This isn't a technology or material science or anything problem, this is a reality problem. In reality, you cannot make an energy dense anything without expendi

This isn't a technology or material science or anything problem, this is a reality problem. In reality, you cannot make an energy dense anything without expending at least that amount of energy. "Fuel" like gasoline is nothing more then a chemical battery, and if you want to remake that chemical battery, you literally have to inject enough energy to form the chemical bonds involved.