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Report
a solid or hazardous waste complaint to the DNR.
Contact information
For information on any of our forms, contact:
Jennifer Semrau
Waste & Materials Management
608-267-7550

Waste and materials management - the climate change connection

Global climate change poses serious threats to public health, to the economies of the United States and Wisconsin and to the natural environment. We now have a clearer understanding of the role waste and materials management plays in global climate change and, most importantly, the opportunities to reduce greenhouse gas emissions within the waste and materials management sphere.

Landfills produce large amounts of methane, a powerful greenhouse gas created by decomposing organic materials. Methane has a global warming potential at least 20 times greater than carbon dioxide, a less potent greenhouse gas. In the United States, landfills produce 23 percent of all methane generated by human-related sources.

Before a product even reaches the landfill, it has already created a considerable amount of greenhouse gases. Extracting raw materials, manufacturing and distribution of products all use energy and produce greenhouse gas emissions. The U.S. Environmental Protection Agency (EPA) estimates 42 percent of U.S. greenhouse gas emissions result from provision of goods and food.

The easiest way to cut down on these emissions? Reduce the number of products you purchase and use, reuse things that are still in good condition and recycle what is no longer usable. Did you know that Wisconsinites currently throw away more than $100 million worth of recyclables in a typical year? Imagine the economic benefit to our state if we recycled everything we could!

Emissions from materials

There are many ways to reduce greenhouse gas emissions from our landfills. But before a product or material even makes it to the trash can, it has already produced substantial greenhouse gas emissions. Consider an aluminum can. To make that can, aluminum ore was mined, shipped, refined, smelted, rolled and formed. The finished can then traveled to a beverage maker, where it was filled, sealed and labeled; and eventually made its way to a distributor, then retailer, then into our homes.

Each step of this life cycle required energy—in the case of aluminum production, very substantial amounts of energy—and produced greenhouse gas emissions. The same pattern holds true for every other product and material we use. Manufacturing, distribution and consumption all use energy and create greenhouse gas emissions.

The energy required to create a new product can either be partially saved through recycling or reuse or wasted through disposal. If the aluminum can in the above example is thrown away, the energy used in every step of its creation is lost. A new can, requiring new energy expenditures, will need to be made from scratch. Conversely, if the can is recycled, a new can may be made with recycled materials, thereby cutting out much of the production and energy needed to make a new can from virgin materials. For aluminum, that energy savings adds up to about 95 percent of the initial energy requirement, meaning that creating a new can from recycled materials only takes 5 percent of the energy required to make a new can from virgin materials.

Although aluminum has particularly large energy savings compared to other materials, recycling saves energy, no matter what the material. The EPA chart below shows energy savings from recycling for a variety of materials.

Graph showing energy savings per ton recycled
Energy Savings Per Ton Recycled* (Million Btu)

Reduce, reuse, recycle

Recycling materials not only saves energy, it also cuts down on the amount of greenhouse gases produced. The EPA has developed a calculator [exit DNR] to determine what amount of greenhouse gas emissions are prevented from recycling a given product.

Besides energy requirements, the EPA calculator also considers landfill gas emissions and "carbon sequestration" by trees. If trees are left standing rather than being cut down, those trees remove and "sequester," or withhold, carbon dioxide from the air, thereby reducing the amount of carbon dioxide that enters the atmosphere. In other words, reducing paper use and recycling used paper not only saves much of the energy required to harvest, transport, digest and convert wood to paper, it also helps preserves the carbon sequestration capacity of the forest.

Besides energy requirements, the EPA calculator also considers landfill gas emissions and "carbon sequestration" by trees. If trees are left standing rather than being cut down, those trees remove and "sequester," or withhold, carbon dioxide from the air, thereby reducing the amount of carbon dioxide that enters the atmosphere. In other words, reducing paper use and recycling used paper not only saves much of the energy required to harvest, transport, digest and convert wood to paper, it also helps preserves the carbon sequestration capacity of the forest.

Even more greenhouse gas emissions can be prevented through reuse of products. Wisconsin's new electronics recycling law is boosting recovery of used electronics for recycling, refurbishing and reuse. The EPA estimates that recycling a personal computer saves more than double its weight in greenhouse gas emissions, while reusing the same computer, which avoids the production of a new computer, saves more than 50 times its weight in emissions.

The bottom line: reducing the amount of materials and products we use, reusing products that are still functional and recycling materials instead of landfilling them saves tremendous amounts of energy and dramatically reduces greenhouse gas emissions.

Reducing landfill emissions

Reducing landfill emissions

When organic (carbon based) materials are thrown away, they begin to decompose. Decomposition occurs at different rates depending on the material-some organic materials, like grass clippings and most food waste, decompose rapidly. Others, like wood and some types of paper, decompose more slowly.

Decomposition of these materials begins as an aerobic process, meaning that the microorganisms that break down the material have access to oxygen and use it in their metabolic processes. The primary waste products of aerobic decomposition are carbon dioxide and water. However, once waste enters a landfill and is covered by other material, oxygen is soon depleted and different organisms take over decomposition. These organisms work in the absence of oxygen and produce methane as a waste product.

Landfills contain large quantities of decomposable organic materials. In Wisconsin, organic materials have been shown to make up more than half the contents of a typical landfill.

Diverting materials from landfills

The best way to reduce landfill generation of methane is to divert discarded organic material to other uses. Grass clippings, for example, have been banned from Wisconsin landfills since 1993, which has substantially reduced methane emissions that would have otherwise been created by decomposing grass. More recently, there has been increasing interest in recovering food waste for use in compost. Food makes up about 10 percent, by weight, of all landfilled materials, so recovering it for more productive uses would make a big dent in the tonnage of material buried in landfills. Because food decomposes relatively quickly and releases methane before gas collection systems can be installed, diverting food would reduce landfill methane emissions significantly.

Beyond food and yard waste, there are many other opportunities to divert organic materials from landfills. Soiled paper that can't be recycled can generally be composted. Lumber scrap from construction sites can be turned into mulch or fuel. And clean scrap wood from demolition projects can often be salvaged for similar uses.

Landfill gas collection and utilization

In situations where lots of methane is being produced in a landfill, there are productive ways to use it without letting it enter the atmosphere.

New technologies allow landfill methane to be used as a fuel for generating electricity, for heating or for other uses. Most of Wisconsin's large landfills in service today operate methane capture and utilization systems. Those that do not are required to collect methane and burn it, converting the carbon in methane to carbon dioxide, a far less potent greenhouse gas.

Unfortunately, for a number of reasons, landfill gas systems are unable to collect all of the methane generated by a landfill. As new waste is disposed of in landfills, rapidly decomposing material creates large amounts of methane before a collection system can be installed. Also, in older, established landfills, leaks, equipment problems and operating constraints prevent all of the methane produced from being collected. For these reasons, it is best to reduce the amount of organic material that enters any landfill, thereby limiting the amount of methane that a landfill produces in the first place.

For more information on landfill gas collection and utilization, see:

Cleaner landfill cleanups

Many closed landfills that did not incorporate modern pollution protections are now undergoing cleanups to take care of environmental contamination. These cleanups use energy supplied by fossil fuels, but they don't always have to. In addition, closed landfills are underutilized land resources that may provide opportunities for siting innovative renewable energy facilities.

Last revised: Friday June 24 2016