Turning Garbage into Gas

  

While incineration endangers lives, gasification will produce transport fuel that can meet half of India’s consumption needs

Delhi’s Chief Minister Sheila Dikshit has been at her wits’ end on how to dispose of the city’s ever growing mountain of garbage. Rising population and growing affluence have raised the daily outpouring of refuse to more than 8,000 tonnes, while simultaneously pushing up the cost of land to astronomical levels. The result: Delhi has run out of land for landfills, and none of the neighbouring States intends to surrender any to meet its needs.

The obvious answer to Delhi’s problem seems to be to burn the solid waste. Cities all over the world are doing it, so why can’t Delhi follow suit? In 2006, the Delhi Municipal Corporation proposed that a small, mothballed, waste incineration plant at Timarpur, that had been put to work for altogether five days since it was built in the 1980s, be reopened to convert 214,000 tonnes of solid waste a year into 69,000 tonnes by sifting out inorganic matter, and drying and palletising the rest to increase its fuel value. Burning this garbage, it was estimated, would produce six megawatts of power per hour, or 5.5 billion units of electricity a year.

The proposal never took off, but it became the springboard for a private sector grab at Delhi’s garbage — investors figured their income would come from the highly inflated tariff decreed by the Central government for ‘green’ energy and the carbon credits they would earn by reducing greenhouse gas emissions.

Their plans are close to maturing. In her 2013-14 budget speech, Ms Dikshit announced that the city already has one incineration plant at Okhla, burning almost 2,000 tonnes a day, and that two more are being set up to incinerate another 4,300 tonnes a day. What’s more, these plants will generate 50 MW of power every hour of the day. More incineration plants are on their way: since the Okhla plant went on stream, the Union Ministry of Environment and Forests has approved eight more plants in various cities.

There is, however, a catch. Incinerating garbage in Delhi will cost an estimated 200,000 ragpickers their jobs. Throughout the world, moreover, countries are closing incineration plants owing to the hazard they pose to human health. The threats come from particulate emissions that greatly exacerbate lung diseases from bronchitis and asthma to emphysema and lung cancer, and from dioxins and furans in addition to the usual nitrogen and sulphur oxide gases in the flue gas.

THE DIOXIN THREAT

To residents of Indian cities who have become inured to dust, smoke, diesel fumes, as well as lead and nitrous oxide poisoning, this may sound like just one more addition to the long list of risks they face in their daily lives. But dioxins belong to another level of threat altogether. The word is a generic term for more than a hundred long lasting chemicals that are produced by burning municipal and medical waste and by a few industrial processes. Dioxins are insoluble in water and when they settle on land and water bodies, they are absorbed in their entirety by terrestrial and aquatic vegetation. They travel up the food chain into animals and fish that feed on plants and thence into humans. Since living organisms cannot metabolise them, they are found in very high concentrations in meat, fish, milk and eggs. In human beings, a prolonged exposure to dioxins — through a ‘rich diet’ — impairs the functioning of the liver and the immune and reproductive systems, and raises the incidence of cancer. In sum, dioxins shorten our lifespan. Men have no way of expelling them. Women can, but only by passing them to foetuses in their wombs or breast-feeding their babies.

Not surprisingly, the U.S. Environmental Protection Agency, which put together the first comprehensive report on dioxins in 1994, described them as “the most poisonous substances known to man.” In Finland, the government has ordered shut an incineration plant built with the most elaborate safeguards when it found, after two years of its operation, that dioxin levels in the surrounding vegetation had risen by 15 to 25 per cent within a distance of 4 km from the plant.

Whenever environmentalists have pointed these hazards out to the Delhi government, its officials and company representatives have assured them that elaborate safeguards have been incorporated into the design of the plants to ensure that they meet prescribed safety norms. But subsequent tests have falsified this claim. In tests carried out at Okhla last year, particulate emissions exceeded norms on four occasions and stayed within them only on six. A test carried out in May 2013 revealed dioxins and furans emissions from its two chimney stacks to be 2.8 and 12.7 times the prescribed maximum!

In the face of such facts, the Delhi government has merely reaffirmed its determination to go ahead with setting up the incineration plants. This has led to the usual accusations of corruption and crony capitalism, but in this case the cause probably lies in two preconceptions that are deeply imbedded in the public mindset. First, that garbage is simply a nuisance and has no economic value whatever; second, since the physical sorting of household refuse is not feasible in India, incineration is the only way out.

Both assumptions reflect the casual ignorance of decision-makers. There is a third way of disposing garbage that not only eliminates all pollutants, but turns garbage into gold. This is to gasify garbage. Gasification is an incomplete combustion of organic matter that replaces a large part of the carbon dioxide we get from combustion with carbon monoxide and hydrogen. These two gases are, and have been for a hundred years, the basic building blocks of the world’s petrochemicals industry. They are also ideal for driving gas turbines to generate power. From India’s perspective, their best feature is the ease with which they can be synthesised into any transport fuel one desires, and into Di Methyl Ether, a condensate gas that is a superior diesel substitute and a complete substitute for Liquefied Petroleum Gas (LPG).

Gasification also eliminates the threat from dioxins. When gasification is carried out with oxygen, it produces only seven per cent of the flue gas obtained from combustion. The reaction takes place, moreover, at such high temperatures —1000 to 3,000 degrees Celsius — that dioxins and furans get broken down into their basic elements, losing their toxicity. The release of dioxins from a 24 tonne-per-day plasma gasification plant that has been running for more than a decade in Yoshii, Japan, has been found to be less than one per cent of that released by corresponding incineration plants. Consequently, city and municipal corporations around the world have begun to switch to gasification. According to the U.S.-based Recovered Energy Inc., a turnkey engineering company specialising in renewable energy projects, there are 200 Municipal Solid Waste (MSW) gasification plants under construction or in operation globally, of which half use the revolutionary new technology called plasma gasification.

ISOLATED VENTURES

Ironically, India already has employed plasma gasification technology — for the past four years, two 68 tonnes-a-day commercial plants employing this technology have been disposing of medical and other hazardous wastes in Pune and Nagpur. Since Indian states do not share information, however, these have remained isolated ventures.

At present, most MSW gasification plants abroad produce electricity. But this is giving way to the production of transport fuels. British Airways is partnering Solena, a U.S.-based biofuels company, to set up a plant that will gasify 1,300 tonnes a day of London’s solid waste to produce 16 million gallons of Aviation Turbine Fuel and 9 million gallons of naphtha in addition to generating up to 40 MW of power. This plant is expected to meet two per cent of British Airways’ global demand for jet fuel. Solena has won contracts for similar plants with Qantas, Lufthansa and SAS. Lufthansa’s plant will have a modification that New Delhi will do well to take note of: instead of naphtha, it intends to produce 9 million tonnes of diesel fuel.

India stands therefore at a crossroads. In 10 years from now, 600 million Indians will be living in cities with more than a million inhabitants who generate at least 600,000 tonnes of garbage a day. Incinerating this garbage will endanger the lives of future generations. Alternatively, this is sufficient to produce more than 35 million tonnes of transport fuel a year and meet half of India’s current consumption of the same. The saving in foreign exchange will lift the threat of a foreign exchange crisis forever. It will also free domestic prices from the yoke of international oil prices forever. And it will do all this without requiring a rupee of subsidies.

PREM SHANKAR JHA

(The writer is a senior journalist)

courtesy: 'THE HINDU'