Goodbye, Terasen. Hello, 60,000 cubic meters of crystalline rock

solar-heated water from the summer months will be stored 65 meters underground in "60,000 m3 of crystalline rock," complete with "100 boreholes... fitted with double U-pipes."

As New Scientist explains, that water will be "kept hot by the rock, and can then be pumped back up to heat homes in winter."

This is referred to as "seasonal storage in rock."

Meanwhile, as the rocky matrix itself slowly heats up from years of use, engineers predict a near 70% drop in "conventional heating" bills – as well as in the use of fossil fuels.

Which is only appropriate, as the Swedish government announced last year that they hope "to become the world's first practically oil-free economy."