Table 3 : On-site Emissions from One Transit Bus Driven for a Year at Dulles International ( Lbs .)
Fuel Type NOx
Volatile organic compounds ( VOC )
Carbon monoxide ( CO )
Particulate |
|
|
matter ( PM ) |
|
|
10 |
PM 2.5 |
SOx |
Diesel |
545.7 |
16.2 |
104.7 |
18.1 |
5.6 |
1.7 |
Electric |
0.0 |
0.0 |
0.0 |
13.9 |
1.8 |
0.0 |
Reduction 545.7 16.2 104.7 4.1 3.8 1.7
While on-site emissions are reduced when converting to electric from diesel , some of those emissions are transferred to the point of electricity generation . Based on the analysis , we calculated that an electric bus would consume 170 kWh per day or approximately 62,050 kWh over the course of a year . Based on the regional generation mix of electricity for our airports , 25 lbs . of NOx and 19 lbs . of SOx would be emitted off-site at the point of electricity generation on an annual basis from producing 62,050 kWh of electricity . Given our use of low sulfur diesel fuel for our fleets , converting to electric buses results in a net material increase of SOx emissions while our NOx emissions are still dramatically reduced even when taking electricity generation into account . The PM emissions generated by electric buses , much like that from diesel buses , comes from dust , brake use , and tire wear and tear .
Economic Analysis of Electrifying Authority Buses
While the local air quality benefits are clear , the economic analysis associated with purchasing electric buses is less straightforward and is subject to the Authority ’ s ability to obtain outside financial assistance from the FAA or other entities . Based on conversations with officials from the FAA and a review of past VALE and ZEV grants , ZEV grants have been the primary source of grant assistance for electric buses . Since 2015 , 8 airports have received a total of approximately $ 16.5 million for the purchase of electric buses and related charging infrastructure . As it relates to VALE grants , no airports to date have received grant funding for electric buses even though the program does not exclude them . The standard ZEV grant is 50 % of project costs . 14 However , certain costs associated with modifications to a standard EV bus to meet specific on-site needs and add-ons such as extended warranties , are not eligible project costs .
While fuels savings and a reduction in operations and maintenance costs are likely when deploying an electric bus instead of a diesel or CNG bus , these savings come at an initial cost premium in today ’ s market . An electric bus can cost hundreds of thousands of dollars more than a comparable non-electric bus . In addition , electric charging infrastructure adds tens of thousands of additional costs . In our analysis , this cost premium can approach $ 500,000 per bus , primarily due to the current cost of the batteries and the required charging and other required infrastructure .
Fortunately , battery costs are falling rapidly and as that occurs , more electric buses will be deployed across the country . This deployment will ultimately translate into more real-world data to confirm the actual level of fuel savings and reduced maintenance costs . In addition , to be competitive and alleviate
14 Zero Emissions Airport Vehicle and Infrastructure Pilot Program . Technical Guidance . Version 1 . Accessed on
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