Anne Mireille Nzouankeu | July 9, 2012
Mary Siri is a 48 year-old farmer from Akum, a village in northwestern Cameroon. She must grow enough on her small farm to feed thirteen people every day. In 2010, Ms. Siri installed a biodigester. This is an underground tank that produces gas from the fermentation of fresh animal dung.
The biodigester delivers gas directly to Ms. Siri’s kitchen. She explains, “Every day I pour cow dung and water into the biodigester. I turn the mixture and the machine does the rest. I have as much gas as I want.”
Now that she has biogas, she has stopped using firewood and butane. She says, “I used to spend a lot of time collecting firewood. Then I used butane gas. But it was too expensive. I spent 12,000 CFA a month (about $25 US). Today, with biogas, I do not spend anything.”
The biodigester has also helped Ms. Siri increase her income. She has been able to buy a refrigerator, a TV and pay school tuition for her children and nephews.
As well as gas, the biodigester also provides organic fertilizer.
Esther Pedie is an expert in renewable energy who works for a local NGO that promotes biodigesters. Ms. Pedie explains that the biodigester produces a liquid substance called digestate. This is easily stored, and when needed can be poured directly onto the fields as a fertilizer. Before installing the biodigester, Mary spent 125,000 CFA francs or about $240 US every year on chemical fertilizers.
Ms. Siri saw no difference in her yields after one year of using digestate. But she saved money on energy. In the second year, she says, “Not only did I continue to save money, but my production increased. For example, I harvested two extra 50-kilogram bags of chili.” Vegetables such as tomatoes, peppers, carrots, green beans and spinach are now thriving on her farm, and she expects a good harvest.
Rodrigue Mbarga is in charge of environmental impact studies for Cameroon’s Ministry of the Environment and Protection of Nature. He is confident that the digestate does not pose a risk to people or the environment, unless the dung comes from a sick animal. Mr. Mbarga has a recommendation: “The digestate loses some properties when processed or packaged. For best results, it should be used immediately after removal from the biodigester.”
Mary Siri’s good yields have drawn the attention of other farmers. Peter Ngu grows maize and bananas. He installed a biodigester so he could benefit from the organic fertilizer and the energy. He adds, “I was told that adding a generator to the biodigester could produce electricity. I want to create a poultry farm. Having free electricity will help me save money.”
Despite its advantages, the biodigester has one serious drawback. The installed cost of the smallest model is 550,000 CFA francs, or more than one thousand US dollars. This is a fortune for many small-scale farmers. But in Ms. Siri’s opinion, it was a good investment.