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New Hydrogen Filling Simulation Tool Drives Innovation for Fueling Stations

June 24, 2020

Man standing at a hydrogen fuel station.
Matt Post fuels a Toyota Mirai and a Hyundai Tucson, two hydrogen fuel cell vehicles, at the hydrogen fueling station at NREL’s ESIF. Photo by Dennis Schroeder, NREL

As hydrogen fuel cell electric cars and trucks grow in popularity, a new publicly available Hydrogen Filling Simulation (H2FillS) tool is laying the groundwork for the safe design of hydrogen fueling systems. National Renewable Energy Laboratory (NREL) researchers, in collaboration with Kyushu University in Japan, designed H2FillS to answer vital questions about the change in hydrogen temperature, pressure, and mass flow when filling a hydrogen fuel cell car.

H2FillS models the flow of gas from the hydrogen station to the vehicle's on-board storage system, using a range of fueling conditions to match common hydrogen fuel cell car fill profiles. The model outlines station performance and vehicle fill characterization based on a variety of parameters.

Hydrogen station designers and operators can use the model to calculate parameters such as the pressure drop that occurs due to pipe friction and resulting heat transferred through the filling equipment. Also, H2FillS users can predict the mass flow rate based on the pressure difference between the hose and on-board tank and control that rate at the pressure control valve to meet the target ramp rate.

“NREL is in a unique position where we can fill a knowledge gap between industry and academia,” said Kazunori Nagasawa, the NREL researcher who developed the graphical user interface. “Our challenge was to allow users to flexibly create a system configuration of a fueling station, like LEGO blocks, with parameters of their interests while not violating the constraints of simulation models.”

H2FillS is the first free-to-use validated model of its kind, helping to inform development of novel methods for hydrogen fueling in transportation. The complete, validated, and industry accessible H2FillS fueling model is critical to understanding and improving hydrogen fueling stations and their interaction with hydrogen fuel cell cars, allowing users to bridge the gap between the hydrogen station and vehicle when fueling. Not only does H2FIllS provide guidelines for a safer fueling station design, but it also offers insight into system design requirements and improvements that could help users reduce operating costs.

“A primary focus of this team was to make H2FillS free to use,” said Mike Peters, an engineer at NREL and project team lead. “By allowing anyone to access this model, we hope to encourage innovation within the industry.”

H2FillS is the result of extensive collaboration with Kyushu University as well as support from the U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy Hydrogen and Fuel Cell Technologies Office and eight industry partners through DOE’s H2@Scale initiative: Frontier Energy (industry lead), Ford Motor Company, General Motors, Honda R&D Americas, Hyundai-Kia America Technical Center, Ivys Energy Solutions Inc., Shell, and Toyota. The software was validated by researchers at NREL. Argonne National Laboratory, Kyushu University, Saga University (Japan), Sandia National Laboratories, and Zero Carbon Energy Solutions Inc. made up the project’s Advisory Council that provided technical and programmatic feedback throughout the duration of the project.

“I am excited that this partnership was able to accelerate the widespread adoption of hydrogen fuel cell technology in the transportation sector,” said Taichi Kuroki, the researcher who developed the internal algorithm to predict temperature and pressure of hydrogen within the H2FillS tool. Dr. Kuroki previously worked with Kyushu University, but moved to NREL to focus on the H2FillS project.

H2FillS is easy to use, with an intuitive “drag-and-drop” graphical user interface and the flexibility to define specific parameters when needed. The full-station model allows users to evaluate the high-pressure ground storage through the dispenser system and ends at the vehicle storage system. For a more simplified simulation, users can try the partial-station model to view dispenser components specifically.

The H2FillS team is looking forward to the next step in fueling model development: expanding the tool to simulate hydrogen fueling of medium- and heavy-duty transportation applications such as trucks, buses, and vans.

Access the H2FillS model.

Learn more about hydrogen research at NREL.