A review by specialist media Ingeniøren has looked into prospective energy use at major new data centres in Denmark.
Facebook's centre near Odense will provide surplus power to local heating infrastructure Fjernvarme Fyn, according to the report, with up to 100,000 megawatt hours, enough to heat 6,900 homes expected to be gained from excess from the data centre.
Other data centres will be located too far away from district heating networks, placing a prohibitive cost on authorities building cables and new installations to use power from the centres, Ingeniøren writes.
Facebook is building a second data centre near Esbjerg, reported to be the largest in Denmark.
The need for stable and cheap electricity was a major factor in the companies' choice of locations close to major electricity supply lines, according to documentation provided to Ingeniøren by Invest in Denmark and Apple.
Professor and energy researcher Brian Vad Mathiesen of Aalborg University stressed the need to make use of surplus power and said failing to do so in the case of the data centres was a serious mistake.
“There is unfortunately a tendency for politicians and officials to wrap things up in green packaging without checking that they are actually green and without following up,” Mathiesen said to Ingeniøren.
Christian Ibsen, director of green thinktank Concito, told the magazine that it was vital to ensure minimum environmental impact by data centres.
“Data centres have a very high energy consumption, so steps should be taken to ensure new wind and solar power production. That could be made a requirement,” Ibsen said.
“Furthermore, any surplus power should be used as far as possible in local energy infrastructures, and consideration should be made as where to locate (data centres),” he added.
No rules currently exist regarding use of surplus energy from data centres. Minister for the Environment Lars Christian Lilleholt told Ingeniøren in a written statement that the issue was "on his mind".
Lilleholt said that he would be disappointed if surplus power from only one of six data centres in Denmark was used, but added it was too early to draw conclusions and thereby place demands on tech giants over use of energy surplus.