Nepal is currently experiencing a combined economic-ecological crisis: rising petroleum imports and a deteriorating environment.
Urban municipal waste management is a pressing issue, even though there is inadequate understanding of waste as a resource puts pressure on landfills and the environment.
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. This is a win-win-win: it improves the urban environment, reduces carbon emission and slashes the trade deficit by substituting LPG and chemical fertiliser use.
Domestic scale biogas technology is one of Nepal’s success stories in the past three decades. The family-level plants offer cooking solutions for more than 0.3 million rural households. However, with growing concern about organic waste management and increasing demand for clean energy, large-scale biogas technology has been gaining traction in recent years.
The government with support from development partners has been exploring the possibility of scaling up the biogas technology and supporting the private sector, factories and municipalities for the installation of large-scale biogas plants.
There are now 344 large-scale biogas plants in the country, but only a few of them have digesters larger than 3,000 cubic meters, considered a threshold for being commercially viable.
These biogas plants primarily utilise biodegradable municipal solid waste, livestock manure and poultry litter as feedstock. After purification, the biogas can be used as an alternative to cooking and transportation fuel.
A recent waste management baseline survey of Nepal indicates that urban municipalities in Nepal generate nearly 2,400 metric tons per year of solid waste on average, more than half of which is organic. This means that almost 10,000 metric tons of purified biogas (bio-CNG) with more than 90% methane concentration can theoretically be produced in the municipalities.
An additional 1.5 million metric tons of bio-CNG per year could be generated using livestock manure across the country. Even if we could use only 10% of this waste, we could still generate nearly 145,000 metric tons of bio-CNG per year — equivalent to more than 10 million LPG cylinders — and help reduce Nepal’s LPG imports by 30%, narrow the trade gap with India and save foreign currency.
Furthermore, the spent effluent from the digesters as a by-product of biogas plants could substantially reduce Nepal’s imports of chemical fertiliser, and promote organic farming.