Nepal has a long history with biogas technology.
To date, more than 431,629 household biogas plants, 321 institutional and 1,812 community biogas plants have been installed in Nepal. A theoretical estimation reveals that the potential of biogas production from available biomass resources, such as livestock manure, crop residue and municipal solid waste, is 5,351 million cubic metres per year, which is equivalent to 185 million LPG cylinders per year.
However, the Central Bureau of Statistics shows biogas has only 3.1 per cent contribution to cooking energy. This means that a maximum number of installed biogas plants are either unused or non-functional or an issue of data reliability.
Currently, approximately 30 million LPG cylinders are consumed per year for cooking, which makes up about 33 per cent of the household cooking energy in Nepal. If the estimated potential of biogas in Nepal is used effectively, LPG consumption can be replaced completely, reducing the import of LPG worth more than Rs 30 billion in 2077 BS. The GGC 2047 model is the most widely adopted biogas plant in Nepal. Although it has been the most accepted model for several decades, it has some serious technological shortcomings.
GGC 2047 models are made by using materials such as concrete, bricks and steel reinforcement.
With time, there has been a hike in the price of these materials; as a result, the installation price for a biogas plant is continuously escalating. Even government subsidies can't significantly reduce the capital costs of its installation. The inflated price is, therefore, a major reason for the decline in the installation of the biogas plant since the last few years.
Another serious issue with the GGC 2047 plant is methane leakage. Due to the inherent design of the biogas plant, significant amounts of methane leakage during the start-up period is very likely. Moreover, it is necessary to consume the produced biogas on a daily basis due to its capacity to hold only a small volume of gas, otherwise, there is a huge leakage of methane from the plant.
There might also be small amounts of leakage due to the inherent properties of the construction materials (sand, cement and concrete), however, it should be negligible depending on the construction quality.
One of the aims of the biogas plant is to capture methane, which has a 25- 30 times higher global warming potential than carbon dioxide (CO2).
There is a dearth of credible scientific investigation on methane leakage from a GGC 2047 biogas plant installed in the Tarai and hilly regions of Nepal. Depending on the ambient temperature and feeding material of the plant, methane production and, thereby, leakage potential would vary.
Hence, the possibility of leakage from a GGC 2047 should be taken seriously by the concerned government authority and supporting national and international organisations, and they need to take urgent initiative for a credible investigation.
We believe Nepali institutions and experts are ready to support if the concerned organisations seek a credible solution. It is our responsibility to assure national and international organisations to ensure our technology and initiatives are in line with climate protection and sustainable development goals.
Another study involving more than 300 households having GGC 2047 biogas plant in Kavre shows that around 83 per cent of biogas users were not satisfied with the performance of their biogas plants mainly due to insufficient biogas production to meet their cooking energy demand in winter. And it is obvious that biogas production would decrease by about 50-80 per cent in winter.
A study at the Renewable and Sustainable Energy Laboratory (RSEL), Kathmandu University shows that biogas plants have a maximum production potential of methane of about 600 ml/gVSin summer and about 120 ml/gVS in winter, or a reduction by more than 80 per cent. This is another major technical hindrance that needs to be addressed sooner than later.
We believe it is possible to adequately resolve the thermal stability issue of a biogas plant at an affordable cost if the concerned bodies are willing to solve the problem.
There has been a steady decline in biogas plant installation for the past few years in Nepal. In this context, to dig into the technical issues of the GGC 2047 plant, RSEL conducted a webinar "Discussion on Household Biogas Plant (GGC 2047)" on September 28. Various stakeholders, including private, public, development partners and academia, attended the webinar.
All the stakeholders agreed that research and investigation on technical improvement of the GGC 2047 design were needed so that the issues of methane leakage and significant reduction of biogas production in winter could be addressed. In addition, research and development for cost reduction of the GGC 2047 biogas plant, including possibility of using alternative materials, were discussed and agreed upon.
The major concern among the stakeholders was the efficacy of the government plans and programme.
The government has been working for several decades in the promotion of biogas technology, which is still unable to shape a market-driven model and continues to rely solely on the subsidy-driven model.
Problems regarding the existing GGC 2047 model have been identified. And this is the right time for the government and supporting national and international organisations to take the initiative and collaborate with the private and public sector and the academia and lead the initiative.
The government should prioritise its research and development activities so as to address the country's need. Depending on the priority of research and development needs of the country, it should collaborate with relevant national and international academic and research institutions to arrive at a solution.
Research and investigation on technical improvement of the GGC 2047 design are needed so that the issues of methane leakage and significant reduction of biogas production in winter could be addressed.
In addition, research and development for cost reduction of the GGC 2047 biogas plant, including possibility of using alternative materials, is necessary
A version of this article appears in the print on October 18, 2021, of The Himalayan Times.