February 10th, 2007
Storing wind power in cold stores
According to Nature, a European-funded project has be launched to store gigawatts of electricity created from wind into the refrigerated warehouses normally used to store food. As the production of wind energy is variable every day, it cannot be easily accommodated on the electricity grid. So the "Night Wind" project wants to store wind energy produced at night in refrigerated warehouses and to release this energy during daytime peak hours. The first tests will be done in the Netherlands this year. And as the cold stores exist already, practically no extra cost should be needed to store as much as 50,000 megawatt-hours of energy.
Here is how Nature describes the — simple, but brilliant — idea behind this project.
The idea seems simple. Say you lowered the temperature of all large coldstores in Europe by just 1°C during the night when electricity demand is low, then let it rise 1°C by switching them off during the day when demand is at peak. The net effect would be that the warehouses would act as batteries — potentially storing 50,000 megawatt-hours of energy — and the food wouldn't melt.
Before going further, below is a diagram illustrating the idea: wind energy is optimally stored or released by following the electricity consumption patterns (Credit: Night Wind project)
In European jargon, the official denomination of the Night Wind project is "Grid Architecture for Wind Power Production with Energy Storage through load shifting in Refrigerated Warehouses." And it is led by Sietze van der Sluis, head of refrigeration and heating technology at The Netherlands Organization for Applied Scientific Research (TNO) in Delft.
Here are the goals of this Night Wind project.
The random production of wind energy cannot easily be accommodated on the grid by switching on and off conventional energy suppliers, like coal fired power plants, which would lead to an increase of CO2 emissions, rather than the reduction of CO2 emissions which is desired.
In order to accommodate the random production of wind energy in the grid, it would be most convenient when alternative (renewable and conventional) electricity producers could balance out the difference between production of wind energy and electricity demand. The Night Wind project aims to store wind energy produced at night in refrigerated warehouses, and to release this energy during daytime peak hours.
Nature adds some more details about the first tests of the Night Wind idea.
Later this year, van der Sluis's team will start a demonstration project by setting up a wind turbine next to the Netherlands' largest coldstore, in Bergen op Zoom, a small town in the SouthWest of the country. It shouldn't be technically difficult, he says — it's really just a question of developing software to match the temperature of the warehouses with electricity demand, turning the fridge on and off as the supply from the wind plant and the demand from consumers change during the day.
This project will officially end in June 2008 and I hope it will be a success. In the mean time, you can read this short presentation of the project, from which the diagram above has been extracted (PDF format, 3 pages, 100 KB).
Sources: Declan Butler, Nature, February 7, 2007; and various other websites
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