Diesel emissions actually account for less than 1% of Microsoft's emissions. Primarily, diesel generators are used as a back-up power solution for the cloud computing branch Azure's datacenters. So, they just kick in in cases of a power outage.
Mark Monroe, an infrastructure engineer on Microsoft’s datacenter advanced development team says, “They are expensive. And they sit around and don’t do anything for more than 99% of their life.”
With the recent developments, hydrogen fuel cells have become a viable solution for such power outages. On top of that, they can fit their power cells with a water electrolyzer that strips hydrogen and oxygen apart. They could use this to provide load balancing services and keep server health and latency more stable during high traffic moments.
The electrolyzer can be turned on when there's an abundance of solar or wind energy in the grid. Then, when there's a high demand, Microsoft could turn on the fuel cells to harness the output of the electrolyzer.
In 2013 Microsoft began exploring alternative fuel cell technologies. They tested the idea of powering server racks with natural gas-powered SOFCs (solid oxide fuel cells). Monroe explains: “They have the ability to make their own hydrogen out of the natural gas feed that they get.” And added, “They take natural gas, a little bit of water, they heat it up to 1112 degrees F (600 degrees C), which is the temperature of a hot charcoal fire.”
At this temperature, a process called steam methane formation occurs, which outputs hydrogen atoms that are fit for electric generation. According to Microsoft, implementation of such technology could make their datacenter energy efficiency 8 to 10 times better. Although, the technology remains too unviable cost-wise to be implemented at a big scale.