Rural School is Powered by Methane Bio-Gas in South Africa's Eastern Cape

A small school in the countryside has built an anaerobic digestion plant, and is turning its food waste into energy, This school is located in the rolling hills of South Africa's Eastern Cape province, and implementing highly sustainable solutions for its agricultural and human waste, disposal, plus creating methane gas for cooking, and a nutrient-rich fertiliser. Finally, we hear that also recycling its water.

(Note: Video content is not associated with the school in the article.)

Read on and enjoy the good news in our article:

Using an integrated biogas system, the Three Crowns Rural School in Lady Frere District is teaching learners, the community, and engineers from around the country a new way of dealing with water, waste, and energy.

According to the Council of Scientific and Industrial Research, if a business as usual approach is followed, South Africa's freshwater resources will be fully depleted by 2030, unable to meet the needs of people or industry. "The problems will be made worse by more frequent incidents of water pollution and increased costs of water treatment," said the 2010 CSIR report author, Peter Ashton.

With over 40 percent of South Africa's dams affected by eutrophication (the process by which water becomes too nutrient-rich and prone to toxic algae blooms), acid mine drainage threatening to poison the water table around heavily populated Gauteng Province, and, according to the Department of Water Affair's 2010/11 Green Drop report, 56 percent of the nation's 821 sewage works either in a "critical state" or delivering a "very poor performance," arid South Africa must develop economical ways of effectively recycling its naturally scarce water resources.

Funded by the Development Bank of South Africa, the Chris Hani District Municipality's Environmental Management System Programme has been doing just that in its two-year-old pilot project at the Three Crowns Rural School.

The school's zero-waste system feeds organic waste from the school's kitchen, gardens, and toilets into an anaerobic "digester" (an oxygen-limiting, gas-tight enclosed pit) where microbial action breaks down the waste, creating methane "bio-gas" in the process.

The digested effluent is sent to a series of ponds, where first the remaining pollutants combine with oxygen and are transformed into a nutrient-rich "algal slurry" that makes excellent fertiliser. The water that emerges from the first pond shuttles to another, where fish like tilapia can feed on remaining algal content. The fishpond eco-system produces another algal fertiliser, and the pond water is irrigation- ready.

The final result is a system that transforms 100 percent of organic waste into biogas for cooking, pathogen-free algal fertiliser, and recycled pathogen-free water for irrigation of the school's gardens. The project also provides an impressive life-science laboratory where learners daily witness and come to understand concepts like decomposition, aerobic and anaerobic biological action, and sustainability.

"It's nothing new for the children to talk about digesters and bacteria and the algal pond and sterilisation. Hopefully these guys coming out of the school will help advance this type of thinking in the future," said Mark Wells of People's Power Africa (PPA), a consortium of environmental biotechnologies companies that was commissioned to install, manage, and monitor the system.

Francois Nel, head of environmental health and community services for Chris Hani District Municipality, emphasised the project's ability to affect the way people think. "The first thing is the education of the children and changing the mindset in terms of energy, waste, and climate change. And the ownership - the children take ownership of the environment and the importance of protecting it."

And it is not only the children who benefit. "This project is very, very important. First I can say to my own life, because I learned a lot of things about nature," said Zothe, the school caretaker who oversees the feeding of the bio-digester. "We've learned how to use things that are connected to nature, like we have a solar cooker, bio-digester, wind power energy, so we don't have to spend a lot of money, and we don't waste."

The Three Crowns project has been a great success, with four schools requesting installation of the same system, and the nearby communities of Intsikayethu and Engcobo planning to install the systems on a much larger scale.

It has also won numerous awards, including the 2011 Netherlands-sponsored Moolah for Amanzi award for best concept in water and sanitation projects, two Eskom ETA awards, and an Eastern Cape flagship project award.

Though adoption of the Three Crowns Project appears to be taking off, not far away in East London's Buffalo City Municipality, another People's Power Africa project is attempting to prove its worth to a sceptical municipality.

Like Three Crowns, PPA's "eMonti Green Hub" is a one-stop shop to recover resources (e.g., nutrient- filled fertiliser, methane gas, and recycled water) from waste, but this time the "feed" includes municipal wastewater, sewage sludge, and the organic fraction of municipal solid waste including garden and abattoir refuse.

Currently 10 million litres of that "feed" in the form of raw sewage are dumped daily into the surf zone by Buffalo City's defunct Second Creek Wastewater Treatment Works. The green hub proposes to use a large-scale anaerobic digester that is heated in continuously stirred reactors to more rapidly process that waste (woody garden refuse would fuel the heating).

Based on PPA's feasibility study, the green hub is projected to produce methane biogas at a rate of 300 kilogrammes/hour (a head-high gas canister holds 40 kg), resulting in "green" methane gas, which can provide a sustainable source of income to run the hub. Mercedes Benz South Africa has already provided a letter of interest to purchase the biomethane for use in their paint shop air dryers and ovens.

Processing the daily "feedstock" (including eight million litres of industrial wastewater, eight million litres of domestic wastewater, two million litres of sewage sludge, 48 tonnes of food waste, 16 tonnes of abattoir waste, and 82 tonnes of garden refuse), the hub would yearly generate 5.8 billion litres of recycled water, 2,300 tonnes of biomethane gas, and 10,000 tons of bio-fertiliser, while diverting 30,000 tonnes of waste from landfills every year.

"That's where it becomes so exciting," Wells explained. "Especially when you look at what's happening in the environment, the municipality needs to get its head around the huge amounts of bio-resources that they're currently not using at all, that are just being thrown into landfill sites and into the sea. It just doesn't make sense."

