Biogas stoves enable rural households to turn the waste of their cows and chickens into gas that can be piped into the kitchen (above). Photo: Jasmine Hyman / E Co.

A national program to promote biogas stoves in Cambodia has an uncertain future, thanks to several significant changes that hampered its initial success, according to a new analysis that originated at Yale University and was finished by E Co. and the Stockholm Environment Institute.

The analysis – published recently as an open-access article in Energy for Sustainable Development – focuses on the lessons learned from Cambodia’s National Biodigester Program (NBP).

In its first decade, the program was a success. It installed more than 20,000 biogas stoves (or biodigesters) that enable rural households to turn the waste of their cows and pigs into a methane-rich gas suitable for both cooking and lighting, as well as bioslurry (predominantly used as a substitute for fertilizer). The numerous environmental benefits include reduced fuelwood consumption, lower greenhouse gas emissions and reduced exposure to household air pollution.

But the rate of installations plummeted in 2015, and has not regained momentum. Researchers from E Co. and SEI identified multiple changes that threaten the program’s future viability.

SEI Senior Scientist Rob Bailis, who is a co-author of the analysis, said no single change led to the decline. Rather, it was the fact that several significant changes took place simultaneously.

“It’s hard to apportion blame across each factor, but it’s clear that a few changes really set it back, despite its initial success,” Bailis said. “Programs like this may be more fragile than they appear, and implementers should be cautious when they make major design changes, particularly when external factors that impact the program are also in flux.”

A biodigester and the hut for capturing bioslurry, which can be used as a substitute for fertilizer. Photo: Jasmine Hyman / E Co.

Recommendations for biogas programs

In their analysis, the authors highlighted changes to subsidies, leadership and microfinance availability. The government removed subsidies in 2015 – after which adoption rates plummeted – and then reinstated them later. At the same time, the program’s leadership changed and the government implemented rules that made it more difficult for people to access multiple microfinance loans.

Structural changes in Cambodia may also have made biogas stoves less attractive to residents. Off-farm employment opportunities have increased, leading to a loss in on-farm labour. Rural families have also been reducing their livestock holdings, leaving fewer families with enough livestock to support a domestic biodigester. Rapid rural electrification also means families no longer need the stoves for lighting.

The analysis offers several recommendations:

  • Biodigesters deployed with government subsidies should be required to include some degree of post-installation service.
  • NBP implementers need to take measures to retain the technicians that they train to build and maintain biodigesters.
  • The financial sector could take on more risk on the biodigester technology, considering a lack of default on microfinance institution loans for the Farmer’s Friend biodigester.

The importance of support services

In the early stages of implementation, the NBP focused intensively on building out a complete network of delivery services around the biodigester. This included available and local credit channels, trained masons, quality control technicians, household level promoters, and local biodigester construction companies that could respond to any operational issue. The study shows the importance of these support services in the on-the-ground impact of a household energy initiative.

“Our overarching conclusion from this recent assessment of the NBP is that while this support network still exists, it is less intensively supported at present,” said E. Co. Principal Consultant Jasmine Hyman, a co-author of the analysis. “That, alongside external factors undermining the market for the biodigester, account for the sales slump. It is notable that the technology itself continues to perform consistently and to be valued by its users.”