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Calculating the Greenhouse Gas Impacts of Residential Waste

What if we could make system-wide comparisons of the greenhouse gas impacts across the lifecycle of various solid waste management options?

Climate change is an issue that affects us all.  Our use of energy and consumption of goods and services, directly and indirectly, accelerates the release of greenhouse gases (GHG) which cause additional heat to be trapped in the Earth’s atmosphere. Businesses and communities across the globe are already experiencing disruptions from the resulting changes to seasonal and short-term weather patterns, and those impacts will get worse if substantial reductions to GHG emissions don’t happen soon.

As a result, many state and local government agencies in the U.S. have set aggressive GHG reduction targets with the message that if policy changes don't happen in Washington D.C., they will happen at the local level.  While these goals are admirable, we often find that numeric targets were set based on consistency with the aims of other agencies, and without a specific action plan. Consequently, staff are sometimes left wondering what is needed from different departments and sectors, and how to assess progress towards long range goals.

The answers are not always obvious. One major U.S. west coast city is actively working to achieve goals for reduction of both the community-wide and municipal GHG footprint, with near-term interim targets and a long-range carbon neutrality goal.  Among inter-related initiatives, the City wanted to better understand the consequences of possible alternatives for management of the solid waste generated by the community. 

To that end, Jacobs developed a "Residential Waste GHG Calculator" to provide City-specific system-wide comparisons of the lifecycle GHG impact of various solid waste management options. The model provides an estimated change to GHG emissions and sequestration as waste is diverted from landfill to other management options. These alternatives include wet or dry anaerobic digestion, in-sink and trucked addition of food waste to wastewater treatment plant headworks prior to digestion, composting, chip & grind, land application of biosolids and recycling using information specific to local conditions and parameters of existing facilities.    

While existing tools, like the U.S. Environmental Protection Agency’s Waste Reduction Model (WARM), provide a high-level comparison of some solid waste management options, the "Residential Waste GHG Calculator” allows for much greater specificity on key variables such as landfill gas collection efficiency, local benefits of biogas use, and specific transportation distances and types of fuels used. This adds up to much more granular and accurate information for waste management staff looking to do their part, as well as providing a strong platform to demonstrate the benefits of waste diversion programs as required to comply with existing and proposed regulations such as California SB 1383. 

Our GHG work with local government clients includes "top-down" analyses of overall reduction strategies and tracking of the portfolio of resulting projects and actions, including use of wedge diagram analysis. It also frequently incorporates "bottom-up" work to support individual departments by executing projects in response to those strategies.  Most importantly, it involves asking the right questions about how GHG or climate resiliency affects the projects and initiatives that are already underway with our federal, municipal and private sector clients.

Doug Huxley is a Principal Technologist and the Carbon Management Community of Practice Leader for Jacobs. He has 20 years of experience in delivering greenhouse gas and climate change solutions for clients in commercial and government sectors and is a key team member of Jacobs’ award-winning program for management of the company’s own GHG footprint.

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