- Landfills are the second-largest industrial source of methane emissions in the US
- Landfill gas is approximately 50 percent methane
- The amount of greenhouse gas emissions destroyed annually at the Denton project are equivalent to removing 11,610 vehicles from the road each year
Source: Al Jazeera
Denton, Texas - On an unseasonably cool summer morning in the north Texas town of Denton, Tyler Hurd, the planning and public outreach manager for the city's landfill, spoke proudly of the rubbish beneath his feet.
"Doesn't smell so bad, does it?" Hurd asked with a smile.
Denton's landfill is special: It is the first in the world to employ a new technique for dealing with city waste that will combine established eco-friendly measures with "mining". This involves going through a long-established tip to find metals, plastics and other goods that can be re-sold, to create a sustainable waste disposal system.
Pointing towards a large, sealed-off hill, Hurd explained that this would be the first to be mined. "We recently drilled down into the mound and found a newspaper from the 1980s, and it was readable. It's a 'dry tomb'," he explained. "Should be good for mining."
Being dry is out of the ordinary for waste in the Denton landfill. Since 2009, the dump has injected leachate, or percolated wastewater, into its rubbish-filled plots to speed up the decomposition of organic waste and generate methane gas, which is then collected by gas wells that burrow into the mounds.
The gas is then used to power a generator that currently supplies electricity for some 1,600 homes in the city. This carbon-catching process is referred to as "biomass energy" and the project is administered in conjunction with DTE Denton, a renewable energy company.
|The technique can be referred to as 'closed-loop waste management'. It begins when landfills are separated into 'cells' [Creede Newton/Al Jazeera]
According to DTE's website, the amount of "greenhouse gas emissions destroyed annually at the Denton project are equivalent to removing the emissions from approximately 11,610 passenger vehicles from the road each year".
Soon, equipment will be added to extend the supply of power nearly 4,000 homes. This is far from the only ecologically friendly project on the landfill's grounds. For example, human waste from the city's sewage treatment plant is combined with garden clippings to make compost, all the tip's lorries are fuelled by biodiesel, and bee hives have been established in the grounds to help pollinate surrounding flowers.
"We're trying to become a sustainable landfill, to have as little impact on the environment as possible," Hurd said. One of the impacts landfills have is their expansion. Normally, once a plot is filled, it is covered and a new location is found. With the mining technique, the search and purchase of new lands will be unnecessary.
"It's going to be a perpetual landfill," Hurd said, explaining that the system will be fully operational by January 2017.
The technique can be referred to as "closed-loop waste management" and begins by separating the landfill site into "cells".
If a landfill has four cells, and it takes 7.5 years to fill one cell, by the time the fourth cell is in use, the 20-year period required to make the organic waste in the first cell harmlessly neutral will have passed. Then, mining for metals, plastics and other goods not recycled at the beginning of the process can begin.
That way, according to Sahadat Hossain - the researcher pioneering the perpetual landfill model through the University of Texas Arlington and the Solid Waste Institute for Sustainability (SWIS) - the waste is recycled and the land is sustained "easily [for] 200 years. Currently, a landfill lasts aroun 30-to-35 years".
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What has stopped many from adopting green solutions to landfills, as well as solar and wind energy systems, is their great cost. Hossain acknowledges that his method has to be profitable for it to survive, and he is sure it will be.
"In a landfill in the US, once the land is full, you cover it and monitor the waste for 30 years to make sure it isn't contaminating the soil or air," Hossain told Al Jazeera. "It costs a million dollars a year to monitor, without profit."
|The amount of greenhouse gas emissions destroyed annually at the Denton project are equivalent to removing the emissions from approximately 11,610 cars each year [Creede Newton/Al Jazeera]
With his closed-loop management, US landfills will save millions because monitoring isn't needed.
Originally from Bangladesh, Hossain talked about experiences in his childhood that showed him the perils of living in unsanitary conditions. As a child, he knew a man whose only housing option was to build a hut on top of a rubbish heap.
"The man had to choose between buying pills to treat his sickness or buying bread to eat. If he bought the pill, he would go hungry, and if he bought the bread he would be sick. He was dying either way. Little did he know, the man's living condition is what required the pill," Hossain said. This experience fostered his real passion is implementing this system in the developing world.
The difference in waste collection rates between developed and developing nations is striking. In the United States, more than 90 percent is collected, Hossain said. By contrast, Egypt's waste collection services only cover 30 percent of municipal solid waste, according to a 2011 study by Imad Khatib, a professor at the Palestine Polytechnic University.
"The waste left in the streets contributes to problems with public health, as does waste runoff seeping into the water supply," Hossain said. More than that, landfills are often built in poor areas, which further lowers the property value of homes in these neighbourhoods.
|Since 2009, the dump has injected leachate, or percolated wastewater, into its rubbish-filled plots to speed up the decomposition of organic waste to methane gas [Creede Newton/Al Jazeera]
The profitability of the technique coupled with the benefits to the disenfranchised could take it across the globe. In the summer of 2016, Hossain travelled to six countries, from Africa to Southeast Asia, to meet with government representatives to work out how to implement his technology.
Hossain offered a workshop last August on "technical and managerial aspects of new sanitary landfill construction" of solid waste management in Dar Es Salaam, Tanzania, for decision-makers there. In January, Hossain and SWIS will host their second "Winter School" on their innovative solid waste management and mining for students from around the globe.
'What we should not do'
That is not to say the technologies will not help the US. According to the US Environmental Protection Agency (EPA), 20 percent of the country's greenhouse gases come from landfills and other waste management centres.
This makes dumps the "the third largest source of [methane] emissions" in the US, according to the EPA report.
On top of that, landfill gas "is approximately 50 percent methane, and landfills are the second-largest industrial source of methane emissions in the US", Enesta Jones, a spokeswoman for the EPA, told Al Jazeera in an interview.
The US signed the landmark Paris Agreement in April, which aims to mitigate climate change by reducing greenhouse gas emissions. As one of the world's top producers of these emissions - China and the US account for 40 percent of global greenhouse gas - the US will need to reduce its output 26-28 percent by 2025.
|The goal is to create a zero-waste economy which produces products that are either biodegradable or as permanent as possible [Creede Newton/Al Jazeera]
When asked if the perpetual landfill model could be codified and made the standard for US municipalities, which will need to greatly reduce their ecological impact in light of the Paris agreement, Jones said that current efforts put the US "well on the road towards meeting our Paris commitment".
But "to the extent that additional methods of emission reductions become available, we would consider those in that review", Jones concluded.
Kyle Ash, the senior legislative representative of Greenpeace, had his doubts.
"On the contrary, federal policy often incentivises what we should not do," Ash told Al Jazeera. "Tax policy and access to public lands are two of many ways the government discourages recycling at all, much less mining landfills."
Ash was unfamiliar with the new perpetual landfill model, but after review, he praised Hossain's efforts: "I don't have any criticism about the process and think it's great work," he said.
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However, the environmentalist warned that these "great projects must not reduce motivation to deal with the root cause of our current unsustainable waste stream". With the ever-increasing world population, these perpetual landfills "would be a problem because they themselves would continue to grow in number", he said.
The goal, Ash added, is a "zero-waste" economy "where we produce products that are either biodegradable or as permanent as possible".
Until then, Hossain hopes his method will make a difference, regardless of profits or accolades. In spite of all the talk about profitability, he says, "I'm not in it for the money."
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Source: Al Jazeera News