Energy from waste
October 26, 2010
Many countries in the world lack the infrastructure needed to provide populations in remote regions with heat and light. For half the world's population, meals are cooked on an open fire fueled by wood, coal, dung, and other smoke-producing combustibles. This not only adversely affects the health of rural populations, it also consumes large amounts of fuel and releases high levels of carbon dioxide.
Now, however, there is an alternative.
These days, biogas plants are providing a mainstream renewable energy solution in rural Nepal, allowing people to produce methane by fermenting human and animal waste. Biogas units provide a cleaner and safer source of energy, enabling rural families to produce their own electricity, heat, and fertilizer.
The convenience factor
One advantage of these plants is that they can be used in exactly the place they're needed, thereby averting the need for extensive, costly power landlines. They are easy to assemble, user-friendly, and depend on nothing more than fuel naturally supplied by domestic waste.
In developing countries, domestic biogas plants are used first and foremost to meet the immediate needs of rural populations in regions without infrastructure.
It's an efficient principle, says Andreas Michel, energy expert with the German Technical Cooperation (GTZ). "The dung produced by two or three cows per day is sufficient to make enought methane gas for five hours of cooking or light," he explains. In recent years, the GTZ has helped fund the installaton of several hundred biogas plants in developing countries such as Bolivia and Rwanda. The nations with the highest number of biogas plants are China, Botswana and India.
According to GTZ research, domestic biogas plants represent the optimal application of biogas production systems. Although larger plants can generate enough electricity to supply entire villages - and are usually installed within existing farms, where a steady supply of biomass can be guaranteed - the benefit of domestic plants in terms of cooking and heating are more significant.
The WWF is currently co-funding the installation of 7,500 biogas methane generators in individual households in Nepal. It estimates that each unit can help save an average 4.5 tonnes of firewood and therefore almost four tonnes of CO2 emmissions per year. As Andreas Michel explains, health improves as a result of less particulate matter in the indoor air. A further benefit is that the slurry generated during production can be used as fertilizer for the fields.
The downsides
One crucial aspect is ensuring that all the methane generated is captured and burned. A relatively potent greenhouse gas, methane has can be 25 times more powerful than carbon dioxide in its potential for global warming.
"This is why it is so important to prevent methane escaping into the atmosphere," says Martin Hofstetter, an agricultural expert with Greenpeace.
A further problem is that biogas units cannot be installed just anywhere. Not only do they cost between $300 and $1,200 depending on capacity and country - they are not even an option for impoverishd rural families who have neither land nor cattle, and therefore lack the requisite organic waste.
When biofuels damage food supplies
Moreover, biogas production becomes counterproductive should it stop relying solely on domestic waste, and if fields hitherto used for food crops are converted for the purpose of growing biofuel crops.
"These days, there is a standoff in agriculture between the need to grow non-food biofuel crops, and food crops," points out Hofstetter. The food-versus-fuel dilemna is exacerbated in some countries, such as Germany, where subsidies and tariffs can lead to damaging effects. These include rising food prices, rainforest destruction, and poor farmers being driven off their land by large companies that want to convert it to biofuel crops.
Ultimately, biogas units make most sense when individual families' interests are the first priority, rather than making a profit. Once a biogas plant has been installed, there is little expense because it costs nothing to fuel it. Enabling people in remote corners of the world to generate their own energy can help them change their lives.
Author: Po Keung Cheung (jp)
Editor: Jennifer Abramsohn