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15 May 2023 | Story Leonie Bolleurs | Photo Supplied
Spineless Cactus
Axel Tarrisse (far left), a PhD student in the Department of Sustainable Food Systems, working on the biogas and fodder potential of spineless cactus in Africa. Pictured with him are Prof Maryna de Wit, his supervisor and Associate Professor in the UFS Department of Sustainable Food Systems and Development, and Dr Herman Fouché from the Agricultural Research Council.

The spineless cactus is a unique perennial plant that is able to yield close to 40 tons of dry matter per hectare per year with a rainfall of 500 mm per annum. “This equates eight tons of biomethane or 11 000 litres of diesel-equivalent energy per hectare,” says Axel Tarrisse, a PhD student in the Department of Sustainable Food Systems and Development at the University of the Free State (UFS), who is working on the biogas and fodder potential of spineless cactus in Africa.

Tarrisse believes biogas, produced from the spineless cactus, has the potential to complement the supply of South Africa’s existing industrial energy companies to produce sustainable jet fuel and diesel and a variety of other products with the gas-to-liquid process they use.

Developing biogas

He says with rainfall, key nutrients, carbon dioxide, and solar energy it is possible to produce biomass from cactus.

“First, we harvest the cactus and macerate it prior to going into an anaerobic digester where it is heated to 38°C, the same as a cow’s body temperature. Inside the digester, naturally occurring bacteria, similar to those found in their stomachs, break down the cactus, resulting in the production of biogas. This biogas is composed of both methane and carbon dioxide,” he explains.

According to him, biogas generated through this process can be used in a number of ways. This includes running generators to produce electricity or burning it to generate heat. It will also serve as a feedstock to replace coal and natural gas used by companies such as PetroSA and Sasol in their production of synthetic renewable fuels.

“The methane can also be separated from the carbon dioxide and compressed into bottles, creating compressed biomethane. This can be used as a replacement for liquid petroleum gas (LPG), as well as petrol and diesel in vehicles, such as bakkies, tractors, buses, and delivery trucks.”

The carbon dioxide produced in the process can, for example, be used to replace the fossil-based carbon dioxide typically used in the production of carbonated beverages. Additionally, it can be applied to extend the shelf life of packaged foods, serve as a water softener, and even be applied to a variety of industrial applications.

Commercialisation 

Biogas/biomethane is already produced in Mexico on a commercial scale. In Northeast Brazil, farmers have planted 600 000 hectares of spineless cactus, also known as Palma Forrageira, but the machinery needed to harvest it only became commercially available this year.

Back home in South Africa, just 30 km outside of Bloemfontein, Barren Energy farm is at Stage 1 with 140 hectares of high-density cactus planted to provide the initial feedstock for anaerobic digestion. With 600 hectares, they will be able to produce five million litres of diesel-equivalent methane.

Tarrisse says, “With the right methodology and management system, producing biogas from the spineless cactus will be adopted relatively quickly on a commercial scale.”

He believes that the lack of investment in cultivating the spineless cactus as a crop for fodder in South Africa may be due to a few factors. “It is easier to stick to what is known, such as irrigating lucerne and maize and managing these crops with existing planters, pest management solutions, and harvesting machinery than to develop local machinery and management solutions for a perfectly adapted crop,” he says. 

Compelling reasons

According to Tarrisse, there are several compelling reasons to consider the spineless cactus as a source of biogas in South Africa.

Firstly, he explains, “Only the cactus pads, harvested from high-density plantations (20 000 plants per hectares), are used for biogas production.”

“Secondly, the spineless cactus can yield large volumes of biomass from marginal semi-arid land where conditions are unsuitable for conventional crop cultivation. This makes it an ideal option for the 65% of South African land that receives less than 500 mm of rainfall annually.”

Thirdly, he says, “The plant contains 30 to 50% of easily digestible sugars, which degrades easily in an anaerobic digester. This simple, low-tech process can provide a substantial amount of baseload energy with relatively limited capital expenditure, which is particularly important in developing countries such as South Africa where capital is difficult to raise.”

“On top of that, anaerobic digestion only extracts carbon, oxygen, and hydrogen molecules from the cactus, while most of the macro- and micronutrients, water, and some fibres remain in the digestate. This nutrient-rich cactus digestate can then be spread on the cactus fields, reducing the need for fertiliser once the plantation has been fertilised in the first two years of implementation.”

Societal impact

Besides the benefits of producing biogas from the cactus plant, there is also the opportunity of job creation. “This farming can create one million direct job opportunities from only 3% of South Africa’s land area, approximately 4 million hectares,” says Tarrisse.

