of batteries can decrease their expected lifespan . With a 12-year battery warranty , this risk can be reduced although not eliminated
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Recharging electric batteries can take more time than refueling our bus fleets with diesel or CNG . Care must be taken in choosing appropriate recharging strategies , such as overnight charging or installation of more costly fast chargers for meeting Authority needs .
Finally , switching to electric buses will increase our reliance on electricity . As a result , recharging strategies should include an understanding of preferred methods to maintain operations in the event of a prolonged power outage . This could include specifying larger onboard energy storage ( batteries ), redundant systems , or other mitigation methods . In addition , to the degree we deploy stationary batteries at our facilities , we may be able to mitigate some of this risk with back-up energy supplies on site .
We are looking at implementing electric conversions as our buses come to the end of their useful lives . In addition , we will likely maintain a certain number of non-electric buses as back-ups and / or install energy storage should grid power be unavailable . As a result , we can prepare for many of these potential operational risks over time . Also , as we add electric buses to our fleets , we will gain important experience related to fueling , maintaining , and operating the fleet concurrently with technological advancements in the electric bus industry . Both factors should make longer-term conversions to electric more straightforward .
Hybrid Car and Truck Fleet
Across our airports and toll road operations , in addition to our bus fleets , the Authority manages a fleet of approximately 750 vehicles . Less than 1 % of these vehicles currently use alternative fuels ( including hybrids and EVs ) of any kind . However , we have near-term plans to trade out non-hybrid vehicles for 41 new hybrid ones , primarily for our Dulles International police fleet . Over time , we plan to continue adding hybrid and potentially electric vehicles to our fleet given the air quality benefits and the potential cost benefits of having a vehicle fleet less dependent on petroleum . For example , one analysis NREL conducted was a comparison of the ozone emissions between hybrid electric vehicles ( HEV ) and conventional light duty vehicles ( LDV ). In particular , the analysis focused on NOx and VOC emissions because these are the main emissions that form ground-level ozone , otherwise known as smog . The results showed that HEVs emit 41 % less of these ground level ozone precursors than LDVs . This benefit would be in addition to the other air quality benefits associated with the electrification of buses , PTVs , and GSE discussed above . It is noted that an initial review of snow removal equipment and emergency response vehicles has been performed and current technology is not available to meet the primary needs of the Authority . These technologies will be reviewed on a regular basis for potential improvements . It is also noted that hybrid electric fire trucks are beginning to be tested in service with some organizations and we will monitor those developments as well .
Additional Transportation-Related Best Practice Opportunities
Beyond our primary electrification efforts , there is more the Authority can do to improve our overall transportation networks and promote more sustainable means of accessing the airports . These include :
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Partnering with our stakeholders to promote alternative fuel use for taxis , transportation companies , and hotel shuttle buses
Improving non-motorized access to Reagan National ( which is discussed in the public transit section of the Sustainability Plan )
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