The newly-elected Mayor of Kathmandu Balen Shah has called waste management of the city his top priority. Even before being sworn in, he visited the Sisdol landfill site to see what a challenge he has given himself.
Mayor Shah wants to incinerate segregated waste at the new dumping site in Bancharedanda, and compost the biodegradable garbage into fertiliser to distribute to farmers.
All good ideas, but what the structural engineer/rapper mayor may have missed is the potential to turn the waste also into biogas.
Urban municipalities across Nepal generate over 2,200 metric tons of solid waste a year, 54% of which is organic, and this could generate close to 10,000 metric tons of methane gas. Gasifying just the waste from Kathmandu Valley could produce 1,700 cylinders of bio-CNG daily.
“Given that more than half of Nepal’s municipal garbage is biodegradable, generating bio-CNG in digesters could be the answer to energy self-sufficiency and sustainability,” writes Sushmita Dulal of WindPower Nepal.
She adds: “This is a win-win, it improves the urban environment, reduces carbon emission and slashes the trade deficit by substituting LPG and chemical fertiliser use.”
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Nepal has already demonstrated that it is a pioneer in household biogas, with more than 300,000 digesters in use that turn farm manure into kitchen gas.
The focus has now shifted from domestic biogas to industrial-scale plants for densely populated urban centres. At present, there are 18 commercial biogas plants across Nepal, nine of them under construction.
One of them is Gandaki Urja in Pokhara, the third industrial-scale biogas plant in Nepal and also the largest, with a digester volume of 3,000 cubic metres. It started operations in December 2019, and has been supplying bio-CNG cylinders to big hotels, restaurants, as well as selling fertiliser made from the effluent.
But the lack of raw material (manure and waste biomass) due to minimal waste segregation at the source, Gandaki Urja is having to feed its digesters waste from agriculture and poultry farms and is only generating 1,200 tons of biogas a day.
Half of the plant’s revenue comes from the effluent which is dried and sold as organic fertiliser in farms in Kaski and Tanahu. The plant can produce up to 11,000 tons of fertiliser a year, and while it is nowhere near Nepal’s total demand of 900,000 tons a year, there will be more organic fertiliser when other commercial plants are built.
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