Elaboration of heat-cold recovery from drinking water

Water companies want to actively contribute to cutting back the societal costs associated with the consumption of fossil fuel energy in connection with drinking water use. Among the ways this can be achieved is by using sustainable ‘water-tied’ energy, for instance, through the recovery of thermal energy from drinking water. Thermal energy can be recovered at three points in the drinking water cycle: in the raw water (groundwater or surface water), in the service reservoirs, or in the drinking water transport mains. This must never, under any circumstances, pose a threat to water supply security or quality. There is, however, little information available about the impact of the recovery of thermal energy on water quality. And there’s a lot that is unclear about the effectiveness (performance) and safety of the installations involved.

In this project we survey and quantify the risks of the application of heat-cold recovery systems from drinking water. We also calculate the associated costs and benefits, thus providing insight into the business cases for such systems. Apart from the technical questions, we also answer questions from the clients’ perspective – for example, whether they actually would like to be supplied with warmer water. We also examine the (possible) positive consequences of extracting heat and cold from drinking water.

The objective of the project is to establish the risks, costs and benefits of systems that recover heat and cold from drinking water, drawing on the experience of a number of working installations in the Netherlands.

Effects and risks of heat-cold recovery systems

The following are the activities involved:

  • Collection of data on and description of operating and planned heat-cold recovery installations.
  • Determination of effects and risks regarding microbial water quality.
  • Determination of energy yields of heat exchangers and of effects on local water quality.
  • Evaluation of a number of business cases and the sustainability benefits achieved.
  • Report outcomes in the form of a BTO report and trade journal articles.

Support for decision-making, design, optimisation and water-quality policy

The results of the research can be used in decision-making about the realisation of new heat-cold recovery projects. The knowledge is useful as decision-support and also, in a later stage, when a new installation is designed. It can also be drawn on for the optimisation of existing installations. Lastly, the knowledge about microbial risks is important for the development of water-quality policy and possible regulations to govern the implementation of such systems. The knowledge is targeted at the MTs and technologists at water companies, and policy-makers (or policy-preparers) in the area of water quality.