Facebook shows off heat-recovery system for its Danish data centre

District heating system transfers heat generated at by Facebook's servers to buildings in the city of Odense

Social media giant Facebook has unveiled a new heat recovery system at a wind-powered data centre in Denmark that uses heat generated by its servers to warm homes in the nearby community.

The district heating system, developed for Facebook by local heating firm Fjernvarme Fyn, transfers heat generated at Facebook's 50,000 square-metre facility to buildings in the city of Odense.

Facebook said it expects to recover and donate 100,000 MWh of energy annually from its banks of servers, enough to warm 6,900 homes.

The company boasted that while similar projects existed, the system at its Odense facility scales the technology to a "level not yet reached" anywhere else in the world, providing as much as 25MWh of usable heat.

Lauren Edelman, energy specialist at Facebook, said the data centre had been specifically selected for its potential to enable heat recovery. "The qualities that drew us to Odense include the ability to connect to a highly reliable Nordic electric grid with opportunities to add new sources of renewable energy, good access to fibre, and the talent needed to build and operate the data centre," she said. "But what really differentiated this site from others was the opportunity for heat recovery."

The heat pump technology deployed at the facility routes water through insulated steel pipes to the roof of the data centre, where it is directed into copper coils located inside cooling units. There, hot air from the data centre's servers heats up the water that flows through the coils. Once the water is warmed in the coils, it is pumped back to the heat pump facility, where it is used to raise the temperature of the water loop that provides hot water to radiators in the local community.

"The entire process, from powering the servers to delivering heat, is supported by 100 per cent renewable wind energy," Edelman explained. "Heat pumps are not new - they are a very big part of the Danish heating strategy to phase out coal and natural gas — and neither are coils to recover heat. It's the pairing of these two at hyperscale that is innovative."

Facebook unveiled the district heating system on the same day as it published its first-ever sustainability report, which saw the company hail a 59 per cent reduction in operational greenhouse gas emissions since 2017.

The tech giant said it had begun reporting on "key Scope 3 activities", including business travel, employee consulting and construction impacts, but declined to disclose these indirect emissions in its new update.

The report highlights how purchasing renewable energy has become a cornerstone of the company's sustainability efforts, noting that at the close of 2019 86 per cent of its operations were powered by clean energy.

The company has in the past faced fierce criticism from green groups for its reluctance to tackle climate misinformation on its platform and its reliance on coal power for some of its data centres.

But the new report stresses that the company now expects to transition all its operations to run entirely to renewable energy by the end of the year.

Facebook now boasts 1.3GW of wind and solar projects, a larger renewables portfolio than many countries. BloombergNEF data shows that the company is now the second largest corporate purchaser of renewables in the world.

Commenting on the release of its report, the Facebook said: "we are proud to be on track to meet our 2020 goals and look forward to continuing to minimize our energy, emissions and water usage. Climate change is an urgent issue facing the world today, and we are committed to continuing to do our part to address this global challenge."

A version of this article was first published on Businessgreen.com