Biogas for farmers in Gauteng

Biogas for farmers in Gauteng
Minor International Entrepreneurship & Development 2017

Gauteng, South Africa

Steven aan het Rot
Rembert Kortenhorst
Sanne Buisman

With a team of three, we have taken on the project “Biogas for farmers in Gauteng”. This project has the mission to support farmers with sustainable energy and waste management. It is chosen to use bio-digesters to try to obtain this mission. In this way, the farmers can turn their bio-waste into fertilizer for their land and will be left with flammable gas for heating their farm at night.

Currently another TU Delft team is busy working on the design and financing of four bio-digesters designed for South-African farms. After the designs are finished we will take over and try to continue their good work. At this stage in the project it is still too soon to define one specific project assignment due to the fact that there is so much that needs to be done. Because of this we have compiled a MoSCoW model to list all our missions in order of urgency.

MoSCoW model
Our exact assignment is one (or more) of the following options, depending on if the applied funding will have come through and how much time every mission will prove to require:

Must (things we have to do during the time we are in South-Africa, or we have to consider the project a failure):

  • Write down all our analyses and conclusions during our stay.
  • Look into the current and third design. This third design is an unscalable design. We will research these designs and propose additions and optimize them. We will also conduct a feasibility study for the third design.
  • Make multiple business models for different sized bio-digesters and also implement the fertilizer in these models. If we are short on time, we will make a beginning for one of the future students groups.
  • It is a possibility that during our stay the funding for the building of the multiple biodigesters comes through, if this is the case then we can start with the supervision of the build of the biodigesters and include encountered problems/improvements in our report. This also includes optimizing the design of these biodigesters.

Should (important things we can do to make to project a bigger success)

  • To extend the network of stakeholders in order to make the project more independent on the long-term. This could mean that it is necessary to collaborate with local companies (or try to start a new company).

Could (things we might do if we have time to spare)

  • Look into the possibility for farmers to become independent from Eskom (the energy company of South-Africa).
  • To make a documentation about the policy of financing and the administration of biodigesters.
  • Make a business model for a small-scale biodigesters for use in the cities

Would (things we probably won’t do, dreams)

  • To make sure that when we leave there is a company who is able to build, maintain and improve biodigesters. A company that is able to conduct after sales and to help with the administration of farmers

Current situation
Farmers in the area of Gauteng experience power-cuts while paying a lot for their electricity. On the other hand they produce a lot of biowaste which releases harmful gasses into the air. Combining these two harmfull things, can however solve both problems since biowaste contains a lot of energy still and can be turned into gas and fertilizer by means of a biogas digester. Biogas digesters are implemented all over the world yet South-Africa lags behind. We believe that there is no good reason for this and believe south africa could really benefit from this technology. South-Africa is namely in a quite far stadium of development, meaning that there is knowledge and a budget for sustainable solutions.

The three most important stakeholders in this project are the Process, Energy and Environment Technology Station (PEETS), the Department of Agriculture, Forestry and Fisheries (DAFF) and the farmers. PEETS is an organization of the UJ supporting sustainable start-ups. They are striving towards a vibrant green economy which is completely in line with our project, making them choose to fund part of the project. The DAFF feel that the environmental impact of farming needs to be reduced and on the other side that the wellbeing of farmers need to be increased. Part of their goal in this project in the increase in local jobs, making it important that local artisans can build the digester. They will provide most of the funding in this project and indicated interest to do so more often in the future. And lastly the farmers, they are the stakeholders whose problems we are trying to solve. They are interested in having a properly functioning, easy to maintain or repair biogas digester of the proper size. In this way they can save on electricity costs or even become independent from the power grid. Furthermore the fertilizer coming out of the biogas digesters can be sold, providing an extra income for the farmers. The contribution of the farmers is providing the services for the workers so the total costs of the digester can be reduced. This includes the excavation but it might also include providing security and a place to stay for the builders.

