Making fuel from filth

Photos: Vijay Pandey

An undulation of hills rise along the eastern fringe of Delhi, towering above the surrounding flat land, and giving a cluster of apartment buildings in the distance a run for their height. They’re easily mistaken for an extension of the Aravalli range that skirts the city — until a putrefying stench hits your nostrils.
As you move closer the mirage vanishes rapidly. In the mid-day glare of the summer sun the hills pixelate into the mounds of garbage of the Ghazipur landfill. Layer upon layer of plastic and refuse reveal themselves compacted into layers so dense that roads have been built on them. Up these, edge massive dump trucks carrying more of the city’s waste.
With more than 14 million tonnes of waste, this is one of the largest landfills in the country. If all the waste here was packed into neat cubes with sides of 1 metre each and lined up, it would stretch 4,500 km, far exceeding India’s northsouth extent. By the Delhi government’s own admission, this landfill has far exceeded its capacity, but for the lack of other landfills, it continues to be used.
In this bleakness, however, hope is emerging in the form of an incipient carpet of grass that covers one of the mounds. Atop this mound, the stench is miraculously absent. If it weren’t for the garbage in the backdrop and the kites circling overhead, it’d be easy to imagine this a green hill.
This is the result of a unique experiment being conducted by the East Delhi Municipal Corporation in collaboration with Gas Authority of India Limited (GAIL), which aims to scientifically close landfills and capture the methane that they release into the atmosphere. This greenhouse gas will then be converted into compressed natural gas (CNG). If successful, it will be a template for other landfills in the country.
Once closed, the landfill will not discharge toxins like lead and mercury into groundwater, or particulate matter into the air.
Of Ghazipur’s 70 acres, 10 were set aside for the project. The topmost layer of garbage in this section was, according to Pradeep Khandelwal, the chief engineer of the municipal corporation, about three years old. The lowest layers which lay more than 25 metres below, dated back 10 years.
“Garbage starts generating methane (natural gas) after three to four years,” says Khandelwal, “and production peaks at 10 years.” After 20 years, methane production drops drastically. This site would, in effect, produce significant quantities of methane for the next 10-12 years.
Landfills, After coal mining, are the biggest source of methane in India. The gas constitutes nearly 30 percent of total greenhouse gas emissions in India; and Indian waste with its high organic content (over 50 percent) produces twice the global average for methane produced by waste.
To start with, the steep slopes of the largest mound on the site were contoured into gentle inclines, after which a 20cm thick layer of soil was put on them. The entire hill was then shrouded in a high strength, impermeable plastic sheet that would trap the gases, and also prevent rainwater from mixing with the garbage.