This is the first product, and is targeting areas where cheap natural gas is plentiful. However, because it's an external combustion engine, I imagine it wouldn

This is the first product, and is targeting areas where cheap natural gas is plentiful. However, because it's an external combustion engine, I imagine it wouldn't be too difficult to build a future product where the heat differential is created from a different source, like solar tiles, or through geothermal differences.