The United States currently generates 390 million tons of trash per year, or 7 pounds per person per day. Municipal solid waste, or MSW, commonly known as garbage, gets picked up from homes and businesses on a weekly basis and is usually sent straight to a landfill. At the landfill, a hole is dug in the ground and then lined with a man-made liner. As trash begins to fill the hole, methane is emitted as a result of waste being broken down by anaerobic bacteria. Once the landfill is full, it is capped to limit water from seeping into it.
Although many states have the physical space for trash, it is environmentally unsustainable to take garbage and bury it in the ground at landfills, where it decomposes and releases potent greenhouse-gas pollution. What’s more, some trash has to be transported by diesel trucks or trains to landfills several hundred miles away, further exacerbating its pollution footprint. Though garbage is not something we tend to actively think about on a daily basis, specifically as it relates to climate change, the United States must begin developing policies to limit the environmental consequences that result from our generation of garbage.
There are already some efforts in place to help manage trash creation. Though America’s MSW generation has significantly increased over the past decades as a result of population growth, the country has also seen tremendous improvements in recycling and composting efforts, for example. In 1960 the United States recycled only 5 million tons of garbage, but today America is recycling and composting more than 90 million tons. This increase is largely a result of many state and local governments introducing recycling requirements as well as recycling incentives.
But there is another alternative waste management option that America has not significantly utilized but that could help stem the flow of waste, and thus pollution emissions, in our country: energy-from-waste, or EfW, facilities. These facilities provide a means for waste disposal while also generating clean electricity. EfW plants burn garbage in a controlled environment that generates electricity, which in turn is sold to utilities and then distributed to residential, commercial, and industrial consumers.
As America’s population continues to increase, greenhouse-gas emissions, specifically methane from landfills, will also rise as more garbage is generated. Scientists in Hawaii found just last month that the amount of carbon dioxide in the atmosphere jumped dramatically to a new record high in 2013. America’s business-as-usual plan has the nation on the wrong path. Federal legislators need to begin to find more ways to decrease the amount of greenhouse gases in the atmosphere, and a plan that combines increases in EfW usage and recycling and composting would be a good start. This issue brief addresses the need for the United States to increase rates of recycling, composting, and EfW to combat climate change, explains the technology at work in an EfW facility, and makes policy recommendations that will drive down the emissions released by landfills.
Energy from waste reduces greenhouse gas emissions
States can have both EfW and recycling strategies that are compatible. Indeed, communities using EfW technology have an aggregate recycling rate above the national average. Figure 1 illustrates the waste-management hierarchy created by the U.S. Environmental Protection Agency, or EPA, that states and cities have begun to follow. Reducing the amount of trash generated is the most preferred and cost-effective method, followed by recycling and composting practices.
Currently, recycling and composting actions together decrease the United States’ 390 million tons of MSW to 296 million tons, but a nationwide waste standard—mandatory levels of waste to be processed at EfW facilities and landfills—that incorporates recycling goals could reduce this number even further. Nevertheless, waste will always be generated, and instead of disposing of it in landfills, America should be sending it to energy-from-waste facilities.
According to the EPA, for every ton of garbage processed at an EfW facility, approximately one ton of emitted carbon-dioxide equivalent in the atmosphere is prevented. This is because the trash burned at an EfW facility doesn’t generate methane, as it would at a landfill; the metals that would have been sent to the landfill are recycled instead of thrown out; and the electricity generated offsets the greenhouse gases that would otherwise have been generated from coal and natural gas plants.
The European Environmental Agency, or EEA, notes that increasing rates of recycling and EfW will decrease the amount of greenhouse gases a country emits. After the EEA study was released, the European Union adopted proactive waste policies, including the promotion of recycling and EfW as alternative waste-management strategies. In fact, the European waste sector achieved a 34 percent greenhouse-gas-emissions reduction from 1990 to 2007, the largest pollution reduction of any industry in the European Union.
The EPA and EEA are not alone in recognizing the benefits of energy from waste. The Intergovernmental Panel on Climate Change called EfW a “key [greenhouse gas] mitigation measure,” and the World Economic Forum included EfW in its list of technologies likely to make a significant contribution to a future low-carbon energy system.
Trapping methane gas isn’t as beneficial as EfW
Landfills in the United States are using different kinds of available technology to help decrease the amount of emissions released. One such method is to trap methane and use it as energy: Of the 1,900 landfills in the United States, all of which are covered by the EPA’s air emissions and solid-waste-management regulations, approximately 560 are using techniques to capture methane gas and turn it into electricity. These landfills are able to reduce the amount of methane emitted compared to the landfills that do not generate electricity, but even those equipped with methane-recovery systems generate significant emissions for a number of reasons.
First, methane collection does not occur over the duration of the emitting cycle. Landfills are not obligated to collect gas immediately, nor are they required to collect it for the entire period during which methane is being generated by anaerobic decomposition. This often means that only a fraction of the gas that is produced is collected. EPA’s Waste Reduction Model, which tracks greenhouse-gas emissions from different waste-management practices, estimated that when garbage in landfills begins to emit methane, only an average of 34 percent is recovered to produce electricity. Another 38 percent of methane emissions in landfills are flared, which is the process of releasing gas and burning it, and the remaining 28 percent of waste experiences no recovery whatsoever. Consequently, landfills are the third-largest contributor of anthropogenic methane emissions in the country, accounting for 16 percent of total methane emissions as a result of human activities in 2011 and preceded only by the natural gas and agricultural sectors, respectively.
Second, the efficiency of gas collection varies over time even when gas-collection systems are active and their average performance falls short of industry claims. A 2012 report prepared by the EPA and ARCADIS U.S., Inc., an international company that provides consulting and engineering services in the fields of infrastructure, water, environment, and buildings, states that:
Most of the existing data that is available to evaluate fugitive emissions from landfills is based on flux box data. These measurements do not account for the majority of losses found at landfills and therefore can potentially understate the emissions that escape to the atmosphere. With the increased interest in improving greenhouse gas emission inventories and strategies for emission reductions, there is a need to better quantify landfill gas collection efficiency.
To better understand emissions from landfills, the researchers undertook source-measurement approaches and concluded that “the methane abatement efficiency [ranged] from 38 to 88 percent.” In other words, the landfills studied are only capturing an average of 62 percent of methane emissions, despite the 75 percent default gas-collection efficiency recommended by EPA’s guidance for emission inventories.
In order to reduce greenhouse-gas emissions, garbage must be diverted from landfills and sent to EfW facilities after significant recycling and composting efforts are accomplished. In fact, EPA scientists concluded that sending waste to EfW facilities is the better option not only for generating electricity, as the technology is capable of producing 10 times more electricity than landfill-gas-to-energy technology, but also because greenhouse-gas emissions from landfills—even those with optimum conditions for capturing methane and turning it into electricity—are two to six times higher than those generated from EfW facilities.