Scientific African (Sep 2021)
Comparative assessment of a hybrid of gas turbine and biomass power system for sustainable multi-generation in Nigeria
Abstract
Nigeria has enormous renewable and natural gas reserves. However, power generation in the country is inadequate and mainly fossil-based. To increase power generation sustainably, a hybrid of a gas turbine cycle (GTC) and biomass power system (BPS) is a potential solution that needs to be considered for installation in the country. In this paper, two configurations of a hybrid power system where a GTC is hybridised with BPS integrated with an absorption refrigeration system (ARS) for combined cooling, heating and power (CCHP) is proposed. In configuration 1, hot water recovered from both GTC and BPS exhaust is used to power an ARS. In configuration 2, the ARS is powered directly by the GTC exhaust and a subsequent hot water recovery system connected to the GT exhaust to produce hot water. A validated thermodynamic model of the systems was developed in Matlab. It is found that the electrical efficiency of the two proposed systems is lower than that of standard recuperated GTC. However, the two proposed systems have an equivalent overall energy efficiency of about 60%, which is the same as the CHP efficiency of a standard recuperated cycle of similar capacity. The proposed systems' overall exergy efficiency is estimated to be approximately 17 and 19 % for configurations 1 and 2, respectively. The highest exergy destruction is contributed by the biomass gasifier (87%), followed by the combustion chamber (5.5%) and syngas engine generator (3%). Emission analysis shows that the systems emit about 30% less CO2 than standard recuperated GTC of the same capacity. The Levelized cost of electricity for the first and second proposed systems is 0.1373 and 0.1328 $/kWh, respectively. The proposed systems, which offer a new way of combing biomass and natural gas, have an advantage in terms of multiple outputs and CO2 emission reduction.
