Are there natural gas powered heat pumps? My friend says yes, but the science is puzzling to me if so. Easy to understand burning gas to make heat, but what economical home system can make cold air from hot burning gas unless the heat turns a dynamo that makes electricity that powers the AC function. But why? Burning gas in the summer to make cold air? Seems to me like Rube Goldberg engineering for the end result; also way too complex and convoluted for a home heating system. Any help out there in product availability and the science involved to accomplish this strange(to me) feat? Thanks.