'Coast', now in its fifth season, attracts five million viewers each week, and in the programme from Norway, which was aired on 25 August, the show trawled the coast from Lillesand in the south to Svalbard in the north. It covered amongst others Norway's close links with the UK through Viking history, World War II, geology and renewable energy.
Osmotic energy segment of the programme featured Stein Erik Skilhagen from Statkraft, a Norwegian company generating gas, wind and hydropower as well as district heating, and he was interviewed on the beach in Smøla about how osmotic energy is produced by mixing fresh water and salt water. He filled an osmotic energy model with salt water and fresh water, and after a few minutes, the turbine starts spinning the way they would at an eventual plant.
Osmotic power or salinity gradient power is the energy retrieved from the difference in the salt concentration between seawater and river water. Two practical methods for this are Reverse electrodialysis (RED), and Pressure retarded osmosis (PRO).
Both processes rely on osmosis with ion specific membranes. The key waste product is brackish water. This by-product is the result of natural forces that are being harnessed: the flow of fresh water into seas that are made up of salt water. The technologies have been confirmed in laboratory conditions, and they are being developed into commercial use in the Netherlands (RED) and Norway (PRO).
The interview was carried out with the Smøla wind farm forming a beautiful backdrop and was particularly relevant as the UK is keen to increase its own production of renewable energy – including wind power.
Last autumn, four TV teams from the BBC spent several weeks in Norway filming for the programme. After visiting Lillesand, Geiranger, Smøla, Lofoten and Svalbard, they retraced their tracks in helicopters to get spectacular images. The first osmotic power prototype in the world is soon ready for testing at Tofte. This will undoubtedly be more exciting than the demonstration at Smøla.
Stein Erik Skilhagen explains the principles of osmotic power to BBC presenter Alice Roberts. Photo: Aslak Øverås