By Aedan Kernan, Greenwell Consulting
In Senegal, the government's Programme National de Biogaz Domestique (PNBD) is helping households install and use biodigesters to convert animal manure into low-emissions fuel for cooking and lighting, and a safe, organic fertilizer.
"Before the families had biogas they either burned the dried dung on a cooking fire or put the manure directly on their field," says Mme Anne Mendy Correa, coordinator of PNBD. Removing cooking smoke from building interiors has health benefits. The biogas digesters not only help the families using the system for cooking and lighting, they also reduce the competition in the area among those foraging for firewood, explains Mme Correa. Therefore, using biodigesters for energy production preserves forested areas and natural vegetation, which diminishes harmful effects on the environment caused by deforestation.
A typical Senegalese biodigester is a 6 cubic meter underground tank, built of brick. Cow manure and water are placed in the tank. As the manure breaks down, the gases it releases are fed into barrels, linked by tubes to burners on the kitchen stove. In most applications, a household biogas installation can provide enough energy for cooking and some lighting. The lighting is produced by connecting the gas to a light fixture with a gauze mantle.
Once the gas has been removed, the residue forms a mineral-rich, easy to handle, and safe fertilizer that can be sold or spread on the family plot. Two sacks of manure can be loaded into the digesters daily to produce sufficient fuel for five to six hours of cooking.
Senegal launched PNBD in the rural groundnut-growing region of Kaolack. The PNBD began training local masons to build biodigesters in January 2010. The first biodigester was completed in June of that year. To date, 209 biodigesters have been constructed and 90 masons have been trained to build them.
The government has set an ambitious target to construct 8,000 biodigesters by the end of 2013.
All biodigesters in the Kaolack region have been fed with cow dung. The PNBD team plans a trial with pig waste from a breeding farm in the peri-urban area that surrounds Senegal's capital city, Dakar. Electricity supply is considerably below demand in the Dakar region, leading to regular black outs. The biogas can provide families in the region with greater energy certainty.
Lack of Capital a Barrier
While there is plenty of demand, few people have the upfront capital needed to build a biodigester. Although the government provides grants for 35% to 50% of the capital costs of the digester, families still need to provide around 300,000 Senegalese Francs (US $630) for construction.
The costs have been considerably reduced by using local, smaller bricks for the tank construction (that also reduces the quantity of cement needed).
The PNBD team is seeking commercial help to improve marketing to potential Senegalese buyers. Some of the masons have been sponsored to visit biodigester schemes in Kenya, where biodigesters are being built and funded by communities rather than individual families – a solution that may have applications in Senegal. Additionally, the PNBD team is trying to identify micro-finance sources.
"We are sure that families can repay the loan within one year," says Mme Correa. "Those who have received a biogas digester and have been using the slurry have earned more than the price of the digester during one year. It can be done."
The program provides initial training for digester users, but Mme Correa believes that they should also provide training on maintenance needs, so that the users understand the value of an ongoing relationship with the masons.
The latest group of masons recently received their certificates from the PNBD. Many of the graduate masons told Mme Correa they were conscious that they need to build more than biogas digesters; they also needed to create sustainable enterprises. "I hope they work on with that sense," she says.
Questions and Considerations
Senegal's program to institute use of biogas digesters as a means to turn a waste product into a useful clean energy producing feedstock affords many environmental, human health, social, and economic benefits. What do you think?
- Can biodigester programs drive energy access for developing and emerging countries?
- What does it take to make a program like this successful?
- What experiences have you had with similar programs?
Weigh in and share your thoughts and knowledge with us.