Transmitted from pigs

...that's clean energy and not mutated viruses, by the way. E&T reports.

"This thing we're doing now - sitting here at this outdoor table while we talk and sip our coffee undisturbed - would have been impossible before," explains Hugo Garcia, the general manager of Cabañas Argentinas del Sol, a pig farm some 50km south-west of Buenos Aires, Argentina. "Back then you couldn't even open your mouth at this spot; we were permanently covered in flies."

By "back then" he means back in the days when his pig farm was run more or less like all other pig farms are still run in Argentina and Latin America.

Pig farms in the region might differ in size, profitability, the breeding techniques they use or the formulas they feed to their animals. But when it comes to waste management, they have all known only one way of dealing with it: dig up some hidden corner of the farm, fill it up with the constant supply of manure and leave the resulting lagoons in the trusty hands of Mother Nature.

Initially, that's exactly how Cabañas del Sol dealt with its waste, too. The farm, which occupies 22 hectares of land, was established ten years ago. Unlike the vast majority of medium-to-large pig farms in the country, which are located in the neighbouring provinces of Santa Fe and Cordoba, Garcia's farm has the advantage of being quite close to the capital and main centre of consumption.

However, as the farm's pig population began to grow, such proximity started to become problematic. Marcos Paz, the nearest urban centre in the Greater Buenos Aires area, has been expanding rapidly and now lies only about a mile away from the farm. Complaints about nauseating odours and flies - accompanied by municipal environmental inspections - soon became too persistent to ignore.

"We were running out of space to make more lagoons," says Garcia. "Besides, lagoons are terrible. They have a very long retention cycle (of between 160 and 180 days) before you can drain them. During the winter it's even worse because, with the lower temperatures, the bacteria don't eat organic matter so the lagoons don't work very well.

"We were contaminating both the air and the subterranean waterways," Garcia admits. "Because the methane would end up in the atmosphere and, even though the bases of the lagoons were impermeable, sooner or later something would end up filtering through."

Biogas balloons

Garcia needed to solve the mounting problem that the thousands of kilograms of daily dung from his pigs were causing. So he began to research and experiment.

He knew that the anaerobic treatment of both human and animal excrement can produce gas. One day in 2005, he filled a plastic fuel container with pig dung and removed all oxygen. Since he didn't have a manometer at hand, he simply attached a short hose to the container, to which he then attached a birthday balloon. People thought he had gone mad.

"As soon as we would put this thing in the sunshine, the balloon would start to inflate, and it wouldn't stop until it burst," Garcia recalls. "We would add another balloon and get the same result. So we realised we were generating something."

That something, of course, was biogas. "One day we brought a lighter next to the tip of that hose and, indeed, we got a flame."

Garcia was convinced that, if he could find an economically sensible way of scaling up his experiment to include the totality of the farm's droppings, he could not only address the environmental problem but he could crucially turn it to his own advantage.

He learned that Germany was at the forefront of the biogas sector. So he flew there to meet with a manufacturer of biodigestors. He was impressed with the quality of their products - but less impressed with their price tag.

"Maybe German farmers can afford these biodigestors thanks to the price of their produce. For us in Argentina it was simply too expensive," says Garcia.

The biodigestors the farmer saw in Germany had a silo-shaped fermentation chamber made out of concrete, covered by an inflatable dome of PVC. Garcia thought that, if he could get a similar plastic material to cover the top of one of his lagoons, he might be able to capture at least part of the methane.

The engineer Garcia met in Germany suggested he contact a Brazilian company called Sansuy, which had been supplying the German firm with a range of PVC geo-membranes.

A few weeks later, Garcia was in Sao Paulo talking to Japanese-owned Sansuy. When Garcia told them about his plans, they told him they had just installed their first ever biodigestor at a small pig farm in Caconde, some 300km away from Sao Paulo.

So there they went. "We saw that the biodigestor had both its fermentation chamber and its methane-capturing area built entirely out of PVC," says Garcia. As if it were a walnut, it had a lower and an upper half, which had been welded together.

While the pioneering Brazilian farmer was raising only about one-twentieth of the number of pigs that Cabañas del Sol was, Garcia could already see how much potential the technology had. Apart from using the biogas to heat water (needed to skin the pigs) and melt fat, the farmer was using it to generate his own electricity.

Precious dung

Fast forward a few months, and Cabañas del Sol had established itself as Argentina's first official producer of biogas.

Sansuy built and installed the farm's first biodigestor, whose fermentation chamber has a 250 cubic metre capacity. This was soon followed by an identical second unit. And then a third, much larger (1,750 cubic metre) biodigestor was added. The Brazilian supplier is currently manufacturing what will be the fourth and final biodigestor, another 1,750 cubic metre unit which will take the total capacity to 4,000 cubic metres.

The farm's 12,000 pigs are housed in 14 different sheds. Each of the sheds has been fitted with a specially designed, perforated flooring arrangement made of plastic (for the smaller animals) or concrete panels. Faeces and urine are automatically collected under the floor, from where they're gravitationally transported to the three biodigestors.

