Turning waste into bottled biogas


Using readily available materials, a slaughterhouse in Kiserian is finding it easy to package biogas in cylinders

By Amos Wachira

In Kiserian, 26 kilometers from Nairobi, the Keekonyokie Slaughter house is bustling with activity. The abattoir slaughters about 100 cows per day to meet the surging demand for meat in Nairobi and its environs. Known for meat production since 1982 when it was started, the slaughterhouse is slowly turning into a green energy hub: By turning all the waste from the slaughterhouse into affordable biogas.
The idea of turning the waste into energy was mooted in 2006 when the slaughterhouse struggled with ways of managing its ever increasing waste from the abbatoir. The waste, made up of water, animal blood and cow dung usually made its way into people’s farms, sloshing the soils and turning farming land into waste. Besides, the malodorous stench emanating from decaying animal waste was a bother to neighbouring homes. It came as no surprise when the National Environmental Management Authority (NEMA) caught up with the slaughterhouse managers and instructed them to find a viable and sustainable way of disposing off its waste.
“At that point, we had two options. Either close down the abattoir or construct a biogas digester. We chose the latter,” says David Chege, in charge of the biogas project.
In 2008, the company constructed two 20-foot-deep biogas digesters to help manage the abattoir waste while producing clean and affordable biogas for the plant. Biogas typically refers to a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen. Biogas can be produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste or food waste.
Initially, Keekonyokie could use the biogas produced to light up the slaughterhouse and to power generators to produce electricity that was fed into the slaughter house’s energy hungry machines, but as they realized later, the two biogas digesters had the capacity to produce more power, enough to supply all the neighbouring homes. Before long, the company had installed a small pipeline system and hooked on the neighbouring households, with meter gauges in place for billing. The idea could soon be a money minter for the slaughterhouse, but as it later turned out, it was an idea whose time had not yet come.
“We met our first challenge when people failed to pay for the biogas they have consumed. Some were so crafty that they disconnected the meters and continued to enjoy free biogas,” says Chege. In 2009, the slaughterhouse disconnected all the homes in the area and sought new ways of using the excess biogas that was being produced daily. At that time, the cost of LPG cylinders was high and therefore out of reach for the common man. Keekonyokie managers toyed with the idea of bottling biogas for sale at a subsidized price.
With the brilliant idea, the slaughterhouse managers approached Spectre International, makers of standardized gas cylinders and designed a 6 kilograms biogas cylinder. Their cylinders are christened ‘Keeko Biogas’ to allow buyers to differentiate them from LPG cylinders. The first challenge was compressing biogas. Biogas is largely made up of methane and a corrosive gas called hydrogen sulphide. Experts say that compressing bio-gas directly isn’t cost effective and can cause issues with tank corrosions, that’s why bio-gas is mainly stored locally in plastic bladder, drums, or domes.
If commercialization of it is motivated, and the production is relatively big, bio-gas has to be upgraded to bio-methane, by water scrubbing for example, which removes carbon dioxide making bio-gas have more energy density. The removal of hydrogen sulphide is done before that, by chemical method (bounding sulfur inside slurry), biological oxidation inside the digester, or using iron wool or dissolution in water. Later, carbon dioxide is removed by dissolution before compression or liquefaction of the biogas takes place.
In the past, all of these processes were only economically justifiable for very large input and required large complex industrial scale plants, but now because of the introduction of compact and very efficient bio-gas plants and the rise of natural gas and propane/butane gas prices it’s now cost effective even on small scale. Keekonyokie Slaughterhouse vowed to use readily available materials to refine their biogas. From bubbling biogas in water to remove to biologically remove water particles from the gas, to passing it through dried bones in a bid to liquefy it, the slaughterhouse managers were motivated to look for the most affordable means of purifying the gas produced.
With a will to succeed in an area where many others have failed before, the managers were unfazed by the complex nature of bottling biogas, and set out to become the first firm in Kenya to package biogas in LPG cylinders.
To achieve this, however, they needed support to test the technical and commercial viability of their idea. That is where InfoDev’s Kenya Climate Innovation Center came in to fill the gap.
In 2012, and with the support of the center, the company tested several alternatives and refined its biogas production and distribution systems. Chege says that the firm started experimenting with ways of making the supply of biogas a reality. One of the most viable ways was through used motor vehicle tyres and an improvised, locally made jiko. The company then installed a packaging unit and their first biogas cylinder rolled out of the filling unit.
“We realized that we could only put two kilogrammes of biogas in a six kilogramme cylinder due to challenges in compression as we were filling the gas in its gaseous form. We are currently working on affordable was of liquefying the gas and bottling it in liquid form,” explains Chege.
He adds that the company wants to start filling the cylinders digitally, with a capacity of at least 100 cylinders per day.
“The good thing with biogas is that it doesn’t explode. It’s friendly, economical and reduces green house gases in the environment.”
The impact of Keekonyokie’s green energy project has been felt widely around Kiserian. Before the company decided to disconnect homes and hotels in the area, over 50 homes and a few hotel had a firsthand taste of affordable green energy. All households with a biogas connection were to pay Kshs600 per month, with the hotels forking out Kshs1000 every month, making great savings.
With the new drive to commercialize this project, the benefits of affordable energy might soon be felt across the Kiserian area. The only obstacle for Keekonyokie now is inadequate funding, lack of clear policies on biogas, and the various regulatory bottlenecks.
If funding comes their way, Keekonyokie will be ready to enter the national market and start a green energy revolution. Chege says that Keekonyokie is ready to partner with county governments to take the technology across the country. If everything goes well, the company will sell the first cylinders at an initial cost of Ksh3,700 for the 6kg-cylinder and Ksh400 for a single refill, almost half the amount for refilling a similar quantity of LPG cylinder.
With the anticipated high demand for the cylinders, the company managers are ready to open another slaughter house in a 30 acre piece of land, doubling biogas production capacity.
But there are challenges. Seeing direct competition from Keekonyokie, LPG players have opposed the idea of bottling biogas.
Keekonyokie managers are however optimistic that through consultative meetings with industry regulators and players, they will be able to turn their dream into reality. Chege says that plans are in the pipeline to partner with a local firm to introduce composite cylinders which are more viable for biogas than standard cylinders. Now that the slaughterhouse is no longer selling biogas until all regulations are put in place, Keekonyokie is making money by selling biofertiliser, a byproduct of biogas production, at a cost of Kshs40000 per lorry.
“We are currently in need of Kshs15 million to install a bigger compressor unit and roll out packaging on a large scale. We are optimistic that this project is capable of creating jobs as there are opportunities in distribution of gas cylinders, installations of biogas systems and training,” says the mechanical engineer who is a passionate biogas consultant.