Q&A: Behind the Scenes with Zeroing in on ZEBs

How quickly are U.S. transit agencies adopting zero-emission buses (ZEBs)? CALSTART tackles this question every year with its Zeroing in on Zero-Emission Buses report. Lead authors Mike Hynes, Deputy Director of Transit, and Kaila Lemons, Project Manager 1, recently spoke to Jared Schnader, Vice President, Bus Initiative, on the Transition to Zero podcast about the March 2025 edition. Their conversation dives into the current state of the transit industry and gives a behind-the-scenes look at the data collection process, struggles, and successes of this annual endeavor. The questions and answers below have been edited for clarity and length.  

[JS]: What are the takeaways from what you found this year?

[MH]: The positive out of this year is the 14% increase [in ZEB adoptions] from 2023. Of course, we always want to see more than that, but that growth is key. More than 7,000 full-size ZEBs are deployed in the U.S. through July of 2024. That kind of pacing shows that we’ll be at about 15,000 or so deployed vehicles by 2030.  

That is phenomenal. Granted, we’ve got a lot more work to do. But that really speaks to the growth in the industry, the level of effort that transit agencies are putting into deploying these vehicles, the planning, and everything they’re doing. It also speaks to the importance of funding.  

[JS]: What is your process for data collection?

[KL]: The first stage involves outreach to individual fleets and transit agencies as well as state DOTs. We prepare an inventory of all the ZEBs that we know have been awarded, ordered, delivered, and operating, and then send it out for validation, updates, and additional details. We use that inventory as our primary source of truth for updating our data set. 

Stage two is federal awards data collection. One source is USAspending.gov. We try and collect data from a couple different programs, whether that’s low- and no-emission programs, congestion mitigation and air quality improvements programs, the airport zero-emission vehicle and infrastructure incentives, etc. We also collect federal award identification numbers so that we can keep track of exactly which funding source every bus belongs to and make sure we’re not double counting anything.  

Finally, the third step is state awards and press releases. We have a whole list of ZEB-related awards for every state that we systematically go through. We aggregate it all together, do several rounds of data cleaning to make sure everything’s consistent, and then get into the analysis. 

[JS]: What would make it easier for you and your team to do this data collection?

[KL]: There are definitely inconsistencies in how different transit agencies are keeping track of their inventories. Some of that comes down to resources and time availability. Also, there can be differing schedules for when they’re required to report things for regulatory purposes, which tends to be a little bit slower than our pace.  

The other thing is we are trying to collect information on funding for each of these buses. Part of that is so we can validate information, make sure we have consistent counts for how many buses are being associated with each award, and be able to compare that with the award descriptions. In the future, we might have an opportunity to analyze how much of an impact these different funding sources have had.  

But most agencies don’t keep that funding information and their inventory in the same place. It can require some extra effort to pair that information together, which we’re helping them with because we send out their inventory each year. Hopefully [that maintained list] can help them think back on “How successful has this funding been for us?” and maybe we’ll give them some ideas on how they can store data on their site.  

[JS]: Was there anything that stuck out in this report that surprised you?

[MH]: Number one, the growth given the current market. Number two, the small bus fleets: a 25% increase. Universities in particular went up over 100%. It’s really interesting to see that growth, but it speaks to reporting and the data work. We can dig into these unique fleets: universities, airports. We can look at fleets by fuel type: battery electric, fuel cell. We can look at the regional level.  

This year in particular is the first year we’ve really started to see some kind of dramatic call outs between the fleet types. That’s exciting because it’s something we can continue to build on. But it’s also helpful for our members. They can dig into specific fleet types that they’re interested in. It’s helpful when we’re talking with FTA regions or different states, and they have different goals and objectives.  

[JS]: Where was the largest growth in terms of states or regions?

[MH]: Obviously, California continues to grow, but we saw noticeable growth in Texas, noticeable growth in Florida, and again, that noticeable growth in university fleets, which was across the country. Often when we’re talking about zero-emission, we tend to focus on the coastal areas. But we’re starting to see that growth more and more in places like Texas, in small fleets across the Midwest, in university systems that are scattered throughout the country. We’re seeing more and more states adopt these vehicles at a pace that we haven’t seen before.  

[KL]: At this point, every single state in the United States, except for North and South Dakota, have been identified as having a ZEB. It’s really great filling in the map and being able to see that progress.  

Interested in more? Listen to Jared’s episode with Mike and Kaila in full or check out the other episodes of Transition to Zero: https://open.spotify.com/show/7wFM3G4aQocb3sbtEWKsaY 

Read the full Zeroing in on Zero-Emission Buses report: https://calstart.org/zio-zebs/  

About CALSTART:
A mission-driven industry organization focused on transportation decarbonization and clean air for all, CALSTART has offices in New York, Michigan, Colorado, California, Florida, and Europe. CALSTART is uniquely positioned to build the national clean transportation industry by working closely with its 285 member companies and building on the lessons learned from the major programs it manages for the State of California. CALSTART manages more than $1 billion in vehicle incentive and technical assistance programs in the United States and is leading a global effort to build the zero-emission commercial vehicle market.