Residents in the German town of Geretsried have long wanted to run their buildings with clean heat and electricity from geothermal energy instead of fossil fuels.Their hopes were dashed about 15 years ago when a drilling company couldn’t find enough hot water close to the surface to be profitable using traditional geothermal technology. That basically left them with natural gas. “We gave up. We had big hopes,” recalled First Mayor of Geretsried Michael Müller, who was raised in the town. Today t...