Drammen, around 40 miles from Oslo in Norway is using the local fjord to heat nearly all the homes and businesses of its 65,000 residents.
The fjord’s water is at 8C, pretty chilly. However, using heat pump technology and a few innovations they have managed to create a system that saves them money and cuts down on carbon emissions.
Heat Pumps are not new, but the ones we’ve seen have all been air to ground or more common examples are your freezer or air conditioning. They absorb heat from a cold space and release it to a warmer one.
It all came about because the city’s heating company realised the water temperature in the fjord was perfect for heat pumps. They ended up turning to a company in Glasgow, Scotland who usually make refrigeration for grocery stores to come up with a solution. Star Renewable Energy suggested using ammonia as a coolant instead of hydrofluorocarbons (HFCs), a greenhouse gas that is being banned by the European Union.
How Does it Work?
Water from the fjord at 8C heats liquid ammonia at four times atmospheric pressure until it boils at 2C and evaporates.
Increasing the pressure to 50 bar, heats the evaporated gas to 120C.
The gas is then used to heat the water in the heating system from 60C to 90C.
Once the heat has transferred to the water, the gas changes back into a liquid state and it all begins again, with the water returning at 60C
Video Showing How it Works
Most heat pumps produce water at about 60 but because this one heats it up to 90C it means that it can be used to power older buildings, that typically require more heat.
The system has already paid for itself with the city saving around $2 million per year and 1.5m tonnes of carbon.
The heat pump does need power itself to work so that also has to be generated cleanly if you are looking for low emissions but the company says it could be used in hundreds of cities.