In September, the company teamed up with McKinstry and Cummins to launch what it called “the world’s first gas data center,” the design of which went on to win the DCD Mission Critical Innovation Award, presented at the end of 2017.

“The Advanced Energy Lab is a 20-rack data center pilot located in Seattle,” Microsoft research manager Sean James said.

“What makes this project so disruptive is how radically it simplifies the process of powering servers and how this could almost double the energy efficiency of data centers - all while reducing costs and improving reliability.”

The project design, known as ‘The Stark and Simple Data Center,’ puts fuel cells at the server rack level. A fuel cell is composed of an anode, a cathode and an electrolyte layer between them.

In the case of hydrogen-fueled proton-exchange membrane fuel cells (PEMFCs), hydrogen molecules split at the anode into protons and electrons, activated by a catalyst. The protons can pass through the membrane while the electrons cannot, causing them to travel across an external circuit, therefore producing energy.

Different fuel cells use different electrolytes and charge-transferring ions, but the two with the most promise for the data center appear to be PEMFCs and solid oxide fuel cells (SOFCs), with the latter using natural gas (methane) directly.

SOFCs have a higher efficiency, larger capacity, and are suitable for continuous power generation, but run at a higher temperature, produce carbon dioxide, and are less responsive to variable load.

PEMFCs remain the cleanest fuel cell variant, producing only waste water, but hydrogen distribution and storage has yet to scale. That could change in the future, however (see Dawn of the hydrogen era below).

SOFCs present a quick and viable alternative to the electric grid and can still provide some environmental advantages over combustion - Microsoft estimates carbon dioxide emissions could be reduced by up to 49 percent, nitrogen oxide by 91 percent, carbon monoxide by 68 percent and volatile organic compounds by 93 percent.

Microsoft is experimenting with both approaches - in the paper Fuel Cell Powered Data Centers: In Rack DC Generation, the company explained that it has run tests using both a Hydrogenics HyPM 10kW PEMFC and a SolidPower Engen 2500 2.5kW SOFC.

The Hydrogenics system is designed with data centers and telecoms facilities in mind, whereas similar products do not exist with SOFCs just yet. The SolidPower system targets the residential and commercial buildings sector, and was designed for the co-generation of heat and power.

The paper states: “It is expected that SOFC systems designed for the in-rack power generation in data centers will produce more electricity and less heat and that such will be cooled with excess air and air ventilation systems already present in the data center.”

Key to the method’s energy efficiency improvement is the decrease in transmission losses. Energy is lost as it travels down the wire and, in a standard data center, these losses are found in the power plant, transmission, substation, transformation, and AC to DC conversion at the server.

With fuel cells spread across the server racks, a method known as a Distributed Fuel Cell (DFC), the loss is limited just to the power conversion in the cell itself.

Microsoft claims that less than 35 percent of energy supplied by a power plant is actually delivered to the data center due to generation, transmission and distribution losses. When energy consumption associated with cooling, lighting and energy storage on the site is taken into account, only 17.5 percent of the energy supplied by a power plant reaches the servers.

In a research paper, Fuel Cells for Data Centers: Power Generation Inches From the Server, Microsoft found that when using its gas fuel cell approach, as much as 29.5 percent of generated power was spent at the server, assuming that the cooling load is proportional to the electric load for both traditional and fuel cell powered data centers. Further gains may be made if one could reuse the fuel cell waste heat for cooling processes.

Efficiency is not the only thing that makes a gas-powered data center attractive. Reliability could also be a major draw, with gas grid infrastructure usually buried underground and safe from severe weather. Gas grid reliability in the US is more than 99.999 percent, compared to the electric grid’s 99.9 percent or less.

This means that data center operators can consider eliminating diesel generators and batteries used for power backup, as well as getting rid of the power distribution system in the data center, which can account for over a quarter of the capital cost of a data center.

Challenges remain, however, with the technology still in the research stages. Of course, whilst operators no longer have to worry about a reliable connection to the electric grid, such concerns are replaced by a need to locate near a robust gas supply, if the SOFC approach is taken.

But perhaps the biggest issue is that of rapidly varying loads. Servers can drastically change their energy requirements at a moment’s notice, which the electric grid can easily accommodate.

But, with fuel cells, there is “a period of time where the fuel cells deliver an insufficient amount of voltage or power, resulting in server damage or shut down, which may lead to data center unavailability,” Microsoft explained in the research paper SizeCap: Efficiently Handling Power Surges in Fuel Cell Powered Data Centers. “We call this phenomenon a power shortfall.”

There are two approaches to dealing with such shortfalls. One is to perform power capping, which throttles server execution, therefore limiting server performance and causing both the fuel cells and data center to be underutilized. The other approach is to use energy storage devices (ESDs) like batteries and supercapacitors to cover the shortfall during load surges.

Provisioning for the worst-case scenario comes at a high financial cost, however. With this in mind, Microsoft has proposed SizeCap, which “coordinates ESD sizing with power capping to enable a cost-effective solution to power shortfalls in data centers.” The hope is to find a middle ground between the two approaches.

Further work on SizeCap and the matter of fuel cells as a whole is necessary, and the cost of the cells remains prohibitively high. Microsoft is hopeful, however, that the method will soon see more widespread adoption. If that happens, concerns over data centers’ impact on the electric grid may become a thing of the past.

Dawn of the hydrogen era