Waste to Energy
Waste to Energy

Waste to Energy

In developing countries like India, most of the people don't care about waste, and so never take efforts to dispose it properly. However, the same is not the case with developed countries. This feature explains the importance of waste management and the options available.

Generation of municipal solid waste (MSW), also called urban solid waste, includes predominantly household waste (domestic waste) with sometimes the addition of commercial waste, construction and demolition debris, sanitation residue, and waste from streets collected by a municipality within a given area. These are in either solid or semisolid form and generally exclude industrial hazardous wastes. MSW can be broadly classified into five broad categories:

Biodegradable waste:
food and kitchen waste, green waste (vegetables, flowers, leaves, fruits), paper (can also be recycled).
Recyclable material:
paper, glass, bottles, cans, metals, certain plastics, etc.
Inert waste:
construction and demolition waste, dirt, rocks, debris
Composite wastes:
waste clothing, tetra Packs, and waste plastics such as toys
Domestic hazardous and toxic waste:
medication, e-waste, paints, chemicals, light bulbs, fluorescent tubes, spray cans, fertilizer and pesticide containers, batteries, shoe polish, etc.
As Delhi being a capital city, we have picked it up for our explanation. However case of any other township or city is no different.
Challenges concerning solid waste management in Delhi
Infrastructure for segregation: At present, mixed waste is usually collected and sent to the dump-sites/waste to energy (WtE) plants/compost plants. Effective system of waste segregation is required at appropriate stages, i.e., source of waste generation, collection, transportation, processing and disposal.
Waste management in unauthorised areas:
Delhi has 1,634 unauthorised colonies in three municipal jurisdictional area. The unplanned colonies pose a major challenge for waste collection and transportation as well. Even though, by the statutory provisions, the municipal bodies are responsible for extending waste management services to these households. In some areas, where there are 932 unauthorised colonies as per the records available, the corporation presently provides only sanitation-related activities.

Concerns for solid waste management in Delhi
Waste generation on roadside by street vendors: Hawkers and roadside eateries generate garbage throughout the day and dump them on the roadside. Poor vigilance and monitoring by the local authorities aggravates the problem.

Waste from fruit and vegetable markets: There is no in-house treatment of wet waste generated in fruit and vegetable markets.

Inventorisation of waste: There is no clear idea about how much waste Delhi generates. Further, figures do not keep into account the quantum of garbage managed by the informal sector.

Optimisation/increased participation of informal sector: Waste pickers/informal waste collectors form a vital part of solid waste management. But they are not authorised/registered yet.

Processing of mixed waste: As per the order dated December 22, 2016 of the National Green Tribunal, a waste to energy plant based on mass incineration, besides having low efficiency of waste to energy conversion, is contrary to the Rules of 2016 which requires segregation at source.

Availability of land: There is an issue raised by the local authorities that they do not have appropriate land for processing and disposal of solid waste.

Bye-laws as per SWM Rules, 2016: Unauthorised disposal of waste in vacant plots and open areas is a big issue in the municipal areas. Construction materials and malba on account of construction activities stacked on the roads of other agencies like PWD, DDA, etc.

Lack of compliance and enforcement capacities: There is lack of supervisory staff to oversee operations of solid waste management, which is a big challenge.

Energy recovery from MSW
Energy recovery from waste is the conversion of non-recyclable waste materials into usable heat, electricity, or fuel through a variety of processes, including combustion, gasification, pyrolisation, anaerobic digestion and landfill gas recovery. This process is often called waste to energy.

Energy recovery from combustion
Energy recovery from the combustion of MSW is a key part of the non-hazardous waste management hierarchy, which ranks various management strategies from most to least environmentally preferred. Energy recovery ranks below source reduction and recycling/reuse but above treatment and disposal.

Co-processing of MSW based RDF It is the most economical and scientific way to tackle the alarming problems of MSW. Talking about the situation in our country, untreated MSW currently leads to GHG emissions of around 19 million tons of CO2 eq., which are expected to grow to 41 MT CO2 eq. in a Business as Usual (BAU) scenario by 2030. Cities with more than 1 million population will contribute over 50 per cent of total emission by 2030.

The waste NAMA (Nationally Appropriate Mitigation Actions) focuses on "co-processing of MSW-based RDF in cement kilns" at the national level in which all cities and towns having more than 20,000 populations within 200 km of existing 180 cement plants are considered. Currently, the use of RDF from MSW in cement kilns is at a nascent stage in India with the industry wide thermal substitution rate (TSR) estimated to be around 1 per cent (the average TSR in the EU is approximately 40 per cent). The NAMA implementation can achieve a TSR of 18.8 per cent by 2030 at cement plants, very close to the 19 per cent goal established in the cement sector's Technology Roadmap.

(IEA, WBCSD - Technology Roadmap 2012). This means that 3.1 MT of fossil fuel per year would be replaced by RDF.

The cost of RDF production in India is much higher than the price that cement plants are willing to pay. The NAMA will help address this challenge by suggesting fiscal incentive in form of output-based market development assistance (OMDA), by developing standards of RDF and long term agreements between municipal bodies, waste management companies for RDF production and cement industry.

Total emission reductions generated over the NAMA period 2018-2030 will reach 183.5 MT CO2 eq., i.e., 73.3 per cent of baseline emissions in which 59 per cent reduction will be achieved from fossil fuel replacement and 41 per cent due to methane avoidance. Additionally, the NAMA will provide important economic, social and environmental sustainable development co-benefits.

The cement technology makes it possible to implement ecologically safe waste utilisation with capital investments lower by an order of magnitude than those at waste incineration plants. The primary expenditures are related to the development of facilities for the production of stable caloric fuel from MSW and the addition of solid fuel storage and a facility for fuel supply to the combustion zone to cement works. The above results in fuel cost savings at cement plants (to 55 per cent conventional fuel is replaced). Waste combustion ash is completely utilised, being included in the composition of cement clinker.

Any solid fuel contains a wide spectrum of substances and trace impurities. The main problem in the production of fuel from MSW is to decrease the concentrations of undesirable substances to permissible limits with the maximum retention of a caloric component.

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