Cheaper Data Centre Power

Evening out demand to match supply is a big problem in the energy industry. One way is differential pricing – charge more at peak times. Another way is energy storage, so you can supply more at peak times. One method of storage is to store the energy using compressed air. The disadvantage is that compressing the air gives off heat, and re-expanding it requires heat. Not supplying heat during re-expansion makes the storage much less efficient.

So which industry has large and fairly constant power costs it would like to reduce by buying some of that power at off-peak prices, equipment which can be placed anywhere, including where land prices are cheap, plus a lot of waste heat it doesn’t know what to do with?

Someone should come up with a gas compression power storage system for data centres.

Cost of power, ballpark: $0.06 per kWH peak (say 8am – 6pm), $0.03 off-peak
Power consumption of server: 1KW
Current cost of power per server per day: $1.02
Potential saving per server per year if all power used were priced at the off-peak price: $110

One issue is that a 5l bottle can store 500kJ of energy (0.14 kwH), so you’d need 500l per server. That’s a lot, so you may not be able to get the full saving unless you use an underground cavern rather than surface storage tanks. But if land is cheap, you could make a dent in your power bill.

Believe it or not, this post was half-written before I saw this Slashdot article.

2 thoughts on “Cheaper Data Centre Power

    • Yes – that’s the point. They can use it to heat the expanding gas, to avoid the cost of having to store the heat which is given off when the gas is compressed. Hence it’s cheaper for data centres than for other potential customers to use this form of storage.