He is of the opinion that if production was at scale, as opposed to the current small orchard-style farming of cactus, there would be substantial biomass available to sustain not only biomethane, but also to support various bio-industries, such as protein production through cactus fermentation, biomaterials as a substitute for wood-based cellulose, organic acids, and bioplastics. “Consequently, cactus provides a climate-resilient, drought-resistant, and perennial feedstock for food, feed, fibre, and fuel in semi-arid Southern Africa,” he says.

Tarrisse states that this initiative also has the potential to significantly reduce migration from rural to urban areas, therefore addressing issues related to the growth of urbanisation, such as the provision of infrastructure and crime.

News Archive

During 2011: Appointments
2011-12-01

Dr Lis Lange: Senior Director: DIRAP

Description: 2011 Appointments_Lis Lange Tags: 2011 Appointments_Lis Lange

Dr Lis Lange, an Argentinean by birth, immigrated to South Africa twenty years ago – a few weeks after Nelson Mandela had walked through the gates of Victor Verster. For the past ten years, she has been involved in quality assurance for higher education institutions at the Council on Higher Education at national level.

She is assisting our university in the areas of quality assurance and academic planning, contributing to the development of deep intellectual debate and multi-disciplinary research.


Prof. Charles Dumas, Department of Drama and Theatre Arts

Description: 2011 Appointments_Charles Dumas Tags: 2011 Appointments_Charles Dumas

Prof. Charles Dumas, Extraordinary Professor in our Department of Drama and Theatre Arts, will be spending three months per year for the next three years at our university to help develop filmmaking, specifically focusing on the development of the Video Unit Planned for the Department.

Prof. Dumas started the year off with the production, Our Father’s Daughters, which was produced during the Mini-festival as well as at the Reitz Four reconciliation meeting. The production was also turned into a short film. Prof. Dumas gave film-acting classes to the third-year drama students. He directed multiple productions, such as the third-year module production Ipi Zombi, the Grahamstown Festival production, Seven Guitars and the Dance/drama production, Race, Reconciliation and the Reitz Four.


Prof. Daniel Plaatjies, UFS Business School

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Prof. Daniel Plaatjies is the former Director and Head of the Graduate School of Public and Development Management at the University of the Witwatersrand. He was mainly responsible for the leading, directing and managing of strategic academic programmes, teaching, research, governance, service management and monitoring. Prof. Plaatjies, who was appointed as Visiting Professor at our Business School this year, will as part of his new duties at our Faculty of Economic and Management Sciences, be lecturing part-time and supervise our PhD students.


Prof. Johann Neethling, Department of Private Law

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Prof. Johann Neethling’s career is now completing its full circle with his appointment as Senior Professor in our Department of Private Law. In 1965 he was a first-year at this university. With his nine law text books and nearly 200 articles, together with 40 years’ experience in academic training he is of inestimable value to this Department. His publications contribute to the establishment of our university as a research institute.


Prof. Hussein Solomon, Department of Political Science

 Description: 2011 Appointments_Hussein Solomon Tags: 2011 Appointments_Hussein Solomon

Prof. Hussein Solomon joined our university this year as Senior Professor in the Department of Political Science. Formerly he worked in peace NGOs, advised diplomats and acts as a serving officer in the South African Air Force.

His area of research expertise includes conflict and conflict resolution in Africa; South African Foreign Policy; international relations theory; religious fundamentalism and population movements within the developing world. He is also the author of a number of books, including one on global jihad and one on India's secret relationship with apartheid South Africa.

He is also member of the internationally renowned Our Humanity in the Balance (OHIB) organisation, where his role is to bring these disparate communities together and to focus energies on a common project.


Prof. André Keet, International Institute for Studies in Race, Reconciliation and Social Justice

Description: 2011 Appointments_Andre Keet Tags: 2011 Appointments_Andre Keet

Prof. André Keet, our Director of the International Institute for Studies in Race, Reconciliation and Social Justice, joined the University of Pretoria on a part-time basis in 2008, whilst being a Commissioner on the Commission for Gender Equality. Later he left the Commission and joined the University of Fort Hare. “I was happy to join academia and now also serve on the Stellenbosch University Council; therefore I am very aware of the challenges facing higher education,” he said.

His vision for the Institute is to support higher-education transformation, promote non-discrimination, reconciliation and human rights, build national, regional and international networks, and developing ‘new’ languages, knowledge and discourses for reconciliation and social justice, all to the benefit of our university and South Africa.”


Prof. Helene Strauss, Department of English

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Prof. Helene Strauss completed her PhD at the University of Western Ontario, London, Canada, where she taught courses on Film Studies, Children’s Literature and South African Literature and Culture. “I was subsequently appointed as an Assistant Professor in the Department of English and Cultural Studies at McMaster University, Hamilton, Canada.” She joined our Department of English this year.