Ultimately PPA wants the hub to benefit local communities, and so plans are for the plant to be held mostly in a joint community and municipal environmental trust, with additional private and public equity. Unfortunately getting the hub operational will involve cutting through extensive administrative red tape, which relies on changes in the attitudes of the city's engineers and administrators.

"We know that everything is possible, but getting the city's approval and endorsement has been a struggle. These projects are very difficult to put together because you're talking about municipal resources and there's all sorts of issues around that. Plus municipalities have to change the way they do things. We're pushing the boundaries. We have the technical understanding, but now it's the how to make it real," Wells said.

Francois Nel agreed that PPA would face an uphill battle in getting the hub approved. "It's a brilliant idea. The problem is that people don't understand. They don't understand the environment, and they don't understand climate change," Nel commented, recalling how even now he struggles to convince engineers to "come to the party," despite the Three Crowns' success.

Nonetheless, PPA and its partners anticipate that the hub's environmental impact assessment will soon begin, and are working with the municipality on moving the public consultation process forward. They remain optimistic that by the end of 2013 the hub will begin producing the nutrients, energy, and recycled water.

"Essentially we see this as the people's resources. Even if the municipality is in charge of it, they're throwing it away, so we want to get the benefits from those resources back into community. Even if we don't capitalise on it ourselves, the project will go forward. The main thing is to solve the problem and demonstrate these solutions," said Wells.

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The Many Sources of Methane and Biogas

Methane is a combustible gas, which exists in two ways as part of the natural biological cycle when it is known as biogas, or biomethane, or as a mineral or fossil-fuel gas when it is called "natural gas".

As a mineral fuel it can be extracted from the earth's crust in the form of natural gas, or from waste sludge and biological sources including organic waste as biogas. Methane is widely accepted as the cleanest burning of all fossil fuels, but the extraction process itself requires careful consideration of the natural environment and local community.

Methane has been recently identified as a powerful greenhouse gas (GHG), and it has also been shown that its atmospheric concentration has been steadily increasing over the past 300 years. It is described as sustainable when it is produced by renewable energy (non mineral) sources, when it does not add to the GHG effect. All mineral sources are non-sustainable sources because they contribute to the GHG effect.

Methane is found trapped in air bubbles in ice cores, and measuring the quantity allows us to work out how much was present in the past. Studies of bubbles from the Greenland ice cap show that the concentration of methane in the air remained steady for 10,000 years, up until about 300 years ago.

If really large "burps" were released, quite substantial climatic changes would probably ensue. Methane is currently emitted in enough volume to make any reductions significant in terms of the overall GHG picture. Geochemical evidence for this process has been observed in numerous marine sediments along the continental margins, in methane seeps and vents, around methane hydrate deposits, and in anoxic waters.

There are two major ways in which methane is removed from the environment and these are aerobic oxidation by a specialized group of bacteria, and atmospheric oxidation.

Biogas /biomethane is produced by anaerobic oxidation by a specialized group of archaea, or methanogens.

Methane is emitted during the production and leaks from the distribution of natural gas and petroleum, and is released as a by-product of coal mining and incomplete fossil fuel combustion. Over many centuries as coal deposits are formed, some methane is absorbed by the coal and that is the usual source from which it is found in mines.

Biogas methane is released as vegetation rots under water. This is is happening in millions of square miles of rice fields throughout Asia.

It is combustible, and mixtures of about 5 to 15% in air are explosive. It is the main constituent of natural gas, a fossil fuel . Methane is far more lethal as a greenhouse gas - assuming that one believes in all this - than carbon dioxide. It is between 20 and 23 times more potent than Carbon Dioxide in terms of its GHG climate warming potential, depending upon how you look at its potency, although it does not last forever in the atmosphere.

Cows produce huge volumes of it. Contrary to what might be expected, organic cows produce less milk than conventionally farmed cattle, so their methane output per litre of milk tends to be much higher than the non-organic type.

When we say that methane is a much more potent greenhouse gas than CO2 we refer to the fact that eight for weight, it traps 21 times more heat energy. However, to get this in proportion methane is just one of six gases held responsible for global warming. Carbon dioxide is the second most abundant greenhouse gas behind water vapor.

There are huge quantities of methane in the permafrost. Permafrost in northern Siberia is reported to be 1,600 meters, (5,250 feet) thick and in in northern Alaska it is estimated at 650 meters (2,100 feet) thick Permafrost lies beneath about 80 percent of Alaska, and a higher percentage of Siberia. Permafrost on land, though, is as cold as -12.4 degrees Celsius.

Why do the GHG potencies vary so much between gases? Gases in the atmosphere, such as methane, absorb light energy and different gases absorb different amounts of energy.

Gas pipeline inspection is essential to maintain gas distribution systems, and minimize leakage, but it is a huge task. Just looking at the figures for Germany alone, with a network of more than 40,000 km of long-distance gas transport pipelines. Also, the need for a fast and remote monitoring system is apparent, to identify damage quickly.

Emissions from animal wastes depend on the method of storage or management of those wastes. When manure is stored as slurry, much of the decomposition is anaerobic and methane is produced in significant quantities. These emissions can and should be controlled by specific regulations.

Anaerobic digesters at local organic waste landfill sites or installed as part of large PFI systems capture and destroy the methane or clean it to comply with consumer standards. Large numbers of these plants installed throughout Europe would help to reverse the upward trend in methane discharges to the atmosphere. Nevertheless, even if large numbers of AD Plants were built rapidly, anaerobic methane oxidation will always remain biogeochemically important because methane is such a potent greenhouse gas in the atmosphere.

Steve Evans writes about methane biogas and runs the united kingdom anaerobic digestion web site http://www.anaerobic-digestion.com