The challenges in generating power from non-recyclables

The emission of dioxins and furans is a major concern in WTE projects
Last Updated : 18 March 2023, 08:54 IST
Last Updated : 18 March 2023, 08:54 IST
Last Updated : 18 March 2023, 08:54 IST
Last Updated : 18 March 2023, 08:54 IST

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The state’s first Waste-to-Energy (WTE) plant fuelled by segregated dry waste rejects is coming up in Bidadi. A collaboration between Karnataka Power Corporation Limited (KPCL) and Bruhat Bengaluru Mahanagara Palike (BBMP), this project remained in the policy documents for years before finally taking shape.

The 11.5MW plant constructed on 15 acres inside the KPCL’s 150-acre land in Bidadi is set to be operational by September 2023 tentatively. M S Srikar, KPCL managing director, says the WTE project is an important step in the energy transition.

He sees it as an effort to achieve the goals of sustainable energy and waste management. “The KPCL will endeavour to make this transition which will also help in waste management for the city,” he adds.

“If successful, it can be replicated with tremendous potential. We need to look at both centralised and decentralised waste management systems. WTE plants are part of that solution,” says Srikar. He says the plant will be completed by June-July.

Powered by reject dry waste

WTE plants that use incineration are facilities that burn solid waste to generate energy. They are used across the globe to reduce the waste that would otherwise end up in landfills.

In such plants, the waste is burned at a high temperature (around 850 to 1,000 degrees Celsius) to ensure complete combustion. The heat generated is used to generate electricity.

The KPCL and BBMP have planned to exclude organic waste and use reject non-recyclable dry waste, collected from segregated dry waste in the city. High Court had said in the past that biodegradable and recyclable material cannot be burned, but the use of WTE for the residual matter could be considered.

Emission norms: India vs Europe
Emission norms: India vs Europe

However, Bengaluru has a history of opposing WTE projects that use incineration, due to concerns about environmental pollution, toxicity and its effect on public health. Many WTE projects running elsewhere in India, including Delhi and Hyderabad, stand as testimonies to the concerns shared by activists, with problematic management, high emissions and air pollution.

A report by the Central Pollution Control Board (CPCB) submitted to the National Green Tribunal and the Supreme Court in September 2020, showed dioxins, furans and PM2.5 (particulate matter at 2.5 microns) among chief pollutants being released at levels beyond permissible limits by WTE plants located in the Okhla, Bawana and Ghazipur areas of Delhi.

“Okhla is burning unsegregated waste. Residents living near Okhla are complaining of smoke and ash deposits on their terraces,” says Dharmesh Shah, a Kerala-based public policy researcher, affiliated with Break Free From Plastic network.

“Nowhere in the country has the WTE worked successfully, though it has been tried out for the past 10-12 years. The Timarpur plant in Delhi is the first failure story,” he adds.

Dioxin concerns

The emission of dioxins and furans is a major concern in WTE projects. These highly toxic chemicals produced when plastic waste gets burnt can cause various health problems, including cancer.

Industry experts say that to minimise the production of dioxins, waste incinerators should be designed to operate at a minimum of 850 degrees Celsius.

A WTE expert who preferred anonymity says that the process is not exactly ‘incineration’ or indiscriminate burning of waste. It is ‘controlled combustion’, with temperature, time and turbulence regulated. The emissions, called flue gas, are treated scientifically.

A temperature of 950 degrees is advisable to be maintained inside the furnace to ensure that dioxins are not formed. However, as the gas starts losing its temperature, the dioxins may re-form. To stop this, activated carbon is added, which takes care of heavy metals and dioxins. In addition, the sulfur and chlorine-based acidic gases are treated to form salt and water.

To address the problem of particulate matter, there is a back filter—a bag, through which gases are made to flow and the PM gets trapped, which is then cleaned. Any problem in the processes can lead to the failure of the emission control system.

A note shared by KPCL with DH mentions all these mechanisms as planned measures of emission control. “There will be challenges which will be overcome,” says Srikar.

‘Segregation important’

Studies say the required calorific value of waste should be more than 2,500 to achieve sustainable burning and maintenance of high temperatures inside the furnace. So the waste needs to be dry with no moisture.

