Material Insights · Understanding the Material World

Shared and district heat reuse: Impact and additionality

Displacing coal boilers with servers, sewage and tunnels

What this tab covers The impact and additionality lens: direct emission cuts, side benefits for water and air, and the risk of prolonging the life of a polluting host plant.

Abatement is the boiler or CHP heat displaced minus the heat pump's power; the Nordic schemes show large savings where grids are clean.

Direct Scope 1 and Scope 2 abatement

Favourable

The Microsoft and Fortum scheme was expected in 2022 to cut about 400,000 t CO2 a year for some 250,000 users; its heat pumps began operating in May 2026. Kalundborg's partners report about 586,000 t CO2 a year saved (an older EU platform page gave 635,000 t; the partnership's own current figure is used). Meta's Odense heat was expected to cut the city's coal use for heat by up to 25%. Data centres used about 2.7% of EU electricity in 2018, with the Commission projecting 3.2% by 2030, so the resource will grow.57111317

Fortum and Microsoft about 400,000 t CO2/yr (2022 estimate)7 Kalundborg CO2 saved about 586,000 t/yr (partnership claim)11 Odense coal cut up to 25%5 Bunhill 2 carbon saving over 500 t/yr13 Data centre share of EU electricity 2.7% (2018); 3.2% projected for 203017

Water and air synergy

Favourable

Kalundborg's partners report saving about 4 million m3 of groundwater a year by using surface water instead. Using data centre heat reduces reliance on evaporative cooling, and replacing coal or gas boilers cuts local air pollution. Katri Vala also cools buildings with treated wastewater, reducing electric chiller use.811

Kalundborg groundwater saved about 4 million m3/yr (partnership claim)11 Kalundborg residual materials reused about 62,000 t/yr11

Avoided lock-in

Mixed

Data centre, sewage and metro heat support no fossil asset. Symbiosis built around a coal plant or refinery can create a reason to keep it running; investors should check that heat contracts let the source change. In Odense the recovered heat is displacing coal.5715

Sources

  1. Odense Data Center 2 Meta (Facebook Engineering), 2020
  2. Fortum and Microsoft announce world's largest collaboration to heat homes, services and businesses with sustainable waste heat from new data centre region Fortum, 2022
  3. Katri Vala heating and cooling plant Helen, 2025
  4. Numbers are worth a thousand words (Kalundborg Symbiosis key figures) Kalundborg Symbiosis, 2026
  5. Bunhill Heat and Power Network brochure Islington Council, 2021
  6. Kalundborg Symbiosis: six decades of a circular approach to production European Circular Economy Stakeholder Platform, 2024
  7. Green and digital: study shows technical and policy options to limit surge in energy consumption for cloud and data centres European Commission, 2020