Night Wind: new concept for storing electricity at low costs

08/09/2009

Refrigerated warehouses might soon be used to store not just food but gigawatt-hours of electricity created from wind.

A plan set up within the European project “Night Wind” could see the giant fridges acting as giant batteries by lowering the temperature of large cold stores during the night when electricity demand is low, then let it rise to the normal value by switching them off during the day when demand is at peak, while none of the food would melt.

Electricity is converted by the refrigeration installation in to thermal energy refrigerated or frozen products. It makes use of existing cold stores, large facilities for storing refrigerated and frozen products. The effect is that the excess electrical energy is converted into thermal energy, into "cold".
By lowering the temperature of all large cold stores 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.

The moments of excess energy correlate to low energy prices, and the moments of energy shortage to high energy prices making sure that the cold store is operated at the lowest possible energy costs because full capacity is provided at low energy price, and zero capacity at high energy prices.

Night Wind, whose official title is Grid Architecture for Wind Power Production with Energy Storage through load shifting in Refrigerated Warehouses, is thus a new concept for storing electrical energy at low costs practically without losses. It implies a new control system for the refrigerating capacity of the cold stores in order to operate it as “battery”. It is a medium term solution, a forerunner of long-term hydrogen storage.

Under EU’s Framework Programme for Research and Technological Development, this project (with total costs of 1,35 million euro and EU funding of 717.600 euro) was implemented for two years under the supervision of Dutch company TNO (contact person: Sietze van der Sluis, +31 88 866 22 06) along with six other European partners. After it was concluded in June 2008, the challenge to develop a working control system for Night Wind was picked up by another Dutch company – Saint Trofee.

The possibility to exploit the Night Wind concept on a national or regional scale depends on the cooperation of cold stores. To be profitable to these, it requires the variability of the energy prices that is only possible with contracts with market energy prices on an hourly basis.

For more information please contact:

Sietze M. Van Der Sluis
TNO http://www.tno.nl/
Sietze.vandersluis@tno.nl
Tel. +31555493162

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