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Storing Wind Power In Cold Stores
Roland Piquepaille writes "According to Nature, a European-funded project has been launched to store electricity created from wind in refrigerated warehouses used to store food. As the production of wind energy is variable every day, it cannot easily be accommodated on the electrical 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 incurred to store as much as 50,000 megawatt-hours of energy. Here are additional details and a picture illustrating this brilliant idea."
Well, this usage pattern resembles much the old idea of a pumped storage power plant (Pumpspeicherkraftwerk), a hydroelectric powerplant where the water, which is used in high load times to produce electric power, gets pumped back uphill to a reservoir by use of the excess power of the basic load power plants like coal or nuclear driven ones.
This is done for decades now in the european grid. I had the opportunity in the late sixties to visit such a power plant at Schruns/Tschagguns in Vorarlberg in Western Austria.
It's a very impressive installation with a entire delivery height of more than 2000m (6000ft) in two stages. In the exhibition is also an impressive display of the entire european powergrid.
CU
It's Roland the Plogger, wrong as usual, spamming to promote his blog. The Slashdot editors gave him two links this time, one without a "nofollow". Ka-ching!
OK, now the real info. Thermal energy storage has been around for years. There are thousands of installations. It's used when there's a big difference between day and night power rates. During the night, water is chilled, or ice frozen; during the day, the cold water is used for air conditioning. See Thermal Energy Storage Strategies for Commercial HVAC Systems for details on how to configure such a system. Also see CALMAC, which makes such gear. It was a spinoff from their ice-rink equipment business.
I think the question is also how many stores Can do this?
I work in the IT section for the biggest refrigeration company in the Netherlands, and from what I've seen every type of food has an specific storage temperature. Apparently a 2 degrees Celcius difference will make a big difference in the quality of food.
home
RTFA. They're not storing energy as heat and then attempting to recover it, they're modulating the energy usage of the cold store to buffer the grid. Cool down the store to -25 C during peak supply hours (which often don't coincide with peak demand), and you can switch off the refrigerator and let the temperature rise to -23 C during off-peak supply hours. This is beneficial regardless of whether the grid is powered by wind, solar or fossil fuel plants; wind power is just the sales pitch.
I'm not sure how things are in America right now, but in Australia, they're rolling out a scheme called 'Time of Use'. Meters are automatically read every 30 minutes, or every 15 for large usage sites, and you're charged based upon the time that you use the energy. Currently it's split into 3 blocks.. Peak (business times) shoulder (evenings) and off-peak (nights, weekends) and differing rates are set for each period.
Energy Australia charge 22c/kwh for Peak, 8c/kwh for Shoulder and 4c/kwh for Off-peak.
Not as elaborate as your suggestion, but far more suitable for the average home user. It would probably benefit such 'cold stores' too, because I wouldn't imagine it would make much difference whether they're -20 or -40, so they could cool right down during the night, then use less energy during 'peak' hours. I would guess future developments might see small sites charging batteries during the night to power appliances through the day.