Exergoeconomic analysis of high concentration photovoltaic thermal co-generation system for space cooling

Abstract

This paper provides an exergetic analysis of a 10 MW high concentration photovoltaic thermal (HCPVT) power plant case study located in Hammam Bou Hadjar, Algeria. The novel HCPVT multi-energy carrier plant converts 25% of the direct normal irradiance (DNI) into electrical energy and 62.5% to low grade heat for a combined efficiency of 87.5%. The HCPVT system employs a point focus dish concentrator with a cooled PV receiver module. The novel "hot-water" cooling approach is used for energy reuse purposes and is enabled by our state-of-the-art substrate integrated micro-cooling technology. The high performance cooler of the receiver with a thermal resistance of <0.12 cm2 K/W enables the receiver module to handle concentrations of up to 5000 suns. In the present study, a concentration of 2000 suns allows using coolant fluid temperatures of up to 80 C. This key innovation ensures reliable operation of the triple junction PV (3JPV) cells used and also allows heat recovery for utilization in other thermal applications such as space cooling, heating, and desalination. Within this context, an exergoeconomics analysis of photovoltaic thermal co-generation for space cooling is presented in this manuscript. The valuation method presented here for the HCPVT multi-energy carrier plant comprises both the technical and economic perspectives. The proposed model determines how the cost structure is evolving in four different scenarios by quantifying the potential thermal energy demand in Hammam Bou Hadjar. The model pins down the influence of technical details such as the exergetic efficiency to the economic value of the otherwise wasted heat. The thermal energy reuse boosts the power station's overall yield, reduces total average costs and optimizes power supply as fixed capital is deployed more efficiently. It is observed that even though potential cooling demand can be substantial (19,490 MWh per household), prices for cooling should be 3 times lower than those of electricity in Algeria (18 USD/MWh) to be competitive. This implies a need to reach economies of scale in the production of individual key components of the HCPVT system. The net present value (NPV) is calculated taking growth rates and the system's modular efficiencies into account, discounted over 25 years. Scenario 1 shows that even though Algeria currently has no market for thermal energy, a break-even quantity (49,728 MWh) can be deduced by taking into account the relation between fixed costs and the marginal profit. Scenario 2 focuses on the national growth rate needed to break even, i.e. +10.92%. Scenario 3 illustrates thermal price variations given an increase in the Coefficient of Performance (COP) of a thermally driven adsorption chiller after year 10. In this case, the price for cooling will decrease from 18 USD/MWh to 14 USD/MWh. Finally, scenario 4 depicts Hammam Bou Hadjar's potential cooling demand per household and the growth rate needed to break even if a market for heat would exist. © 2014 Elsevier Ltd.