“The first WTE plant established in Timarpur in 1987 was a complete failure because Indian waste contains a high percentage of organic waste,” points out Shwetmala Kashyap, a senior research fellow at Bengaluru-based Ramaiah Public Policy Center.

“The way our dry waste quantity is increasing due to lifestyle changes, clearly there is a need for this kind of WTE plant. However, a successful WTE project needs source segregation of waste,” she adds.

“If mixed waste with high moisture content reaches the WTE plant, the calorific value will drop. Burning it will take more energy than what it will produce. The system will become imbalanced and unsustainable,” she reasons.

“Even when the fuel is 100% segregated, there are concerns. The technology is often substandard. The main challenge in the WTE plant is pollution control. 50% cost goes into this, as the emission is very high. That is where most of the project proponents go for cost-cutting,” says Dharmesh.

“We compared a 210-tonne capacity Germany plant with the Timarpur-Okhla plant. The cost was three times higher. The WTE technology is very expensive. Environment protection standards are stringent in Europe so they invest in high-standard high-quality pollution control mechanisms,” he says. He was formerly associated with Global Alliance for Incinerator Alternatives.

The project status

The BBMP will bear half of the construction cost—about Rs 130 crores, while the KPCL will bear the rest and take care of operations and maintenance.

“The KPCL has imposed a condition that the waste should have a calorific value of 1,700 or more. Supplying such waste with high calorific value will not be a problem,” says BBMP Special Commissioner (SWM) Harish Kumar.

As per the plans, the BBMP will supply 600 tonnes of refuse-derived fuel (RDF) every day to the plant modelled on the lines of a similar plant being run in Jabalpur considered successful by officials.

The SWM Rules 2016 in India define RDF as “fuel derived from the combustible waste fraction of solid waste like plastic, wood, pulp or organic waste, other than chlorinated materials, in the form of pellets or fluff produced by drying, shredding, dehydrating and compacting of solid waste.”

However, in this case, segregated reject dry waste from dry waste collection centres that otherwise will go to landfill will be the RDF.

Industry experts point out two problems. Will the BBMP be able to give RDF with required calorific value in the long run? Also, the waste has to be supplied continuously by BBMP to make sure the supply is not hit.

The note KPCL shared with DH addresses one of the concerns. A waste pit that can store 4,200 tonnes of RDF is being built. “Even if any interruption occurs in the supply chain, the plant can run for 6-7 days,” says the note. It says that BBMP is responsible for the collection and transportation of dry waste to the Bidadi plant.

“A joint committee has been set up with BBMP to ensure proper coordination, and standard operating procedures will be drafted to make sure a proper supply of quality waste,” says Srikar.

‘Ash can’t be used for bricks’

Dharmesh points to another serious problem. “Countries like Japan and Singapore spend billions on waste management. But they are also in trouble because the ash generated in plants is hazardous. It needs to be disposed of safely.”

“Using toxic RDF waste ash to manufacture bricks and other things is wrong. In India we do it. All toxins in the waste including heavy metals will be in the ash. In Japan, they use a process called vitrification to compress the ash under high pressure and make glass, which is disposed of in landfills. They believe dumping ash directly in landfills can cause pollution,” he adds.

“In India, we don’t have the capacity to deal with this (toxic waste). Therefore we dilute our laws to allow the making of bricks or laying roads with them,” he notes.

KPCL is aware of the issue with the ash produced, though it mentions that the ash generated from WTE plants is used for mixing with concrete products like bricks, hume pipes, paver blocks and roads.

“These users may reject the usage of bottom ash and fly ash if the residue contains toxic content due to the burning of plastic and other inorganic materials. In such situations, this bottom ash shall be disposed of in the landfill site maintained by BBMP,” it adds.

Standards: Europe vs India

Bidadi WTE plant will follow SWM Rules 2016. An expert says that these days, there is a slow shift towards European emission standards, which are much more stringent than the Indian emission norms of SWM Rules 2016. Clients specify emission limits as per European standards, as they feel that emission norms will be stricter in future, he adds.

Dharmesh points out that European countries are phasing out incinerators. “They have come up with a circular economy package where reduction is the main focus. Despite incinerating waste for 30-40 years, their problem has only gotten worse. They end up exporting a lot of waste to Asian countries,” he adds.

“How long do you keep burning plastic? The focus should be on the reduction in the production and consumption,” he says.

Published 17 March 2023, 19:19 IST

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