Toyota is boosting hydrogen-powered vehicle technology with liquid hydrogen system design which includes an autopressurizer to save leaking gas and reuse it as fuel to increase engine efficiency.
Toyota introduced a liquid system in the GR Corolla H2 concept in 2023which keeps hydrogen at -253 degrees Celsius during filling and storage in the tank. Hydrogen exists as a gas at room temperature, so pumps must run cold to prevent the liquid from boiling. Inherently, the system still has boiling gas that is wasted.
So what is the solution? toyota exposed a “self-pressurizer” at last weekend’s 2024 Super Taikyu Series race that “uses boiling gas pressure to increase pressure two to four times and produce reusable fuel without using additional energy.” It then hopes to feed any additional boiling to a small fuel cell pack to power the hydrogen bomb motor for greater efficiency.
Liquid nitrogen vehicles are a much more technically grueling affair for both storage and system setup. “Hydrogen bombs are the components most prone to failure in all hydrogen systems, whether cryogenic or gaseous,” writes Dr. Jacob Leachman, a professor at Washington State University, in an email to The edge. “What Toyota seems to have done smartly is develop a hydrogen bomb that harnesses some of the cold energy for compression purposes, a breakthrough needed by anyone developing cold hydrogen vehicles.”
Leachman, who directs the university's Hydrogen Properties for Energy Research (HYPER) Laboratory, said another challenge is that sealing a container of liquid nitrogen and letting it boil will increase its pressure to “more than 140 megapascals (20,000 psi).” .