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Off-shore wind could stabilize utility grids

Use of wind power resources for generating electricity is problematic because wind fluctuates rather than providing steady power. But a group of researchers now hypothesize that wind power output could be leveled out, and thus be more useful, if wind generators were located in a meteorologically designed configuration so that some of them generated power all the time.

The researchers looked at 5 years of wind data from 11 meteorological stations, distributed over 2,500 km along the U.S. East Coast. They then figured out how much power output per hour at each site would be generated under these conditions.

Each individual wind power generation site exhibited the expected power ups and downs. But researchers then simulated a power line connecting them, which they dubbed the Atlantic Transmission Grid. They found that the output from the entire set of generators rarely reached either low or full power, and power on the grid changed only slowly.


Notably, during the 5-year study period, the amount of power shifted
up and down but never stopped.

To figure whether their idea was economically practical, researchers looked at the 2,500 MW of offshore wind generation already approved or requested by states from Delaware to Massachusetts. It would take 350 miles of HVDC submarine cable to connect them. At early European offshore wind capital costs of $4,200/kW and submarine cable capital costs of $4,000,000/mile, the installed costs of planned offshore wind generation would be approximately $10.5 billion; the connecting transmission would add $1.4 billion . The transmission facilities add less than 15% to the capital cost of generation, researchers say. This is in line with the market cost of leveling wind via existing generation, currently estimated to add about 10% to the cost of energy (10% cost added for wind penetrations up to 20%, then a higher percentage cost added at higher penetration of wind).


All in all, researchers say transmission is far more economically effective than utility-scale electric storage (e.g. pumped hydro), whose capital costs are approximately equal to generation. They maintain their approximate comparisons suggest that transmission costs are commensurate with the value of leveling.

You can read the full paper here:

http://www.pnas.org/content/early/2010/03/29/0909075107.full.pdf+html

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