The National Trust house that is heated by sea water
22 May 2014 Last updated at 06:01 BST
With fears over Russia's hold over gas supplies, Europe's governments are seeking methods to heat homes and businesses that do not rely on gas.
The National Trust is unveiling a new project on Thursday to suck heat from the sea to warm one of its historic homes in North Wales.
It uses a similar technology to refrigeration.
BBC Environment Analyst Roger Harrabin reports.