Many proponents of renewable-energy sources seem to believe that they have to make their case by opposing all other forms of energy. In particular, they argue that we should turn to wind power instead of nuclear energy - which also produces emissions-free electric power - for much of our electricity in the future.

In turn, supporters of nuclear power seem to go out of their way to emphasize the shortcomings of wind energy. Both sides often act as if the future of our energy policy is an all-or-nothing decision between wind and nuclear.

It's time for a truce. In reality, nuclear and wind are not competitive, but complementary. And beyond that, large amounts of both are essential, if we hope to continue meeting our power needs while cutting back on the fossil-fuel emissions that are heating up the global environment.

For its part, nuclear power is the only emissions-free source of affordable, large-scale electricity that can be counted on to generate power 24 hours a day, seven days a week. This capability is crucial. Our high-tech economy, based heavily on computers and other electronics, requires total reliability in its electric power. Even brief blips in service can cause havoc - with airline safety, financial services and thousands of other sectors of our economy that rely heavily on electronics. For cities, factories and major computer operations, it takes a major power source that works around the clock. That means nuclear power.

Wind power cannot meet this need. It's too diffuse and too dependent on the whims of the weather. But what it can do is provide electricity to meet demand at peak times of the day, reducing the need for electricity from high-priced natural gas.

Working together - with energy efficiency and other renewables as they develop - they can help us meet the great challenge of the century: to provide the energy that the world needs (both the industrialized world and rapidly developing countries) while limiting our release of global-warming gases. We know that we will be unable to completely forgo the use of fossil fuels. But to the extent possible, we need to replace them with emission-free sources. That means recognizing that with the population of the United States topping 300 million people, adding the equivalent of one California every 10 years, the renewal of nuclear power and the further expansion of renewables are essential.

Simply calling for more of both is painless. The hard part is agreeing on the sites for new reactors and wind farms, given not-in-my-backyard sentiments that have turned energy development into a nightmare for many companies. There are several ways to make that happen. Congress should require the Environmental Protection Agency to regulate carbon emissions, raising the cost of burning fossil fuels and giving state and local officials an incentive to get serious about facilitating the use of nuclear power and renewables. In this regard, several utilities, with state and local support, have applied to the Nuclear Regulatory Commission for early site approval, so that when they decide to build a new nuclear-power plant, a site will be available.

As many as 35 new advanced light-water reactors, using four or five designs already certified by the Nuclear Regulatory Commission, will probably be built within the next decade around the country. But at least double that number of new reactors will be needed if we hope to meet an anticipated increase in "base-load" power demand and still reduce greenhouse emissions to 1990 levels.

Because government policies determine access to nuclear power and renewables, policy change on carbon emissions can make a huge a difference. Congress has an opportunity to make nuclear power and wind energy a major component of our energy supply and limit global warming. By pulling together, proponents of each will be in a better position to persuade Congress to take strong action.

***************

CAROLYN D. HEISING is a professor of industrial, mechanical and nuclear engineering at Iowa State University.