The data center industry is rethinking its approach to backup power, prompted by pledges from hyperscale operators to end the use of diesel fuel in their emergency generators. This trend is prompting new approaches to one of the most critical points in the digital infrastructure power chain, and will be carefully considered as mission-critical operators seek to strike the right balance between reliability and sustainability.

The shift won’t happen overnight. With generators deployed at virtually every data center around the globe, transitioning off diesel fuel is a big task. The data center industry was created to ensure that mission-critical applications never go offline, and that goal has typically been achieved through layers of redundant electrical infrastructure, including uninterruptible power supply (UPS) systems as well as emergency backup generators.


But early movers are implementing new approaches to backup power. Here’s a look at several approaches being implemented for power resiliency, including alternative fuels, large-scale batteries, fuel cells and geothermal.

Kao Data, Microsoft Try Greener Fuels

Switching to less carbon-intensive fuels is a logical first step, as it protects the massive investment in generators by data center operators and service providers. Microsoft and Kao Data each have initiatives with alternative fuels at data centers in Europe.

This month UK data center provider Kao Data transitioned all the backup generators at its Harlow, England campus to HVO (hydrotreated vegetable oil) fuel, which Kao says will eliminate up to 90% of net CO2 from their backup generators while reducing emissions of nitrogen oxide, carbon monoxide and particulate matter.

“HVO fuel is dramatically better for the environment compared to traditional, mineral diesels,” said Simon Lawford, Technical Sales Manager at Crown Oil, the fuel supplier for Kao. “It is 100% renewable, biodegradable, sustainable and non-toxic. We’re proud to have worked with Kao Data to initiate a first-of-its kind project, which will be transformative for the data center industry, and help point the way forward for significant reductions in industrial greenhouse gas emissions.”

HVO is synthesized from vegetable oils, requires no modification to existing infrastructure and can be used as a direct replacement for diesel. It eliminates microbial growth, which generates sludge that can contaminate fuel lines and potentially lead to engine shut down. Kao Data will replace an initial 45,000 liters of diesel and switch to an HVO provision of more than 750,000 liters when the campus is fully developed.

A backup generator at a Microsoft cloud data center. (Image: Microsoft)

A backup generator at a Microsoft cloud data center. (Image: Microsoft)

“This move effectively eliminates fossil fuels from our data center operations, and helps us reduce Scope 3 emissions in our customers’ supply chain, while delivering no degradation to the service they receive,” said Gérard Thibault, Chief Technology Officer at Kao Data. “Most importantly, it shows how our industry can take a simple and highly beneficial step forward for the good of the environment, ahead of COP26 (the UN Climate Change conference being held in Glasgow, Scotland in November).”

Microsoft will use low-carbon renewable fuel to provide emergency power for its cloud region in Sweden, the company said today. The backup generators at a new Microsoft data center in Sweden will run on Evolution Diesel Plus, a fuel that incorporates tall oil, a renewable byproduct of forestry and paper production. The “Eco-labelled” diesel is made by Swedish energy company Preem, which has worked with Caterpillar to ensure it will work in the generators at the Microsoft Azure cloud data center, which is scheduled to begin operating later this year.

The announcement advances Microsoft’s goal of ending its reliance on diesel fuel by the year 2030 as part of its goal to be carbon negative. The eco-diesel contains more than 50 percent renewables, and thus will have half the carbon impact of using petroleum-based diesel.

For more on “Drop in” substitution of alternatives to diesel, see fuel usage guidance from generator manufacturers Caterpillar and Cummins.

Google, Switch Eye Large Lithium-Ion Batteries

Utility-scale energy storage has long been the missing link in the data center industry’s effort to power the cloud with renewable energy. Energy storage could be a key enabler, addressing the intermittent generation patterns of leading renewable sources (solar panels only generate power when the sun is shining, and wind turbines are idle in calm weather). Large batteries could also lead to innovation in load-sharing with utilities and grid management.

Early players in this technology include Google and Switch.

Google will use large batteries to replace the diesel generators at one of its data centers in Belgium, describing the project as a first step towards using cleaner technologies to provide backup power for its millions of servers around the world. Joe Kava, Vice President for Data Centers at Google. describes it as “a first step that we hope will lay the groundwork for a big vision: a world in which backup systems at data centers go from climate change problems to critical components in carbon-free energy systems.”

The pilot project at Google’s Belgium data center begins this summer, and will use large lithium-ion batteries to replace generators. The price of lithium-ion batteries has fallen by about 80 percent over the past five years, enabling the integration of storage into solar power systems.

In March Microsoft and French energy company Total established a partnership to assess the long-term feasibility of deploying large batteries as backup power for critical infrastructure, working with Total’s battery specialist subsidiary, Saft.

