Metro has released the results of their trolley environmental and life-cycle evaluation study, recommending that new trolley buses are purchased. The report concludes that:
- It is more cost-effective to replace the existing fleet with electric trolley buses based on reasonable federal fixed guideway funding scenarios.
- The electric trolley bus generates significantly lower GHG emissions and has a lower total annual energy consumption. Seattle City Light generates 98 percent of Seattle’s electricity from non-GHG emittingsources (hydroelectric, nuclear, wind, and biomass).
- The environmental comparison favors the electric trolley bus regarding traffic, noise, air quality/climate change, energy, and environmental justice.
The primary component of the study is the life-cycle cost comparison, which includes cost of the buses, fuel or electricity, bus and overhead maintenance, removal of the trolley overhead system, and construction of new fueling facilities at Atlantic base. This section also included a sensitivity analysis which is helpful when projected costs or income are likely subject to unpredictable variation.
The report unequivocally shows the GHG benefit of the trolley system, which emits 21 times less CO2e (equivalent units) than a diesel system, due to the fact that Seattle City Light gets 98% of its energy from non-GHG emitting sources.
Another interesting section, especially for those of you that have been following, is the section on the auxiliary power units (APU). The study looked at both battery and diesel based APUs, comparing their costs, performance, and impact on operations. The report goes on to recommend a lithium ion battery system that can propel buses 1-mile or more. A system like this would reduce 75% of diesel replacement requests and be more redundant in the case of unplanned interruptions of power or reroutes.