The Lounavoima waste incineration plant in Salo, Finland (source: Lounavoima)The operation and design of the well was developed by QHeat, the company that had previously worked on Finland’s first geothermal heating plant in the district of Varisto in Vantaa. The well was drilled by the GM2000 drilling rig, a first-of-its-kind down-the-hole (DTH) drilling rig developed by Geomachine and designed to maximize the speed of drilling and minimize rig down-time.
This is the second well drilling for deep thermal storage in connection with the Lounavoima waste incineration plant. The first deep thermal well, which has now been in test use for more than a year, was drilled to 1600 meters depth. A pump building with the technology for deep heat storage had also been built over the summer, with heat pumps to be installed this autumn. The objective is for deep heat storage to be operational by the winter.
“The operation of the plant generates energy steadily for the district heating network. In the network, however, the heat consumption load changes all the time, so when the consumption is at a low level, the plant has produced wasted energy. This energy can now be stored in deep geothermal wells and released from there later when consumption increases,” said Erika Salmenvaara, CEO of QHeat.
Salmenvaraa further added that a similar solution at a waste incineration plant has never been used anywhere in the world, and that the next step would be to expand the energy storage facility to a total of six wells. Drilling of the third well proceeded immediately after the second well. The heat storage of the six wells will be enough to supply 10 GWh per year, or the annual heat demand of 400-500 detached houses.
Deep drilling is key to high heat recovery
Prior to this project, the record depth of geothermal wells designed by QHeat was 1600 meters. With the GM2000 drilling rig now able to drill to a 2000 meters or even deeper, the utilization of geothermal energy can be taken to a much higher level.
“Since there won’t be any more land for geothermal wells in the future, the wells must be able to be drilled deeper than at present. One geothermal well drilled to 2,000 meters produces the same amount of energy as more than a dozen traditional shallower wells, and it is also suitable for heat storage and cooling,” said Samuli Salmela, CEO of Geomachine.
Salmenvaraa explains that the increase in drilling depth results in substantially higher thermal output. “Annually, 950 megawatt hours were obtained from a 1,500 meter deep well, and 1,530 megawatt hours from a 2,000 meter deep well.”
The geothermal well drilling solution of Geomachine has been specifically optimized for hammer drilling in hard Scandinavian soil. In the future, it is forecasted that the GM2000 drilling rig can provide benefit to large real estate sites where geothermal is viable as a regional energy source. From a single well, enough energy can be extract to supply heat to more than 300 A-class 70 square meter apartments.
