Not since President Jimmy Carter had solar panels installed at the White House has there been as much hype for renewable energy sources as we are witnessing now. Congressional leaders once again are pushing for passage of legislation that would mandate a "renewable portfolio." South Carolina is wisely letting the free market determine whether or not renewables will catch on. But 25 states have adopted renewable energy requirements, committing nearly half of our country's population to obtaining as much as 25 percent of their electricity from solar, wind and other "green " sources by 2020.

Increasing our use of renewable energy sources is a worthwhile goal. But if we allow the heavy hand of government to mandate their use, we're setting solar and wind energy up to fail. While they have a place on the electric grid, the notion that they can replace base load capacity from coal and nuclear power is irresponsible and dangerous. Renewables provide just 3 percent of the nation's energy, and the Department of Energy forecasts their share will reach 4.2 percent by 2030.

Wind power has appeal, but not because it's non-polluting. Tax breaks and subsidies for wind are now so large that their value to wind farm owners - not any possible environmental benefits - is the primary motivation for building a wind farm.

Over the past decade, large-scale wind farms have been built in Texas, California, Kansas, Wyoming and other states. But at best, the wind blows only 40 percent of the time. Wind is so unpredictable that electricity shortages have hobbled businesses and industries in both Texas and California, the two states with the most wind energy capacity, mainly because the wind stopped blowing and wind turbines were operating at only 5 percent of capacity.

On the other hand, high-wind areas, where the costs of wind power are lowest, tend to be far from population centers where the demand is great. This creates a need for miles of transmission lines.

Despite substantial federal support and state mandates requiring their use, wind power churns out less than 1 percent of the nation's electricity, and solar energy's contribution is one-hundredth of 1 percent. By comparison, coal and nuclear power provide more than 70 percent of America's electricity.

This hasn't stopped federal and state policymakers from climbing on the renewable bandwagon. If government subsidies lead to unrealistic reliance on renewables, the result will be terrible. What happens when dire reality sets in, and policy makers conclude that desperate measures are needed to meet the shortfall in energy production? Now is the time to take stock of the situation before it's too late.

There are two routes forward that need to be followed to achieve energy security. The first is developing ways to capture and store carbon dioxide emissions from coal plants. Injecting carbon dioxide deep under ground into salt caverns or depleted oil and natural gas fields needs to be tested in large-scale demonstrations so it can be determined whether coal has a future in a carbon-constrained world. This makes tremendous economic sense. Especially since the United States has 270 years worth of coal reserves, it means energy security would be possible without damaging the environment.

The second is to build the next generation of nuclear plants. We can get still more power from existing nuclear plants by renewing their operating licenses, but we must have new plants to meet the growing demand for electricity, which is projected to rise 50 percent by 2030. Nuclear power is carbon free and produces no air pollution. Nuclear-generated electricity accounts for the single largest avoidance of carbon emissions. Electric companies are gearing up to build a new generation of nuclear plants using advanced technologies. It's expected that about eight new nuclear will begin operating by 2015. When these plants go on-line, construction is expected on the next group of nuclear plants.

The great advantage of nuclear plants is that they generate electricity more than 90 percent of the time and take up much less land than wind farms.

Jesse Ausubel, a professor at Rockefeller University in New York, has calculated that in terms of watts per area disturbed, nuclear power has a huge environmental advantages over wind and solar energy. Wind farms covering a 462-square-mile area are needed to produce as much energy as one 1,000-megawatt nuclear plant - and would produce electricity at double the cost. To meet U.S. electricity demand - and assuming round-the-clock wind at the right speed - an area the size of Texas, some 468,000 square miles, would need to be covered with wind turbines and transmission lines.

Likewise, a solar photovoltaic plant would require 90 square miles plus land for energy storage and retrieval in order to equal the power output of a large nuclear plant.

What a triumph it would be for common sense if Congress were to support nuclear power development and clean-coal technology with actual funding for large-scale demonstrations of carbon capture and storage. Ensuring adequate electricity for the future should have nothing to do with partisan politics.

Instead, the House of Representatives has approved $18 billion in tax incentives for renewable energy sources - a move that would do little to reduce carbon emissions or dependence on foreign oil. It's time for federal and state policymakers to adopt energy policies that serve the public interest.

Mr. Madison, now retired and living in Greenville, was engaged in reactor operations, radiation protection and radiation safety for the U.S. Air Force, the Knolls Atomic Power Laboratory, the Argonne National Laboratory (West), and the Daniel Construction Co.