| dc.description.abstract | Improved energy supply is the main challenge facing most African countries because
energy is fundamental for the sustainable development of all sectors of an economy.
Currently, 65% of the Kenyan population do not have access to electricity. Therefore,
there is need to reverse this situation by investing in energy generating projects and
improving the efficiency of the current power plants by adopting or researching on
new technologies to reduce energy and exergy losses. In this study, we have focused
on geothermal energy with the aim of improving the power output by lowering the
exergy losses in the condenser. Condensers of geothermal power plants need to
operate at low pressures to ensure optimal use of energy resources. To optimize the
condenser pressure, cooling water temperature is varied to determine the value that
gives a higher condenser efficiency resulting in more power output. This study
focused on modelling the cooling system towards lowering the temperature of cooling
water in which an absorption chiller was integrated into the system. The relevant
energy and exergy balance, and efficiency equations for the Olkaria II (Kenya)
geothermal power plant subsystem were derived. Codes were then developed from the
equations and solved using the Engineering Equation Solver software. The evaporator
temperature was varied for a constant refrigerant load temperature and changes in
condenser exergy efficiency and turbine output were recorded. Simulation results
shows that by adoption of an absorption chiller as the secondary cooling system,
cooling water temperature reduced to 16oC from the current temperature of 25oC. The
exergy destroyed in the condenser and turbine decreased from 2.89 MW to 2.3 MW
and 7.7 MW to 7.3 MW respectively. The power output increased by approximately
1.6 MWh which translates to an annual cash flow of US $ 981,120 having taken the
electricity sale price at 0.07 US $/kWh. The economic analysis of investing in the
absorption refrigeration system in terms of discounted payback period resulted in
payback years being approximately 9.4 years. Therefore, investing in the absorption
chiller system for Geothermal Power Plants is economically feasible | en_US |
