Rewiring the planet for renewable energy

The Bush Administration and McCain campaign camps might be accused of being asleep at the wheel. Their calls for revivals of offshore oil drilling, nuclear energy and conventional coal-fired electricity generation in response to the current energy "crisis" are unnecessary and irresponsible. Irresponsible because reliable and plentiful renewable energy alternatives to these options are well within reach.

With a little help from its friends (DC transmission lines, smart grids) wind energy is poised to help provide clean energy solutions to generating electricity and powering our automobiles.

It's time to get strategic and put the pieces together that will set the stage for a sustainable energy future . (GW)

Trade Winds

The Economist
June 19, 2008

ON A ridge near Toledo in Castile-La Mancha stands a row of white windmills. Literary buffs, even if they have never been to Spain, will recognise them as the ferocious giants attacked by Don Quixote, Miguel de Cervantes’s fictional 17th-century hero. These days, however, they are dwarfed by legions of modern wind turbines that grind out not flour but power, helping to make Spain one of the leading producers of wind-based electricity in Europe.

Does this amount to tilting at windmills? There is no doubt that Spain’s wind turbines would not have been built without assistance from the highly visible hand of a government that wanted to prove its green credentials. But wind power is no illusion. World capacity is growing at 30% a year and will exceed 100 gigawatts this year. Victor Abate, General Electric’s vice-president of renewables, is so convinced that by 2012 half of the new generating capacity built in America will be wind-powered that he is basing his business plan on that assumption.

Wind currently provides only about 1% of America’s electricity, but by 2020 that figure may have risen to 15%. The one part of the United States that has something approximating a proper free market in electricity, Texas, is also keener than any other state on deploying the turbines. In May, T. Boone Pickens, one of the state’s most famous oil tycoons, announced a deal with GE to build a one-gigawatt wind farm—the world’s largest—at a cost of $2 billion.

What was once a greener-than-thou toy has thus become a real business (GE alone expects to sell $6 billion-worth of turbines this year)—and one with many advantages. For example, as Lester Brown, the president of the Earth Policy Institute, a think-tank in Washington, DC, points out, a farmer in Iowa who gives up a tenth of a hectare (a quarter of an acre) of land to a turbine might earn $10,000 a year from it (about 3% of the value of the electricity it produces). Planted with maize, the same land would yield a mere $300-worth of bioethanol.

Moreover, wind farms can be built piecemeal, unlike most power stations. A half-finished coal-fired or nuclear power plant is a useless waste of money, but a half-finished wind farm is simply a wind farm half the size originally intended—and one that has been providing revenue since the first turbine was completed.

One consequence of this rapidly growing market is a virtuous circle of technological improvement that is pushing wind-generated electricity closer and closer to solving Google’s cheaper-than-coal equation. The first turbines were cobbled together from components intended for ships. Now the engineers are borrowing from aircraft design, using sophisticated composite materials and equally sophisticated variable-geometry blades to make those blades as long as possible (bigger is better with turbine technology) and as smart as possible (a blade that can flex when the wind blows too strongly, and thus “spill” part of that wind, is able to turn when other, lesser turbines would have to be shut down for their own safety). The theoretical maximum efficiency of a turbine, worked out in the early 20th century by Albert Betz, is 59.3%. Modern turbines get surprisingly close to that, being about 50% efficient.

They are also more reliable than their predecessors. According to Mr Abate, when GE entered the turbine business in 2002 the average turbine was out of commission 15% of the time. Now its downtime is less than 3%. As a result, the cost of the energy cranked out by these turbines has come down to about 8 cents a kilowatt-hour (kWh) and is still falling.

That makes wind power competitive with electricity generated by burning natural gas. Coal power is still cheaper, at about 5 cents a kWh. But according to a study by the Massachusetts Institute of Technology (MIT), that would rise to 8 cents if the CO2 from coal-fired power stations had to be captured and stored underground (see article)—or, for that matter, if a carbon tax of $30 a tonne were imposed.

The power companies that buy the turbines are also getting smarter. They employ teams of meteorologists to scour the world for the best places to put turbines. It is not just a question of when the wind blows, but also of how powerfully. A difference of as little as one or two kilometres (one mile) an hour in average wind speed can have a significant effect on electrical output. And another lot of meteorologists sit in the control centres, making detailed forecasts a day or two ahead to help a company manage its power load. For one problem with wind is that if it stops blowing, the turbines stop turning. After cutting costs, that is the second great challenge of the spread of wind power.

The third is that people do not necessarily live where the wind blows. Indeed, they often avoid living in such places. Solving these problems, though, is a task not for the mechanical engineers who build the turbines but for the electrical engineers who link them to places where power is wanted. That means electricity grids are about to become bigger and smarter.

Bigger means transcontinental, at least for people like Vinod Khosla. His analogy is America’s interstate highway system, built after the second world war. The new grids would use direct, rather than alternating, current. AC was adopted as standard over a century ago, when the electrical world was rather different. But DC is better suited to transporting power over long distances. Less power is lost, even on land. And DC cables can also be laid on the seabed (the presence of all that water would dissipate an AC current very quickly). In the right geographical circumstances that eliminates both the difficulty of obtaining wayleaves to cross private land and the not-in-my-backyard objections that power lines are ugly. Indeed, there is already a plan to use underwater cables to ship wind power from Maine to Boston in this way.

Rewiring the planet

As it happens, Europe already has the embryo of a DC grid. It links Scandinavia, northern Germany and the Netherlands, and there is talk of extending it across the North Sea to the British Isles, another notoriously windy part of Europe. By connecting distant points, this grid not only delivers power to market, it also allows the system some slack. It matters less that the wind does not blow all the time because it blows at different times in different places. The grid also permits surplus power to be used to pump water uphill in Norwegian hydroelectric plants (a system known as pumped storage), ready for use when demand spikes.

Smarter grids, however, would help to smooth out such spikes in the first place. The ability to accommodate inherently intermittent sources such as wind is only one of several reasons for wanting to do this, but it is an important one.

A smart grid will constantly monitor its load and (this is the smart bit) take particular consumers offline, with their prior agreement and in exchange for a lower price, if that load surges beyond a preset level. For this purpose, a consumer may not necessarily be the same as a customer. The grid’s software would be able to identify particular circuits, or even particular appliances, in a home, office or factory. Their owners would decide in what circumstances they should shut down or boost up, and the smart grid’s software would then do the job. Water heaters and air-conditioners might stock up on heat or cold in anticipation of such shutdowns. Fridges would know how long they could manage without power before they had to switch on again.

Reducing spikes in demand that way will cut the need for what are known in the industry as “peakers”—small power plants such as pumped-storage systems that exist solely to deal with such spikes. Parts of America’s existing dumb and fragmentary electricity grid are so vulnerable to load variations that their owners think they may be able to cope with no more than about 2% of intermittent wind power. Clearly peaks will never be eliminated entirely. However, Mr Abate reckons that a combination of smart grids and gas-fired peakers should push the potential for wind power up a long way.

To prove the point, GE is collaborating with the government of Hawaii, a state which is served by a series of small, isolated grids highly vulnerable to disruption. The firm’s engineers reckon that clever grid management will allow up to 30% of local power to come from wind without any blackouts. If that improvement can be translated to the grids on the mainland, wind’s future looks assured.