From the website Sustainable Bus:
The Xcelsior CHARGE H2 bus is a battery-electric vehicle using compressed hydrogen as an energy source, as well as Ballard Power Systems fuel cell technology. Fuel cell electric technology complements battery-electric propulsion with the ability to provide extended range of fully zero-emissions operations.
According to MTD, the buses will arrive in 2021.
Photo from Sustainable Bus.
*Correction: MTD is the first to order 60 foot articulated buses.