The National Trust has completed Britain’s biggest marine source heat pump project which will be used to generate heat for a 300-year-old mansion on the North Wales coast.

The project at Plas Newydd is the first of five schemes to be completed in a £3.5 million pilot phase of the Trust’s Renewable Energy Investment Programme, which was launched last year in partnership with partner Good Energy.

The marine source heat pump will provide 100 per cent of the heating needed by Plas Newydd Country House and Gardens in Anglesey. The 18th-century mansion used to be the National Trust’s biggest oil user and on some winter days would consume 1,500 litres of oil a day – the same as a typical house would use in ten months.

Plas Newydd will be now heated with a new local and clean energy system, which pumps a small amount of sea water from the Menai Strait in Anglesey, through pipes to and from a heat exchanger on the shore, and then up 30 metres of cliff face to the mansion’s boiler house.

The 300kW marine source heat pump – one of the first and the biggest in the UK – cost £600k to install in total and is expected to save around £40,000 a year in operating costs.

Adam Ellis-Jones, the National Trust’s assistant director for operations in Wales, said:

'With the Irish Sea right on the doorstep of Plas Newydd, a marine source heat pump is the best option for us. However, being a pioneer is never easy. There are very few marine source heat pumps and none of this size in the UK, so it has been a challenging project but a very exciting one.

'From the start, we’ve worked closely with SEACAMS (Sustainable Expansion of the Applied Coastal and Marine Sectors), led by the School of Ocean Sciences at Bangor University, and conservation experts to make sure we got the best from the technology while protecting the site’s fragile environment and archaeology. We’re now very keen to share what we’ve learned with others.'

The remaining pilot projects in the Trust’s Renewable Energy Investment Programme are expected to be completed within the next year. If they are successful, the Trust is planning to invest in a further 43 renewables schemes at its properties.

The organisation has committed to reducing its energy use by 20 per cent, halving fossil fuel consumption and generating 50 per cent of its energy from renewable energy sources by 2020, enabling it to reduce energy costs by more than £4 million per annum.