Solar Energy: Power from the Sun

What's the first renewable energy technology that comes to mind?

You probably answered solar, the star of renewable energy options.

Yet, solar power produced less than 0.05 percent of America's electricity and only 0.66 percent of the world's electricity in 2007.

What's the promise of solar and what role will it play in our clean energy future?

The Promise

Every hour, the sun delivers as much energy to the Earth as all of humanity uses in a year. The total energy from just 20 days of sunshine is equal to all the energy available in the total reserves of coal, oil, and natural gas.

If we converted only 10 percent of this solar energy into electricity, a square of land 100 miles on a side (about 0.26 percent of America's total land area) could meet all of America's electricity needs.

Solar energy is clean, safe and inexhaustible. It can be harnessed many ways—from passive solar heating, to rooftop solar cells that convert sunlight to electricity, to large scale solar power plants that use the sun's heat to generate steam. Depending on local regulations, some homeowners who use solar energy to generate their own power can sell surplus electricity to local utilities.

The Challenge

Despite its promise, solar power faces several technological hurdles.

First, the sun doesn't shine 24 hours a day or every day of the year—far from it in some regions. This means solar must be paired with a backup energy source or, better yet, with a way to reserve energy for those times when the sun isn't shining.

The price of solar has been another major obstacle to its broad deployment. In 2007, a conventional rooftop photovoltaic solar system cost about $4 per watt for the cells, nearly twice that installed, or about $21,000 for a typical 3-kilowatt installation.

Most industry analysts agree the price must come down to about $1 per watt (and the storage problem must be resolved) before solar-generated electricity power can compete with coal-fired electricity virtually everywhere.

There are three ways to make solar cells more competitive:

1. Build a better solar cell – Continue streamlining existing technologies, which are primarily based on crystalline-silicon cells.
2. Mass produce cheaper, more flexible cells – Emerging next-generation "thin-film" technologies will make it possible to produce acres of lower-efficiency solar cells, which can be integrated right into roofing material or glass.
3. Concentrate solar energy – Invest in the most efficient, smallest possible cells, then wrap those cells in optics that concentrate the sunlight, multiplying its intensity 500 or even 1000 times.

Solar thermal power—using mirrors to harness and convert the sun's heat into electricity—is another approach. Solar thermal is already competing with gas-fired power plants and has the potential to match coal in price and scale.

However, solar thermal plants are large and costly to build. And, since lenders currently view renewable energy investments as riskier than conventional energy, financing solar plant construction is a significant challenge.

The Future

A December 2007 report in Scientific American promotes "a massive switch to solar power" as the "logical choice" to free America from fossil fuels.

According to the report, "at least 250,000 square miles of land in the Southwest alone are suitable for constructing solar thermal power plants… Converting only 2.5 percent of that radiation into electricity would match the nation's total energy consumption in 2006."

The U.S. Department of Energy predicts that within 10 years, "photovoltaic power will be competitive in price with traditional sources of electricity." This evolution can, of course, be sped up with a national cap on global warming pollution that would price the cost of emissions into the market, rewarding clean energy sources like solar.

The Solar Energy Industry Association (SEIA) predicts that with the right policies and investments, half of all new electricity generation in the U.S. could come from solar power by 2025.

While these reports offer promise, the U.S. has been falling behind. For years, the U.S. was the world's leading producer of solar cells. However, the Earth Policy Institute reports that the U.S. now ranks fifth in production behind Japan, China, Germany and Taiwan.

According to an MIT study, Japan's solar production increased twenty-two–fold from 1994 through 2003—while Japan was in a recession.

During this same period, while the U.S. economy surged, the U.S. solar industry remained flat.

The U.S. is also lagging on solar installation. Because of consistent government policies, Japan and Germany together command 70 percent of the world's solar market, despite the fact that neither country is particularly sunny.

Why hasn't the U.S. maintained its competitive edge in solar energy despite having some of the best solar resources on Earth?

The answer is simple: we haven't made clean renewable energy a priority. Both Germany and Japan have aggressive national policies promoting solar energy and both countries have ratified the Kyoto treaty, which mandates global warming pollution reductions.

By adopting a national cap on global warming pollution, Congress can unlock America's abundant solar—and technological— resources, creating huge opportunities to unleash the 21st century's clean energy economy.

Sources:

• Earth: The Sequel–The Race to Reinvent Energy and Stop Global Warming
• http://en.wikipedia.org/wiki/Solar_energy
• http://www.seia.org/index.php
• http://www.seia.org/roadmap.pdf
• http://www1.eere.energy.gov/solar/
• http://www.nrel.gov/learning/re_solar.html
• http://www.sciam.com/article.cfm?id=a-solar-grand-plan
• http://www.ucsusa.org/clean_energy/renewable_energy_basics/how-solar-energy-works.html
• http://www.seia.org/Year_in_Review_2007.pdf
• http://www.earthpolicy.org/Indicators/Solar/2007.htm

Posted: 01-Jan-1900; Updated: 18-Jun-2008