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Measuring Greenhouse Gas Emissions from Waste
Solid waste managers have several different options for managing waste (e.g., source reduction, recycling, incineration, landfilling), all of which affect greenhouse gas emissions differently. In order to determine the best option for minimizing emissions, waste managers need to be able to compare the greenhouse gas impacts of each option. Below are answers to questions on how greenhouse gases from waste management are measured, as well as EPA's role in assisting stakeholders in their measurement efforts.
- How do you measure the greenhouse gas reduction benefits of waste reduction?
- How can I calculate greenhouse emissions from solid waste management?
- How can I calculate life-cycle greenhouse emissions and energy impacts of items I purchase and/or manufacture?
- Why is recycling more beneficial than waste reduction for some material types?
- Can EPA's waste emission factors be used for assigning "ownership" of greenhouse gas emissions reductions?
How do you measure the greenhouse gas reduction benefits of waste reduction?
Currently, the U.S. recycles approximately 32 percent of its waste which saves an equivalent amount of greenhouse gases to removing 39.6 million cars from the road. Increasing the recycling rate to 35 percent would reduce greenhouse gas emissions by an additional 5.2 Million Metric Tons of Carbon Dioxide Equivalent.
The emission factors for these material types for various waste management
scenarios can be viewed in metric
tons of carbon equivalent (MTCE) or in metric
tons of carbon dioxide equivalent (MTCO2E).
Note that the emission factors represent the greenhouse gas emissions associated
with managing 1 short ton of MSW in the manner indicated. Greenhouse gas savings
should be calculated by comparing the emissions associated with the alternative
scenario with the emissions associated with the baseline scenario, as opposed
to simply multiplying the quantity by an emission factor. For instance, the
greenhouse gas savings of recycling 1 short ton of aluminum instead of landfilling
it would be calculated as follows:
(1 short ton × -3.72 MTCE/short ton) - (1 short ton × 0.01 MTCE/short ton) = -3.73 MTCE
The Waste Reduction Model (WARM) incorporates the emissions factors and enables waste managers to analyze their potential to reduce greenhouse gas emissions based on the characteristics of their community's waste stream and the management options available to them. In terms of climate benefits, waste prevention is generally the best management option. Recycling is the next best approach.
Recycling materials reduces greenhouse gas emissions. EPA estimates that current national recycling efforts-32 percent recycling in 2005-yield annual greenhouse gas emission reductions of 49.9 MMTCE, compared to landfilling/combusting the same material. This is equivalent to removing over 39.6 million cars from the road. Increasing the recycling rate to 35 percent would reduce greenhouse gas emissions by another 5.2 MMTCE, for a total reduction of over 55 MMTCE.
Every little bit helps! For example, by recycling all of its office paper waste for one year, an office building of 7,000 workers could reduce greenhouse gas emissions by 546 MTCE, when compared to landfilling. This is the equivalent to taking nearly 400 cars off the road that year. If an average family of four were to recycle all of its mixed plastic waste, nearly 340 pounds of carbon equivalent emissions could be reduced each year.
How can I calculate greenhouse gas emissions from solid waste management?
EPA created the WAste Reduction Model (WARM) to help solid waste planners and organizations track and voluntarily report greenhouse gas emissions reductions from several different waste management practices. WARM is available for free download in Microsoft Excel and as an on-line calculator.
How can I calculate the life-cycle greenhouse gas emissions and energy impacts of products I purchase or manufacture?
EPA created the Recycled Content (ReCon) Tool to help companies and individuals estimate life-cycle greenhouse gas emissions and energy impacts from purchasing and/or manufacturing materials with varying degrees of post-consumer recycled content. ReCon is available for free download as a Microsoft Excel file.
Why is recycling more beneficial than waste prevention for some material types?
For some materials (e.g., aluminum, corrugated cardboard, newspaper, dimensional lumber, and medium-density fiberboard), the greenhouse gas benefits of recycling are greater than source reduction for the current mix of virgin/recycled inputs. This is because recycling is assumed to displace 100 percent virgin inputs, whereas source reduction is assumed to displace some recycled and some virgin inputs. For more information please see "Why Recycling Some Materials Reduces Greenhouse Gas Emissions More than Source Reduction."
Can EPA's waste emission factors be used for assigning "ownership" of greenhouse gas emissions reductions?
EPA’s waste emission factors were designed to estimate the greenhouse gas impacts of the entire life-cycle of the materials analyzed. The emission factors are not intended to assign ownership for greenhouse gas emissions reductions.