The manure from one cow can provide enough fuel to heat seven houses.

Nij Bosma Zathe is an experimental Dutch farm with 200 dairy cows.

The manure these cows produce is used to make biogas. The gas is turned into electricity in a generator which feeds it into the national grid.

The heat this releases goes directly to houses in the new estate in Techum.

The heat arrives, through a grate in the wall, in Carla Koelstra's home five kilometres away.

"Just a push of the button and the house is warm," she says. Her children are surprised it doesn't smell: "They must use a lot of perfume on it."