Microsoft is to use banks of lithium-ion batteries it has installed at its data centre in Dublin to help Irish grid operators provide an uninterrupted service.

Nearly 400 wind farms in Ireland collectively generate more than 35% of the island’s electricity. These carbon-free electrons travel on power transmission lines to farms, businesses and homes, helping utilities avoid emissions of carbon dioxide and other greenhouse gases from burning fossil fuels to generate electricity.

The fluctuating intensity of the wind causes variable power production. As the supply of renewable energy increases, a growing problem for electric power grid operators is created. That’s because they need only to put on the exact amount of energy that users are pulling out.

Banks of lithium-ion batteries at a Microsoft data centre in Dublin will help solve this problem later this year, according to a Microsoft blog post.

These batteries, which typically provide back-up power for the data centre in case of emergency, have been certified, tested and approved for connection to the grid in a way that helps grid operators provide uninterrupted service when demand exceeds the supply generated elsewhere on the grid by wind, solar and other sources.

Providing this grid service “is a way for us to unlock the value of the data centre,” said Nur Bernhardt, a senior programme manager for energy at Microsoft.

Power grid operators around the world typically rely on running coal and natural gas fired power plants to maintain what is called spinning reserve, or excess capacity, that can respond quickly to provide grid services.

The ability to use the data centre’s batteries to provide these services reduces the need to maintain spinning reserve at power plants, which lowers power sector carbon emissions, Bernhardt said.

The batteries are part of the uninterruptible power supply (UPS) for the data centre. The UPS in Microsoft’s Dublin data centre includes technology that enables real-time interaction with the electric power grid.

If grid-interactive UPS systems replace the grid services provided by fossil fuel power plants in Ireland and Northern Ireland, about two million metric tons of carbon dioxide emissions could be avoided in 2025, according to Baringa, an energy advisory firm that Microsoft commissioned to analyse the potential impact of the technology.

“This is definitely moving the dial on emissions at a national level,” said Mark Turner, a partner in Baringa’s energy practice who helped perform the analysis.

Two million metric tons of carbon dioxide emissions are about one-fifth of the total emissions expected across the island of Ireland from the power sector in 2025, he explained.

What’s more, by relying on grid-interactive UPS technology for grid services, end consumers across Ireland would save tens of millions of dollars on fuel and other costs required to maintain the spinning reserve at coal and natural gas fired power plants.

“The third win is you reduce the amount you have to turn down renewables,” Turner said. “That’s because if you turn gas-fired power stations on to provide this service, you’ve got to turn something else off. Often that’s renewables. If you provide this with UPS, you no longer have to do that.”

Data-centre operators rely in part on the batteries in the UPSs to kick on the moment a power outage occurs and provide power to the servers while the backup generators are fired up.

The main purpose of the UPS is to provide power conditioning for the servers. The UPS is always on, providing protection to the servers. In 2017, Microsoft started to explore the potential to leverage these assets.

“The concept was to use the UPS, which is providing continuous protection, change the controller on the UPS and provide services back to the grid,” said Ehsan Nasr, a senior design researcher who works in Microsoft’s data-centre development group.

Grid frequency is becoming more volatile as the supply of variable renewable energy on the grid increases, said Christian Belady, vice president of Microsoft’s data-centre development group.

This increase in volatility, in turn, increases the value of assets such as batteries that can help maintain the balance between supply and demand, he explained.

“We have this battery asset in the data centre that is just sitting there,” Belady said. “Why don’t we offer it to the grid and come up with a dynamic way of managing it as a dual-purpose asset and thus drive more efficiency and asset utilisation? That’s what drove this win-win situation.”

To that end, his team partnered with power management company Eaton to develop and test a grid-interactive UPS. They performed proof-of-concept experiments in 2020 at a Microsoft data centre in Chicago and have continued to refine the technology at Microsoft’s data centre in Quincy, Washington.

“We are making sure that we can provide the exact functionality of the UPS and, at the same time, provide ancillary services back to the grid with secure communication between the data centre and the utility,” Nasr said.

With the grid-interactive UPS technology demonstrated as a viable provider of grid services, the next step was to find a market with a business case for deployment, said Mycah Gambrell-Ermak, a principal programme manager at Microsoft who worked on this project and is now on the supply chain strategy team.

Microsoft found an opportunity in Ireland, where variable renewables already account for more than 35% of the island’s electricity and that figure is expected to grow to 80% by 2030. This level of variable power production requires grid-stabilisation services typically provided by fossil fuel power plants.

“In areas where municipalities or utilities are trying to get away from fossil-based solutions, if there is a dip in renewable reserves, what we can do as a company is take our large amount of load and we can reduce our load by putting our own batteries to use,” Gambrell-Ermak said.

EirGrid, the transmission system operator in Ireland, runs a market for grid services that prioritises non-carbon-emitting options. Microsoft is participating in this market through Enel X, an energy services provider that aggregates industrial and commercial energy consumers into virtual power plants.

“Utilities, by way of aggregators, can give us a signal that tells us to discharge our batteries to compensate for our load, which then takes the burden off of the grid,” said Gambrell-Ermak.

EirGrid’s market for grid services is a blueprint for how technologies, such as grid-interactive UPS systems at data centres and other industrial facilities can help decarbonise electric power grids around the world, according to Paul Troughton, senior director of regulatory affairs for Enel X.

“I often think of Ireland as a vision of the future of what other systems’ grids will be like,” he said.

As other countries transition to a greater reliance on renewable energy, they will encounter a similar situation.

“As you add renewables, your conventional plants will retire and you can’t call on them to provide the services they would traditionally provide,” Troughton said. “You need to do something to get better at managing frequency.”

Microsoft is exploring opportunities to provide grid-stabilisation services with grid-interactive UPS technology at its data centres around the world to accelerate progress towards grid-decarbonisation, Bernhardt said.

The grid-interactive UPS initiative is part of the company’s commitment to be carbon negative by 2030, which also includes experiments at data centres with liquid immersion cooling for servers, hydrogen fuel cells for backup power generation, along with changes in operation to increase efficiency and design such as high-density cold plate.

“The long-term vision is to turn the data-centre assets into something that can provide social benefit outside of our own operations,” Bernhardt said.

EirGrid’s grid-services market, he explained, provided an opportunity for companies such as Microsoft to deploy technology that addresses grid reliability concerns associated with the growth of renewables.

“We can still maintain our requirements around reliability to our customers but at the same time utilise our infrastructure to provide reliability to the grid, as well as lower CO₂ emissions and reduce costs for all energy consumers,” he said.