Sustainable heating from the sea

Author: Keith Jones, National Trust

Location: Anglesey, Wales

Plas Newydd, an 18th century mansion on the Anglesey coast, Wales, is the first National Trust property to install a marine source heat pump, providing a long-term, low-maintenance, sustainable heating approach for the property.

Until 2013, Plas Newydd was using 128,000 litres of oil each year to heat the mansion and it was considered the largest oil consuming property in the National Trust. The property – former home of the Marquis of Anglesey, on the edge of the Menai Strait – used an oil boiler which presented the Trust with issues relating to high operating costs (£76,000 annually), danger of leakage from the 15,000L of oil stored, and decreasing efficiency of the old boiler (43 years old).

In 2010, as part of the National Trust energy strategy, the Trust committed to using 20% less energy, halve fossil fuel use and generate 50% of the energy needs from renewable resources by 2020. In 2011, 50kW solar photovoltaic panels were installed in a nearby field at Plas Newydd. The PV panels produce 45,000kWh per year, which goes towards meeting the electricity demand within the mansion.

The 300kW marine source heat pump system was installed as part of the 2013 Renewable Energy Investment program, and it was delivered in 16 weeks, from the point of starting on site.

The heat pump replaced the two oil boilers in providing conservation heating for the building, enabling an 80% reduction in carbon emissions. It has also removed the need for storing large high-risk oil tanks (15,000L capacity) directly above the Menai Strait, which is a European special area of conservation and SSSI (Site of Special Scientific Interest). The pump house was also designed to be flood proof to minimise structural damage in the event of a flood.

This new system has saved the National Trust £40,000 per annum in operating costs at the property; money, which will be fed back into conservation. With the addition of the RHI (Renewable Heat Incentive) payment, this should see a payback period of less than 7 years for the £579,000 investment.

The project has won the Wales Green Energy Award for Outstanding Renewable Energy Project in 2014 and the 2015 Business Green Leaders Award for Outstanding Project of the Year.

Many island and coastal communities, as well as NGOs and organisations, are showing interest in learning, researching and emulating the project. This is in line with the vision for the project: creating a model, which could be replicated to benefit communities around the country.