Solves one of the biggest challenges with solar energy
In a small shed at the University of Ås, storage challenges with solar energy will be history.
Solar cells in private homes are becoming increasingly popular, but saving energy using batteries or waterborne heat is both challenging and very bulky. Researchers at the university in Ås have now found the solution.
– Heat has been drilled for in recent years. But boreholes often gets colder and colder as you extract the heat, and heat pumps have therefore less and less to work with, says Petter H. Heyerdahl.
The associate professor of the NMBU in Ås stands in a campus shed and looks down at 20 energy wells in the ground in front of him. On the roof over his head 64 square meters of solar collectors are installed.
But in addition to heat domestic water as ordinary solar collectors do, solar energy will contribute to heating of space.
Adapted to Norwegian climate
– While other geothermal facilities run constantly on credit and lose power or get permafrost in the ground after a few years, we instead fill up the account in advance by sending solar heat into the ground. In summer, the hot water from the solar collectors drops to the ground and warms it up before returning to the ceiling for reheating. In the cold season, heat is found in the same way as a common geothermal system. In this way we solve the problem of cold wells and at the same time save the volatile solar heat, Heyerdahl explains.
Already in use in Canada
The technology in the project, which has come to life with the help of Innovation Norway and Anergy AS, is not new. In Canada, the Drake Landing Solar Community, a neighborhood of 52 detached houses in the city of Okotoks, has solar heating in the same way and has been in operation for many years.
Heyerdahl explains that the university’s facility is based on the same technology, but with some adjustments.
-We will see if we can get enough solar energy to supply a single home with heat for the whole year without the use of heat pumps. We use most of the ceiling to retrieve as much heat as possible.
The price of a full scale system adapted to an average Norwegian detached house, according to Heyerdahl, may be around NOK 600,000. However, the investment is rerieved in other areas.
Cuts in insulation
– You can expect to cut costs on insulation with the equivalent when building the house. With ample access to heat, you can have thinner walls. If you go down 20 cm in thickness on the walls, you get eight square meters more living space per floor in a common detached house. So you almost go to zero cost already at construction, saving money from day one when you move in, explains Heyerdahl.
He adds that there are very few with geothermal facilities that check the heat pump’s effect after a few years. This can cause the heat pump to be very ineffective without the consumer being aware of it.
The pilot plant may be just the beginning of the use of the technology in this country. A larger plant is already under construction, and the tests from the test facility show good results. Heyerdahl is convinced that collecting solar energy will give great results in terms of energy use in the future.
– The larger the plant, the larger the potential heat storage. A large heat storage unit will have less loss relative to the volume and thus higher recovery rate. Therefore, it is beneficial to think of common warehouses in a local district heating system for a group of homes or for larger buildings. With this on the ceiling in addition to a solution with PV solar panel and batteries, you may be able to disconnect the mains. One will be able to approach self-sufficiency, even with the climatic conditions we have in Norway, he says.
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