What we (and MTA) are saying is that by building a medium or high investment BRT system in the corridor, this would reduce GHG emissions from current levels by getting more people out of single vehicles and moving them more efficiently along the corridor than is currently the case. The significant fuel savings from this system would lead to the reduced GHG levels.Now I understand this argument, but I have to dive in a little deeper. I'm wondering if the following thought is true. If you build an electric system, bus or rail, more electricity has to be produced during peak periods where the rail line is more efficient than the buses burning diesel. At the same time, during the off-peak, does the powerplant have to produce extra power or does that energy already exist in the grid.
The reason light rail would increase GHG emissions over No Build is due to the electricity source, which for this region is primarily coal-fired power plants. While people would leave their cars and move more efficiently along the corridor with light rail, the coal plant emissions generated to produce the electricity required for the Purple Line would exceed the emissions savings from getting people out of their cars.
I've heard ideas about the power grid benefitting from off peak power usage because the plant was going to run no matter what, but I'm wondering if the GHG's are already being produced, therefor any other emissions such as those from the bus are on top of what already existed from the power plant whether the light rail line was there or not. If this were the case, doesn't that reduce the emissions factor of the LRVs because the emissions are already out there from the coal plant? Does anyone know the answer to this or other ideas?