Kathmandu, Dec. 21 -- In Tanahu district, one of the many areas where Nepal has promoted household biogas for decades, the technology is now showing clear signs of decline.

As researchers moved through mid-hill settlements, they found plants in disrepair-digesters split by cracks, mixers jammed in place, and pipelines corroded after years without maintenance.

Nearly 59 percent of the biogas plants inspected in the district were no longer functioning, the highest failure rate among the areas visited.

Tanahu's experience reflects a wider national pattern. Even in places where biogas took hold early, many systems are now struggling to survive, according to a new study by the Renewable and Sustainable Energy Laboratory at Kathmandu Univers...