Evaluating the sustainable potential of biogas generation in South Africa

Thesis (MScAgric)--Stellenbosch University, 2018.

ENGLISH SUMMARY: With a global movement towards a more sustainable way of living, the two most noteworthy hurdles to overcome in the quest for sustainable development are the unsustainable management of waste and availability of clean energy. This study investigates the potential of biogas generation in South Africa, referring specifically to its potential as a sustainable agricultural practice and evaluates the process of anaerobic digestion and biogas utilisation as a strategy to improve the country’s performance measured against two determinants of sustainability, namely: 1) the provision of a clean and affordable energy supply and 2), organic waste management. A literature review was conducted to create a contextual framework against which biogas generation potential can be evaluated. The status of the global biogas industry and how South Africa compares to the world, not only in terms of the extent of the industry, but also in terms of its sustainability performance as a country, is outlined. The status, as well as the specific challenges and opportunities that are present in the South African biogas industry, were further researched by means of face-to-face semi-structured interviews with major role-players, among others representatives of the South African Biogas Industry Association (SABIA) and GreenCape. This investigation indicated an interest in the development of medium and commercial-scale biogas digesters which could be attributed to opportunities that the biogas industry offer in terms of job creation, energy provision, carbon mitigation, organic fertiliser production and waste management. The study confirmed that the South African industry is currently faced with numerous challenges in terms of renewable energy generation and supply, e.g. lack of government support, financial commitments involved in its development, skills shortages, ethical challenges, limited water resources and sustainable access to waste as a biomass source. However, innovative enablers do exist and can promote the growth of the industry. These findings support the notion that biogas generation can contribute significantly to sustainable development in South Africa. By applying enabling factors such as streamlining EIA processes and licencing requirements and creating a market for surplus energy generated, biogas generation can provide tax relief through the anticipated implementation of carbon tax; create innovative solutions for waste management and the organic fertiliser industry, while delivering ecosystem services such as carbon sequestration in soils and improved water and soil quality and ultimately, an increase in food production. In addition, by integrating waste management and renewable energy technologies, biogas generation could potentially contribute to the alleviation of poverty and the well-being of society. The rationale of the third part of the study was to establish the potential of farm-scale biogas generation as a sustainable agricultural practice in South Africa. Findings are based on interaction with two groups of farmers – 1) those without biogas digesters and 2), those with biogas digesters. Purposive data collection was conducted through two self-administered electronic surveys that were sent to farmers in both groups. The quantitative data obtained was further supported and clarified through personal conversations with participants in both surveys and measured against what is defined in this paper as sustainability: economic potential, social potential and environmental potential – the three pillars of sustainability. For this reason each of these categories were defined and the applicable factors that may impact these categories, described. The fourth part of the study aimed to identify the farm-scale biogas production system with the most sustainable potential in an agricultural application that can benefit the pursuit of a more sustainable future under local conditions. However, it was established that the numerous variables in the South African biogas generation scenario complicate implementation and that implementation should be site-specific to be feasible. A generic model was developed to enable the evaluation of the sustainable potential of a specific digester type at a specific site, taking all the variables into account. The model, a decision- making tool, is based on the scoring of the three determinants of sustainability namely environmental, social and economic according to a set of defining factors. Based on literature and local expertise, collected through interviews, a comparison of the characteristics of digester types with agricultural requirements enabled the identification of the Continuously Stirred Tank Reactor (CSTR) digester as the type that could show the most potential when implemented as a sustainable solution to address energy poverty, the rising costs of electricity and waste management demands. The validation of the sustainable potential of the CSTR digester type through further studies is recommended. Although numerous existing challenges hinder the potential of biogas generation in South Africa, the study concludes that biogas generation has potential to contribute to sustainable agriculture and that it presents a substantial opportunity to promote sustainability and simultaneously address prominent challenges like waste removal, energy supply, water recycling and skills development.

