as we run out of energy