Biogas & bioslurry: an energy and agricultural solution for the rural poor?

March 24, 2013

Download a publication of Hivos on 'Bioslurry: a supreme fertilizer'. 


 This blog describes shortly the problems related to climate change, agriculture, and the energy crisis to be followed by a solution for marginalized people in developing countries: poo, or better, biogas and bioslurry. Biogas and bioslurry is a good solution for rural poor in developing countries to secure their energy demand as well as crop security and increase.


Population, agriculture and climate change

The world population is growing exponentially due to medical advances and massive increase in agricultural productivity. Indeed, by 2050 the global population will have increased to around 9 billion, counting for 50% increase compared to 2007. All these people need food and thus, agricultural production and efficiency must increase. Currently, agricultural lands occupy 40 % of land surface worldwide and the sector contributes 4% to the global GDP, providing employment to 1,3 billion people. However, climate change has a significant impact on agriculture and vice-versa, agriculture is GHG intensive. Indeed, the IPCC (2007) concludes that the direct effects of agriculture counts for 14 % of global GHG emissions in CO2 equivalents (5.1 to 6.1 Gt CO2-eq/yr in 2005) and indirectly it accounts for 17% of emissions when biomass burning, deforestation and conversion to cropland and pasture are included (Lybbert and Sumner, 2010). As such, climate change and agriculture are interrelated (Smith et al., 2007; Rosenzweig and Parry, 1994). The changes in the global climate system and the demands for more food together with more nutrients and meat for the growing population will require innovations in policy as well as institutions (Lybbert and Sumner, 2010).



Energy is a vital aspect for development and is a catalyst for a country’s economy. ‘The lack of access to affordable and efficient energy keeps huge mass of people in developing world in a poverty trap’ (Centre for Energy Studies Institute of Engineering, 2001, p. 24). Indeed, over 2 billion people lack access to clean, safe and sustainable domestic energy. In many developing countries there is insufficient generation capacity, unreliable supplies, high energy prices and a poor energy infrastructure. Therefore, poor and marginalized people often use firewood and/or LPG for cooking, kerosene for lighting, and diesel for electricity and mechanical power. These are measures with serious negative impacts. Kerosene and diesel can be expensive, unreliable and is also harmful to the environment. Firewood causes 2 million deaths per yeardue to the soot and smoke. Additionally, especially women and children not only deal with respiratory and eye diseases but they also often suffer from firewood burns. On a bigger scale, firewood increases deforestation in many areas, and the firewood collection is labor physically intensive. Also agricultural and animal waste is often used for cooking, which can therefore not be used as an organic fertilizer. Hence, there is a great demand for reliable, alternative, renewable and environmentally clean energy. This can be wind, solar, (micro) hydro, and …..biogas.



Biogas and bioslurry produced from cattle and buffalo dung (and possibly other excrement, e.g. human) can be a solution to problems such as energy security, poverty, climate change, and soil degradation. ‘Biogas is a combustible gas produced by anaerobic fermentation of organic materials by the action of methanogenic bacteria’ (Centre for Energy Studies Institute of Engineering, 2001, p. 41). Biogas is a simple, affordable, uncomplicated to operate and easy in maintenance energy and fertilizer supply for rural households in developing countries. ‘This makes it an ideal renewable energy source for smallholder farmers with a few cattle’ (Warnars, 2012, p. ii).

The biogas consists of methane and carbon dioxide and the flame from these gases is smokeless and non-toxic. It also produces more heat than kerosene, wood, charcoal or cow-dung. However, the heating can only be done with small biogas installations while bigger ones can be used for lighting, electricity (refrigeration, lighting) and mechanical power (engines). The other aspects can be done with bigger installations. The minimal daily feed for a 4 m3 digester is 20 kg of animal dung (around two adult cows / buffalo or 5 pigs).  The biogas production of 25 kg dung per day replaces 5 kg of firewood, 1.5 kg of charcoal or 0.6 litter of kerosene per day. Generally, a biogas plant can last for 20 years, but it also needs operation and maintenance (SNV, 2011, b). The investments in a biogas plant in Asia lies between US$ 350 and 800 while in Africa this lies between $ 600,- and $ 1000,- due to the higher costs of cement, labor and more (SNV, 2011, a).

Biogas and the biogas market will significantly improve living conditions of poor households in developing countries due to its innovative, independent and clean energy and composting characteristics. A biogas installation creates employment, saves the use of traditional cooking fuels and increases the availability of clean fuels for the poor. It contributes to the rural energy use of cooking and lighting which accounts for 95% of the rural domestic energy use. It furthermore reduces the workload particularly of women and children by avoiding the collection of firewood, tending the fire and cleaning the utensils from soot of smoke. There will be more time available for other activities than wood collection and the employment opportunities will increase through the new established domestic biogas business sector.  Since it is smokeless, it can lead to a significant decrease in eye irritations, eye infections, coughs and breathing difficulties (Mucharam, Pariatmoko and de Groot, 2012).  Cooking with a biogas installation can be done in up right positions, instead of kneeling down, while the kitchen is cleaner and the women can stay cleaner themselves too. This contributes to the increase of women’s self-esteem and dignity. It also increase the time available for reading, socializing and other activities in the evenings (SNV, 2011, a).

