Solar Energy Conversion Through Seaweed Photosynthesis with Combustion in a Zero-Emission Power Plant

Abstract

A proposed ‘closed cycle’ power plant scheme, referred to as SOFT (Solar Oxygen Fuel Turbine), is described. The scheme involves the cultivation of macroalgae in a pond, combustion of their organic matter in a fluidised bed boiler that generates steam for a Rankine cycle steam power plant and the return of the combustion products to the pond to feed the algae. Oxygen, equivalent to that used for combustion, is re-released to the atmosphere by photosynthesis, while the carbon dioxide that is produced by combustion is absorbed by photosynthesis and thereby recycled. It is proposed that the seaweed Ulva, which is common in Irish coastal waters, can be used in the solar pond. The solar energy conversion efficiency is less than that which can be achieved by the use of photovoltaic panels, but the energy expenditure to construct algae ponds as solar energy receivers is much less. Therefore the proposed scheme can be economically, as well as environmentally, attractive. For a power unit of 100 kW the pond surface area in Ireland would be about 6 hectares