Chemosynthesis is a process used by certain types of bacteria to make carbohydrates in the absence of light. A spacecraft that utilizes chemosynthetic farms would be far more efficient and cost effective than spacecraft with conventional food crops. Growing conventional food crops requires light, which is plentiful close to the Sun. But missions to Mars, Jupiter, Saturn or further will require artificial lights to grow food. The best fluorescent lights are only 20% efficient, converting 80% of the energy they consume directly into heat. The air conditioning system needed to get rid of this excess heat consumes more power than the lights, so that eventually somewhere between 80-95% of the energy used for conventional agriculture is wasted. This waste of energy increases exponentially with each additional crew member added to the spacecraft's mission. For more precise estimates see my website: http://www.geocities.com/womplex_oo1/StarshipGenerations.html Chemosynthesis does not require light, only heat, which is obviously very easy to produce in space. A chemical reactor would add exact amounts of heat, or activation energy, to measured quantities of chemical reactants. The resulting compounds would be used by autotrophic bacteria to produce carbohydrates. The bacteria in turn would be eaten by higher organisms. These higher organisms could then be used as the basis of processed foods that are high in energy. This would replace wheat, rice, and maize which currently represent more than 50% of the world's food energy intake, and which need light to grow. Genetic manipulation could make this process even better, permitting some organisms to also produce vitamins in their tissues. Consuming these would partially or completely satisfy human nutritional needs. Perhaps the most immediate benefit of chemosynthetic food crops is that there is no need for large radiators to eliminate excess heat. At current launch costs of $10,000 per pound, there is clearly a very substantial benefit inherent in chemosynthetic food production.