Energy without the Backache

By Aedan Kernan, Greenwell Consulting
March 2012

One person can carry enough fuel to cook for their entire family and to light their house for a day in a virtually weightless backpack. In areas where there is little firewood or other fuel, dung collection is a major part of people’s daily routine. Some households operate their own biogas facilities, but this requires three conditions: access to capital, four cattle to produce sufficient dung, and access to large quantities of water.

"Those three basic conditions exclude the majority of people who could benefit from biogas programs," says Katrin Pütz, developer of the Biobag, based in the Department of Agricultural Engineering at the University of Hohenheim in Stuttgart, Germany. The Biobag is a lightweight backpack used to transport biogas from a central facility, where biogas can be produced more efficiently, to a home.

Biobags leverage the value of a community-wide biogas plant. When filled from a central plant, Biobags have the potential to increase the energy yield from the activity of dung collection and provide a consistent source of energy. The Biobag can be worn like a backpack when full, and then connected to a burner in the home. By placing weights (usually a wooden board with stones) on top of the bag, the pressure of gas pushed through to the burner can be adjusted to the user’s needs. The system is not very scientific, but it works.

A 100m3 biogas plant, using the dung of a herd of 100 cattle, is sufficient to provide biogas for around 30 families. It can be built to much the same robust, simple, domed design as household biogas plants. There are construction savings. Larger biogas facilities deliver more biogas output for a given input. The temperature of larger volumes is more stable and the pH balance is less easily changed. The system can be more professionally managed and there is no need to train members of each household to operate and maintain it. In certain circumstances, larger biogas systems may justify agitation systems or heat to maximise biogas output or to reduce the retention time that is needed. But, on the whole, Pütz believes systems for rural areas in developing countries should be designed simply, and should operate without electricity.

illustration of cattle in field

Business around a Bag

The Biobag is intended to be a part of a small-scale energy business. Biobag users would pay a small fee each day for their biogas and that revenue would encourage system maintenance and re-investment, says Pütz. Ideally, each household would purchase their own bag, but that may not be possible. Pütz is searching for a cheaper manufacturer of the four-ply, gas-tight, bags to make them more affordable for the rural poor.

Millions of people who collect and dry animal dung to burn as a cooking fuel in countries across Africa and Asia meet these criteria, and could benefit from the Biobag.

Certain criteria make the Biobag system more successful. For example, a village structure is needed to centralize the biogas facility and limit the distance customers must travel for fuel. Customers should not be expected to walk more than two kilometres each day for their fuel supply. Furthermore, the system would not be economical where firewood is plentiful and free. People who are already used to using bottled gas or electricity for cooking are unlikely to switch to the less convenient Biobag system. Efficiency of biogas systems can vary considerably from locality to locality – depending on daily and nightly temperatures and humidity, feedstock, and other factors.

Usefulness Test: Willingness to Pay

Pütz asserts that a critical component of success is that funding for biogas projects come from investors, donors, or institutes in the host developing country. Pütz, who gained on-the-ground experience working on aid projects in Rwanda, has seen too many development projects fail once outside funding disappears.

"If the government of a developing country appreciates the project and wants to implement it, then they will find a way to finance it," she argues. "If they don’t really want it – if it is just another project that brings temporary financing into the country – they will say they want it but not follow through....The test is whether they will put in the finance and effort to make it work."

Other efforts around the globe are making progress. The Horn of Africa Regional Environmental Centre and Network in Addis Ababa, Ethiopia, plans to investigate the system’s commercial viability. The network has members in seven countries in the Horn of Africa region. Should pilot projects prove successful, model business plans based on hard data will be developed to attract potential investors.

Investors, manufacturers, and institutions in Bangladesh have also expressed interest in developing a Biobag market in the country. The Grameen social enterprise in Bangladesh may develop the Biobag as a new social business concept.

In Indonesia, a biogas producer is testing the Biobags. The backpack solution would alleviate the current system where Indonesians are using truck-tire inner tubes to transport biogas. Five inner tubes weighing 25kg are needed to transport the 1m3 of biogas that the Biobag holds. They make an awkward load, requiring two people to carry them. Implementing the Biobag as an alternative could make a tremendous difference in the ease and comfort of generating power in rural areas.