Heat harvested from the sea could supply energy to Shetland in Scottish first

The system is currently heated by burning the islands' household and industrial rubbish. The plan is to meet growing demand for connections to the system by adding an extra source of heat through the extraction of heat from the seawater in Lerwick harbour.

The project was devised because, despite importing rubbish from neighbouring Orkney as well as from the Highlands, the sparse population of the north of Scotland means that there is insufficient waste to burn to meet demand from the town's district heating system.

The current waste-to-heat system burns around 22,000 tonnes of waste each year to supply around half the heat demand of Lerwick's households and businesses.

Shetland Heat Energy & Power Ltd (SHEAP) is currently in discussion with the Glasgow-based heat pump manufacturer Star Renewable Energy about the project and a final decision about whether to press ahead with the project is expected to be made later this month.

Star Renewable Energy's director David Pearson said that seawater from Lerwick harbour is already extracted to cool Shetland's diesel-fuelled power station. The seawater-to-heat project will either use this water source or pump ashore seawater from elsewhere in the harbour.

In order for the project to take advantage of the government-funded Renewable Heat Incentive subsidy scheme, Pearson says that the project will not be allowed to use the hot water effluent (the hot water produced by cooling) from Lerwick power station as the rules stipulate that no industrial sources of heat can be used.

Instead fresh seawater would be cooled down from around eight to four degrees, harnessing enough energy to add a further 2MW of capacity to the town's 6.3MW district heating scheme.

"We are an industrial refrigeration company and have already installed refrigeration systems in the nearby Shetland Catch fish plant," Pearson said. "With this project instead of the heat from the refrigeration process being thrown away we would capture the heat from the seawater and use it."

The revolutionary technology has been successfully installed in lakes, rivers and estuaries in Scandinavia and Japan and was separately pioneered by Star Renewable Energy when it installed a 14-megawatt seawater based heat pump in the fjord next to the Norwegian town of Drammen in 2011.

Steven Peterson, operations managers of Shetland Heat Energy and Power, said that going ahead with the project would allow Lerwick's district heating scheme to reduce its reliance on oil, which is used to top up the system's supply of heat during peak periods.

The project would also reduce carbon dioxide emissions by allowing more homes and non-domestic properties in Lerwick to get away from oil-fired and electric heating.

Peterson added that, as it is cheaper to heat buildings using district heating than with conventional central heating systems, there is currently a two-year waiting list to be connected to the Lerwick district heating scheme.

Adding capacity by using heat from seawater would allow around 200 extra households in Lerwick to be connected to the district heating scheme.

�¢ A scheme to heat the University of Glasgow by drawing heat from the River Clyde has been put on hold as one of the main sources of funding for the proposed scheme insisted that all construction work be completed within twelve months. A university spokesman said that a feasibility study into the scheme, completed earlier this year, had found that it was technically possible but that, given the engineering challenges of the project and the time needed to obtain consents, the decision had been taken not to press ahead for the time being while the university completed a rebuild of its district heating system.

"The ongoing district heating project has been adapted to ensure that the potential to connect a heat pump at a later stage can be realised," the spokesman said.