This report has reviewed critically the feasibility of using a Photobiological system to produce energy on a commercial scale. Two possible candidates have been identified. The first is to use our knowledge of the initial light-driven charge separation reaction in photosynthesis as a blue-print on which chemists could base the design of more efficient second generation solar cells. The details of this possibility are being considered in a separate report. The second is to harness the ability of anaerobic photosynthetic bacteria to support light-driven hydrogen production. This second option is the definite front runner, however as with other schemes to harness solar energy it does have the drawback that large surface areas will be required in order to produce commercially significant quantities of energy. A detailed evaluation of photobiological hydrogen production has been presented. (author).