Landfills pose a major problem for climate change around the world. They release methane, a greenhouse gas. In most developed world countries, 50% of landfill gas is methane, and this contributes significantly to climate change. Although recycling schemes have been introduced, the issue of methane gas is still a problem to be solved.
Happily, the solution may have been developed at the Denton landfill in Texas, US.
Landfills typically last for a set number of years before they are deemed to be filled. Once this happens it can take hundreds of years for the waste to breakdown and no more waste can be added. One of the reasons recycling was introduced was to separate the waste that takes years to breakdown from organic waste. This has helped considerably to fight climate change.
In Denton, they now mine their filled landfills, extracting their recyclable waste and selling it on. This not only prolongs the life of the landfill, but it gives the plant an income. Arguably, what is more impressive is that they capture released methane gas. This is now used to power 1600 homes in the city.
Since 2009 they have pumped leachate- percolated wastewater into the landfill cells. This actually releases methane gas which is captured by gas wells. As well as reducing green house gas emissions, the life of each cell is increased.
This reduces greenhouse gas emissions considerably. To give you an idea, the amount of methane gas captured is the equivalent to the same amount of greenhouse gases generated by 11,610 vehicles a year.
Closed-Loop Waste Management
Landfills are typically made up of cells and each one lasts for around seven and a half years. Once a cell is full it takes around 20 years until the waste can be considered neutral and recyclable materials can be mined. Say the landfill has four cells, the first cell can be mined for waste as the forth cell comes online.
This process prolongs the life of a landfill site. Most landfill sites are full after 30 years. The Denton site is predicted to last 200 years.
Not only does the closed-loop model have fantastic climate change fighting features, it also saves expenditure on land monitoring. Normal landfills require land monitoring to ensure the waste does not contaminate surrounding land. This process costs a million dollars a year. With a closed-loop model there is no need to monitor the land.
Similar schemes to Denton are being developed all the time. Gatwick Airport has just invested in a waste processing plant that will provide electrical power to their North Terminal. Scotland has one of the most advanced glass recycling plants in the world. In many respects recycling and waste management is undergoing a revolution bringing a zero waste economy that little bit closer to becoming a reality.
Hopefully, with the cost savings and income generation that Denton landfill is experiencing, this closed-loop landfill system will be adopted in the developed world. In strong industrial nations such as the US and China, this will be a significant step in fighting climate change.