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Microsoft data centres heating homes in Finland

Tue 29 Mar 2022

Fortum, a state-owned energy company in Finland, has announced a deal with Microsoft to use waste heat from two new data centres to heat homes and businesses in Helsinki. This plan improves the environmental impact of the new construction, it will also help Microsoft cut carbon emissions.

Microsoft announced the plan to build the two data centres at the same time, noting that the location was chosen to support its plan to recycle heat for residential use. The data centres are expected to supply 40% of Fortum’s heat supply in Helsinki, serving around 100,000 homes and businesses.

Cindy Rose, president of Microsoft Western Europe, hopes that the project will set a standard for future similar applications of waste heat recycling. “We are incredibly proud of the novel way this data centre will sustainably power Finnish digital transformation, while also heating Finnish homes and businesses and helping cities achieve their emissions targets,” she said.

Microsoft did not release the amount it will invest in the data centres or in heat recycling; but Fortum will spend an estimated 200M EU. This will help the company to reduce annual CO2 emissions by approximately 400,000 tonnes; as well as help Fortum maintain a reliable heat supply when it decommissions its last coal-fired plant in Finland.


Similar projects and their impact

Other data centre companies have created similar projects, exploring the viability of recycling waste heat from the data centre. A successful waste heat recycling project supports a variety of benefits for the data centre. It is a demonstrable effort to reduce the environmental impact of data centres, while providing a benefit to local communities which are increasingly hostile to data centre construction.

In Stockholm, a group of data centre providers including IP-Only, Interxion, and Advania are partnering on an energy-efficient campus that will supply heat for 35,000 residential apartments in the city. And in the Netherlands, Switch replaced gas generator units with direct liquid cooling (DLC). This allowed the company to heat their own office and a neighbouring property with heat exchangers from server waste heat, rather than gas.

The main benefit of liquid cooling is that servers can run hotter, increasing the temperature of the waste heat and making it more useful. Erik Barentsen, Senior Policy Officer at the Dutch Data Centre Association noted that liquid cooling doesn’t improve data centre efficiency overall. It does make it easier to re-use waste heat.

“In essence, the amount of waste heat recovered compared to the electrical input will remain the same: 90 percent of the thermal energy that goes into a data centre can be recovered.” He says: “However, at least for the time being, the residual heat temperature will make a difference because with liquid cooling the residual heat is easier to use in a district heating system.”

Facebook has also found success with recovering waste heat at their data centre in Odense, Denmark.

“While we typically design our servers to minimise the heat they create, in Odense we direct this heated air over water coils, recovering the heat by raising the temperature of the water. This warm water is then delivered to the heat pump facility where the temperature is raised further and delivered to the district heating network and distributed to the local community.”

In the period 2011 – 2017, the company reportedly avoided 2 million tonnes of CO2 emissions, and provided the local residents with 100,000 MWh of energy per year.

However, there are challenges associated with waste heat recycling. First, the heat generated in data centres is at relatively low temperatures, limiting its usefulness in a recycling scheme. Secondly, it is quite difficult to transport heat, particularly over long distances. In projects like Microsoft’s in Helsinki, the company partners with an energy firm that already owns the infrastructure that will be used for heat transport. If that isn’t available, the heat must be used either on-site or very near the data centre itself, or build the pipes for transport themselves.

Transporting heat requires insulated plumbing and ducts, which are quite expensive. Adding piping to share heat from a data centre to a location only 400 metres away could add a million dollars to data centre construction costs.

The return on investment for these costs is dependent on the reduction in operating costs, the reduction in fees and fines associated with meeting environmental goals, and the value of reducing local community resistance to the data centre. Some businesses even get paid for the energy they are returning to the grid, as part of their agreement with local energy providers.


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