Microsoft and GE’s Wind Farm in Ireland is a Sprawling Testbed for Fully Renewable Cloud
The 37 megawatts Microsoft will be getting from GE’s new Tullahennal wind farm in County Kerry, Ireland, will bring the total amount of energy the company is getting through renewable generation around the world to 600MW. But its power purchase agreement in Ireland to supply data center energy, announced earlier this month, is about much more than that.
The project is a pilot designed to understand how much energy storage the hyper-scale cloud operator needs to fully run on renewable energy, Brian Janous, Microsoft’s general manager of energy, said in an interview with Data Center Knowledge.
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Like other renewable energy sources, wind is intermittent, which makes it inferior to coal or gas-fired power plants in terms of predictability of output. That means regardless of how many wind turbines or photovoltaic panels you string together, you still need conventional generation capacity online to supplement the supply whenever the weather is not optimal for renewable generation. As more and more renewable sources contribute to the overall energy mix, the industry is looking for ways to even out the peaks and troughs without relying on fossil fuel.
The most common technique today is pumping water used by a hydroelectric power plant uphill overnight, when demand is low. Also common are using that cheap off-peak energy to compress air and store it in the caves of old salt mines and storing heat absorbed by solar facilities in molten salt, using it to drive turbines overnight.
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Microsoft and GE are taking a simpler and smaller-scale approach, pairing each wind turbine with an integrated battery. The idea is to use GE’s industrial analytics solution, Predix, to combine weather forecasts and a “digital twin” of the turbine (GE’s name for the totality of data available about an industrial asset, which includes things like sensor data, service information, and reports from other turbines) to predict how much power each turbine is going to generate.
If a turbine produces more power than the grid needs, the excess gets stored in the battery; if it doesn’t produce as much power as predicted because the wind speed has fallen, the battery can top up the output. That makes the wind farm’s power output more consistent and predictable (a must for a data center energy supply) and brings it online more quickly when there’s demand.
That sounds so logical, you might wonder why it’s not already common. This is the first production wind farm in Europe with integrated batteries, although GE has been selling hybrid wind turbines with battery cabinets since 2013 and can retrofit batteries to existing turbines, while rival Vestas tested a lithium ion battery on a turbine in Denmark the same year. (This is also Microsoft’s first renewable energy project outside the US.)
Predictive analytics has become much more powerful in the last few years – and batteries are dropping in price. “Part of the reason that it hasn’t generally been done is that batteries on the whole are expensive,” Janous told us. “We’re getting to the point now with the cost decline in batteries that this is the beginning of what I expect to be a longer-term trend with the integration of renewables and storage.”
The Tullahennal wind farm has what he calls a relatively small amount of short-term storage. “With this pilot, what we’re really trying to do is show the viability of this solution to do the integration of wind and batteries. The focus we have is proving that the technology can work in the field. We have other projects where we’re working on longer-duration batteries, like flow batteries, but there’s still some work to be done on discovering what does the electrical grid actually need in terms of storage and how best to integrate it; so we’re casting a relatively wide net right now.”
How Much Energy Storage is Enough?
There are still some fundamental questions about what storage is needed for renewables. One of them has to do with the amount of storage you need. “People think that if you put 400MW of wind or solar on the grid … you need 400MW of storage to integrate that, and you really don’t. You need something far less than that, because there’s a tremendous amount of variation on the grid, in terms of demand and variability.”