Most electrical power sources are designed for efficiency NOT; elegance of wave form, low (let alone no noise), and ability to delivery high current at the top of the cycle with no voltage sag. A motor generator combo that meets these specs can be purchased off the shelf. Any DC source such as fuel cells, solar cells, batteries etc. would need an inverter. Most inverters suffer from the shortcomings listed above.
I was seriously looking at solar cells, batteries and inverters last summer based on the California tax credit and concluded that I couldnt get really clean AC power from a DC source unless I used a DC motor to drive an AC generator. Im sure that PS Audio units would be cost effective alternatives to DC sources.
I want to thank Karl for reminding everyone of the Motor-Generator combo. I think Ill look into it. Karl have you checked out any manufacturers?