Evaluating the sustainable potential of biogas generation in South Africa

[摘要] 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.

[发布机构] Stellenbosch University