Dutch Tap Solar Heat from Asphalt Roads
If you've ever blistered your bare feet on a hot road you know that asphalt absorbs the sun's energy. A Dutch company is now siphoning heat from roads and parking lots to heat homes and offices.
Solar energy collected from a 200-yard stretch of road and a small parking lot helps heat a 70-unit four-story apartment building in the northern village of Avenhorn. An industrial park of some 160,000 square feet in the nearby city of Hoorn is kept warm in winter with the help of heat stored during the summer from 36,000 square feet of pavement. The runways of a Dutch air force base in the south supply heat for its hangar.
And all that under normally cloudy Dutch skies, with only a few days a year of truly sweltering temperatures.
A latticework of flexible pipes, held in place by a grid, is covered over by asphalt, which magnifies the sun's thermal power. As water in the pipes is heated, it is pumped deep under the ground to natural aquifers where it maintains a fairly constant temperature of about 68 F. The heated water can be retrieved months later to keep the road surface ice-free in winter.
"We found we were gathering more energy in summer than we needed, so we asked a building contractor what we can do with the extra energy," said Lex Van Zaane, the commercial manager. The answer was to construct buildings near the tarmac and pipe hot water under the floor.
The water usually isn't hot enough on its own, and must go through an electricity-powered heat pump for an extra boost, Van Zaane said. The installation cost is about twice as much as normal gas heating, but the energy required is about half of what would otherwise be needed. That translates into lower monthly heating bills and a 50 percent savings in carbon emissions.
Tags: Asphalt | Road | Heat | Energy