Climate Change and the Solid Waste Industry
The Earth's atmosphere is like a greenhouse. Life-sustaining heat is trapped within that atmosphere, while some of the sun's harmful rays are reflected away. Climatic changes caused by natural cycles have led to ice or glacial ages and periods of intense heat. During the last two decades, scientific studies have shown a significant increase in atmospheric concentrations of greenhouse gases, primarily carbon dioxide generated by burning fossil fuels such as coal and oil. Other greenhouse gases include methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. Scientific consensus is clear: these emissions are making the earth warmer in an unusually fast time period.
The solid waste industry has successfully reduced its greenhouse gas emissions during the last 3 decades while also continuing to play its vital role in protecting America’s public health and environment. Yet, even as we succeed, we still leave a carbon footprint on the environment. According to the U.S. Environmental Protection Agency, America’s total anthropogenic (man-made) greenhouse gas emissions were 7150.1 teragrams of carbon dioxide equivalent (TgCO2Eq) in 2007. Of this, 160.5 TgCO2Eq were produced by the solid waste and recycling industry.
Learn more by downloading NSWMA's climate change fact sheet (updated May 2011).
Solid waste industry greenhouse gas emissions in TgCO2Eq
||Landfilled yard trimmings and food scraps:
|Percentage of U.S. Totals:
|All data except trucks/process energy from EPA’s Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2007 (http://www.epa.gov/climatechange/emissions/usinventoryreport.html). EPA analyzes America’s greenhouse gas emissions on a yearly basis. Waste industry data can be found at the Greenhouse Gas Reporting Program (http://www.epa.gov/ghgreporting/index.html). That chapter also includes emissions from wastewater treatment plants. They are not included in this discussion of solid waste and recycling greenhouse gas emissions. Data for truck and process emissions is from “Municipal Solid Waste Industry Reduces Greenhouse Gases through Technical Innovation and Operational Improvements”, NSWMA, 2005 http://www.nswma.org).
Carbon dioxide comprises 80 percent of all greenhouse gases emitted in America by human activities. Burning fossil fuels creates most of these emissions according to EPA. The solid waste industry produces less than one half of one percent of America’s carbon dioxide emissions. These come from trucks used to collect garbage, recyclables and compost; truck emissions and energy use at waste transfer stations, materials processing facilities for residential and commercial recyclables, composting facilities; and energy use at landfills and waste-to-energy facilities. As the industry fleet switches to hybrid or alternative fuel trucks, its greenhouse gas emissions should decline. About 4,000 alternative fuel trucks were in use in 2010.
After carbon dioxide, methane is the next most emitted greenhouse gas. Enteric fermentation is the largest source of anthropogenic methane emissions. Landfills are the second largest source, producing less than one quarter of the methane emissions. These emissions account for 88 percent of the total greenhouse gas emissions generated by the solid waste industry. Compost piles also produce a very small amount of methane.
Another greenhouse gas, nitrous oxide, is produced in very small quantities by compost piles and waste-to-energy facilities.
Landfills and climate change
Lowered landfill gas emissions are a tremendous success story for the solid waste industry. Current landfill methane emissions would have been almost twice as high if landfill gas-to-energy projects did not recover methane as an energy source or flare off recovered gas. As of Februrary 2013, according to EPA’s Landfill Methane Outreach Program (LMOP) at least 594 operational projects in 48 states generate approximately 1,813 megawatts of electricity per year and deliver 312 million standard cubic feet per day of landfill gas to direct-use. The energy saved by these projects powers more than 1,001,972 homes and heats more than 729,280 homes. Some of that gas can even be converted into a biofuel and used as a fuel source by specially designed garbage and recycling collection trucks. Environmental benefits of landfill gas recovery are the equivalent of the annual greenhouse gas emissions from nearly 18,500,000 passenger cars or eliminating carbon dioxide emissions from nearly 11 billion gallons of gasoline consumed. Landfill gas recovery plays a part in reducing our dependence on foreign oil. Another way to look at the value of landfill gas recovery is that it is also the equivalent of sequestering carbon yearly from 20.6 million acres of pine or fir forests.
Landfill gas recovery has the potential for even greater returns. EPA also estimates that 510 additional landfill projects have a total gas generation potential of 580 million standard cubic feet per year or electric potential of 1,165 megawatts per year. It is worth noting that the Nobel-winning Intergovernmental Panel on Climate Change (IPCC) states that landfill gas recovery directly reduces greenhouse gas emissions.
Microbial methane oxidation also reduces a landfill’s methane emissions into the atmosphere. In this instance, any uncollected landfill gas goes through the landfill’s cover on its way to being released into the atmosphere. This cover contains bacteria that will react with oxygen and consume some of the methane before it is released. Oxidation reduces another 14.8 TgCO2Eq in methane emissions
Landfills also reduce greenhouse gas emissions in one other important way: they sequester carbon due to incomplete degradation of organic materials such as wood products and yard waste. The IPCC estimates that half of the “organic” fraction in a landfill does not degrade because lignin (a key component of wood) is “recalcitrant” and resists degradation. Cellulose (another key component of wood) also does not degrade quickly.