Our approach
We have split up the different goals we want to achieve into three different categories. The first category focuses on the design of the biogas digester itself. We will try to improve upon a current design of a biogas digester and if necessary design our own. Using different parts might be cheaper, more efficient or more reliable. To be able to adapt the design to the needs of the farmer in question, we will also investigate the requirements that the biogas digester should have for different sizes and types of farms.

The second category focuses on the business and social side of this project. We want to investigate the different financing structures and business models suitable for South-Africa. This step is crucial for the continuation of the project. At the moment funding is being requested for the built of one biogas digester. If this funding comes through on time, we will supervise the built of this digester. Furthermore we will take pictures of the steps in the building process in order to expand existing information packages in order to continue the project without loss of knowledge.

The last category entails the designing of the water harvesting system. This system harvests water in the fertilizer drying process since a lot of water is necessary in the feeding of the biogas digester. A general note to all activities is that since neither of us have ever built a biogas digester before, we will gather knowledge by means of meeting with experts and doing literary research on the field of biogas digesters.

The members of this project group are Steven aan het Rot, Sanne Buisman and Rembert Kortenhorst. The academic background of Steven and Sanne is mechanical engineering and Rembert Kortenhorst is an aerospace engineering student. We look forward to go to Johannesburg to execute the project we are preparing so hard here in Delft.

Steven aan het Rot, Rembert Kortenhorst and Sanne Buisman


This project focusses on the implementation of biodigesters for farmers in the area of Gauteng, South Africa. These biodigesters are (mostly underground) containers in which manure is fed and turned into fertilizer and biogas by an anaerobic digestion process performed by micro-organisms.

The three master students from who we have taken over the project had come up with a scalable brick and mortar design. Part of the project was completing this design by adding an agitator. This design can be built fully locally but is still fairly expensive. Due to the fact that it can be built locally, the government is very willing to fund this design. Yet straight-away from the beginning of the internship it became obvious that funding is an unreliable factor. This made the necessity arise of cheaper (less local) designs. Since the farms in South Africa differ greatly in size, the designs need to be scalable. As a result, two new designs were made which are both half the price of the initial brick and mortar design through the entire size range. Choosing between these designs is a matter of size since it differs per size which design is optimal. One design is made of a rectangular, brick and mortar basin covered by a plastic sheet where a few centimeters of water in a ridge make an air-tight seal. This design is a plug flow digester which has the advantage of less water usage. The drawback of this design is that the sheet needs to be imported from China, reducing the locality of the design. Fortunately, this is only approximately 10% of the total costs. The second alternative design is made of underground water-storage tanks. These tanks are made in the province of Gauteng meaning that the government money stays inside the area. Yet the drawback of this design is that approximately 50% of the costs are the water-storage tanks built by an already successful company, reducing the local stimulation of entrepreneurship.

Furthermore, work was done on optimizing the biogas process. Part of this was adding knowledge to what already existed about the gas cleaning system which is applicable to all three different designs now existing in the project. Next to this it was found that using yeast as a catalyst can increase the gas yield of a biodigester which is already proven to work on a laboratory scale. Contact was established with the largest yeast producer of Southern Africa. An experiment proposal was written for this three months lasting experiment.

Since funding had proven to be unreliable, the farmers might be interested in making the investment themselves. For this, it is crucial that all relevant parameters are known. This lead to the necessity of a business model. This business model includes more than just the economical side, it also includes the social and environmental costs and revenues. Due to the great differences between different farmers, this could not only exist out of text. As an extra it was necessary to make an Interactive Business Model in which the farmer can fill in all relevant parameters to get the right size of design combined with parameters like the Yearly Return on Investment and many more.

To have the largest impact with this project, it lasts longer than only the three months internship (which was from 3 November to 30 January). Halfway February the project is taken over by three mechanical engineering students from the University of Johannesburg. They take over three separate parts of the project: the water harvesting (different ways of saving water since the digester needs a lot of water and water scarcity is an issue); the gas cleaning and the yeast experiment. Furthermore, at the end of February Marco Cioli takes over part of the project involving the business, policy, institutional and entrepreneurial opportunities and environment for three months. After this, the project will have to wait until the beginning of November for new enthusiastic students from the minor Sustainable Entrepreneurship and Development.

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