On a broader scale, biogas installations contribute to national policies on sustainable development and it simulates the involvement of women and other disadvantaged groups within democratic decision making in their regions and/or countries (SNV, 2011, a). Biogas installations also reduce carbon dioxide, nitrogen, and methane emissions since these gases are captured and used for the installation instead of being emitted into atmosphere (SNV, 2011, b; Warnars, 2012).


A biogas installation can be filled with locally available raw materials, crop residues, and animal and human waste such as urine and dung. The content which is left is called bioslurry. Bioslurry can be used to build healthy fertile soil for crop production and it is an easier available form of compost compared to traditional compost. It can be used in liquid, composted and dry form. It not only has higher amounts of nutrients and micronutrients, but it also has a higher quality than farmyard manure and composted manure. As such, a rural family owning a biogas plant will have the additional advantage next to clean and cheap biogas of continuous and readily available supply of high quality fertilizer for crops. Indeed, ‘[…] bio-slurry increases crop revenues with an average of 25 percent annually’ (Warnars, 2012, p. 64). Furthermore, often the slurry combined with chemical fertilizers shows better yields than slurry utilization only. However, the use of bioslurry is a great innovative and profitable alternative as to fertilizers which are often expensive and have negative (environmental) effects on the soil.

The savings of kerosene, firewood and increased nutrients in the slurry increases with the size of a biogas plant, but the costs of the installation do not increase at the same rate. All in all, a biodigester user survey of 2010 shows that the average family saves US$ 14,0 per month on energy, fuelwood (2200 kg/year) and kerosene while over US$ 50,- per year is achieved by replacing chemical fertilizers with bioslurry (NBP, 2011). Furthermore, bioslurry has many other positive side effects such as that it can be used as a basal manure, to be used as animal freed, production of vitamin B12, production of earth worms and algae:, to decrease soil erosion, and the slurry is effective for over three years while chemical fertilizers are effective for only one crop (BSP, 2001; Gurung, 1997 & 1998; Shahabz, 2011; SNV, 2011, c). Bioslurry in itself also reduces GHG emissions through different ways: carbon sequestration increase due to crop yield increase, methane emission avoidance due to biodigester, and by the avoidance of chemical fertilizers (Nitrogen emissions and energy necessary to make chemical fertilizers). However, these aspects would have to be measured and researched further.


In conclusion, biogas and bioslurry can have many additional positive effects next to the energy supply for a rural household. Setting up a market for this would be very beneficial for rural households and the world in general due to GHG emission reductions, increased crop yields, energy security and food security. Therefore, Hivos is for example stimulating and assisting in building this market. Check it out on




Gurung. (1997). Review of Literature on Effects of Slurry Use on Crop production. Nepal.

Gurung. (1998). Training programme on proper use of slurry for the technical staff of SNV/BSP.  A training manual.

Lybbert, T., and Sumner D. (2010). Agricultural Technologies for Climate Change Mitigation and Adaptation in Developing Countries: Policy Options for Innovation and Technology Diffusion, ICTSD–IPC Platform on Climate Change, Agriculture and Trade, Issue Brief No.6, International Centre for Trade and Sustainable Development, Geneva, Switzerland and International Food & Agricultural Trade Policy Council, Washington DC, USA.

Mucharam, I.S., Pariatmoko, and de Groot, R. (2012).Turn waste into Benefit: Credit Access to Diary Farmers in East Java, Indonesia for Biogas Units. A partnership of Nestlé Indonesia and Hivos. In: Company- Community Partnerships for Health in Indonesia. Case Study.

Rosenzweig, C., and Parry, M.L. (1994). Potential impact of climate change on world food supply. In: Nature. Vol. 367. 13 January 1994.

Shahabz, M. (2011). Potential of bioslurry and compost at different levels of inorganic nitrogen to improve growth and yield of okra (Hibiscus esculetus L.). A thesis submitted in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE (HONS.) In SOIL AND ENVIRONMENTAL SCIENCES INSTITUTE OF SOIL AND ENVIRONMENTAL SCIENCES FACULTY OF AGRICULTURE. UNIVERSITY OF AGRICULTURE FAISALABAD, PAKISTAN 2011.

Smith, P., D. Martino, Z. Cai, D. Gwary, H. Janzen, P., Kumwar, B. McCarl, S. Ogle, F. O’Mara, C. Rice, B., Scholes, O. Sirotenko (2007). Agriculture. In Climate Change 2007: Mitigation, Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. [B. Metz, O.R. Davidson, P.R. Bosch, R. Dave, L.A. Meyer (eds)], Cambridge University Press, Cambride, United Kingdom and New York, NY, USA.

SNV. (2011, a). Introduction Relevance of domestic biogas for development. PPRE Oldenburg University biogas compact course April 26 – 28, 2011.

SNV. (2011, b). Appliances for domestic biogas plants. Biogas compact course PPRE- Oldenburg University April 26 - 28, 2011. 

SNV. (2011, c).  Technology and Mass- Dissemination Experiences from Asia. Biogas compact course PPRE- Oldenburg University April 26 - 28, 2011.

Wikipedia (2013). On:

Warnars, P. (2012). FROM BIOMASS TO BIOGAS: PRESENT DAY STATUS & FUTURE REQUIREMENTS. Master thesis International Development Studies. Utrecht University.



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