Browsing by Author "Van Heerden, Hendrik Petrus"

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    Avian impact of South Africas first concentrating solar power tower facility in the Northern Cape
    (Stellenbosch : Stellenbosch University, 2020-03) Van Heerden, Hendrik Petrus; Esler, Karen J.; Hudson, Adrian; Stellenbosch University. Faculty of AgriSciences. Dept. of Conservation Ecology and Entomology.
    ENGLISH ABSTRACT: Through its commitment to a greener economy that is less dependent on nonrenewable energy resources, South Africa’s Integrated Resource Plan aims to diversify the energy system by including energy resource alternatives such as concentrating solar power (CSP). All CSP facilities harvest solar thermal energy by utilising reflectors that focus energy to a receiver where the energy is concentrated and eventually converted into electricity via a conventional thermoelectric power cycle. Four main types of CSP technologies exist in today’s global market of which central receivers, also known as CSP towers, are one of the dominant types. Recent studies suggest that the potential impacts of utility-scale CSP tower facilities on avian populations may be substantial given that these impacts are driven by factors such as project location, footprint size and technology. It is anticipated that these factors mainly impact avifauna by altering the demography of avian communities and by exposing birds to singeing and collision risk. However, given the novelty of tower CSP and the global shortfall of publicised data on avian impacts, conclusive investigations into the avian impact of these facilities have yet to be established. Further rigorous investigation of these factors is therefore encouraged. This study was the first to investigate the impact of a solar power tower facility in South Africa, seeing that it was conducted on the only operational CSP tower facility in southern Africa. The study aimed to evaluate the impact of the Khi Solar One CSP tower facility on avifauna of the area with special attention to biodiversity dynamics and avian mortalities and injuries. Industry best practice guidelines and peer-reviewed literature were used as the point of departure from which the fieldwork methodology was developed. Data on avian mortality and injury were gathered over four seasons by conducting weekly monitoring and identifying patterns of avian use by means of vantage point surveys and parallel-line transects that were conducted inside and outside the facility footprint. Data collected during the field surveys were analysed to determine a suitable risk analysis model for this kind of development and to determine whether and to what extent the development had caused a change in avian behaviour. The findings demonstrate that concerns about the impacts of CSP towers on bird populations are not completely unsubstantiated, even though some results remain inconclusive. Avian species diversity, abundance and density per unit area were found to be higher in the neighbouring untransformed habitat than within the facility footprint. Data suggest that certain shrubland/woodland species favoured the CSP facility, however, they did not represent an unaffected population by default. In contrast, generalist and open country/grassland species were not adversely affected by impacts caused by the CSP tower facility. The presence of constructed water bodies and structures within the transformed habitat also appeared to have an indirect impact as in this otherwise rural habitat, they lure a diversity of aquatic and other species that favour a more urban habitat. Breeding observations indicated that reproductive activity within the transformed habitat was lower than within the untransformed habitat. A total of 324 avian impact detections were recorded during the monitoring year, involving 34 identified species. Of the total avian impact detections, 61% of injuries/mortalities were found to be caused impact trauma and 14% by singeing related trauma. Most collisions were recorded in the solar field with trending evidence of impact occurring on the lower quarter of the heliostats’ reflective surfaces. Singeing data displayed a significant increase in detections during the summer months and revealed that most recorded detections were of aerial feeding migratory birds. A clear correlation was found between the peak singeing detection months and the positioning of heliostats into the standby position during this period. It was difficult to make a meaningful assessment of the overall avian fatality at CSP tower facilities and to formulate accurate hypotheses regarding the risk of avian mortality among these facilities and other sources of solar electricity generation. Still, data suggested that fatalities per area may be a more suitable metric for estimating cumulative impacts among CSP tower facilities since the efficiency of this technology is continuing to improve and change in design and operation over time. Ultimately, this study offers several findings and recommendations that may contribute to the compilation of a mitigation framework that will ensure that the industry develops in a sustainable manner in South Africa.