Solar 'Storm' Hits Data Centers by Peter Judge
There has been a lot of talk - and disagreement - this week, about the role of solar energy in powering data centers.
Maybe it’s sensationalist to call this a “solar storm”, but I like the phrase, and we have seen it a lot in recent months. Luckily this week’s solar storm was not a coronal mass discharge of Carrington proportions, taking out GPS and mobile phones. You would probably have heard about that already.
Thankfully, this week’s “solar storm” was more of the tea-cup variety. Someone at a data center firm that doesn’t use solar power, said some things that everybody knows, pointing out that there are good reasons not to rely on it heavily to run data centers.
Specifically, it was Amazon vice president and data center guru James Hamilton, who said: “I love solar power, but in reflecting carefully on a couple of high profile data center deployments of solar power, I’m really developing serious reservations that this is the path to reducing data center environmental impact.”
Putting it more clearly, he wondered “if these large solar farms are really somewhere between a bad idea and pure marketing, where the environmental impact is purely optical.”
In a very good blog, Hamilton looked at the figures behind recent solar power installations at rival data centers. Facebook’s 25MW data center at Prineville Oregon, has a 100kW solar array. Anyone giving it publicity (including Greenpeace and, I admit it, my site TechWeekEurope) should remember that this is 0.4 percent of the total power used there - or it would be, if the clouds and latitude of Oregon didn’t take the output down to 13.75kW. Enough to run the lights in the data center.
Over at Apple’s iDataCenter in Maiden, North Carolina, there is a bigger solar array, which takes up 171 acres and is rated at a peak output of 20MW. The actual power from that will be about 3.2MW says Hamilton, estimating that the total needs of the data center are 78MW.
In other words, America’s biggest commercial solar deployment is still only big enough to provide about four percent of a data center’s power.
Hamilton’s rule of thumb is that every space foot of data center space would require 362 square feet of ground outside, if it was going to be powered by solar energy. And given that Apple’s solar farm was made from forest, the overall green benefits have to be dubious.
And then there is the irony in the fact that good areas for solar power are hot, which makes them bad areas to place equipment which needs cooling down. And solar power goes away at night, so any data center using it needs to sell any surplus and has to have another source to buy in more power then.
Given all that, it’s not surprising to see those solar power plants labelled “accessories” elsewhere in the media.
Solar has uses but, we have all known for a long time that its value in power data centers is severely limited.