Reducing Waste and Reducing GHG Emissions

By Sunil Sainis

Solid waste reduction has traditionally been motivated by a desire to minimize environmental pollution. In decades past, immediate concerns over local pollution shaped solid waste reduction efforts, and the success of these efforts spawned the global recycling industry. Today, recycled materials are part of the global supply chain for various products.

With the globalization of the economy, we have also seen a rise in awareness of the non-local costs of poor waste management. Extremely large scale pollution effects like the “garbage gyre” phenomena in our oceans are well documented, and these impacts are driving critical innovation in the solid waste management field.

The most pressing global pollution problem is greenhouse gas (GHG) emissions. As the International Panel on Climate Change (IPCC) 2018 report indicates, extremely high atmospheric GHG levels are likely to result in irreversible and abrupt climate change.

In the light of this, one is compelled to recognize the following two points:

1. Our GHG emissions are intimately linked with our lifestyles, which emphasize a “single-use” culture—i.e., use an item like a plastic bag once and throw it away. This single-use culture leads to staggering levels of waste.
2. Any recycling process we propose for reducing solid waste carries with it an associated GHG emission footprint, which may not be favorable to reducing the drivers of climate change.

The first point is relatively easier to comprehend. We simply need to identify key elements of our lifestyle that increase GHG emissions and solid waste. If one were to focus on these elements, then we could see significant progress towards the goal of 45% GHG emissions reduction by 2030 set by the IPCC.

The second point is much harder to grasp. At the conceptual level, one has to recognize that waste management is like any other industrial process. Every industrial process has some inputs, some outputs and a feedback loop. Every process is deliberately engineered or evolves to operate at an optimal cost (usually defined as a yield or an energy cost). Any attempt to change either the inputs or the feedback or the outputs results in the process walking away from its optimal state. In the case of recycling efforts (the feedback loop for solid waste), if one defines the cost in terms of GHG emissions, a similar departure from optimum will be observable.

To illustrate some of the challenges described above, consider the case of plastic bottles. People use these bottles as a cheap substitute for reusable glass or metal containers. Only a small fraction (6%) of these bottles are presently recycled, with the remainder ending up in solid waste. From a recycling perspective, eliminating the use of these bottles is ideal. There is a catch, however: the plastic recycled from these bottles is used to make blended textiles, toys, and other plastic containers. If people were to stop using these bottles, the associated recycling stream would disappear and that would lead to increased demand for virgin plastics from the industry that currently use recycled plastics. As virgin plastics typically have a much higher carbon footprint than recycled plastics, this shift does not bode well for reducing GHG emissions.

There are other environmental benefits to removing single-use plastic bottles from the waste stream besides their availability as a feedstock. Plastics in the ocean, affecting the food chain, is a major concern. But this example illustrates that some comprehensive thinking is in order when proposing to disrupt industrial processes.

The Environmental Protection Agency (EPA), for its part, has looked into these issues in some detail and prepared a set of opportunities for GHG reduction through waste management. It has also offered some guidance in the form of WARMs (WAste Reduction Models) to help with understanding feedback loops in the current process. A careful study of these will be necessary to identify pathways for success in combined reduction of GHG and solid wastes.

Sunil Sainis is a member of the Melrose Recycling Committee and a device physicist by profession.


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