Waste to energy: the plants that B’luru needs

A couple of years ago, Sweden ran into a unique problem, forcing it to import garbage from Norway and Britain to fuel its power plants. Thanks to an innovative waste-
to-energy (W2E) programme, Sweden was running out of garbage, actually forcing it to import trash from other nations who paid Sweden to accept their garbage because it was cheaper than paying landfill taxes.

A waste-to-energy plant converts solid waste into electricity by burning trash at high temperatures releasing heat to turn water into steam in a boiler. The high-pressure steam turns the blades of a turbine generator to produce electricity. Thirty-four of Sweden’s W2E power plants drop plastic trash bags discarded by hundreds of thousands of homes into power plant boilers that burn trash. About 150-200 tonnes of garbage are normally required to feed a 5 MW plant.

Another bonanza — now that the trash is burnt, it need not go to landfills to decompose and release greenhouse gases causing massive environmental and health disasters leaching toxins into soil and water supplies.

In India, Chennai has plans for two W2E plants in the project report stage, in Perungudi and Kodungaiyur, to generate 32 MW by incinerating waste. Elsewhere, one W2E plant has just started operation in Okhla, New Delhi. Another at Timarpur, Delhi failed due to improper design and an inadequate waste collection system. Two other W2E plants at Hyderabad and Vijayawada also did not work for similar reasons.

Bengaluru generates an estimated 4000-4200 tonnes of waste per day, an ideal quantity to run W2E plants. This requires the Bruhat Bengaluru Mahanagar Palike (BBMP) to streamline its waste collection system, which it has not yet been able to do. It is stuck on segregation of waste with instructions given out to the pourakarmikas (sanitation workers) to collect only segregated waste from households — wet waste every day and dry waste twice a week.

Arguments between sanitation workers and residents have been reported over collection of unsegregated waste. Sanitation workers claim that residents continue to default and then dump waste on roadsides when they refuse to accept unsegregated waste.

Households, on the other hand, are horrified to find carefully segregated waste often mixed up by the sanitation workers. Segregation issues have been overcome by Swedish W2E plants through technical solutions where digital sensors detect unsegregated garbage for organic waste, that gets batted aside by machines onto another conveyor belt to be trucked to a nearby biogas plant.

Another problem staring at the BBMP is the low calorific content of the waste generated by the city which makes it difficult to harness energy by converting the waste to fuel. Moreover, the burning results in pollution and illnesses. Here too, technical solutions exist. A careful choice of the boiler to incinerate the available combustible mix and a boiler stack to dispose of polluting flue gases can ensure a solution at the set-up stage of the W2E plant itself.

With the Karnataka Power Corporation Limited ( KPCL) initiating a tendering process, the city may soon get a W2E plant at Bidadi with 5 MW being generated from garbage. Ironically, there are several unanswered questions about the civic body being able to provide sufficient trash to meet the power plant’s fuel needs.

To generate 5 MW, the BBMP needs to supply 150-200 MT (metric tonnes) of the available 4,000-odd tonnes of Refuse Derived Fuel (RDF) on a trial basis to analyse the characteristics of the fuel and finalise boiler design. The BBMP, sadly, is unable to supply this quantity since dry waste collection is yet to be stre­amlined across its 198 wards!

Nevertheless, the BBMP is also talking to several W2E companies, pre-feasibility reports are being submitted, Detailed Project Reports are being readied and financing is being tied up. Earlier, proposals for seven waste-to-energy plants were cleared by the State Cabinet and the civic body was to float global tenders to use the city’s waste to generate energy.

Each of the proposed W2E units would consume 200-500 tonnes of garbage, take only segregated waste and have a mix of burn technology for the dry waste and biomethanation for the wet waste whereby organic material is microbiologically converted to biogas. While this portends well for the future, three plants approved earlier at Kannahalli-Seegehalli villages, Doddabidarakallu and Chikkanagamangala have yet to materialise, possibly due to opposition from villagers, delayed land acquisition, lack of requisite permissions and infrastructure development related issues.

The W2E plants are an urgent necessity for Bengaluru. Not only does the city’s ever increasing waste require disposing off, but the considerable pressure on landfill sites also decreases. Technical solutions definitely need to be adopted while BBMP’s waste collection needs streamlining.

For the Bengaluru resident, who continues to dutifully pay-up a hefty solid waste management cess along with his property tax to the BBMP, the phrase ‘garden city to garbage city’ isn’t just a cliché. It is a sentiment in itself, associated with the city’s diminishing lustre.

(The writer is a former director on the Board of BEML)