A pre-feasibility study of a concentrating solar power system to offset electricity consumption at the Spier Estate

The Spier Estate – a wine estate in the Western Cape Province of South Africa – is engaged in a transition towards operating according to the principles of sustainable development. Besides changes in social and other environmental aspects, the company has set itself the goal to be carbon neutral by 2017. To this end, Spier is considering the on-site generation of electricity from renewable energy sources. This study was initiated to explore the technical and economic feasibility of a concentrating solar power plant for this purpose on the estate. The investigation was carried out to identify the most appropriate solar thermal energy technology and the dimensions of a system that fulfils the carbon-offset requirements of the estate. In particular, potential to offset the annual electricity consumption of the currently 5 570 MWh needed at Spier was investigated using a concentrating solar power (CSP) system. Due to rising utility-provided electricity prices and the expected initial higher cost of the generated power, it was assumed that implemented efficiency measures would lead to a reduction in demand of 50% by 2017. Sufficient suitable land was identified to allow electricity production exceeding today’s demand. The outcome of this study was the recommendation of a linear Fresnel collector field without additional heat storage and a saturated steam Rankine cycle power block with evaporative wet cooling. This decision was based on the combination of the system’s minimal impact on the sensitive environment and the high potential for local development. A simulation model was written to evaluate the plant performance, dimension and cost. The analysis followed a literature review of prototype system behaviour and system simulations. The direct normal irradiation (DNI) data that was used was based on calibrated satellite data. The result of the study was a levelised cost of electricity (LCOE) of R2.74 per kWh, which is cost competitive to the power provided by diesel generators but more expensive than current and predicted near-future utility rates. The system contains a 1.8 ha aperture area and a 2.0 MWe power block. Operating the plant as a research facility would provide significant potential for LCOE reduction with R2.01 per kWh or less (favourable funding conditions would allow for LCOE of R1.49 per kWh) appearing feasible. These results are cost competitive in comparison to a photovoltaic (PV) solution. Depending on tariff development, Eskom rates are predicted to reach a similar level between 2017 (the time of commissioning) and the year 2025. The downside of this plan is that the plant would not solely serve the purpose of electricity offsetting for Spier which may result in a reduced amount of generated electricity. Further studies are proposed to refine the full potential of cost reduction by local development and manufacturing as well as external funding. This includes identification of suitable technology vendors for plant construction. An EIA is required to be triggered at an early stage to compensate for its long preparation.