Kawasaki has taken a bold step in attempting to integrate hydrogen technology into motorcycles, developing motorcycle and scooter prototypes that run on hydrogen.
Recent patent drawings showcase a hydrogen-powered motorcycle and a scooter, highlighting significant challenges. Unfortunately, these designs inadvertently showcase that current hydrogen technology may not be practical for such applications due to space constraints.
Hydrogen’s Lower Energy Density
The root issue with using hydrogen as a fuel lies in its lower energy density than traditional gasoline. Although one kilogram of hydrogen contains nearly three times the energy of one kilogram of gasoline, the volume required to store hydrogen is immense. For instance, a kilogram of gaseous hydrogen occupies around 11 cubic meters (or 11,000 liters), which is impractical for vehicles without significant compression.
The Need for High Compression
To make hydrogen usable as a fuel, it must be compressed to extremely high pressures to become a liquid, occupying much less space. Typically, hydrogen is compressed to 700 bar, which reduces a kilogram of hydrogen to about 25 liters. Despite this compression, considerable space is still required to store enough hydrogen for practical vehicle use. For instance, a scooter would need to house two 25-liter high-pressure tanks, while a motorcycle might need three or four such or two large 50-liter tanks.
Tank Design Challenges
Another challenge is the design of the hydrogen tanks. Because of the high internal pressures, these tanks cannot come in any form but must be cylindrical, resembling large canisters. This makes them cumbersome and difficult to integrate into the streamlined design of motorcycles or scooters, leading to bulky and awkward vehicles.
Hydrogen Production Inefficiency
Additionally, the production of hydrogen itself poses a significant challenge. While hydrogen can be produced from water through electrolysis, this process is highly inefficient. To generate one kilogram of hydrogen, around 60 kWh of electrical energy is required, nearly double the energy content of the hydrogen produced.
These challenges illustrate why hydrogen-powered motorcycles, while an exciting concept, face numerous obstacles that currently make them impractical. Significant technological advancements in storage, manufacturing, and efficiency will be required for motorcycles and scooters to use hydrogen fuel effectively.
