Amazon’s web infrastructure rockstar James Hamilton writes on his blog that he’s not convinced that solar power is a good fit for powering data centers. He points to the two most high profile examples of Internet companies embracing solar for data centers — Facebook’s tiny solar project in Prineville, Ore. and Apple’s massive planned solar installation in North Carolina — and says that based on these projects, solar doesn’t seem to be a big win for data centers.
Hamilton points out that the 100 kW solar array at Facebook’s 25 MW Oregon data center is so tiny — contributing 0.055 percent of the facility power, he calculates — that it’s a pure marketing move.
It might run the lights in the datacenter but it has almost no measurable possible impact on the overall energy consumed. . . . As a point of comparison, this entire solar farm produces approximately as much output as one high density rack of servers consumes.
On the other hand, Apple’s 20 MW planned solar farm for its estimated 100 MW data center, is so large that Apple is clearing trees off of 171 acres to make room for part of it. Solar panel farms indeed take up a lot of space, and because the sun doesn’t shine at night, and can also be variable during the day, they only have a certain amount of usable output (Hamilton says a 20 MW solar farm has a 15.8 percent output and would yield around 3.2 MW). Hamilton crunches the numbers and says that Apple’s solar farm would have to be 24.4 times larger, at 488 MW, and on 4,172 acres, to power the entire Apple data center.
Hamilton says he’s looking to energy efficiency first, before intermittent clean power such as solar. No word on what he thinks of powering data centers with fuel cells, like Apple plans to do.
A few Internet companies have been slowly experimenting with sourcing clean power for data centers, either building their own solar farms (like Apple is doing), or investing in clean power projects (like Google does). What Hamilton doesn’t factor into his analysis, is a couple things:
- 1). Building or buying clean power can pay off over the life of the system. Since tapping into the sun is free, it can deliver a return over many years, particularly if local energy prices rise. So the choice to go solar can also be an economic one.
- 2). The externality of climate change. If more and more data centers are built and run off of entirely coal power, the development of the Internet will be contributing to climate change.
Hamilton, has a point: solar technology is relatively new in the grand scheme of energy, is more expensive than fossil fuel power and is variable, while data centers need baseload power. But I think solar can be part of the equation, and particularly in the way Google is doing it. Google is investing in solar power projects, like BrightSource Energy’s solar thermal farm, that are selling clean power to the local utility. Instead of building its own solar plant, Google could then build a future data center in the utility’s footprint.
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