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August 14, 2019

From waste to energy


August 14, 2019

The recent heavy downpour in Karachi has brought the issue of Municipal Solid Waste (MSW) collection and disposal issue to a high pitch. Indeed the issue has acquired dangerous and colossal dimensions.

The issue is intertwined with the social, political and economic issues of the city – as with most metropolitan cities in the third world. We will throw a light on the technical and economic dimensions of the problem and examine various possible solutions in the context of energy production playing a subsidizing economic and technical role.

Minister Ali Zaidi has in a recent press talk raised and solved an important an important economic puzzle of the issue. What he said is thus; most people reject the waste-to-energy production option as uneconomic and producing expensive electricity; on the contrary, energy production should be understood as a waste disposal option producing energy as a byproduct and supporting the economics of waste disposal.

He is absolutely right. One has to change the way to look at the problem. Still more severe has been a misconception among successive local governments and politicians and administrators, treating MSW as a precious commodity that would yield income. Several investors’ proposals have been rejected in the past on the altar of this fallacy. As a result many rentiers (politicians, administrators, local goons and others) have tried to make money from the so-called 'precious' waste stream, making any waste disposal-cum-energy proposal impossible.

There are two or three components of the problem: waste collection, segregation/recycling and disposal. Disposal requires a lot of space, if not converted/burnt into energy. Thus, not only does energy production generate cash, it also saves space. There are many technical paths starting from simple incineration and using the resulting heat in firing a boiler to produce steam which drives a steam turbine and generator producing electricity. Composition of the waste, however, creates problems; calorific value variations and hazardous substances create dangerous or unhealthy emissions.

Waste-to-electricity power plants have low thermal efficiency (16- 25 percent) comparable to or even lower than bagasse, making MSW an inferior and uncompetitive fuel, breaking the myth mentioned earlier. Secondly, collection cost is very high equalizing its fuel value. It is not like solar and eind Energy that is available at site without transportation. Third, MSW is not a clean fuel.

Emissions generated have to be cleaned and require substantial investments, maybe more than what is required in coal power plants.

So, it is demonstrated that MSW is not to earn money from but a liability to be disposed of. If this premise is accepted, a solution is possible. It will cost about 10-14 USc per unit of electricity. It is not cheap. However, in the context of what the minister said, it is not expensive, if it solves the waste collection and disposal problem. Under the waste-to-energy concept, the power company running the power plant would collect the waste, relieving the government or municipal agencies of the problem that they usually fail to handle reasonably. Karachi’s issue is a ready example.

Electricity is being produced at varied prices. Coal based at 8.5 USc, RFO at 14 USc and RLNG at 10-12 USc depending on seasonal variations of fuel prices. New solar and wind at 4-5 USC, though not yet installed at those rates yet in Pakistan. One of the older wind power plants is costing 18 USc, thanks to capital padding and early entry into wind power. Expensive MSW power in small volumes of 100-200 MW can be tolerated and absorbed in overall cost of generation.MSW is a local fuel costing no foreign exchange.

The cost issue can be handled in a number of ways. DISCOs of the areas can be made legally responsible to buy electricity from the WtE IPP. Nepra may determine the tariff on cost-plus basis, requiring the local government to provide cost-free franchise to collect waste. In Karachi’s case, KE can do this job, as it should have acquired by now quite some skills in dealing with the complex local politics of the city.

Waste disposal methods and technologies vary among countries – depending on a host of factors including waste composition (which in turn depends on living standards), land availability, environmental standards and affordability etc. There was a time in Pakistan when most of the domestic waste was just vegetable waste; now plastic is a major issue.

In the US, 52.5 percent of MSW is land-filled, 25.8 percent is recycled, 12.8 percent is converted to electricity and 8.9 percent is composted. There are 71 WtE Power Plants generating 14 billion kWh from burning about 30 million tons of combustible material. In New York, one of the WtE power plants consuming 2800 MT per day of MSW produces 65 MW of electricity. With Karachi’s MSW, 4-5 times of this much can be produced. In the US, there is land surplus, hence space is available for landfills, which is why there is lesser role for WtE incineration and power plants and more for landfills. In Europe, there are 420 WtE power plants and much fewer landfills for a comparable population and waste generation.

There are a number of other technical variants that could be examined. Waste could be segregated and biomaterial be digested in landfills and biogas can be produced which can be cleaned and used as normal gas or converted to CNG. Inorganic material like paper, plastic and glass could be recycled and remains (if something is left) converted to RDF (Refuse Derived Fuel) which can be burnt in cement plants or coal-fired power plants. All of this can be done. All the governments have to do is reduce the risks of hooliganism and law and order to encourage investors to invest in this area. The issues of federal vs provincial vs local government must also be resolved.

Politics apart, Lahore has been quite successful in solving its MSW problem. Lahore generates 5000 tons/day of MSW, half to one-third of Karachi's MSW generation. Two Turkish companies have been hired to manage waste collection at a charge of 18-20 USD per ton. The landfill site, once a source of stinking smell, has been converted to a park, thanks to the compost being produced out of MSW. Private-sector involvement has led to adoption of many innovative approaches and technologies. Resource Derived Fuel (RDF) is being produced and scientific MSW sorting is being done.

The D G Khan Cement Company is reportedly planning to acquire 1000 tons per day of MSW to use it (after processing) in their furnaces. However, waste-to-electricity production proposals have not materialized, perhaps due to the higher investments required. Salient features are $400 million according to a study done in 2013; burning 2000 tons of MSW per day; and generating 35 MW of electricity, with generation cost estimated at 14 USc.

Law enforcement is an important component of a MSW management system along with the cooperation and awareness of citizens. In some jurisdictions, pre-segregation of waste in homes in two or three bags is a requirement; in Pakistan, it may take quite some effort to take people around to dispose waste in collection boxes. Maintenance of collection boxes often is an issue. Due to local politics and disgruntlement, there are groups in Karachi which attempt to block sewerage system by throwing sacks and refuse in the sewerage lines and spots. Poverty has its own problems and issues. But the problem is solvable, and neither money nor technology is a constraint. Let's do it.

The writer is a former member of the Energy Planning Commission and author of ‘Pakistan’s EnergyIssues: Success and Challenges’.

Email: [email protected]

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