A piping network leads the gas originating at each of the biodigestors onto a compressor, where gas pressure is raised from the 12 millibar (equivalent to a negligible 12.2 grams-force/cm2) with which it comes out of the biodigestors to 1.47 bar (1.5kg-force/cm2), enough to transport the gas throughout the farm.

Green energy

The biogas network currently spans 200m. The green energy is used for three main applications: soybean deactivation, pig-shed central heating, and electricity generation.

Soybean deactivation is a thermal process that needs to be applied to raw soybeans in order to eliminate the antitrypsin factor, a component naturally present in the soy protein which negatively affects digestibility in monogastrics. Since soybeans make up nearly 20 per cent of the diet fed to the pigs by Cabañas del Sol, the farm has a soybean deactivation plant equipped with two rotating ovens.

Before its biogas installation, the farm was buying natural gas (in the shape of industrial-sized cylinders) to power the two ovens, which together deactivate around 10,000kg of soybean per day. Now, all gas used to fire the ovens comes directly from the biodigestors.

During their first few days, piglets need an environment where the temperature is around 30°C. Heating all sheds housing piglets is vital. Previously, this was carried out through a combination of expensive electric heaters and natural gas-powered boilers. Today, this is handled by a central-heating system fully powered by biogas.

Generating your own electricity is the other big advantage of turning your pig farm into a biogas production facility. A V8 internal combustion engine stripped out of an old F100 truck and converted to run on gas is used to turn methane into electrical power at Cabañas del Sol. The engine has a 50kVA generator attached to it.

"Most of the biogas we produce is currently used to run the soybean deactivation plant and the central-heating system for the piglets," says Garcia. "As for the electricity generation, we're mainly using that as backup. If there's a power outage, the soybean deactivation machines stop working because they have some electronic controllers. This allows us to continue to operate as normal."

Garcia says the investment in the biodigestors and the rest of the biogas system has already paid for itself. The 15,000 Argentine pesos (£2,800) a month he was spending on gas cylinders is history. And his electricity bill, which 18 months ago was 12,000 pesos (£2,240) per month, has now been slashed to 5,500 pesos (£1,030) a month.

On top of the energy savings, the farm is also saving thousands of pesos a year on fertilisers. Much of the soy and wheat used to feed the pigs is grown in 400 hectares of farmland that the company rents nearby. The only 'waste' now being generated by the pigs (a liquid substance rich in nitrogen and phosphor which is left after the biogas has been captured) is actually recycled as it's an ideal bio-fertiliser for the plantations.

From customer to partner

When Sansuy agreed to build Argentina's first biodigestor, the company's only previous experience (with the much smaller Brazilian farm to which it had supplied its initial unit) didn't count for much.

While the average annual temperature in Caconde, Brazil, is 26/27°C, winter temperatures in Marcos Paz can easily drop below zero. "We did a technological exchange with Sansuy," says Garcia. "We sent them a day-by-day report in order to come up with the exact temperature curve. This allowed their Japanese engineers to optimise the manufacturing of the biodigestors through the development of the PVC material."

Temperature variations require modifications not only to the way the biodigestors are physically built, but also to how they're operated. "During the winter we had to reduce the load of the biodigestor," says Garcia. "The water was coming out of it crude because, with the low temperatures, the bacteria were not eating the incoming organic matter."

With biogas now smoothly flowing through Cabañas del Sol - and news about the successful deployment quickly spreading among other farmers interested in replicating the experience - Sansuy decided the time had come to open its Argentine branch. The company was going to need someone to head it.

Unsurprisingly, the job went to Garcia. After more than 20 years working in the pig farming sector, he knows practically everyone involved in it. This - together with the fact that he can use his biogas experience and own installation as a showroom - made him the ideal candidate for the job.

Biometanos del Sur, a wholly-owned subsidiary of Cabañas Argentinas del Sol, was recently created to supply the local market with biogas consulting services, as well as to develop and install Sansuy's products.

"I'm already training employees [of Biometanos del Sur] so they can learn how to weld the PVC membranes and how to deal with any issues regarding the operation of the biodigestors," says Garcia. "We're taking them to Brazil three to four times a year to install biodigestors there, in order to gain experience."

Biometanos del Sur's first product for the Argentinean market will be a kit targeting small farms. Consisting of two biodigestors of 200 cubic metres each (accompanied by their own lagoon, which also needs a special plastic material), the kit will be enough to let a farm about one-tenth the size of Cabañas del Sol become energy self-sufficient.

"It's a scalable system so, as the farm expands, new pairs of (or individual) biodigestors can be added as necessary," Garcia explains. "The good thing about this modular approach is that it provides the gas network with redundancy. Should a problem arise with one of the biodigestors, the rest will keep on working, whereas having just one large unit would eliminate this benefit."

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