The study was a comparison between diesel hybrids and electric trolleybuses with off-wire capability. All other technologies were dismissed as having either too much environmental impact or being insufficiently mature.
On environmental criteria, the trolleybuses came out ahead on every metric except visual impact. As Seattle City Light’s energy comes mostly from hydro, the Carbon footprint was much smaller. Importantly, overall energy consumption is over 30% lower. This is important because electric vehicle critics often point out that the marginal unit of energy consumed often is quite dirty, since SCL’s surplus is often sold to other jurisdictions, where the alternative might be coal.
One might argue that environmental impacts are nice, but really ought to be addressed in a budget that isn’t supposed to be used for getting people around. Fortunately, the study indicates that, barring a 70% cut in federal fixed guideway funding, a trolleybus system is actually cheaper to operate. This finding, illustrated above, contradicts last year’s audit result.