Dept. of Energy taps Piasecki Aircraft to study feasibility of hydrogen fuel cells for UAM

May 28, 2024
The study will assess the use of hydrogen fuel cells as a power source for vertical takeoff and landing (VTOL) urban air mobility (UAM) vehicles, which are anticipated to play a significant role in urban transportation.

ESSINGTON, Pa., - Piasecki Aircraft Corporation (PiAC) in Essington, Pa. announced it has been awarded a Small Business Innovation Research (SBIR) contract by the Department of Energy (DOE) to evaluate the feasibility of hydrogen fuel cell powered urban air mobility (UAM) rotorcraft.

The study will assess the use of hydrogen fuel cells as a power source for vertical takeoff and landing (VTOL) UAM vehicles, which are anticipated to play a significant role in urban transportation. Piasecki has completed the first phase of the program and will begin the second phase later this year.

Under the SBIR program, Piasecki will conduct a technical economic analysis, develop conceptual and preliminary designs, and ultimately develop and test a hydrogen fuel cell-powered VTOL UAM aircraft. The first stage compares hydrogen technology to internal combustion engines and battery rotorcraft to determine metrics such as mission performance, greenhouse gas abatement potential, total cost of ownership, and technology readiness level.

Piasecki's initial study compared a baseline internal combustion Robinson R44 helicopter with three variants: hydrogen fuel cell propulsion with gaseous hydrogen, hydrogen fuel cell propulsion with liquid hydrogen, and battery-powered propulsion. Using the DOE’s Techno-economic Energy & Carbon Heuristic Tool for Early-Stage Technologies, the study showed that hydrogen fuel cell and battery variants have negligible greenhouse gas emissions during use. All variants abate more than 1,300 tons of greenhouse gas emissions over five years compared to the R44 powered by an internal combustion engine conducting the same UAM air taxi mission.

Related: Six hydrogen-powered aircraft that are hitting the skies soon

The study found that the liquid hydrogen fuel cell variant offered the best performance. It matched the range of the internal combustion variant (270 nautical miles) and had superior range compared with the gaseous hydrogen and battery variants. The high specific power of the High Temperature Proton Exchange Membrane hydrogen fuel cells, coupled with the high energy density of liquid hydrogen, allowed the liquid hydrogen variant to complete up to five 50-nautical mile sorties before refueling, compared with less than two sorties for the gaseous hydrogen variant.

The battery-powered variant could not meet the minimum performance required by DOE’s nominal UAM mission profile without stopping to recharge. Additionally, the lower direct operating costs of both hydrogen fuel variants allowed for the recoupment of additional acquisition costs over the internal combustion engine variant within one to four years for the liquid and gaseous hydrogen variants, respectively. The battery-powered variant, while suitable for shorter-range missions, could not recover its acquisition cost premium due to the limited cycle life of batteries under high discharge and recharge rates required by VTOL UAM flights.

The U.S. is developing hydrogen infrastructure as part of its long-term energy security and transition away from fossil fuels. In October, the Biden administration and DOE announced $7 billion to launch the country’s first clean hydrogen hubs and develop a hydrogen infrastructure network.

Related: Airbus-led European liquid hydrogen project underway for aviation and ground operations

Piasecki also announced a $37 million STRATFI contract with the U.S. Air Force to accelerate development of the HTPEM hydrogen fuel cell propulsion system for its PA-890 Slowed Rotor Compound Helicopter, expected to be the world’s first zero-emission hydrogen fuel cell powered commercial helicopter. In partnership with ZeroAvia in Hollister, Calif., Piasecki will develop and test HTPEM hydrogen fuel cells for VTOL applications, including a proof-of-concept flight demonstrator and a full-scale 660kW HTPEM hydrogen fuel cell propulsion test stand for the PA-890. Piasecki recently acquired a 219,000-square-foot helicopter manufacturing facility from Lockheed Martin Sikorsky in Coatesville, Pa., where it plans to assemble the PA-890.

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