GreenHeat performance evaluation : slurry-separation technology (SST) biogas systems in Uganda

Abstract

Green Heat was sponsored by SWFF to reach more farmers with their innovative Slurry-Separation

Technology (SST) biogas systems in Uganda and beyond. The technology was intended to separate water

from the waste to be reused for mixing. In addition to recycling water, the SST was expected to create an

easily managed high-quality fertilizer product while increasing gas production for energy consumption.

This field evaluation was conducted to evaluate the performance of biogas technology in general and

the slurry-separation innovation in particular. The survey was conducted July through August, 2019, in

Uganda, four years after the introduction of the slurry-separation innovation.

The sample respondents interviewed included 51 percent men and 49 percent women. Thirteen districts

from across all four regions of Uganda were covered. Farmers? experience with biogas technology ranged

from two months to 11 years.

Through face-to-face interviews, respondents reported benefits of the innovation were energy for

cooking and lighting, soil fertility and productivity, household income improvement, and environmental

sustainability. Fifty-four percent of farmers reported very significant improvement in their household

income, while 96 percent confirmed improvements in the survival rate of their crops. However, the

innovation?s impact on water consumption was not as promising. Of the interviewees, 61 percent reported

their water consumption was increased due to the innovation. This was mainly attributed to the amount

of water required to mix cow dung. Biodigesters equipped with SST contribute toward achieving most of

the UN Sustainable Development Goals (SDGs). However, this survey confirmed that slurry-separation

systems were not properly used in the biogas plants visited. No communal or individual negative impact

resulted from biogas or the SST.