Waste keeps school stoves burning

Energy from waste technology is mushrooming in the Transkei and could soon be taking root in Nelson Mandela Bay.

Gordon Ayres, CEO of Agama Biogas, which is driving the quiet boom in the Transkei, said on Monday new integrated biogas digesters had been installed in three schools in Lady Frere, Cofimvaba and Ngcobo.

“These schools generate about 20kg of waste each day from their school feeding scheme consisting of peelings plus the waste water that has been used to clean their pots and plates.

“It’s enough waste to keep a school in gas to cook for over 2½ hours a day on a commercial stove.

“Each of these schools is saving R60,000 a year on LPG gas that they no longer have to buy.

“At the same time they are generating slurry that they use to improve the quality of the soil in their food gardens and boost the production and quality of their vegetables.

“It’s a perfect closed loop system.”

The simplest biogas digesters comprised two tanks with their tops cut off with one fitted into the other, and cost less than R5,000, he said.

“To maintain, they are very easy and cost-effective.

“One unit should be good for 20 years and have a return on investment of about three years.

“Every now and then a filter needs replacing, otherwise they are cost free.”

The capital to install and maintain the biodigesters in impoverished rural schools and communities could be sourced in various ways, he said.

“The schools have to buy LPG to cook their daily meal.

“This money can be used to install the digester and, as soon it has paid for itself, then this becomes money saved — to be added to the savings from no longer having to buy fertiliser.

“Households in the communities around the schools can finance their units in the same way.”

Ayres said municipalities could use sewage sludge from their sewerage treatment plants to feed their digesters.

“They would put this sludge through their digester, capture the gas in a holder, scrub and pressurise it  and use it to power generators, to fuel fleets of rubbish trucks like they do in Europe, or to transform it into electricity.”

In urban areas, waste water was a particularly good feedstock for biogas digesters, he said.

“A lot of food processing plants such as abattoirs use a huge amount of water that then becomes contaminated. This is fantastic for a biogas system.

“The process of generating biogas means that anaerobic bacteria eat all the ‘volatile solids’  — the bits that make the waste smelly.

“What’s left is water, minerals and ash. This is a fantastic organic fertiliser that can be used to grow plants.

“It increases stem width and length, colour, fruit quality, leaf size and the general  robustness of the plant.”

While the biogas sector was still in its infancy in SA, successes overseas pointed to its huge potential, he said.

Nepal had created 270,000 small digesters in three years and the programme had been so successful it was working towards one million, while India already had three million biogas digesters.

Nelson Mandela Bay municipality environmental health department acting executive director Andile Tolom said on Monday the metro was working on a project that would capitalise on the biogas digester technology.

“We are looking at extraction of gas from our landfill sites via public-private partnerships.

“The aim is that the gas will be transformed into energy to allow for the electrification of nearby communities.

“We are focusing first off on Arlington Waste Disposal Site and will be calling for expressions of interest soon.”

Following on the success of the three Transkei school biogas digester projects, Agama is planning to launch similar initaliatives in 30 more Eastern Cape schools next year.