AFRIKAANSE OPSOMMING: In die wêreldwye strewe na ‘n meer volhoubare lewenswyse is daar twee struikeblokke van belang – onvolhoubare afvalbestuur en die voorsiening van energie. Hierdie studie ondersoek die potensiaal van biogasopwekking in Suid-Afrika, met spesifieke verwysing na die potensiaal om as ‘n volhoubare landboupraktyk geïmplementeer te word en evalueer die proses van anaerobiese vertering en biogasgebruik as ‘n strategie om die land se prestasie in volhoubaarheid te verbeter, met spesifieke verwysig na 1) die voorsiening van skoon en bekostigbare energie en 2), organiese afvalbestuur. ‘n Literatuurstudie is geloods as agtergrond waarteen die potensiaal van biogasopwekking ge-evalueer kan word. Die status van die wêreldwye biogasindustrie en ook hoe Suid-Afrika vergelyk met die res van die wêreld, nie net in terme van die omvang van die industrie nie, maar ook in terme van sy volhoubaarheidprestasie, word bespreek. Die status, sowel as die spesifieke uitdagings en geleenthede wat die biogasindustrie in Suid-Afrika bied, is verder ondersoek aan die hand van aangesig-tot-aangesig semi-gestruktureerde onderhoude met sleutelrolspelers in die industrie – onder wie verteenwoordigers van SABIA (South African Biogas Industry Association) en GreenCape. Hierdie ondersoek het aangedui dat die belangstelling wat heers in die ontwikkeling van medium tot groot (kommersiële) biogas reaktors toegeskryf kan word aan die geleenthede wat dit bied in terme van werkskepping, kragvoorsiening, koolstofmitigasie, produksie van organiese bemesting en bestuur van afval. Die studie het bevind dat die Suid-Afrikaanse biogasindustrie deur verskeie uitdagings in die gesig gestaar word, soos die opwekking en voorsiening van hernubare energie, tekort aan regeringsteun, finansiële vereistes tydens ontwikkeling, vaardigheidstekorte, etiese uitdagings, beperkte waterbronne en toegang tot afval as voermeganisme, maar dat daar innoverende meganismes bestaan om die groei van die bedryf te kan stimuleer. Dit bevestig die aanname dat biogasopwekking ‘n sleutelbydrae kan lewer tot volhoubare ontwikkeling in Suid-Afrika. Deur hierdie innoverings toe te pas – soos die vereenvoudiging van die omgewingsimpakproses en lisensiëringsvereistes asook die skep van ‘n afsetmark vir oortollige energie wat opgewek word – kan biogasproduksie belastingsverligting meebring deur die verwagte implementering van koolstofbelasting, meer doeltreffende afvalbestuur en die produksie van organiese bemesting terwyl ekostelseldienste gelewer soos koolstofsekwestrasie in grond en verhoogde water- en grondkwaliteit wat uiteindelik kan lei tot ‘n verhoging in voedselproduksie. Hierbenewens kan biogasproduksie ook moontlik bydra tot die verligting van armoede en die welsyn van gemeenskappe deur afvalbestuur en die opwekking van hernubare energie te integreer. Die mikpunt met die derde gedeelte van die studie was om die potensiaal van biogasopwekking op plase as ‘n volhoubare landboupraktyk te evalueer. Bevindinge is gebaseer op interaksie met twee groepe boere – 1) diegene wat nie biogasreaktors het nie en 2), diegene wat biogasreaktors het. Doelgerigte data is versamel met die hulp van selftoegepaste opnames wat elektronies aan boere in albei groepe gestuur is. Inligting ingewin is verder aangevul deur persoonlike gesprekke met deelnemers aan albei opnames en gemeet teen dit wat in die artikel gedefineer word as volhoubaarheid, ekonomiese potensiaal, sosiale potensiaal en omgewingspotensiaal – die drie bakens van volhoubaarheid. Ten einde dit te kon doen, is elk van hierdie kategorieë gedefinieër en die faktore wat elkeen van hierdie kategorieë bepaal, uiteengesit. Die vierde gedeelte van die studie het ten doel gehad om die biogasreaktor met die meeste potensiaal vir toegepassing in die landbousektor en wat dus Suid-Afrika se visie in terme van ‘n volhoubare toekoms kan bevoordeel, te identifiseer. Daar is egter vasgestel dat die groot verskeidenheid veranderlikes in die Suid-Afrikaanse biogas scenario die implementering van ‘n enkele tipe biogasreaktor as ooglopende oplossing verhinder. Dit het aanleiding gegee tot die ontwikkeling van ‘n generiese model wat as besluitnemingsmeganisme gebruik kan word om die evaluering van die volhoubare potensiaal van spesifieke tipes biogasreaktors op ‘n spesifieke terrein moontlik maak. Tweedens, gebaseer op literatuur as ook onderhoude met kenners in die veld, is vergelykings getref tussen die eienskappe van bestaande biogasreaktors en hoe dit antwoord in die vereistes van die landbousektor. Op grond daarvan is die ‘Continuously Stirred Tank Reactor’ (CSTR) geïdentifiseer as die reaktortipe wat die meeste potensiaal het om in die landbou geïmplementeer te word as volhoubare landboupraktyk om die voorsiening van ‘n betroubare en bekostigbare bron van krag en en sinvolle afvalbestuur moontlik te maak. Daar word dus voorgestel dat die volhoubare potensiaal van die CSTR reaktor tipe gebruik word vir die evaluasie van die geldigheid/validasie van die generiese model vir implementasie van hierdie biogasreaktor tipe volgens die behoeftes van ‘n spesifieke terein. Die gevolgtrekking was dat, selfs in die lig van die verskeie struikelblokke wat bestaan, biogasopwekking in die Suid-Afrikaanse landbousektorvolhoubare potensiaal het, en ook sodoende ‘n geleentheid bied op volhoubaarheid sowel as om prominente uitdagings aan te spreek soos afvalverwydering, enegie voorsiening, watersirkulering en die ontwikkelling van vaardighede.