25 June 2012 - Two South African developed biogas digesters earned their inventor second place in the SA Cleantech Competition. AGAMA Biogas was recognised for the innovation and the quality of its BiogasPro and SmartTop prefabricated biogas digesters. The first small digester to achieve certification from the South African Pipeline Gas Association, the BiogasPro is a patented system that is engineered, designed and manufactured in South Africa.
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 four hours burning time on a single gas plate, 0.8 kg liquefied petroleum gas (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 7.0 kPa when fully primed.
AGAMA Biogas’s Greg Austin says the use of biogas in the rural environment is increasingly becoming acknowledged by municipal officials as a viable and useful option. The company has installed a number of systems in rural and urban areas with municipal planning approval, including numerous brick dome digesters. It has been designing and implementing biogas systems for even longer, with the first digester in rural KwaZulu-Natal (South Africa) still operating perfectly after five years, without any maintenance needs or problems.
He says the benefits of the BiogasPro range are many. “These biogas digesters are 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. They are exceptionally robust, quick to install and convenient to use. Being pre-engineered, they also circumvent the complex brickwork required to build a digester from scratch.
“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 produce the maximum possible amount of biogas, the BiogasPro should be fed with up to 40 kg of mixed organic raw material daily. It therefore presents a cost effective solution to many waste management problems, and it has a range of applications, from sewage waste water treatment to co-digestion of different substrates including food waste, manures, grasses and garden wastes.
The BiogasPro also garnered the attention of The Chicago Athenaeum: Museum of Architecture and Design's Green Good Design Award 2011 and was selected as an award winner for making a positive contribution in the area of more sustainable design and environment.
The award-winning SmartTop was developed partly as a job creation initiative. A smaller unit than the BiogasPro, it comprises just the working parts and the gas storage tank. Functionality is unimpeded.
As the base has to be built, this creates an additional task, and another job. It can also accommodate people who have more waste than the BiogasPro can handle, as the base can be built up to double the size to double the amount of waste and water that can be put into the system. However, the gas storage capacity remains the same, so gas needs to be constantly tapped off to reap the benefits of the greater capacity.
Being smaller, the Smart Top is also cheaper to ship overseas or to isolated areas where truck access may be limited.
“We anticipate that with an increasing number of reference projects our biogas systems will become more mainstream,” Austin concludes.
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