Economic Analysis for Solar Energy Integration in a Microbrewery

In order to reduce the energy cost of a microbrewery, the integration of a combination of two solar technologies is proposed. The aim is to provide from solar 50% of the annual electricity consumption and 30% of the heat requirements. For this purpose, a solar thermal system (ST) composed of 14.6 m2 of flat-plate collectors and a 1.4 m3 storage tank is modelled. In addition, a 2.86-kWp on-grid photovoltaic (PV) system is studied. The location selected is Seville, Spain, where the annual Global Horizontal Irradiation is 1,755 kWh/m2. The results are obtained by transient hourly simulations throughout the year employing TRNSYS. The Net Present Value (NPV) and Discounted Payback Period (DPP) are calculated for four scenarios. The PV system shows a positive NPV and a DPP of 8.3 years under a net-billing scheme. The NPV for the solar thermal system is negative, owing to the low cost of natural gas. Thus, it is not attractive to install it under the existing scenario. Nevertheless, an alternative solution has been studied, heat recovery from the cooling water to be used for the next batch. This case results in lower investment than the ST and leads to a positive NPV and a DPP of 8.1 years. In order to assess the environmental impact, the CO2 emission reduction is also calculated. The favorable results obtained in this study show the potential benefits of solar energy integration in the small-scale industry with a batch process.