Solaris Urbino 12 hydrogen

Background

Solaris Bus & Coach began producing city buses under its own brand in 1999, launching the Solaris Urbino family. In 2001, it introduced its first electric-powered vehicle, the trolleybus Solaris Trollino 12. In 2004, Solaris unveiled a low-emission bus powered by CNG, followed in 2006 by the world's first serially produced hybrid city bus, the Solaris Urbino 18 Hybrid. Hybrid buses in the MAXI class were later added to the lineup.^[1] In 2011, Solaris presented the fully electric MIDI-class urban bus Solaris Urbino 8,9 LE electric, followed by 12-meter and 18-meter electric buses in 2013 and 2014, respectively. The Solaris Urbino 12 electric became the first electric bus to win the Bus & Coach of the Year title in 2017.^[1] By 2018, Solaris was Europe's second-largest electric bus manufacturer, holding a 14% market share.^[2]

The first Solaris urban bus using electricity from hydrogen fuel cells was delivered in 2014 under a contract for two Urbino 18,75 electric buses for Hochbahn Hamburg. This technology enabled a daily range of up to 300 km, unachievable by battery-only electric buses without midday recharging.^[3] In 2018, Solaris supplied trolleybuses, Trollino 18,75, to Riga's municipal operator. Equipped with fuel cells, these vehicles could travel up to 100 km without overhead lines, emitting no exhaust and eliminating the need for bulky energy storage batteries.^[4][5]

Urbino 12 hydrogen

In June 2018, Solaris announced plans to unveil the hydrogen-powered Solaris Urbino 12 hydrogen in 2019.^[6] Before its debut, the Urbino 12 hydrogen received the Concept Vehicle award from the German magazine Busplaner.^[7] In April 2019, the bus was pre-released for testing at the depot in Piła.^[8] In May 2019, Solaris secured its first order for 10 Urbino 12 hydrogen buses, with an option for two more, for Bolzano, Italy, to be delivered in 2020.^[9][10] The bus officially premiered in June 2019 at the International Association of Public Transport exhibition in Stockholm,^[10] with plans announced for a 10-week trial by RATP Group in Paris.^[11] The Paris trials took place in 2020.^[12] In August 2019, the prototype bus underwent its first passenger trials with Postbus in Graz, Austria.^[13] In 2021, RVK in Köln, Germany, became the first operator to receive Solaris Urbino 12 hydrogen buses.^[14]

In 2022, Solaris introduced a second hydrogen-powered model, the Urbino 18 hydrogen.^[15]

Drivetrain

The Solaris Urbino 12 hydrogen is a zero-emission vehicle. Hydrogen, the primary power source, is stored in composite tanks above the front axle, holding up to 37.5 kg. The hydrogen feeds a 60 kW fuel cell, where the reaction of hydrogen with oxygen generates electricity stored in 29.2 kWh lithium-ion "Solaris High Power" batteries.^{[6][14][16][17]} The batteries can also be charged via a plug-in connector. The batteries supply electricity to the motors, supporting the fuel cell during peak power demands. The vehicle is powered by a ZF electric drive axle with 2 × 110 kW output.^[10][16] This configuration allows the Urbino 12 hydrogen to travel up to 350 km on a single refueling, consuming approximately 9 kg of hydrogen per 100 km, a range unattainable by battery-only buses without midday charging.^[6][17] The only byproducts of the fuel cell reaction are water vapor and heat, which can be used for bus heating.^[6][7][18]

Chassis

The chassis is based on the fourth-generation Solaris Urbino 12 electric. The front axle is an independent or optional rigid ZF unit, while the rear drive axle is a ZF AVE110. Like other Solaris Urbino models, the bus features an ECAS suspension with kneeling (70 mm) and raising (60 mm) functions. The steering system is a ZF Servocom. Safety systems include ABS, EBS, ASR, optional ESC, a bus stop brake, and a handbrake.^[16]

Body and interior

The bus frame is made of corrosion-resistant stainless steel, with removable side and front panels. Its interior and exterior design draws directly from the fourth-generation Solaris Urbino, updated with a 2018 facelift. Access is via two or three double-leaf doors (with optional single-leaf first doors) measuring 1,250 mm wide. A manual or electric ramp for disabled passengers is installed at the second door, opposite a space for wheelchairs or strollers. The bus is fully low-floor with no transverse steps in the passenger area. It can accommodate up to 37+1 seats, depending on the operator's configuration. Optional air conditioning is available for the passenger area and driver's cabin.^[16] Heating uses a CO₂ heat pump, leveraging heat from the fuel cell to extend range while maintaining zero emissions, eliminating the need for electric or oil-based heating used in battery buses.^[6][19]