An illustration of the Tesla Megapack, which provides 3 megawatts of energy storage capacity. (Image: Tesla)

An illustration of the Tesla Megapack, which provides 3 megawatts of energy storage capacity. (Image: Tesla)

Data center technology company Switch has announced plans to use new large-scale energy storage technology from Tesla to boost its use of solar energy for its massive data center campuses in Las Vegas and Reno. Switch broke ground last year on its Gigawatt 1 power project that will use photovoltaic panels to generate a total of 555 megawatts (MWs) of solar power at three locations. Switch says the project will feature one of the first large-scale installations of the Tesla Megapack, a new bulk energy storage product being manufactured at the Tesla Gigafactory, which is a Switch’s neighbor in a business park near Reno.


Although Switch hasn’t explicitly said how the system will impact its use of diesel generators, the company expects to use the Tesla Megapacks to create more than 800 megawatt hours (MWhs) of energy storage capacity.

Microsoft Testing Hydrogen Fuel Cells

Fuel cells are another potential tool to overhaul the traditional power architecture of mission-critical facilities, eliminating the need for expensive UPS systems and emergency backup generators. The use of fuel cells in data centers has been limited due to challenging economics, but that is beginning to change, and climate concerns may accelerate their arrival.

But what fuel to use? That’s an important question in addressing carbon impact.

One of the most promising tests cane in July 2020, when Microsoft said it successfully tested the use of hydrogen fuel cells to power its data center servers. The company called the test “a worldwide first that could jump-start a long-forecast clean energy economy built around the most abundant element in the universe.”

Beyond Generators: Data Centers Pursue New Approaches to Backup Energy 2

Microsoft used hydrogen stored in tanks on trailers parked outside a lab near Salt Lake City, Utah, to fuel hydrogen fuel cells that powered a row of data center servers. (Photo: Power Innovations)

Microsoft said it ran a row of 10 racks of Microsoft Azure cloud servers for 48 hours using a 250-kilowatt hydrogen-powered fuel cell system at a facility near Salt Lake City, Utah. Since most data center power outages last less than 48 hours, the test offered a strong case that fuel cells could be used in place of diesel generators to keep a data center operating through a utility outage.

“It is the largest computer backup power system that we know that is running on hydrogen and it has run the longest continuous test,” said Mark Monroe, principal engineer for Datacenter Advanced Development at Microsoft, who said the next step will be to procure and test a 3-megawatt fuel cell system to see how the system scales on a larger deployment of servers.

In 2017, the company created an Advanced Energy Lab in Seattle that powered 20 racks of servers with fuel cells powered by natural gas, teaming with McKinstry and Cummins on the project.

Meanwhile, colocation provider Equinix is continuing to expand its use of Bloom Energy Server fuel cells supported by natural gas. The company recently said that its flagship Silicon Valley campus in South San Jose will have 20 megawatts of Bloom capacity, and will be the first site where Equinix will use the system as primary generation, with utility electrical grid and generators as backup sources.

Equinix uses “Bloom Boxes” at 12 data centers in California, New York and Los Angeles. The company says the Bloom fuel cells will provide power that is 20 to 45 percent cleaner than the equivalent utility power backed by natural gas generation.

The Bloom Energy Server uses solid oxide fuel cell technology that converts fuel to electricity through an electro-chemical reaction, without any combustion. It can work with either natural gas or biofuels, such as biogas from landfills. Bloom says that its on-site fuel cells offer “better electrons” by making more efficient use of fuel than coal-fired power plants, eliminating power loss during distribution, and sharply reducing emissions. The Bloom boxes offer a better carbon profile than most utility power, and can be used with renewable energy to create a carbon-neutral solution.

What About Geothermal?

Another option is geothermal energy, which appears to be in a lengthier development cycle. But the effort is underway, as Google will soon begin using geothermal energy to power its data centers in Nevada with carbon-free energy. Google will be the first hyperscale cloud operator to tap the earth’s own heat to power its servers, an approach that can provide green energy around the clock.

Google will work with clean-energy startup Fervo Energy to develop a next-generation geothermal power project that will begin adding carbon-free energy to the Nevada power grid in 2022. The system will use underground fiber optic cables as sensors to identify the best locations to find geothermal energy.

“Not only does this Fervo project bring our data centers in Nevada closer to round-the-clock clean energy, but it also acts as a proof-of-concept to show how firm clean energy sources such as next-generation geothermal could eventually help replace carbon-emitting power sources around the world,” said Michael Terrell, Director of Energy at Google.

The Road Ahead

The goal of eliminating diesel fuel from data center operations is challenging, due to both economics and operational considerations, as summed up last year by The Uptime Institute.

“Almost every operator and owner would like to eliminate generators and replace them with a more modern, cleaner technology,” Andy Lawrence of the Uptime Institute noted in a blog post.  “But to date, no other technology so effectively combines low operating costs, energy density, reliability, local control and, as long as fuel can be delivered, open-ended continuous power … Few – very few – can even contemplate operating production environments without diesel generators.”

The good news – the world’s largest and most innovative technology companies are on the job and investing in change.

We’ll continue to track these efforts here at Data Center Frontier. Watch our Energy and Sustainability channels for developments, or sign up for our newsletter for updates right to your Inbox.