Engineering firm Tauw harnasses sewage waste heat technology

Sewage waste heat recovery doesn’t sound particularly attractive, but it could be a sustainable solution to reducing greenhouse gasses and help the Dutch government reach it's sustainability goals.

Sewage waste heat recovery

Sustainable sources

The temperature of sewage water is about 15 degrees Celsius. Heat exchangers around sewage pipes can use the waste heat to warm up water to be used in central heating. The natural warmth in the ground also heats the water and the ground insulates the sewage pipes at the same time. This system can make up for 70 percent of heating in homes, a school or swimming pool. An electric water pump heats the water further until it is warm enough to heat buildings. The water from the heat exchanger can easily be connected to the existing central heating systems. As a result natural gas is no longer needed and the electricity required for the pump can be generated by sustainable sources, such as windmills and solar panels.


Dutch engineers have been looking at sewage waste heat recovery in the last five years. Their calculations show that 150 metres of underground sewage pipes can heat 100 houses. There is 100,000 kilometres of sewage pipes underground in the Netherlands. The Dutch government aims to end the use of gas in homes and industry by 2050. For this reason, using waste heat from the sewers is an interesting prospect.  

Ice-free roads

The investment for sewage waste heat recovery is high, however, the system pays for itself within 7.5 years. The savings are made by no longer using gas to heat buildings. In addition, factories and companies can add their waste heat to the equation. At present much of this heat goes to waste in the ground.

The technology is relatively new there is still a lot of research to be done. However, projects in Germany and Switzerland are already showing positive results. It could also be used to keep roads free of ice in the winter.

Sewage pipes due for renewal

By chance this is a good time to introduce sewage waste heat recovery technology. The Netherlands sewage pipes are due for renewal as they were laid around 50 years ago. Although the costs are high, so are the savings, which makes it interesting for public-private investment.
Tauw has implemented the system at a school in the Dutch seaside town of IJmuiden, which opened earlier this year  and a swimming pool in Urk, due to open in April 2017. And there are more projects in the pipeline, so to speak.