Skip to content

Ruden creates “underground batteries” from waste heat

Published 7 Jul 2022 (updated 7 Feb 2024) · 2 min read

Quick information

At a glance

  • Geothermal storage of industrial waste heat
  • Utilises naturally occurring or induced fractures and groundwater
  • Provides plants with clean energy for heating

Ruden has created the HEAT concept to store and recover seasonal waste heat from industrial processes, turning bedrock into large-scale natural thermal batteries. The stored heat can be recovered whenever needed.

Between 20 and 50 per cent of industrial energy output is lost as waste heat, according to the US Department of Energy.

This loss is a needless drain on finances for industrial plants and creates enormous greenhouse gas emissions.

Saving and storing the waste heat would reduce both costs and emissions.

Energy storage for industrial waste heat

Ruden has created the High Enthalpy Aquifer Technology (HEAT) system for underground energy storage. HEAT is particularly suitable for industrial plants with constant high levels of waste heat, for example solid waste incineration plants.

Ruden maps and models fractured rocks in the subsurface. By cementing and enhancing the fracture network, the HEAT system creates a reservoir for waste heat storage directly under an industrial plant.

Waste heat from the plant is stored in the rock formations by transferring the heat through circulation of water via fractures and fissures, thereby taking advantage of the unlimited storage capacity of rocks. Surplus heat from district heating systems can be stored and exploited in this fashion.

The heat storage does not incur emissions and has minimal energy loss.

Illustration of underground heat storage in winter

Concrete benefits

Ruden’s HEAT system provides clean energy storage for industrial plants, helping them to turn their waste heat into a seasonal productive resource. It moreover makes district heating plants more resource effective.

Seasonal storage recovers energy that is otherwise lost, and therefore reduces carbon imprint while increasing profit.

Market potential

The potential for waste heat recovery in the EU is about 300 TWh per year, enough to power a medium-sized country for an entire year.

Ruden AS was established in 2007 and draws on a large international network, with operations in Norway and abroad. Ruden’s LEAT system is installed on several signature projects in Norway, while the company is also developing a large-scale iHEAT system for renewable energy storage.

Helene Ree Ruden


Send an email


Mariusbakken 1D, 1628 ENGELSVIKEN, Norway