Avian impact of South Africas first concentrating solar power tower facility in the Northern Cape

Van Heerden, Hendrik Petrus (2020-04)

Thesis (MScConsEcol)--Stellenbosch University, 2020.

Thesis

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.

AFRIKAANSE OPSOMMING: In die strewe na 'n omgewingsvriendelike (groener) ekonomie, is dit van kritiese belang, vir Suid-Afrika, om minder afhanklik te wees van fossielbrandstowwe of, anders genoem, nie-hernubare energiebronne. Suid-Afrika se Geïntegreerde Hulpbronplan maak dit dan ook moontlik vir rolspelers, op hierdie gebied, om betrokke te raak in die voorsienning van hernubare energie vir die land. Sonverwarmingstelsels of te wel “concentrating solar power” (CSP) is een voorbeeld van so 'n alternatiewe wyse van kragopwekking. ‘n CSP-aanleg produseer termiese sonkrag deur gebruik te maak van spieëls wat die sonstrale gefokus weerkaats na 'n ontvanger, waar die energie gekonsentreer word. Hier word die termiese energie dan omgesit in elektriese energie deur 'n konvensionele termo-elektriese energiesirkel. Daar is vier basiese wyses (tegnologieë) waardeur bogenoemde bereik kan word, met CSP-torings as een van die mees prominente. Daar moet egter ook, wat hernubare- energieopwekking, betref, deurgaaans bepaal word wat die invloed van hierdie tipe ontwikkeling op die omgewing is. So toon verskeie studies byvoorbeeld aan, dat voëls tipiese slagoffers van die tipe ontwikkelings is, met die ligging, omvang asook die tipe aanleg (tegnologie) wat bepalend is tot in 'n hoe groot mate die impak is. Aanlegte kan 'n invloed uitoefen deur habitatversteuring, verskroeiing en dan ook deur fisiese botsings met hierdie nuwe, vreemde objekte in die voëls se natuurlike hou areas. Siende dat CSP-torings onlangse ontwikkelings is, is daar plaaslik sowel as internasionaal, beperkte inligting wat spesifiek, oor hierdie potensiële impak op voëlbevolkings, handel. Dit het dus dringend noodsaaklik geword om hierdie veld in diepte te ondersoek. Hierdie navorsing is die eerste van hierdie aard in Suid-Afrika en is onderneem op die enigste operasionele CSP-toringaanleg in suidelike Afrika. Die navorsing is gedoen om te bepaal wat die impak, van die Khi Solar One CSP Tower op die verskillende voëlbevolkings in die gebied het, werklik is. Spesifieke aandag is geskenk aan die invloed op biodiversiteit, verskroeiing (solar flux) en botsings tussen voëls en objekte in die CSP aanleg. Riglyne daar gestel deur die industrie, sowel as reeds toepaslik nagevorste inligting in die verband, is as vertrekpunt gebruik in die ontwikkeling van 'n model vir die veldwerk. Die versameling van data, van geaffekteerde voëls, het oor vier seisoene geskied. Weeklikse monitering en identifisering is gedoen op die terrein van die aanleg self, sowel as op die aangrensende areas. Hierdie aksie het op 'n bepaalde wyse geskied en is daar seker gemaak dat die gebied deeglik gefynkam word deur vanuit verskillende hoeke, met oorkruisaksies die gebied te deursoek. Data is bestudeer om gebruik te kan word om 'n risiko-analisemodel, vir hierdie tipe ontwikkeling, daar te stel. Hieruit kon bepaal word watter invloed en in hoe 'n groot mate, die voëls se gedrag, indien enigsins, verander of beïnvloed is. Die resultate toon wel aan dat CSP-torings 'n invloed op die verskillende voëlbevolkings het, maar kan dit nie sonder meer as ingrypend beskou word nie. Baie interessant, wel, is die waarneming wat gemaak is dat die spesie-diversiteit, -getalle en -digtheid, van die verskillende voëlbevolkings, hoër is in die aangrensende gebiede as op die aanleg self. Tog is daar ook bewyse dat sommige spesies, veral die wat normaalweg in bos- en woudagtige habitatte voorkom, in 'n redelike mate na die CSP-toringarea gelok word. Hierdie spesies verteenwoordig egter nie 'n ongeaffekteerde groep nie, en word, in 'n beduidend kleiner mate, deur die aanleg benadeel. Verdampingsdamme en ander bronne van water, binne die aanleg, het ook 'n indirekte invloed op veral akwatiese-voëls, deurdat hulle na die bronne aangetrek word. Ook spesies wat daarvoor bekend is dat hul in beboude gebiede aangepas het, is ook geredelik deur die aanleg gelok. Tog ook hier, herhaal die tendens, dat die voëls steeds die gebiede, aangrensend tot die aanleg, as broeiplek, verkies het. Gedurende die tydperk van monitering (12 maande) is 324, beseerde of noodlottig beseerde voëls gevind, verteenwoordigend van 34 spesies. Daar kon bepaal word dat 61% van die beseerde of noodlottig beseerde voëls, in botsing was met strukture op die aanleg, terwyl 14% deur skroeiing beseer of gedood is. Verder is vasgestel dat die meerderheid van die botsings van die voëls met strukture, plaasgevind het in die heliostat-gebied, met die meerderheid botsings in die onderste kwart van die heliostats. Data vir voëls deur skroeiing gedood of beseer, toon dat dit veral migrende, lugjagters (aerial feeders) is wat hier ten prooi val, veral gedurende die somermaande. Wanneer die heliostats in die bystandposisie geposisioneer is, is die ongevalle dienooreenkomstig kleiner. Dit is moeilik om 'n sinvolle assessering in die algemeen, wat beserings en sterftes van voëls, spesifiek vir CSP-toringaanlegte, asook ander vorme van opwekking, te maak en om te bepaal wat die werklike risiko vir voëlspesies is. Nogtans het data getoon dat sterftes per ‘n spesifieke gestandardiseerde area 'n meer geskikte wyse kan wees vir die beraming van die kumulatiewe impak onder CSP-toringfasiliteite. Hierdie studie bied verskeie bevindings en aanbevelings wat kan bydra tot die daarstel van 'n versagtingsraamwerk. Dit sal verseker dat die bedryf op 'n sensitiewe en volhoubare wyse verder in Suid-Afrika ontwikkel.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/107937
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