Thought I'd comment on the two prominent articles in the New York Times on data centers (here and here) in a series of posts rather than one long one.
The second article by James Glanz in the Times focused some attention on the pollution produced by backup diesel generators at data centers, and certainly criticized those occasions when generators are used beyond testing or to pickup load when utility service is down.
There is no question that backup diesel generators, whether used for data centers or any other critical load, are pretty serious pollution sources, which is why they are strictly regulated by local or statewide air quality agencies.
The regulators typically allow very limited testing hours for generators, and assume that additional run time for service outages will be quite limited. In the Bay Area, generator owners are allowed twenty hours of testing a year. In exchange for these limitations, owners do not have to install expensive pollution control measures.
Even with these limitations, air boards have had to wrestle with the concentration of diesel generators needed for utility-scale data centers. And when there is a concentration of data centers in a given area, this concern is obviously magnified. (Think of the example cited in the article, Quincy WA, as well as the City of Santa Clara's Space Park Drive area, and Digital Realty's data center campus in North Carolina.)
I'd like to make two points on this issue.
First, data center operators should limit diesel generator use to testing and emergency backup only, and utilities should not promote generator use for demand response programs absent the installation of the best available pollution control measures on the generators.
It's hard to discern what was really happening with generator use at the Microsoft data center in Quincy; I could guess at only two reasons for it and only one of those comes close to a "no foul" situation.
If data center operators are encouraged by utility programs or policies to run generators outside of testing and emergencies, then they should be obligated to work both with their customers and air quality regulators to ensure that suitable pollution control improvements are installed. Substituting the operation of distributed diesel generators with limited emissions controls for the use of peak power generators (that are usually quite dirty too) may make some economic sense, bu is probably a loser when it comes to overall emissions output.
Second, it's time for data center operators with multi-MW of generator capacity to consider cleaner options. (If you don't agree, stand in a yard full of 2 MW generators when they fire up at once - I won't pay for your dry cleaning bill.)
Diesel generators will operate on natural gas with a fifteen percent diesel portion, significantly reducing emissions. I know data center operators want to have sufficient fuel on site to guarantee a given run time, and don't consider natural gas from a local utility a reliable enough source. So what we need from the generator companies is a switchable unit that can rely on natural gas when available, then switch over to 100% diesel if needed.
I think regulators are going to force this issue, especially in areas with high concentrations of generators.
A utility/regulator/data center operator deal that works around these issues could yield lower emissions, the ability to run generators for demand response, and easier permitting for new utility scale facilities.
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