“The primary reason all scenarios saved energy relates to using recovered recyclable materials in remanufacturing relative to processing virgin materials,” the report said. “Thus, the primary means of energy savings when diversion from landfill scenarios are considered is from recycling. Yard waste or mixed organics composting results in some additional fossil energy use due to activities such as curbside collection and pile aeration; as a result, energy savings are slightly reduced for these scenarios.”
However, the report also noted that composting has “other significant environmental benefits.”
“The use of compost has been shown to improve soil quality and structure, control erosion and sedimentation and improve water retention,” the report said. “These benefits would not be captured in impact assessments focused solely on GHG and energy use, such as the one performed in this study.”
Transportation emissions are a relatively small percentage of total emissions, but can still have an effect, the report found.
“This is especially true for materials with more marginal emissions benefits associated with their recycling such as fiber and glass,” it said. Those two materials negate their recycling benefit after going 360 miles by truck for fiber and 1,150 miles by truck for glass.
Plastics and metals can be transported the farthest without negating recycling benefits, upwards of 3,200 miles by truck, or coast to coast.
Actions in control of the industry
Between 66% and 70% of emissions are caused by product manufacturing and consumer behavior, the report noted, and are therefore out of the control of the waste and recycling industry.
“Of the activities the waste industry can control, landfilling has the largest impact on GHG emissions, and efforts to improve gas capture rates provide the highest GHG benefits,” the report advised.
Improving how well residents correctly sort recyclables into the recycling bin can reduce emissions significantly, the report suggested, and there is “significant room for improvement through activities such as education, outreach and labeling.”
Boosting landfill gas capture rates and minimizing downtime of landfill gas management equipment would provide the highest emission reducing benefit for landfilled materials, the report suggested, and transitioning collection vehicles to compressed natural gas or electric would help reduce emissions on the collections side.
Although decisions about remanufacturing processes are not directly within the industry’s control, the report noted that improved MRF design and operation could create better bales to allow better end uses and markets.
“To remain viable long term, the success of recycling and composting rests upon the ability to demonstrate that it can achieve the triple-bottom line of people, planet and profit,” the report said.
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