Implications of LCA Studies on Curbside Recycling in the U.S.

Curbside recycling has been proven to have significant environmental benefits, according to a recent Life Cycle Assessment (LCA) report released by the Environmental Research & Education Foundation (EREF). The study highlights the importance of various factors in determining the effectiveness of recycling programs and their environmental impacts.

The LCA emphasizes that curbside recycling can lead to substantial reductions in greenhouse gas (GHG) emissions and energy use compared to landfilling. However, the environmental benefits of recycling are influenced by several factors. These include the types of materials being recycled, the efficiency of source separation by residents, the structure of the recycling program, and the viability of end markets for recovered materials.

It’s crucial to recognize that waste management entities have limited control over these factors. While they can dictate the type of recycling program, they cannot directly control source separation or the viability of end markets. This highlights the complex interplay of various stakeholders in making recycling economically and environmentally viable.

The LCA study reveals that different materials have varying levels of GHG and energy savings when recycled. Aluminum cans provide the highest emissions avoidance, with 9,130 kg of CO2 avoided per ton of aluminum recycled. In contrast, recycling glass results in the lowest emissions avoidance. Energy savings follow a similar trend, with aluminum providing the highest savings.

However, it’s important to note that these results are based on an idealized recycling scenario. The actual benefits will depend on the recycling system, whether it’s a closed-loop system or an open-loop system where materials degrade in quality over recycling iterations.

The inclusion of different materials in recycling programs has a significant impact on overall GHG emissions reduction. According to the LCA study, including aluminum containers in curbside recycling programs results in the most substantial reduction in GHG emissions. Fiber recycling, including old, corrugated cardboard and mixed paper, provides the largest program-wide energy savings. Glass and ferrous containers show the least benefits in GHG emissions reduction and energy savings, respectively.

However, it’s important to consider that in certain scenarios, recycling certain materials could potentially result in higher emissions or energy use than not recycling them at all. Improving the curbside capture rate in recycling programs presents a significant opportunity to reduce GHG emissions. The study suggests that a 10-percentage point increase in curbside capture could decrease program-wide GHG emissions by nearly 25 kg CO2e per metric ton of Municipal Solid Waste (MSW) managed. Focusing on materials with higher GHG offsets, like aluminum cans, could lead to even greater emissions savings.

The transition to single-stream recycling programs, despite increased contamination rates and energy demand for sorting equipment, has resulted in a significant net reduction in GHG emissions. The increased quantity of recyclable commodities sent for remanufacturing outweighs the negative environmental impact.

The end use of recovered materials from Material Recovery Facilities (MRFs) significantly impact system-wide GHG benefits. Materials with marginal emissions benefits, such as fiber and glass, are particularly affected. However, any deviation from closed-loop or best-case recycling scenarios could substantially reduce or even negate the environmental benefits of recycling.  For example, using recycled glass in non-closed loop situations should be considered carefully, particularly when the transport distance from the recycling facility is significant.

Recycled materials are transported via Over-the-Road (OTR) vehicles, rail, or ocean-going vessels. OTR vehicles have the highest energy use and GHG emissions, while rail and ocean shipping significantly lower these impacts. Maximizing the load on transport vehicles reduces overall GHG emissions, highlighting the importance of transportation efficiency in recycling programs. The geographical location also influences the environmental superiority of recycling compared to landfilling or Waste-to-Energy (WTE) options.

LCAs often rely on ‘best-case’ assumptions due to limited end-use data. However, more comprehensive research is needed to understand how the end use of materials impacts LCAs. For materials with low market demand and negligible environmental benefits in their recovery, landfilling may be a more sustainable short-term option.

EREF’s LCA highlights the complexity of recycling programs and the need to consider multiple factors in their design and evaluation. While recycling is beneficial in reducing GHG emissions and energy use, these benefits are material-specific and influenced by various factors. Waste management entities, residents, and end markets all play essential roles in making recycling economically and environmentally viable.