Can the sea heat a Country House?

A SEACAMS team of marine scientists are working with the National Trust to investigate whether coastal properties could benefit from renewable energy generated by the sea.

Most people think energy from the sea involves harnessing tidal action or building offshore wind farms, but this project explores a fresh concept: can the sea be used a direct source of heat?

Anyone swimming in the sea in late summer will testify that the sea is warm. Sea water, like any water, has the ability to retain heat for a long period of time. It takes a lot of heat to warm it or indeed cool it. This begs the question could this ability to retain heat allow us to extract it to heat large coastal properties?

Plas Newydd is a Country House on the banks of the Menai Strait on Anglesey. Built in the 18th Century, it was the holiday home of the 1st Marquess of Anglesey who commanded the cavalry at the Battle of Waterloo. Now thousands of tourists flock to the property to see the house, its setting and the 58’ mural by Rex Whistler in the 1930s dining room. Maintaining this 2,000 m2 property is expensive and a high proportion of this cost can be attributed to the oil-fired heating.

The size and coastal location of Plas Newydd makes it an ideal candidate for the SEACAMS project. SEACAMS, is a project which brings university expertise to the aid of the Marine and Coastal sector in Wales in order to promote innovation and expand research. Keith Jones, Environmental Practices Advisor at the National Trust, is keen to explore whether the sea will provide less reliance on fossil fuels and a welcome reduction in fuel bills. “If we can engineer and optimise a sea-based technology to provide economical heating for large coastal properties this has exciting implications, not only for the National Trust, but also for the renewable energy market,” reflects Keith. “There is a wide range of questions that we need to answer before this becomes a commercial reality and engineers can create a commercial renewable energy technology, but in years to come all coastal properties could be heated, thanks to the unique heat-retaining properties of the sea.”

Dr Hilmar Hinz is a leading marine scientist working on the project. He began to look at the possibilities of using the sea as a source of heat six months ago. “Using the ground as a source of heat is already established renewable energy technology in homes,” explains Hilmar. “Known as a ground source heat pump this technology operates on the principle that the sun warms the ground that retains heat at a constant 12 oC. This heat can be captured by burying a series of pipes in the ground filled with a fluid that will absorb the heat. This fluid is passed through a compressor that raises it to a higher temperature. The heat can be extracted and used to heat water that in turn heats the house. The cooled fluid passes back through the pipes in the ground to repeat the process. The technique works as there is a net return of energy. For every one unit of energy needed to power the system, 4 units of energy are generated.”

The amount of pipe that needs to be buried in the ground is dependent on the size of the property you need to heat. Typically a domestic home requires about 1000 metres. A large property like Plas Newydd would need the grounds to be extensively excavated to install a much bigger system. However, using the sea, with its currents and the ability to retain heat, offers a powerful combination of factors that could reduce the length of piping avoid disruption to often historic landscapes or archaeology, and lower installation costs while achieving far greater efficiencies by extracting heat continuously.

The two year project has begun by examining the environment in which a sea-based heat source pump would operate. “We have already established that the heat exchange principle, by which ground heat source pumps operate, is feasible; now we need to understand the practicalities of extracting the heat and the short and long term effects that may have on the marine environment in which it operates. We want to be sure that the impact of the system, both in terms of installation and operation, will not have any detrimental effect to marine life. Conversely, we also need to be sure that marine life will not have any detrimental effect on the operating efficiency of the system,” says Hilmar.

The work has started with sophisticated survey techniques from the Research Vessel RV Macoma, designed to operate in shallow water. The survey work will determine where to site the pipes to extract the heat and the configuration to put them in. Swathe bathymetry has been used to examine the morphology and depth of the seabed. This technique emits multiple acoustic beams to provide a detailed visual map that marine scientists are analysing currently. Further analysis will involve sub-bottom profiling that will examine the substrata of the seabed. This will be used to determine how best to fix the pipes to the seabed in the light of expected currents and eddies in the Menai Strait that is famed for its fast moving water.

Keith Jones is excited by the project. “The National Trust is committed to reducing its environmental impact and this project is a significant investment in future innovative renewable energy technology. Early results are looking promising and the SEACAMS programme is providing first class scientific expertise in a partnership project that could benefit a wide range of businesses in the future,” he comments.

The development of an efficient sea heat source pump could provide a unique product that Welsh businesses can lead an international field in installing and operating.

The SEACAMS project is run jointly by the Universities of Bangor, Swansea and Aberystwyth and is part-funded from the European Regional Development fund through the Welsh European Funding Office, part of the Welsh Government.