A mile and a half northeast of Copenhagen's city center, beyond the stone walkways, gargoyle fountains and slate-roof housing flats, lies the Kastellet, a 343-year-old fort overlooking the lush shoreline of Oresund (Danish for "The Sound"). Standing motionless on the bunker's edge is a 30-ft.-tall windmill, once used to grind and store grain for soldiers, now sustained for nothing but tourism and history, by nothing but a new coat of red paint. Past this artifact, over the hills of an ancient land and out in the coast guarding a pioneering country, the symbol of modern Denmark's landscape looms larger: a handful of wind turbines, 360-ft.-tall and egg white, catching an ocean breeze in the shallows. With one-fifth of all its energy needs satisfied by wind power, Denmark is a forerunner in this burgeoning if frustrating alternative-energy platform, helping Europe to maintain its dominance in world wind energy production, and leaving America in the dust. For now.
It is Texas, of all places, the U.S. leader in energy production and consumption, that quietly has become the center of wind power in the past year. This ain't no Scandinavian shore, but just an earshot from the dry, rolling hills and mesquite trees of Abilene (population: 128,030) you can see not hear a shocking breakthrough in green technology: the turbines of Horse Hollow, the largest onshore wind farm in the world. Spread out across 100 acres, 421 rotors and their three giant arms rotate continuously, each one turning a three-step gearbox that activates a generator, each sweeping over an area larger than a football field. "Texas has always prided itself on being the biggest and the best," says Abilene mayor Norm Archibald. "The wind farms will be no exception."
This country's contributions to the international wind energy circuit remain some of the biggest our installed capacity of 11,600 megawatts (1000 kilowatts) represents nearly 15 percent of wind energy worldwide. But you don't usually hear about these accolades because wind power accounts for just over one half of 1 percent of our annual consumption. In the past two years, capacity in this country has risen by more than 4800 MW, but the U.S. would need to raise the bar by 382,800 MW about as much as it takes to power 4.8 million homes per year to match Denmark's commitment to this free, ever-present energy source. What's more, some fear that without new technology or improved infrastructure, the current growth rate will be as fleeting as the tax credits and rising natural gas prices that have fueled it. The U.S. has a long road ahead if (and that's a big "if") it wants to make wind as American as big oil; here are three major obstacles facing our wind-powered future, with solutions that could overcome that turbulence and make turbine-tapped energy a larger part of what runs your house.
Wiring the Rural WindsSources of wind power are becoming a common sight for more and more people across the country. The catch? Most of these people live in Texas or California, with over 23,000 turbines churning out 4693 MW annually in these two states combined. The ideal? More than 2 million times that nationwide, with the American Wind Energy Association predicting overall potential as high as 10,777 billion kilowatt-hours per year. That estimate, however, relies upon vast resources in hard-to-reach, unpopulated regions in states such as North Dakota and Kansas. These rural areas, with their steady breeze and power-pumping plains, may be the ideal sites for a wind energy buildup, but many are nowhere near powerlines that could carry energy to towns and cities. "You can't bring fuel to the grid for wind power," says Gregg Fishman, of the California Independent System Operator, which acts as a liaison between utilities and power plants. "You need to connect the grid to the fuel."
New transmission lines don't come cheap, and can cost well over $1 million per mile. At these prices, it doesn't make economic sense to lay lines for wind power alone. But if wind can and should be taken into account when lines are being built for other energy projects, it could become a powerful bargaining chip for "the integration of balanced resources," says Ward Uggerud. When his company, Otter Tail Power, and other utilities proposed building a 600-MW coal plant in South Dakota two years ago, shareholders and stakeholders raised concerns about the lack of alternative energy plans. So the utilities promised to bulk up their transmission lines from Big Stone, S.D., to Granite Falls, Minn., making room on the power grid for future wind projects in the region.
A month ago, the Federal Energy Regulatory Commission approved financing transmission lines to connect alternative energy sources in California, which wants to have 20 percent of its energy coming from renewable resources by 2010. In order to reach that goal, Fishman says. "Cost recovery for transmission lines is needed. And that is happening, now that the value of renewable resources is being recognized."
Charging the Crowded GridAs long as there is wind, the rotors remain in motion, creating potential for power. But modern systems do not take advantage of wind energy's unceasing generation; in fact, they don't even use half. For instance, when demand for power is low (during the night), the grid is too full to accept more electricity, regardless of how much a turbine is capable of making. This wasted power devalues wind energy compared to other on-demand sources such as nuclear and coal plants. Plus, there's no quick fix for a windless day. "We need predictability in energy, and to rely on wind energy is questionable, until you have a means of storing the energy," says Mary English, research leader at the Institute for a Secure and Sustainable Environment.
The solution is straightforward: Hook wind turbines to a battery array. When energy demand is up (during the day), turbines will sink energy directly into the grid. When demand is down, the turbines will store energy in the battery array to be used when it is most needed. The array could also provide supplemental energy during peak demand times, and could even support an emergency center during brownouts or natural disasters.
