From blood and guts to biogas: ibert’s green energy
Waste from abattoir is converted through anaerobic digestion to generate electricity
The sour stench of manure smacks you in the face as you enter the gate to the Cavalier Group abattoir, just outside Cullinan. In the distance, sheep bleat so incessantly one can’t help but wonder if they have a clue to their imminent demise.
There is very little product from a slaughterhouse like this that cannot be sold. Be it meat, heads, eyes or tongues, almost every part of an animal has a market in SA.
There are, however, some things that are not easily offloaded; like blood and entrails filled with faeces.
Disposing of these unwanted remnants can be a real bother for abattoirs. Use of designated waste disposal facilities or even burying it on private land is common practice. However, it is not unheard of for unscrupulous operators to improperly, and illegally, dispose of waste by dumping it in a nearby river for example.
ibert, a company which converts bio-waste into energy, has a business proposition for those abattoirs in a quandary over disposing animal waste.
The deal is: "We take the waste from the abattoir, we convert that through anaerobic digestion, make gas, run an engine, make electricity, and give it back to the abattoir,” says ibert director Otto Hager.
And that is precisely what is happening at the Cavalier abattoir.
Stomach contents must first be sorted through. Plastic and rocks are a regular feature. “Every second day we fish out about 50kg of ropes,” says Horst Unterlechner, ibert’s technical director.
The organic contents, blood and offcuts are then cooked and shredded before being fed to the digester, a large round structure inside which feedstock and bacteria meet. Anaerobic digestion takes place and methane, a greenhouse gas, is released. It is captured and used to run an engine motor which generates electricity, which is sold back to the operation at a rate competitive with Eskom’s.
The biogas plant has the potential supply of 0.3MW, or 25%, of the abattoir’s 1.2MW power needs. Heat produced by the plant also goes to heating water at the abattoir.
Cavalier’s is the seventh such plant ibert has established. The first was built in the Northern Cape in 2012.
At the time, incoming legislation was anticipated to make it harder for abattoirs to dispose of waste. While the legislation did come in, poor enforcement means little change in behaviour. And being at the forefront of a fledgling industry has been a hard slog.
Unterlechner has experience with more than 70 operational sites in Europe. While there are two digesters in his original design he says there are three in the SA plants, simply because it is difficult to get parts.
“This industry hasn’t developed so there’s no infrastructure,” Hager explains. “If something breaks or something goes wrong with your digester and you need a big pump or a fancy mixer there’s nobody to help you.”
A revenue stream for a biogas operation like this is digestate, a dusty brown and nutrient-rich substance left at the very end of the anaerobic digestion process, typically used for fertiliser. But not in SA.
“In Europe everyone is fighting over it, in SA nobody wants it,” Hager says. “They think it is poison.”
ibert hopes that SA’s carbon tax, which comes into effect in June, will tip the odds in its favour. Electricity users will be taxed 12c per kilowatt hour of power consumed. “So, theoretically every kilowatt that we generate they don’t have to pay that extra 12 cents,” Hager says.
He and Unterlechner hope to apply the lessons they have learned since 2012 to a new project located in the Dr JS Moroka local municipality in Mpumalanga, although they are yet to secure the necessary funding.
The technology is the same, but the feedstock will be sludge from a sewage farm and napier grass. The gas would be supplied directly to households, replacing wood-fired cooking, and would also replace diesel in municipal vehicles. The project would create some 200 jobs.
Correction: January 28 2018
This article initially incorrectly said that 50km of rope is fished out every day. It is in fact 50kg.