Next Generation Energy

Historically, the biggest challenges mounted against wind farms are the effects on views and bird life. Neither of these are serious problems. The objections of James Lovelock and Kennedy family of Cape Cod to the contrary, there is no objective reason to consider windmills eyesores. There's one big one (94 metres tall) on the Toronto waterfront and to my eyes, at least, it's an improvement, not a detraction. As for the avian death toll, while early designs used nest-friendly latticework towers, today's solid-tower machines kill far fewer birds than your typical skyscraper.

The threat posed to bats, however, may be more difficult to resolve. A new study in Current Biology (Volume 18, Issue 16) by a University of Calgary in Alberta team suggests that turbulence generated at the tips of turbine blades could create pockets of low air pressure that can collapse the lungs of bats as they fly past. This has come as a surprise, because bats have evolved an extraordinary facility with sonar, with many species able to track fast-moving prey. Surely, then, they should be able to avoid something a big as a wind turbine blade?

Unfortunately, their sonar may be useless when it comes to judging air pressure. In "Barotrauma is a significant cause of bat fatalities at wind turbines" the study's authors details their examination of dead bats at the base of windmills. Many of them had burst lungs. This is big deal, because bats are critical species in many ecosystems, serving as pollinators for a large number of plants and eating agricultural pests.

Taking into account bat migration flight paths is just another item on a growing list of factors to consider when evaluating potential wind farm sites. First you have to have enough wind. Typically you need to be able to generate a third of your mechanical capacity to warrant the expense. Then you have to make sure the installation, access roads and connecting electrical grid lines don't disturb critical habitat. While that still leaves a lot of the planet's land mass available, there is an alternative approach that avoid most if not all of the objections that might be raised: offshore.

Denmark, which already gets much of its electricity from windmills, has just approved another 400 MW of turbines in the North Sea. The Danes want the wind to supply half their power by 2025, most of that off-shore. Of course, Denmark has more offshore territory available than it does land, but there's plenty of coastline in the U.S., too.

For example, there is absolutely no rational reason why the Cape Winds project should not go ahead. Planned for five miles off the coast of Cape Cod, Mass. between Hyannis and the island of Nantucket, the 130 turbines would be tiny dots from land on clear days, and seen in their full glory only by sailors and ferry passengers. (Simulation above from evworld.com) And even then, so what? Opponents raise the problem of bird kills again, but is seems likely that seagulls would learn to avoid the giant slice and dice machines.

As for the rest of the planet, consider this recent summary of the potential as found in the journal Nature (454, 816-823):

Britain, which has been much slower to adopt wind power, has by far the largest offshore potential in Europe -- enough to meet its electricity needs three times over, according to the British Wind Energy Association. Industry estimates suggest that the European Union could meet 25% of its current electricity needs by developing less than 5% of the North Sea.

Yes, it costs a bit more to build in the water — 50 to 75% more, says Nature — but even that makes it competitive with natural gas, and among the cheapest sources when carbon comes with a price. Plus, there's the advantage that most of the world's biggest cities are on coasts. The best terrestrial sites, by comparison, tend to be long way from where the demand will be greatest.

The US National Renewable Energy Lab reported a mere 617 megawatts of offshore wind projects worldwide in 2004, with another 11,455 MW proposed through 2010. But the real potential is much greater. In the U.S. alone, we're talking about 908 GW. That's almost equivalent to the total electricity demand of the country, which is about 1 TW. In other words, wind could provide a third of the country's electricity (remember the 33% of capacity rule) without building any of T. Bone Picken's Texan farms.

Of course, there remains the difficult problem of how to store the electricity for use during calm periods. That problem shrinks the more turbines you build in more places, as the wind is always blowing somewhere. And it seems wise to assume that flow batteries, pressurized geological caverns, fuel cells and other technologies as yet undreamed of will get cheaper as time goes by. So why no anticipate the advent of increased storage capacity and start building as many windmills now as we can?

(Image at top: Bahrain World Trade Center, with integrated wind turbines)