Hydro-electric power is being used to light and heat a Cumbria youth hostel.
The hydro-electric project is cutting carbon emissions
The £44,000 Derwentwater Youth Hostel Association (YHA) project involved rebuilding a dam across the beck that flows through the hostel grounds.
The water was redirected, with some channelled through an electricity-generating turbine.
The system provides 40% of the electricity requirements for the building - saving £4,000 a year in fuel costs and cutting carbon emissions.
YHA environmental officer Ewan Boyd said: "This is a very exciting development as it is our biggest hydro scheme to date and the first that feeds directly into the National Grid.
"Not only does this project provide energy from a sustainable source, which is extremely environmentally friendly, but it also gives us a lot of educational potential."
Funding for the project came from government grants and the Lake District Sustainable Development Fund.
The hostel is on the site of a 200-year-old mansion near Keswick.