Biogas

Biogas from waste in rural Kenya


Deforestation is ravaging rural Kenya as people strip forests for vital cooking fuel. Yet biogas, produced from animal and human waste is a viable alternative. What is lacking is training and awareness. Sky Link provides both via a network of local entrepreneurs. 200 domestic biogas plants and six large-scale ones in schools and a prison have been sold benefiting at least 5,200 people. And, as impressively, wood use has been reduced by 800 tonnes per year resulting in an estimated 1,100 tonnes a year reduction in carbon emissions.

Sky Link Innovations is a small biogas company in Kenya installing domestic and institutional biogas systems, as well as importing and selling high quality biogas accessories – e.g. cooking equipment and lamps.

Biogas systems take organic material such as animal dung into an air-tight tank, where bacteria break down the material and release biogas – a mixture of mainly methane with some carbon dioxide. The biogas can be burned as a fuel, for cooking or other purposes, and the nutrient-rich residue which remains can be used as organic compost. The biogas systems used by Sky Link are fixed-dome designs, built from brick in underground pits.

Sky Link installs 12 to 16 m3 size domestic systems which are designed to use mainly animal dung. Such a system requires the household to have between about three and eight cows. The gas is used mostly for cooking but can also be used to generate electricity.

Sky Link also installs larger systems for institutions, ranging in size from about 30 m3 for schools to 124 m3 in Meru prison. These can also process animal dung, but the main purpose of the larger ones is to manage human sewage from latrines.

The cost of a 12 m3 domestic biogas system is about US$1,850 (KSh 150,000). This is a substantial amount, but can be paid back in about four years through savings on increasingly expensive fuelwood. This time can be reduced to about three years if savings made from substituting commercial fertiliser for biogas residue are included, since these amount to about US$230 (KSh 18,600) per year for a small farm.

Households buy the construction materials and provide unskilled labour. 50% of the cost of Sky Link labour is paid on signing the contract, 30% when the work is almost completed, and the remainder when the system is fully commissioned. In this way households are able to spread the cost of buying a biogas system. Sky Link does not offer any credit to customers, but offers help to households wishing to borrow money from their local Savings and Credit Society.

Biogas plants cut greenhouse gas emissions, by reducing the use of unsustainable fuelwood and (particularly for the larger plants) reducing methane emissions from poorly-managed sewage disposal.

Based on typical measurements on biogas systems from elsewhere, a SkyLink domestic system probably saves about 3.5 tonnes/year of unsustainable wood or 5 tonnes/year CO2, and a school system about 10 tonnes/year wood and 15 tonnes/year CO2. From estimates made by SkyLink, the prison saves about 22 tonnes/year wood and 33 tonnes/year CO2. The savings related to reduced methane emission have not been estimated but are probably significant as the system was installed to replace a connection to the municipal sewage system, which had frequent leaks.

All the biogas systems installed to date therefore save about 800 tonnes/year of wood and reduce greenhouse gas emissions by the equivalent of about 1,100 tonnes/year CO2.

Sky Link has been trading for two years and is growing. In 2010 they were one of the top five East African energy SMEs in the Access to Clean Energy Challenge. They also won an Ashden Award. GVEP and the Ashden trust are providing seed funding and advice to enable the company to further expand its activities.