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Evaluation of Strategies to Reduce Greenhouse Gas Emissions

Executive Summary

As a leader in environmental responsibility, the Los Angeles County Metropolitan Transportation Authority (Metro) is pursuing a variety of sustainability strategies to maximize transportation efficiency, access, safety, and performance while minimizing energy use, consumption, pollution, and the generation of waste. This report evaluates current and potential future Metro sustainability strategies for their costs and impacts on greenhouse gas emissions. Strategies include those focused on Metro’s vehicle fleet, buildings, and opportunities to reduce vehicle miles traveled (VMT).

The figure below shows the greenhouse gas reduction cost effectiveness of the strategies that could be quantified. For some strategies, the results are sensitive to a single parameter with a high degree of uncertainty; for these strategies, cost effectiveness is shown as a range (long bar).

The figure shows that a variety of strategies can potentially reduce greenhouse gas emissions for Metro at low cost or a net savings. The most cost effective strategies appear to be:

  • Ridesharing/transit programs for employers
  • Transit oriented development
  • Vanpool subsidy
  • 45-foot composite buses
  • Hybrid non-revenue cars
  • On-board railcar energy storage
  • Red Line tunnel lighting retrofits
  • Facility lighting efficiency
  • Recycled water for bus washing
  • Low water sanitary fixtures

Note that the cost effectiveness metric provides no information on the magnitude of the greenhouse gas (GHG) reduction. Some cost effective strategies produce emission reductions that are several orders of magnitude larger than others. The table below groups the strategies according to cost effectiveness and maximum emission reduction potential. From a greenhouse gas reduction perspective, the most desirable strategies are those that achieve a net savings and offer large emission reductions.

This study considered a number of additional strategies, but did not quantify their emission reduction cost effectiveness due to a lack of data to reliably estimate strategy costs or emissions impacts. These strategies include subway tunnel wind energy capture, battery upgrades in CNG buses, battery electric buses, and buses powered by a hydrogen/CNG blend.

The results presented in this report can help inform Metro’s decisions about future investment in sustainability strategies. As the state of California, and potentially the nation, seeks to achieve greenhouse gas reduction targets, public agencies like Metro will be expected to develop and implement new emission reduction strategies. Moreover, if the U.S. develops a robust market for carbon trading in the future, Metro may be able to generate revenue through its greenhouse gas reduction measures.

It is important to view these results understanding that greenhouse gas reduction cost effectiveness is only one of a number of factors that influences Metro’s investment decisions. All of the strategies evaluated in this report have benefits in addition to greenhouse gas reduction, such as reducing transit operating costs, increasing transit ridership, improving mobility, reducing water use, and providing employee benefits. Some strategies involve significant costs.

Decisions to support any individual strategy should be made based on a composite assessment of all these potential benefits and costs, rather than greenhouse gas impacts alone.