Waste to energy and climate change
Waste-to-energy facilities lower America’s greenhouse gas emissions by displacing fossil fuel sources. Energy produced at the 86 facilities in the United States produce enough electricity to power almost 1.7 million homes and avoid the production of an equivalent amount of electricity from conventional coal or oil-fired power plants. Along with landfill gas recovery systems, these facilities help reduce our dependence on foreign oil. Energy recovery facilities also lower landfill methane emissions by diverting waste from landfills.
Recycling, composting and climate change
Recycling and composting are other tools the solid waste industry uses to reduce greenhouse gas emissions. Recycling provides tremendous energy savings by converting old products into new products. These energy savings occur because less energy is needed to break down and remanufacture, for instance, a used aluminum can into a new aluminum can, than to extract the raw materials for the can from the ground and process them into materials that can then be used to make a new can.
Percentage of energy saved by recycling compared with raw materials usage
|Source: "Environmental Benefits of Recycling," National Recycling Coalition, 2005. Recycling calculations include emissions from materials collection, separation, treatment (composting), and transportation to a remanufacturing facility.
Americans recycled or composted slightly more than one third of our wastes in 2009, leading to a 2.5 percent reduction in America’s total greenhouse gas emissions. That reduction is more than the amount of greenhouse gas produced by our collection, processing and disposal activities. Recycling paper also increases carbon storage in trees by easing the pressure to cut down our forests.
In fact, researchers estimate that between 1974 and 1997, solid waste and recycling greenhouse gas emissions declined by 78 percent even though waste generation increased by 70 percent in the same time period. These gains were a result of increased recycling, composting, landfill gas destruction and recovery and waste-to-energy, along with better regulation of our landfills.
NSWMA climate change policy
The National Solid Wastes Management Association (NSWMA) believes that improved solid waste management will continue to significantly reduce greenhouse gas emissions. The solid waste industry has dramatically reduced its overall greenhouse gas emissions even as the amount of municipal solid waste has increased.
America's solid waste industry achieved these reductions through increased recycling, composting, landfill gas destruction and recovery, and waste-to-energy, along with better regulation of our landfills. We are developing new technologies such as bioreactor landfills that enhance our ability to more effectively collect and use landfill gas. We are advancing new technologies that allow the use of alternative fuels and engine designs that will lower greenhouse gas emissions from collection and transport vehicles. We continue to find more efficient ways to recover valuable materials through increased recycling and composting.
NSWMA believes that a national greenhouse gas control program should recognize inclusion of landfill gas recovery as an offset in a cap and trade program and as a renewable energy source; support recycling and compost programs; recognize “early actions” that achieved greenhouse gas reductions (e.g., flaring or recovering landfill gas for energy and recycling); and support emission reporting rules that address anthropogenic greenhouse gas emissions and recognize net emissions and reductions on a lifecycle basis to include methane oxidation in landfill covers, carbon storage in landfills, and the impact of flaring off or recovering landfill gas as an energy source. We are proud to be one of the few industries whose greenhouse gas emissions have declined over the last 20 years.
Enteric fermentation - The digestive process used by ruminant animals such as cows, is the leading source of anthropogenic methane emissions.
Greenhouse gas - A naturally occurring chemical that absorbs infrared radiation from the sun and traps the heat in the atmosphere. Major greenhouse gasses are carbon dioxide, methane, and nitrous oxide. Other important greenhouse gases are hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride. In the United States, most of the man-made greenhouse gas emissions come from carbon dioxide emissions associated with combustion of fossil fuels such as petroleum, natural gas, and coal.
Landfill gas - Gas that is generated by decomposition of organic material at landfill disposal sites. The average composition of landfill gas is approximately 50 percent methane and 50 percent carbon dioxide and water vapor by volume. The methane percentage can vary from 40 to 60 percent, depending on several factors including waste composition (e.g., carbohydrate and cellulose content).
Sequestration (storage) - Provision of long-term storage of carbon in the terrestrial biosphere, underground, or the oceans so that the buildup of carbon dioxide concentration in the atmosphere will reduce or slow. In some cases, this is accomplished by maintaining or enhancing natural processes that are part of the carbon cycle, which is the movement and exchange of carbon among its sinks (reservoirs), namely the atmosphere, oceans, vegetation, other living creatures, soils, and geologic deposits and minerals. Waste disposal is one part of the carbon cycle. For example, photosynthesis removes carbon dioxide from the atmosphere and stores it as carbon in trees and plants, which end up in trash as wood, paper and food waste. When this material decomposes, methane is released into the atmosphere, which oxidizes to carbon dioxide and water, and the cycle begins again.
Teragrams of Carbon Dioxide Equivalent (TgCO2Eq) - A teragram is 1x1012 grams. This is the standard measurement of greenhouse gases.