Well water as a central heat source for small residential areas
Sustainability is a large priority in the Fuchstal administrative association. And it needs innovative solutions. Working with the consultant Ingenieurbüro IIIB Energie, Puchschlagen, bifa examined a local heat supply using near-surface groundwater for the "Am Lech" and "Seestall Ost" housing development areas in Dorstetten and Fuchstal respectively.
Can cold groundwater be used as a heat source for residential buildings? What seems nonsensical initially, is enabled by heat pumps: Heat acquired at a low temperature level is raised to a higher level. Several variations of this principle were tested for the heat supply of new building areas of the Fuchstal administrative association.
Hydrogeological test drilling by GeoUmweltTeam, Marktoberdorf, verified the availability of groundwater. Based on this, supply options were developed and checked for viability. From several concepts prepared, bifa and IIIB Energie worked up two sustainable supply solutions.
One solution is for an uninsulated cold water network. In these, the temperatures are increased for heating and water by on-plot heat pumps. Photovoltaic systems can be integrated on the roof for the heat pumps’ power demand. Additional stratified storage tanks are recommended for accumulator storage of the heat.
The special feature of the other option is a central groundwater heat pump system. Space heaters can be supplied directly at a system temperature of 30-40 °C. An outdoor photovoltaic system supplies electricity for the heat pump system. Local, on-plot hot water heat pumps are necessary for domestic tap water heating.
The economic assessment was based on detailed revenue and cost forecasts. Low heat prices as well as ecological, long-term operation were central requirements of the municipality.
For the small supply areas, the two solutions highlighted are economically more viable than, for example, a biomass hot water network, and the costs for the municipality and heat customers are similar. The ecological advantages of the innovative approaches were clearly substantiated.
Following intensive consultation with experts on hand to provide information and advice, the two municipal councils voted to implement the cold water solution. Important aspects included the investment level, the cost to the municipality and homeowners as well as risks.
As a result of the resolutions, in both new housing areas, sustainable heat supply solutions will be set up for the municipality without further grants. Regardless of this, the developers can make use of the heat pump grants provided by the Federal Office for Economic Affairs and Export Control (BAFA). The heat customers benefit in the long run from a forward-looking, climate-friendly heat supply and favourable supply costs.
The studies were funded by BAFA as part of the Heat Networks 4.0 programme.
You want more information?
You are welcome to contact me:
Dr. Wolfram Dietz
wdietz@bifa.de