Editor’s note: The second of three parts.

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Thirty years ago during the “first energy crisis,” efforts to develop wind as an indigenous, renewable and clean source of power raised high hopes, but they were quickly shattered. Some wind installations were built, but there were two problems.

First, eventually oil prices dropped, and wind power ceased to be economically competitive with fossil fuels. When government subsidies for renewable power expired, new wind development ceased. Second, at the largest project in Altamont Pass, Calif., there was large-scale killing of birds. Altamont was a heavily used bird migration path, and hawks were attracted to the towers as a place to perch. Thousands of birds died.

Now in the throes of a second energy crisis and a newfound awareness of the global warming threat, it is time to think again about wind. Unlike fossil fuels, harnessing the power of the wind does not create any air pollution or release greenhouse gases, the drivers of global warming. Wind power, of course, is inexhaustible – it won’t run out, and it is plentiful right here in Maine. Wind is Maine’s most promising new source of renewable energy.

This time the economics and environmental impacts of wind power will be very different, due to recent technological developments. Today, wind turbines (the modern term for windmills) have much longer blades that turn slowly in the wind; each one is more than 200 feet in length. These turbines need to be positioned on tall towers in order to reach steady wind currents with plenty of ground clearance. They rise as high as the Statue of Liberty.

The towers are sleek, enclosed pillars with three blades that rotate approximately 15 times a minute. Unlike the old 1970s technology, these wind turbines are smooth-sided (unlike the crisscrossed steel struts of old), so they do not serve as perches for hawks that were drawn to the towers as hunting sites. The blades turn more slowly, so they are more visible to birds and are far less likely to strike and kill birds. Studies of these turbines confirm that they cause relatively few bird deaths.

The new wind turbines are also far more efficient because the blades are much longer. To explain this simply, think of sixth-grade math class: we were taught how doubling or tripling the radius causes the area of a circle to increase four to nine times. Energy output is proportional to the area of the turbine circle, so these new turbines generate far more power at more efficient cost.

There are several challenges that wind developers must still overcome. First, some people think wind turbines are ugly and do not want them in their view or in favorite recreation areas. Local opposition can delay projects and discourage financial backers. But other people view wind turbines as a symbol of renewable power and see beauty in these large structures.

Second, although the wind blows everywhere, there are relatively few places that have enough steady wind to be economically successful. However, the single greatest limitation in finding a good site is staying close to existing electrical transmission lines. The cost of new transmission lines is too large to justify building at sites that are more than a few miles away. Large wind farms require large-capacity transmission lines, and these exist along only a few developed corridors in the state.

New wind-power projects have been built throughout Europe and in the Plains states, and they are operating successfully. In the next three years nationwide, developers will build more than 5,000 megawatts of new wind turbines – most of them in the Midwest – thereby doubling U.S. wind-power levels.

Currently developers are seeking permits to build large wind projects in five locations in Maine – two in Aroostook, two in Franklin and one in Washington County, all rural areas that need economic boosts. Their combined output would be more than 900 megawatts – a capacity equal to Maine’s two new gas-fired generating plants in Westbrook and Veazie combined, and one and a half times the output of the now-closed Maine Yankee nuclear facility. These are large projects that will have a big impact on energy production in Maine. The Conservation Law Foundation (CLF) is trying to encourage wind development and has a contract to work with one of them.

But wind power only works when the wind blows more than 5 mph to turn the turbines – about 70 percent of the time at good locations – and they do not reach full efficiency until winds reach much higher speeds. As a result, wind farms generate only 30 to 40 percent of their rated capacity. This means that wind needs to be paired with another source of energy to meet steady demand for electricity. In Maine, some hydropower can provide this, but some fossil fuel plants will be needed to supplement supplies.

The most affordable option for backing up wind is gas-fired power plants. They can come online relatively quickly and have low air emissions. CLF’s interest in expanding gas pipelines and siting a new liquefied natural gas terminal for New England is based on the need to convert aggressively to wind power with clean gas as the backup source.

Maine needs wind power and will benefit from it. Citizens must recognize that a lot has changed since wind farms killed birds and went bankrupt 30 years ago. New projects today have strong economics and are far more benign environmentally. Considering the extremely negative effects of fossil fuels – pollution, global warming and sending money overseas – it is vital that people give wind a fresh look. More wind power in Maine will be great for our future.

Rob Gardiner is vice president of the Conservation Law Foundation.