Wednesday, 27 June 2012
Biogas digesters have been installed in the Upper Thukela area in KwaZulu-Natal as part of a natural resource management project to enhance the quality of life of people living there. Agama Biogas’s Greg Austin reports back on the impact this sustainable technology has had.
Before her Agama bio digester was installed, Mama Ethel Khumalo spent R800 of her R1 140 monthly pension on energy – R100 on electricity and R700 on wood. Unfortunately, both the electricity and the wood never lasted a full month, and the family often spent nights at a time with only candles to light their home and no fire to cook over.
Today, she uses the dung from her five cattle to feed the bio digester. The gas it produces is used for cooking and the electricity she purchases to light the home. As a result of the digester, the family always has light and Mama Khumalo has cut her Eskom expense to R50 a month and no longer buys wood.
Mama Miya’s household is large – three adults, two children out of school and eight school-going children. Before the biogas digester project, she used R200 a month of electricity for lighting and ironing, and spent close to three hours a day collecting wood to use for cooking. She points out that the digester saves her time and money, as she no longer needs to collect wood and she has cut her electricity spend to R50 a month.
In a nearby valley, Velam Khumalo used to spend R800 of his pension each month to buy wood for cooking. This never lasted the full month and so his wife and children would go out to collect wood and cow dung. With the bio digester providing all the energy they need for cooking, they don’t need to forage for fuel and he can spend that R800 on other items like clothing, school books, candles and more food to supplement the family’s meagre pantry.
These three stories provide anecdotal evidence of the benefits of biogas, an alternative energy technology fulfilling all the criteria relating to environmental sustainability, requiring relatively low technological input and being cost effective to implement.
Although biogas is used all over the world (India for instance has more than 12 million digesters), biogas in South Africa is practically unknown. Less than 100, mostly small scale domestic installations, have successfully been built and commissioned to date locally.
The BiogasPro, the first small digester to achieve certification from the South African Pipeline Gas Association and that installed in the Upper Thukela area, is a unique, patented system that is engineered, designed and manufactured in South Africa for African conditions.
The unit has a total capacity of 6 000 litres and can produce a nominal amount of 1.9 m3 of biogas every day, which is equivalent to 4 hours burning time on a single gas plate, 0.8kg LPG, or 3.5 kWh continuous electrical output.
The biogas is captured and stored within the upper part of the digester itself, which has a gas storage capacity of 0.95 m3, and relies on hydraulic pressure to produce gas pressure at 7 kPa when fully primed.
The benefits of the Biogas Pro range are many:
- prefabricated from linear, low-density polyethylene (LLDPE) using a roto-moulding manufacturing technique which makes them ideal for a wide range of applications and situations.
- exceptionally robust
- quick to install because they are pre-engineered to circumvent the complex brickwork required to build a digester from scratch.
- convenient to use
Installations can be performed by certified drainage and gas technicians, who are accredited by Agama Biogas. Alternatively there is a ‘DIY option’ where customers install the digesters themselves from comprehensive manuals supplied with the digesters.
To prove the efficacy of the technology locally two senior researchers from the University of KZN, Dr Monique Salomon and Dr Terry Everson will be working with Mama Khumalo, Mama Miya, Velam Khumalo and others to plot their electricity and wood use both before and post installation.
The biogas household owners provided input regarding the variables that they would measure during the project. Monique created a data sheet using photographs to facilitate recording of data by both illiterate and educated household members. Each participant has been given a file with copies of the data sheets and an information leaflet on ways to save energy when cooking.
We look forward to receiving the results of the project, as we believe it will help fuel the demand for bio digesters in other areas around the country. We anticipate that with an increasing number of reference projects, our biogas systems will become more mainstream.
It is important to note, though, that this project is focused on reducing the wood used for cooking and heating purposes. The gas produced by the digesters can also be used for lighting and heating, and this is a ‘second phase’ that could be introduced at a later date.