vehicle. The down side would be the fact you are dependent on wood chips or other solid fuel. maybe not the best thing to run when you are old. But it can be made cheap with many recycled parts. If you are already growing wood to use to heat in winter then this and the garden would be a good solution to the leftover wood. I personaly like the hybred poplars that grow fast and easy best of all after your first buy you can plant cuttings.