Biogas not only for big boys

Methane-from-manure operations are viable for farmers both large and small, who should think carefully before signing away the rights to any carbon credits they earn in the process, writes Shelby Tyne.
Issue date: 14 March 2008

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In the changing climate we live in, we as farmers are finding the profit margins ever shrinking, and are constantly scrabbling to make ends meet. In Robyn Joubert’s article Money from Manure, in Farmer’s Weekly’s 22 February issue, Cleaner Climate SA seemed to have found a solution for the environmental needs of large-scale livestock farmers, helping them earn carbon credits by generating methane from manure and thus raising a profit from a waste product.

However, having studied and worked with anaerobic digestion and methane capture techniques for the past five years, I would differ on some of the facts that Cleaner Climate has put forward, who by their own admission are interested only in big returns and thus ignore the huge smaller market. Cleaner Climate say anything under a 1 000-cow dairy isn’t profitable in terms of carbon credits. That may be true for a company that subsidises and installs expensive digesters to capture methane, as their profit margin would shrink, but there are cheaper digester designs on the market that achieve the same goals with far less cost. With new ideas and developments being made in the biogas sector, digesters that effectively produce methane and offset carbon emissions are available to smaller livestock owners. They may not be able to power their entire operation, but they’ll certainly provide some energy.

Every farmer is different and their biogas needs will differ too. The most effective way of using methane is for heating. Therefore poultry farmers have access to huge savings. Any reasonably sized farm can produce its own methane for its needs. Obviously this goes in accordance with economies of scale. The set-up on our farm is a prime example. The manure from the neighbour’s 10 000 layers generates enough methane to run the generator for the farm all year round, not just in summer. And the plant is so efficient we’re generating surplus electricity. Unfortunately at this stage Eskom won’t buy our excess so we’ve scaled back our output. We let the chicken litter form a slurry and fill our digesters with a slurry pump. This gives off methane which we burn in a diesel motor. Generators run on methane, using diesel only for pilot ignition. Spark ignition motors can run exclusively on methane and need only a fairly simple modification. A bonus is that the residue after digestion is free of harmful pathogens and can be used as a quality fertiliser. Our approach allows massive savings in the cost of generating methane from a three-cow, home-cooking digester to anything bigger.

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Biogas has been around for a long time and farmers worldwide are now harnessing its power for their own benefit. The input costs on commercial digesters are quite substantial in Europe and the US. Many of these projects are subsidised by government or anti-pollution agencies, so the farmer doesn’t have to put in huge costs. There are no subsidies in SA, and it’s left to the farmer to determine whether the project will be feasible or not. Most SA farmers know about biogas, but not enough to design and install their own system at their own cost. The fact of the matter is that Cleaner Climate has climbed on the environmental gravy train and farmers are once again standing in line to get milked. The article provides very little hope for the small- to medium-scale livestock farmer. Cleaner Climate SA also flares the methane, as well as using it to generate electricity, which is akin to setting fire to a wad of banknotes. There is more than one company trading in carbon credits, and as they’re becoming one of the hottest commodities on exchange markets today, many other traders can give you better deals. The main hurdle is that most of farmers’ projects have to be certified to be recognised as carbon offsetting practices, and this is where everyone is climbing on the bandwagon. he real question is, who will benefit from the part farmers play in offsetting climate change? Is Cleaner Climate’s motivation to produce a cleaner environment – or to become rich at the expense of farmers?

Shelby Tyne invites interested readers to tour the plant on his cane farm in Eston. Contact him on 083 642 8229 or visit his website at for more on biogas generation. |fw