Bodies of water are often excellent sources of geothermal energy. The heat stored in water can be extracted in two main ways, either directly using open loop technology, or indirectly via closed loop technology in a similar method to that of ground source heat pumps.

Groundwater from a well or aquifer, or water directly from a river can provide an excellent source of energy. Water is a very effective heat transfer fluid and groundwater in the UK tends to remain at a fairly constant 10-12°C year round. In an open loop system water is pumped directly through the heat pump and the water is then returned to the ground via another well or borehole. In ideal circumstances an open loop water system can be the most cost effective and efficient collector solution available. Open loop systems generally require Environment Agency permissions as well as comprehensive site suitability testing. Econic can advise on all these requirements. Significant amounts of heat can be produced from an open loop system. Econic has experience of all aspects of open loop systems and can advise on projects from design through to installation.

In a conventional closed loop system the pipes are buried in the ground. If a suitable body of water is available then it’s possible to consider a closed loop water collector. Instead of being buried in the ground the pipe array is simply sunk to the bottom of the lake, large pond or river. This reduces the cost of ground works required and can provide a more efficient solution.

Theoretically removing a large amount of energy from a lake could cause it to freeze solid so it is important to design such a system with great care. If a lake or pond is to be used it must be large enough to support the planned heating system, ideally with a flow in and out. The amount of sun falling on the water also needs to be understood. Econic have experience of designing and installing closed loop water systems and can advise whether this approach would be suitable for your project.