Garbage to gas
- Converting waste to biogas could be a solution to Kathmandu’s mounting energy problems
May 10, 2014-The Kathmandu valley generates around 550 tonnes of solid waste each day and the majority of it is biodegradable. The organic fraction of the municipal solid waste can be converted into biogas in a closed loop-anaerobic digestion plant, also known as Waste-to-Biogas (WtB) system—with the recovery of biogas and nutrients. Biogas is an important energy carrier which can be used for electricity generation or as transport fuel and the nutrients as bio-fertilisers. An integrated WtB system can address the trilemma of energy security, energy equity (national debts on oil imports), and environmental sustainability in Kathmandu.
Short of energy
An absence of energy security and a dirty urban environment are the main problems in Kathmandu. The Kathmandu metropolitan city alone utilised around 25 percent of the total municipal budget, ie, Rs. 443 million in the fiscal year 2012 for solid waste management—mainly to collect and transport the waste to the landfill sites. But frequent disturbances in the collection of waste routinely increase the pile of organic residues and make the city more malodorous than ever.
Likewise, the shortage of electricity supply has resulted in as many as 12 hours of blackout even in the Capital. Also, the government’s response to the price hike on petroleum products and the subsequent roll-back on the decision followed by public unrest has resulted in a huge outflow of foreign currency to India. As of May, 2014 the projected monthly loss stands at Rs 696 million. Nepal is diverting a colossal amount of national developmental budget to finance the import of oil—the country has a total of Rs. 28.5 billion outstanding debt in fiscal year 2012/13, which is close to the national budget of Rs. 30.4 billion in health sector for the current fiscal year 2013/14.
The Valley also noticeably consumes a significant amount of commercial energy. For example, 30 percent of the total electricity generation, 50 percent (300,000 liters per day) of petrol and 60 percent of liquefied petroleum gas (LPG) is utilised to provide energy to around four million urban dwellers—including its 1.5 million temporary population—and 0.7 million vehicles. And it is the urban people who mostly benefit from subsidies given on imported petroleum products. The payment on oil debts could have otherwise been used for ensuring basic needs such as healthcare and education, especially in poor rural areas.
Despite consuming such a large amount of the country’s total available commercial energy (electricity and petroleum products), the Valley’s energy demands remain unmet. This has a negative impact on economic growth. The energy and environment problem spirally increases when the population rises as a result of rapid urbanisation resulting in a huge energy demand and waste generation in urban centers. All of this is testimony to thegreat challenges regarding energy security, financial burdens, and environmental sustainability. In a wake of such crisis, Waste-to-Biogas (WtB) system could be a green solution.
A possible solution
The Waste-to-Biogas (WtB) system
not only manages municipal waste but also helps earn revenues from the
sales of methane-enriched biogas/bioelectricity and bio-fertiliser. The WtB technology is currently being commercialised in developed countries such as Sweden and Germany. Biogas can be used to produce around one-third electricity while two-thirds of it becomes heat. Both light-duty vehicles (cars and jeeps) and heavy-duty vehicles (buses and trucks) can run on methane-enriched biogas and be a substitute for imported petrol and diesel. The utilisation of biogas as a vehicle fuel could be one of the best ways to decrease Nepal’s fossil fuel dependency and cut foreign debt resulting from the import of oil. Additionally, methane-enriched biogas can also be used to substitute LPG for cooking.
The total amount of biogas potential is 101.5 Gigawatt hours (GWh) per annum considering one tonne of biodegradable waste generates 57kgs of methane—equivalent to 87 liters of gasoline or four cylinders of LPG gas. In total, biogas can replace around 10 percent of gasoline or six percent of LPG consumption in Kathmandu Valley. Alternatively, 3.5 MW of reliable, clean and green electricity can be generated by converting waste to biogas. It would result in an annual net savings of around Rs 908 million (petrol) or Rs 829 million (LPG), considering the price at Raxaul gate. The WtB has the potential to avoid a minimum 22,000-27,000 tonnes of greenhouse gas emissions and improve the quality of urban environment. Besides municipal waste, the use of sewage sludge and agricultural waste can also significantly increase the biogas production capacity. The WtB is a closed loop system with a simultaneous recovery of energy and nutrients or biofertilisers. Therefore, it is important to realise these tangible multiple benefits.
The Waste-to-Biogas is not a new concept or technology; many countries have been implementing the WtB system for the production of energy. In Nepal, the implementation of the WtB requires a clear waste-to-energy policy, including legislative framework, institutional arrangements, and financing mechanisms.
The WtB system should then be implemented through a strong government commitment, an active role of private entrepreneurs along with a broader participation of people through awareness creation. Initial investments can come from government subsidies, international carbon financing (carbon investment funds), and private sector fundings similar to several countries who also have direct subsidies, incentives, and low-interest loans for the development of biogas projects.
Revenues generated from a tipping fee (service charge for managing a given amount of waste), the sale of generated energy and bio-fertiliser are the direct cost-recovery options. On the other hand, operational and market incentives such as feed-in tariffs and creation of green certificates based on carbon-neutral and non-polluting fuel can make the WtB system the best option to attract investments from private sectors.
Lastly, the WtB system could contribute in providing energy security, in reducing financial burdens due to the import of subsidised petroleum products and help direct scarce resources to other developmental projects. It can also ensure environmental sustainability with the production of a green energy from abandoned renewable source. A public-private-people partnership approach could also go a long way in creating green cites.
Khatiwada is a postdoctoral researcher at the Energy and Climate Studies Unit, KTH Royal Institute of Technology, Sweden
Published: 11-05-2014 07:58