Owing to the weightlessness of space and the complete lack of drag which slows down terrestrial aircraft, the actual energy requirements of space travel are relatively small. So small in fact that a small, efficiently designed craft could theoretically travel at 1,000 mph using no more than 1,200 Joules — the energy released by a 400 gram candle in one hour.
As is often the case, however; the Candle Ship is competing for research and design dollars with another similar project called the Boxing Ring Ship.
The Boxing Ring Ship utilizes the heat given off by the human body during strenuous exercise. Enclosed in a special room whose special walls absorb heat and convert it into electricity, two astronauts would literally fight it out in order to power their space ship and reach their destination.
Owing to the design of the Boxing Ring Ship, a much larger crew would be required but they would not have to be so carefully picked or trained. In fact, a ship with a particularly poorly trained crew and much less discipline may actually move faster and generate more energy than the average well-trained and highly selected crew which NASA currently favors for all its missions.
The Boxing Ring Ship came about as a spin off from the Screaming Crew Ship which was powered by the sound waves generated by the crew screaming in a specially designed compartment made to collect vibrations and convert them into electric power. Early on however, it was found that crew members had much less endurance when it came to screaming than fighting and so the Boxing Ring method was substituted.
Most researchers favor the Candle Ship design although it has been suggested that a combination of all three would add greater reliability.