Population growth and urbanisation levels have increased substantially over the years, outstripping the pace of economic development in the country. These developments have been accompanied by the generation of an increasing quantum of municipal solid waste (MSW) across urban centres. At present, India generates about 62 million tonnes per annum (tpa) of solid waste. Therefore, government bodies face the daunting task of undertaking effective solid waste management (SWM), including segregation, collection, treatment and disposal. However, the growth of the country’s waste
treatment sector continues to be slow. While currently about 75-80 per cent of MSW is collected from the source, only 22-28 per cent is actually processed and treated. However, numerous benefits can be derived by treating and reusing waste. One key benefit is the ability to utilise it as a source of energy. As per industry estimates, one tonne of solid waste is capable of producing about 500-750 kWh of energy, which is equivalent to the energy generated using one barrel of crude oil or 0.25 tonnes (250 kg) of coal. Given this immense potential, there is a need to focus on the development of the waste-to-energy (WtE) generation segment, which could result in significant savings.
WtE scenario
At present, there are over 33 operational WtE plants in the country, spanning 18 states and union territories. These plants have a combined installed generation capacity of 275 MW. Of the total capacity, about 74 MW capacity is installed in the state of Andhra Pradesh alone, followed by Uttar Pradesh and Maharashtra with 58 MW and 36 MW respectively.
The Hyderabad Integrated Solid Waste Management Project in Telangana is one of the key projects in the WtE domain. Developed at a cost of Rs 7.27 billion, the plant has the capacity to treat 5,500 tonnes per day (tpd) of waste. Under the project, two power plants of 24 MW capacity each have been installed at Jawaharnagar. A WtE plant has also been operationalised under the Timarpur Okhla waste management project in Delhi. The plant has the capacity to process 2,050 tpd of waste. The project generates an estimated 121 million units of power.
Meanwhile, six SWM projects for generating energy by treating waste are currently under construction. Once completed, these projects will be able to treat over 9,600 tpd of waste. Besides this, 12 major WtE projects are currently in the pipeline. Together, these projects will have a combined capacity of treating over 8,100 tpd of waste. They are being developed at a total cost of Rs 29.21 billion and are located across eight states. Among these are the Taloja WtE project in Maharashtra and the Gorur MSW management project in Karnataka. These projects will have the capacity to treat 2,500 tpd and 1,000 tpd of waste, respectively, and convert it into energy. Both projects are being developed on a public-private partnership basis.
In spite of these developments, there is still huge untapped potential in the WtE segment. According to Ministry of New and Renewable Energy (MNRE) estimates, India has the potential to generate 2,556 MW of energy through waste processing. Consequently, the MNRE had set a target of 500 MW to be generated from WtE projects during the Twelfth Five Year Plan period (2012-17). In a bid to meet this target and give the much-needed thrust to the WtE segment, the ministry is currently implementing a programme on energy generation from urban, industrial and agricultural waste/residues. Under the programme, the MNRE is implementing five pilot projects for generating power from MSW. Of these, the 16 MW WtE plant at Okhla, New Delhi, has already commenced operations. Work on the remaining four projects, two in Delhi, one in Hyderabad and one in Pune, is currently under way.
The MNRE has also extended central financial assistance to projects implemented under this programme. It will provide Rs 20 million per MW as central assistance, limited to Rs 100 million per project. In addition, incentives such as excise duty exemption, concessional customs duty, accelerated depreciation, a 10-year income tax holiday, and preferential tariffs for grid-connected WtE and bio-compressed natural gas production projects are also being provided. Meanwhile, the Swachh Bharat Mission (SBM), which was launched by the Ministry of Urban Development in 2014, also pays special attention to SWM. Solid waste collection and treatment, and the development of WtE plants form an integral component of the mission. To facilitate such projects, the centre is providing assistance to meet 35 per cent of the total project cost. The funds will be extended in the form of viability gap funding/grants from the central government.
Technology
WtE plants currently operating in the country are primarily based on two kinds of technologies – thermal (mass incineration/refuse-derived fuel burning) and biological (biomethanation). While thermal technology-based projects largely utilise dry mixed waste for their processes, source-segregated wet waste is used in projects based on biological conversion technology.
Both these technologies can further make use of incineration, pyrolysis and biomethanation technologies as a part of their processes. These three technologies not only differ in terms of the type of waste processed but also in terms of the end products. The incineration technology is more suited for processing waste with calorific values greater than 2,500 kCal per kg. The end products generated from this technology are steam, purified flue gas and ash. On the other hand, the pyrolysis technology is more suitable for processing wet organic waste. The end products are often a mixture of combustible gaseous products consisting of simple hydrocarbons and hydrogen, charcoal or bio-oil. The third and the most commonly used technology, biomethanation, is suitable for processing waste with high organic matter and moisture content. The use of this technology leads to the generation of effluents and methane-rich biogas.
Besides the type of waste treated and end products of the treatment, the environmental footprint of technologies used in the WtE generation process also differs. For instance, while incineration and RDF burning is one of the most effective techniques to reduce the volume of waste, it is also accompanied by a high degree of air and water pollution.
Challenges faced
Owing to the varied environmental impact of WtE technologies, several WtE projects have faced public criticism and protests. For instance, the Timarpur-Okhla WtE plant in Delhi constantly receives flak from civic society for its proximity to residential areas, as it poses a potential health hazard. Therefore, it is difficult for civic bodies to identify appropriate land for setting up WtE plants and for garbage disposal. Keeping this issue in mind, developers are considering a cluster-based approach for the development of WtE plants. Further, some state governments such as those of Uttar Pradesh, Madhya Pradesh, Tamil Nadu, Andhra Pradesh, Maharashtra, Haryana, Karnataka, Gujarat and Rajasthan have adopted policy measures for land allotment, garbage supply, and the provision of facilities for sale and purchase of energy. Land for such facilities is provided by the urban local body at a nominal rent to the developer.
Besides this, WtE plant operators also face issues in setting rational price tariffs for the power generated from waste at their sites. This often leads to delays in the finalisation of terms of the power purchase contract. Meanwhile, there is also a need to find solutions to source-based problems such as the absence of waste segregation and ensure that civic bodies are equipped with appropriate technical expertise and skilled manpower.
Conclusion
Treating MSW to generate energy is a promising solution for India’s waste management problem. Not only does it reduce the quantum of hazardous waste, but it also acts as a source of renewable power. Moreover, WtE plants have the potential to reduce the net environmental pollution caused by garbage dumping, in spite of their own environmental footprint.
However, the WtE segment in India is far from reaching its full potential. There is a need to develop effective systems for waste segregation, collection, transportation and treatment. In this context, government initiatives such as the SBM and the programme on energy generation from urban, industrial and agricultural waste are measures in the right direction. Such initiatives will go a long way in strengthening the SWM system in the country.