Monday, May 23, 2005

Wind Energy: Nasa Funded Study Identifies 72 Terawatts of Global Wind Power Potential

Stanford researchers have produced a new map that pinpoints where the world's winds are fast enough to produce wind power. The map may help planners place wind turbines in locations that maximize power harnessed from winds and provide widely available low-cost energy. After analyzing more than 8,000 wind-speed measurements to identify the world's wind-power potential for the first time, Cristina Archer, a former postdoctoral fellow, and Mark Z. Jacobson, an associate professor of civil and environmental engineering, suggest that wind captured at specific locations, if even partially harnessed, can generate more than enough power to satisfy the world's energy demands. Their report appears in the May Journal of Geophysical Research-Atmospheres, a publication of the American Geophysical Union.

"The main implication of this study is that wind, for low-cost wind energy, is more widely available than was previously recognized," said Archer.

The researchers collected wind-speed measurements from approximately 7,500 surface stations and 500 balloon-launch stations to determine global wind speeds at 80 meters (300 feet) above the ground surface, which is the hub height of modern wind turbines. Using a new interpolation technique to estimate the wind speed at hub height, the authors reported that nearly 13 percent of the stations had average annual speeds strong enough for windpower generation.

Wind speeds of 6.9 meters per second (15 miles per hour) at hub height, referred to as wind power Class 3, were found in every region of the world. Some of the strongest winds were observed in Northern Europe, along the North Sea, while the southern tip of South America and the Australian island of Tasmania also featured sustained strong winds. North America had the greatest wind-power potential, however, with the most consistent winds found in the Great Lakes region and from ocean breezes along coasts. Overall, the researchers calculated hub-height winds traveled over the ocean at approximately 8.6 meters per second and at nearly 4.5 meters per second over land (20 and 10 miles per hour, respectively).

The authors found that the locations with sustainable Class 3 winds could produce approximately 72 terawatts, that's 72,000 Gigawatts or 72 million Megawatts. A terawatt is one trillion watts, the power generated by more than 500 nuclear reactors or thousands of coal-burning plants. Capturing even a fraction of those 72 terawatts could provide the 1.6 to 1.8 terawatts that made up the world's electricity usage in 2000. Converting as little as 20 percent of potential wind energy to electricity could satisfy the entirety of the world's energy demands.

The study, supported by NASA and Stanford's Global Climate and Energy Project, may assist in locating wind farms in regions known for strong and consistent breezes. In addition, the researchers suggest that the inland locations of many existing wind farms may explain their inefficiency.

"It is our hope that this study will foster more research in areas that were not covered by our data, or economic analyses of the barriers to the implementation of a wind-based global energy scenario," Archer said.

Update: The excellent group blog WorldChanging has an image of the Global Wind Power Map

Original Article on Stanford University's Website

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Blogger Engineer-Poet said...

James, there is only one N in "Identifies".

In 2003, the USA generated 3848 billion kWh of electricity and imported another net 6 billion kWh.  That's an average power of 440 gigawatts.  Total nameplate generation capacity in the USA is over 900 GW.

stormy:  There are other ways to deal with intermittent availability of wind power.  For instance, you can make ice for cooling things later (putting your air conditioning "in the bank" as it were) or you can dump excess electricity to resistance heaters where some fuel would otherwise be burned for heat.

This makes a big difference.  If you can shave the peaks off the supply by using the excess elsewhere, you can displace a lot more generation (because you have more wind capacity, thus greater average wind generation) and you can start taking bites out of the consumption of other fuels.

5:42 am, May 23, 2005  
Blogger Engineer-Poet said...

Oh, you wanted a map?  I got your map right here.

6:46 am, May 23, 2005  
Blogger Engineer-Poet said...

stomv:  The 2nd Law isn't a major factor in this case.  You are going to use electricity to cool something, no?  So instead of cooling air to 40 °F, you cool water to ~30 °F today and use it to cool air tomorrow.  You are doing exactly the same thing with not terribly dissimilar performance issues; you might want a variable-speed compressor to compensate for the reduced vapor density out of the evaporator when operating in ice-making mode.

You are right that the losses from the banking process would have to be made up from cheaper energy costs at the input.  That's the beauty; the difference between peak and off-peak electric rates is a lot bigger than the difference between 40° and 30° performance.  (This page has performance curves for heat pumps in heating mode, not directly applicable but suggestive.)

There are issues with the use of GO-HEVs for energy storage in the near term; there won't be enough of them for quite a while, and they will have perhaps a day's worth of storage on board so storage from day to day is not consistent with maximum fuel economy.  The real electricity hog in much of the country is air conditioning, and you can store ice for months using centuries-old technology.

"once you're in the situation where the marginal benefit of another wind turbine is substantially lower because there is probability that it will be used to "store" energy for later (at a lower effeciency than just dumping it into the grid), its marginal value has consequently decreased."

If the cost of electricity during good winds falls low enough, people will invest in storage hardware to take advantage of it.  This will keep the spot price of wind power from falling as low as it would otherwise, and generate more investment in generation.  The greater the difference between the cost of wind power and e.g. gas-fired peaking, the more it pays to install wind capacity and storage.  The cycle could continue until most A/C demand is met by stored ice made with off-peak wind power, and peaking generation is rarely used even in hot spells.

The ice-storage A/C could be a money maker; the owners (or an aggregator) could sell grid-regulation capacity to the utilities, draining power when the grid has an excess.  AC Propulsion has investigated this role for grid-connected cars, but nothing says they have to be the only players.

9:32 pm, May 25, 2005  
Anonymous Anonymous said...

stomv and engineer-poet:

Good arguments from both and thanks for you comments...

But I have a thought for you: Why are you still thinking locally and in modern terms? The global wind map shows us that there is more than enough wind to power the earth. If we think on a global scale, linking wind energy across the globe, and build a little more than we need, peaks disappear. Wind is strong in some areas of the world but weak in others. The one supports the other.

What is needed is a global shift in the way we think and interact.

But perhaps I'm wrong. Perhaps the energy loss over distance is too great to make this feasible?

6:00 am, June 13, 2005  

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