Concentrating solar power technologies for solar thermal grid electricity in Nigeria: a review
Grid electricity generation in Nigeria has been unstable for a long time now. With respect to her continued dependence on oil and gas and seasonal variations on water level for hydropower, immediate reliable and steady electricity generation in the country is not guaranteed. Incorporating alternative source of energy like solar is a solution. Solar Chimney technology is not yet technically and economically mature, as investment on it is still low, thereby posing more financial risks at least at the megawatt capacity. Photovoltaic and Solar Thermal technologies are technically and economically more established, but they can only ensure 24 h power supply with the aid of energy storage systems. Solar thermal value addition is on its propensity for thermal energy storage and hybridization with liquid fuels at commercial capacity. Hence, due to technology advancement and the country's high direct normal irradiation potential, concentrating solar power is the more suitable solar power technology for commercial electricity generation in Nigeria. In this paper, concentrating solar power technologies are analysed under operational, environmental and social conditions in Nigeria using data from desktop survey to determine the most suitable technology for solar thermal electric power plant. It is observed that the technical maturity of parabolic trough concentrator distinguishes it for preference to all other technologies and would exert moderate pressure on land requirement even though, it is the most expensive and water demanding technology. In terms of unit cost of electricity and water usage capabilities, parabolic dish concentrator is least expensive and uses least water but lacks proven commercial application. Solar tower is technically simpler and possesses better thermodynamic properties than the rest but its low installed capacity increases its financing risk. Hence, the trough system is the most suitable for immediate and medium term projects given its proven technology maturity and flexible financing mechanism.