Green Power: The Basics

What it means to buy it, and a rundown of power sources

Posted: 19-Jul-2006; Updated: 28-Dec-2006

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Buying green power ensures that more of the power supply is generated by renewable, efficient sources.

Traditionally, utilities sold us just one "brand" of electricity, and unless you were one of the largest electric customers, you paid one price. No negotiations. No choice. Today's electricity landscape is different. Now there are options.

In 1998, some 30 million American utility customers began choosing their power suppliers. Customers in California and parts of New England could decide which company to buy their electricity from, which brand to buy, and what prices to pay. In other states, utilities offered "green pricing," allowing customers to direct some of their electric bill toward clean, renewable energy, like solar and wind power.

Today, about 75 million electricity customers in 42 states have the option to buy green power through their utility or an alternative power supplier, according to the government's National Renewable Energy Laboratory. (To find out if green power is available in your area, visit the Department of Energy's green pricing page.)

Suddenly, we Americans have new responsibility and opportunity of choice, but not a lot of information. Unfortunately, reading our electric bills does not tell us where our electricity comes from, how much it really costs or how much pollution it causes. The green power revolution arrived quietly, without much education and preparation. It's time to get caught up.

What does it mean to buy green power?

Buying green power is less direct than buying recycled paper towels—you can't specify that only wind-generated electrons show up at your wall outlet.

Imagine the electricity delivery system as a system of pipes delivering water to and from a lake. Power generators pour water into the lake, and electricity consumers take water out. By buying green, you ensure that the water going into the lake is as clean as possible. The more green consumers there are, the cleaner the whole lake will be. But everyone still draws water out of the whole lake.

Where does conventional electricity come from?

Before diving into the cleaner sources of energy available these days, it's worth looking at conventional sources. Burning fossil fuels like coal and oil supplies about 97 percent of America's electricity and is responsible for about 33 percent of the country's global warming pollution. Reducing the amount of electricity we use in our homes is a key factor in creating a sustainable energy future.

Coal. Coal is energy stored in dead plant matter from prehistoric times. Coal burning generates more than 50 percent of the electricity in the U.S. and accounts for about one-third of the country's CO₂ emissions. Though coal reserves will last for centuries at current rates of usage, long before supplies run out, global climate change will require that restrictions be imposed on burning coal.

There are cleaner ways of burning coal than the traditional steam turbine. (More about coal gasification.)

Nuclear. Nuclear power comes from splitting uranium or plutonium atoms. Nuclear power provides about 20 percent of electricity generated in the U.S. Although generating electricity from nuclear fuels emits little CO₂, nuclear power poses grave risks to both human health and the environment. Safely storing nuclear waste is an extremely difficult problem. Although supplies of uranium and plutonium should last for more than a century, no more nuclear plants are being built, in large part because of high costs.

Natural gas. Natural gas is the most environmentally benign fossil fuel. These two factors have greatly increased the use of natural gas to generate electricity. About 18 percent of electricity in the U.S. comes from natural gas. Natural gas does produce air pollution, but not nearly as much as other fossil fuels: for the same amount of energy, it produces half the CO₂ of coal. Although natural gas reserves will last for many decades to come, they are finite. Prices have already started to tick up and, as supplies shrink, the price will rise even more.

Oil. Oil provides only about three percent of electricity in the U.S. Oil burns cleaner than coal, but still produces large quantities of CO₂ emissions for each unit of energy produced. Most of the oil that is easiest to obtain in the United States has already been extracted, so continuing to use oil as an electricity source will require an increase in imports or improved technology. Increasing reliance on oil imports, especially from politically unstable regions, is unwise.

Large-scale hydropower. Dams provide electricity by guiding water down a chute and over a turbine at high speed. Although hydropower does not produce any air emissions, dams—especially large ones—cause serious environmental problems.

The reservoir behind a dam often requires flooding many square miles, destroying entire ecosystems. Dams block the natural flow of water and degrade water quality, damaging vegetation and wildlife. They interfere with fish migration, and though fish ladders can help, they don't solve the problem.

Hydropower provides about six percent of the electricity generated in the U.S. This percentage is unlikely to increase. Few sites remain where large dams could be built, and the environmental concerns are strong.

Where does green electricity come from?

By harnessing wind, sunlight, plant matter or heat from the Earth's core, we can produce electricity in ways that curtail global warming pollution. And because electricity demand is based on consumer choices, the more we demand green power, the more cleaner sources will be used. That means a lot less heat-trapping pollution.

Wind. Wind turbines, or windmills, use strong wind to create pollution-free, renewable electricity. Wind power is already as cheap as fossil fuel-generated electricity in some places. The windier the location, the lower the cost is, and the more energy that can be produced. Wind energy is most economical in places where average wind speed is at least 17 miles per hour. New York-based Brooklyn Brewery is one company powered completely by wind. Its annual savings of heat-trapping emissions are about 335,000 lbs of CO2.

Solar. The sun's energy can help produce electricity in two ways: photovoltaic (PV) systems and solar thermal systems. PV systems change sunlight directly into electricity. They are common where it is relatively expensive to run electrical wires or use batteries, such as in rural homes, remote research stations and freeway call boxes. Solar thermal systems use the sun's energy to heat a fluid that produces steam, which then turns a turbine and generator. California's Luz SEGS plants are the principal solar thermal generators in America. Although solar technologies are more expensive than other options now, they are cost-effective where people are allowed to sell electricity back to the grid, and several states offer subsidies to stimulate investment.

Geothermal. Geothermal energy is generated by converting the hot water or steam from deep beneath the Earth's surface into electricity. Geothermal plants emit very little air pollution and have minimal impacts on the environment. They are very economical, competing favorably with fossil fuel generation. Currently, geothermal plants in the U.S. provide enough electricity to supply the homes of 3.5 million people. Known geothermal reserves and technology could supply the entire country with electricity for 30 years.

Biomass. Biomass—crop parts or animal waste that can make energy—is an extremely versatile fuel source. It can provide electricity, heat buildings and factories, and power cars and trucks.

When the technology first took off, biomass was burned in an incinerator to produce energy. In newer facilities, the biomass is converted into a combustible gas, allowing for greater efficiency and cleaner performance. Biomass sources include agricultural, forestry and food processing byproducts, as well as gas emitted from landfills. Though not as clean as wind and solar energy and a bit more expensive (because of transportation costs from source to incinerator), its environmental benefits are a significant plus because biomass generates few or no heat-trapping gases. Biomass supplies 2% of the electricity used in California.

More resources

The Department of Energy's Buying Green Power.

Solar Pioneer Program offers New York homeowners the opportunity to supplement their home's energy needs with solar electricity, also known as photovoltaics or "PV." Investing in solar electricity to supplement your home's energy needs will enable you to not only generate clean electricity for your home's electric requirements, but you could also reduce the amount of electricity purchased from LIPA and potentially sell power back to LIPA through net metering. Visit the Solar Pioneer Program for more info.

Sources

Emissions of Greenhouse Gases in the United States 2003. Energy Information Administration. www.eia.doe.gov/oiaf/1605/gg04rpt/carbon.html (18 February 2006).

National Renewable Energy Laboratory.

Renewable Energy Trends, 2003, Energy Information Administration, July 2004, www.eia.doe.gov/cneaf/solar.renewables/page/rea_data/trends.pdf