Off-Grid Power: "When I retire to my desert shanty I'll need a 4 kW generator. This one costs a little more (OK, it costs a lot more) than the gas powered ones, but it doesn't require any fuel. It should pay for itself in less than two years. MARS is a lighter- than-air tethered wind turbine that rotates about a horizontal axis in response to wind, generating electrical energy.... Helium sustains MARS and allows "