Though it's not yet economical on the scale of wind farming, battery-powered wind technology is available for residential use, such as the 7.5-Kw Bergey Excel or the home system rigged up by Popular Mechanics's energy family. There are an estimated 1700 "residential" turbines installed in the U.S. that create from 1 kw to 100 kw each, in addition to tens of thousands of systems creating under 1 kw. If all this electricity were to be connected to the grid, excess power from wind farms could then feed water desalination or, better yet, trade off-grid time with hydropower plants, which can be turned off with no potential energy loss, says General Electric engineer Vlatko Vlatkovic. That nighttime overcharge shouldn't cost utilities overtime quite yet, but as new wind projects emerge Hawaii will have installed 21 MW of wind power on the Big Island by year's end, making wind account for nearly 30 percent of its power output they should test the grid and help provide information. This will help accommodate heavier growth down the line.
Reaching the Urban CoastA glut of wind farms in Texas and South Dakota won't help provide energy to Manhattan. New England and the mid-Atlantic have large population centers with less potential-packed land. "For the Northeast, we could either run a really long power cord from Montana," says University of Delaware marine biologist Willett Kempton, "or we could look to offshore power." The advantages of offshore wind farms are numerous. They can provide energy close to cities (saving money on transmission lines) and catch smooth, strong winds, making for a more efficient turbine. The potential energy is enormous: An estimated 1 terrawatt (1,000,000 MW) exists up to 50 miles off the U.S. shore.
Unfortunately, the best spots to catch wind off the nation's coasts are deeper waters in areas prone to storms both major problems for current technology, which Laurie Jodziewicz, policy specialist for the American Wind Energy Association, calls "essentially water-friendly onshore turbines." In seas deeper than about 90 ft., turbines also become exponentially more expensive. "Wind technology is in its infancy," Jodziewicz says, "and new turbines will expand our choices."
Engineers at the National Renewable Energy Laboratory (NREL) are working on maturing the options for deep-water tech. Most offshore wind turbines are supported by large pilings, or monopiles, buried deep in the ground. "In order to maintain the stiffness of the tower, the monopile has to get larger in diameterand that adds to cost," says Walter Musial, a senior engineer at NREL. "This begs for a different types of foundation." One solution would be to use lattice-type bases, such as those found on oil and gas platforms, which have been around for decades. These platforms hold large loads in deep water and can withstand major storms and surges, but they aren't designed to withstand the horizontal loads required to gather wind energy. To perform effectively as turbines, "you're going to have to beef up the rigs quite a bit," says Marshall Buhl, senior mechanical engineer at NREL. "The turbines are as big as a football field, and you're going to need to add bracing and more steel." By 2009, Musial expects to come up with suggestions for how industry can begin development on economically feasible deep-water turbines.
In open waters deeper than 150 ft., tripods and monopiles are not cost-effective: The turbines would have to float. "There are a dozen ideas on how to float a turbine," Buhl says. Concepts include the spar buoy, composed of a long slender bobber and floating barges with a variety of anchor systems. The tension leg platform, developed by Paul Sclavounos, a professor of mechanical engineering and naval architecture at MIT, will work in waters up to 600 ft. deep. Like other anchor systems, it involves long steel cables that are connected to a concrete anchor on the ocean floor. But unlike other systems, the tension-leg platform would be stable enough for boats to tow the turbines to and from shore for repairs, or to another coastal city if there were plans to shift the infrastructure.
Offshore wind farms line much of the coast of Denmark, where wind power satisfies one-fifth of the country's energy needs. Weather and infant technology are holding up turbine-laden seas near urban hubs in the U.S.
Turning to the FutureThis month, the National Research Council forecast the future of wind power in the U.S. in the congressionally mandated "Environmental Impacts of Wind Energy Projects" report. "A country as large and as geographically diverse as the United States and as wedded to political plurality and private enterprise," the authors wrote, "is unlikely to plan for wind energy at a national scale in the same way as some European countries are doing." Using projections from the Department of Energy, the group estimated that 4.5 percent of CO2 emissions could be offset with wind power by 2020 if falling fuel prices and emissions-reduction technology don't make fossil fuels more appetizing. Mary English, who served on the report committee, says the balance of energy sources is a "very, very complicated equation that will change with regulation, technology and demand for electricity."
Currently, coal represents nearly 50 percent of electricity production in the U.S., and it continues to grow. Nuclear power represents 19 percent, followed by natural gas (18.7 percent), hydroelectric (6.7 percent) and oil (3 percent). What the Energy Information Administration calls "other renewables" biomass, geothermal, solar thermal, photovoltaic, wind and wood accounts for 2.3 percent of total electricity production. That leaves wind energy at the bottom of a diverse energy portfolio. But, as President Bush said in a speech this past February, "Obviously people think there's potential when it comes to wind energy." And now some financial weight is blowing in the wind: $44 million for wind energy research in the 2007 budget ($5 million more than 2006), plus continuing tax incentives and a number of state-by-state renewable portfolios.
On the outskirts of Abilene, Texas, if you get close enough, the whoosh of giant, energy-pumping blades might convince you that wind power is destined to grow. But for now, it still accounts for less than 1 percent of electricity produced in the U.S. and until more companies copy Horse Hollow and more towns start to look like Abilene, the future for wind power remains, as it is, up in the air.