Aquathermal energy is a sustainable energy technology that extracts thermal energy (heat or cold) from surface water, drinking water or wastewater and uses it to heat or cool buildings.
As countries work toward reducing dependence on natural gas and fossil fuels, aquathermal energy is gaining attention as a reliable, locally available and low-carbon alternative for the built environment.
Sources of aquathermal energy
There are three main water sources, each with its own characteristics:
- Surface water (TEO — thermische energie uit oppervlaktewater) — rivers, lakes, canals and harbours. Water temperatures fluctuate with the seasons, typically ranging from 4 to 25 degrees Celsius, making surface water suitable for both heating in winter and cooling in summer.
- Drinking water (TED — thermische energie uit drinkwater) — water in the mains distribution network sits at roughly 10 to 15 degrees Celsius year-round, providing a stable source.
- Wastewater (TEA — thermische energie uit afvalwater) — effluent leaving homes and businesses is relatively warm (10 to 25 degrees Celsius), and large volumes flow through the sewer system continuously.
How it works
A heat exchanger placed in or near the water source transfers thermal energy to a heat pump. The heat pump raises the temperature to a level suitable for space heating or domestic hot water (typically 40 to 70 degrees Celsius). In cooling mode, the process is reversed: excess heat from buildings is rejected into the water source.
The coefficient of performance (COP) of the heat pump determines the efficiency. A COP of 4 means that for every unit of electrical energy consumed, four units of heat are delivered.
Advantages
- Reduces CO2 emissions compared to gas boilers.
- Water sources are widely available, especially in the Netherlands and other delta regions.
- Can provide both heating and cooling from the same system.
- Complements other renewables such as solar and wind.
Challenges
Large infrastructure investment is required for collector pipelines, heat exchangers and district heating networks. Ecological impact on water bodies must also be assessed and managed.
Related terms
- Heat pump
- District heating
- Geothermal energy
- Thermal energy storage (TES)