since you are looking for alternative energy vehicles, you would need to study applied physics, electronics, and also learn about renewable energy sources. the course content would depend on what type of alternate energy source you are looking for. If you are trying to work on a power source that does not depend on internal combustion engine designs, possible alternates would be fuel cells, Electric vehicles, or solar sources. if you are trying to use alternate fuels in internal combustion engines, then you would need to learn Bio-chemistry and mechanics. in either case you would also need knowledge about automobile engineering.