Genbrug byvarme

New Scientist skriver i denne uge om genbrug af byens varme. Artiklens forfatter foreslår, at man skal lægge varmepumper ned i metroerne, for på den måde at udnytte dens varme, - og måske også nedkøle den:
"There is an alternative, though, and it's far better: use heat pumps to recapture urban waste heat. Just as ground source heat pumps pull the heat from the ground, urban waste heat pumps could mine the vast trove of accumulated waste heat beneath our cities – from subway systems to sewers. They could then divert it to where it is needed, using a system of pipes and heat exchangers, creating an urban heat grid."

Faktisk er varmen i byen i sig selv en forurening. Byens overskudsvarme stiger op i atmosfæren og forstyrer jetstrømmene:
"... waste heat doesn't just disappear if we don't recycle it. Concentrated into cities and radiated into the atmosphere in small dense pockets, it ends up shifting the jet stream"

De nordiske lande bliver nævnt som værende førende i genbrug af byvarme:
"Denmark, Sweden and Finland lead the world in using heat pump technology to manipulate their cities' exhaust. Helsinki in particular has won awards for its large heating and cooling system, which features 1200 kilometres of underground heating pipes, connecting 93 per cent of the city's heated spaces."

Læs hele artiklen her.