Tall, imposing structures line the crest of Mars Hill in Aroostook County, just this side of the New Brunswick border. These are wind turbines, part of a 28-turbine wind farm that became fully operational last March, generating enough electricity at maximum output to supply 16,000 homes.

Larger wind farms will soon be erected on hilltops in Washington and Franklin counties. Residents of Swan’s Island and Vinalhaven Island are exploring the merits of small wind farms.

Will Maine’s wind turbines be real players in a coming revolution in energy production? Or should we view them as mere curiosities, or perhaps as the imagined adversaries of some crazed future Don Quixote?

Wind farms, in fact, are already bringing us benefits by modestly easing our reliance on electricity generated from coal, oil and gas. Generating electricity with these fossil fuels adds chemical pollutants to our air and gives rise to carbon dioxide emissions, contributing to global warming. And our imports of oil and gas increase our dependence on foreign countries, including some that are unstable or hostile to us.

Wind energy, on the other hand, powers the economy without causing pollution, generating hazardous wastes, depleting natural resources, or increasing our dependence on other countries. And the wind itself is free. Remarkably, the prices of electricity from today’s larger, more efficient wind turbines are increasingly competitive with prices of power from fossil fuels.

For Mainers, wind energy brings concrete advantages. Electricity from Maine wind farms already is being fed into the New England electricity grid, adding to the reliability of the region’s electricity supply and reducing regional air pollution. And wind energy companies will pay taxes to Maine localities and employ local workers.

Wind farms on Maine’s islands could modestly lower islanders’ electricity bills. Electricity co-ops on Vinalhaven, North Haven and Swan’s Island currently pay very high prices for the power they receive from the mainland through underwater cables.

Still, some people oppose wind farms, maintaining that the turbines harm wild bird populations and degrade the beauty of the landscape. Others argue that the new larger turbines do not harm birds. And some view the turbines as beautiful, or at least attractive, alternatives to conventional power plants.

So far, wind energy’s advantages have attracted many consumers, environmentalists and businesses – and the industry is growing rapidly. Worldwide, installed generation capacity increased from 1,700 megawatts in 1990 to 40,000 megawatts in 2003, a 24-fold increase. In just four years, from 2001 to 2005, U.S. electricity production from wind almost tripled. In Denmark, wind-generated electricity has grown so rapidly that it now provides 20 percent of all electricity.

Still, wind energy will not soon displace coal, oil or natural gas. The European Wind Energy Association, a champion of wind energy, optimistically forecasts that wind power could provide 12 percent of the world’s electricity supply within the next 15 years. So other fuels would still provide 88 percent. The U.S. Energy Information Administration forecasts that by 2025 all renewable energy sources combined will meet only 9 percent of total global energy demand – and wind energy is just one of several renewable sources. This forecast recognizes that much energy is used for transportation – cars, trucks, ships and airplanes – and wind energy at present cannot be used for transportation.

Yet, in the very long run, wind energy could be used even for transportation, and this would expand greatly the demand for wind energy. Wind power can be used to separate hydrogen from water and this hydrogen can be stored in containers. George Baker, a Harvard economist and a seasonal resident of Frenchboro, points out that stored hydrogen could be transported cheaply and eventually could displace fossil fuels as a power source for cars and other vehicles. Such developments, though, would require major advances in hydrogen technology.

What does all this imply for the future role of wind energy? For Maine and New England, the growing capacity of wind farms is clearly good and significant news. But for the U.S. and the world, wind power is unlikely in the next few decades to reduce significantly our use of fossil fuels.

These conclusions have important policy implications. We need policies designed to hasten the day when fossil fuel consumption begins to decline rapidly. We need, especially, more research on better technologies for producing energy from renewable resources – not just wind resources, but also solar, biomass and probably even nuclear resources.

We also need to subsidize both the production and consumption of energy from renewable sources.

Finally, we need financial incentives to discourage fossil fuel use. We need higher taxes on fossil fuel consumption, especially in our transportation system, and we need a national cap-and-trade system for reducing greenhouse gas emissions. Many studies have found a pressing need for these policies.

What should we do with the revenues yielded by taxes on fossil fuel consumption? This one is a no-brainer: increase our support for energy production from renewable sources.

Those big turbines on Mars Hill are not mere curiosities. They deserve the attention not only of some Yankee version of Don Quixote, but of our leading policymakers.

Edwin Dean, an economist and seasonal resident of Vinalhaven, writes monthly about economic issues.