Prof. Strauss has an on-going preoccupation with questions concerning social justice, race, gender and ethical interpersonal interaction in South Africa and beyond.


Prof. EC Ejiogu, Centre for Africa Studies

Description: 2011 Appointments_EC Ejiogu Tags: 2011 Appointments_EC Ejiogu

After 22 years in the United States of America, Prof. EC Ejiogu decided to return to Africa – to his roots – to join our university’s Centre for Africa Studies at the beginning of 2011.

Before joining the Centre, he was Assistant Research Professor in the Centre for Innovation at the University of Maryland, College Park. As Senior Researcher at the Centre, he has already helped with the streamlining of the academic programme, restructuring it to enable students to gain skills necessary to deliver a research proposal towards a dissertation after their three years of study. He has also taken up PhD and Master’s supervision.

His latest publications include a book published in March 2011 with the title, Roots of Political Instability in Nigeria, and a book co-edited with Prof. Kwandiwe Kondlo, Director of the Centre for Africa Studies, Africa in focus: Governance in the 21st century, published in April 2011.


Pura Mgolombane, Vice-Dean: Student Affairs

Description: 2011 Appointments_Pura Tags: 2011 Appointments_Pura

Bringing with him a decade of experience in Student Affairs our new Assistant-Dean for Student Life and Leadership, Pura Mgolombane, has big plans for student development. He says his office wants to help Kovsies increase its throughput rate and produce socially well-adjusted and employable graduates in South Africa, the continent and anywhere in the world.

Before joining Kovsies, he was employed as Director: Student Life, Governance and Culture at Walter Sisulu University. Pura, who has a background in Human Resources, Business Management and Corporate Law, says his academic training has empowered him with skills to ensure that the Student Life and Leadership is properly led, governed and managed.


Prof. Hasina Ebrahim, School for Social Sciences and Language Education

Description: 2011 Appointments_Hasina Ebrahim Tags: 2011 Appointments_Hasina Ebrahim

This former academic from the University of Kwa-Zulu Natal was appointed as Associate Professor at our School for Social Sciences and Language Education in the Faculty of Education. Amongst others, she is the project coordinator for the Faculty’s Early Childhood and Foundation Phase Teacher Education Programme and the MEd and PhD supervisor in the programme.

Prof. Ebrahim is also the Deputy-President of the first South African Research Association for Early Childhood Education (birth to nine). “This is certainly a milestone to profile the university in terms of its thrust towards excellence in research,” she says. One of the main aims of the association is to shape the research agenda for a marginalised field in South Africa. 


Prof. Corli Witthuhn, Faculty of Natural and Agricultural Sciences

 Description: 2011 Appointments_Corli Witthuhn Tags: 2011 Appointments_Corli Witthuhn

Prof. Corli Witthuhn, a former Bloemfonteiner, attained her PhD in Microbiology at our university. Therafter, in 1999, she was appointed as a lecturer at Stellenbosch University and later as Vice-Dean.

Currently she is our Vice-Dean in the Faculty of Natural and Agricultural Sciences. She hopes to sustain her research here at our University.

Her life motto? “Opportunities are presented in the form of obstacles,” she says.
 


Prof. Melanie Walker

Description: 2011 Appointments_Melanie Walker Tags: 2011 Appointments_Melanie Walker

Prof. Melanie Walker is a prominent South African scholar who has been working as Professor of Higher Education Studies at the world-leading University of Nottingham in the UK, where she been Director of Postgraduate Students and a Director of Research in the Faculty of Social Sciences. She will join the University of the Free State in February 2012 as Senior University Professor in the Postgraduate School.

She is a graduate of the University of KwaZulu-Natal and the University of Cape Town, where she completed her PhD, after teaching in disadvantaged secondary schools for a number of years. Prior to working at Nottingham she worked at the Universities of Sheffield, West of England and Glasgow, as well as the Universities of Cape Town and the Western Cape. She is also a Fellow of the Human Development and Capability Association. She is currently Director of Research Training and a senior researcher in the EU-funded Marie Curie EDUWEL project, which includes senior researchers from eight European countries and 15 early-stage researchers.

With a long-standing commitment to social-justice research and equality practices, she is currently widely recognised internationally as leading in the application of the capability approach and human development to higher education policy and practice. Among others, she has led or participated in research projects funded by the NRF (South Africa), the Higher Education Academy (UK), HEFCE (UK), EU, and ESRC/DfID, which funded the Public-Good Professionals’ Capability Index research project. 
 

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