Session: 12-03: Hydrogen Energy, Alternative Fuels, Bioenergy, and Biofuels

Paper Number: 138281

138281 - Hydrogen Leak Modeling for Development of Smart Distributed Monitoring Under Unintended Releases 

Abstract: 

Hydrogen is a versatile and clean energy carrier that can be produced through water electrolysis using various renewable sources, such as wind, solar, and hydropower. Hydrogen has the potential to play a crucial role in decarbonizing industrial processes that are currently reliant on fossil fuels and provide long-duration and/or seasonal energy storage to enable electricity decarbonization. Fuel cell electric vehicles (FCEVs) are hydrogen powered, providing a zero-emission alternative to traditional internal combustion engines. DOE launched the Hydrogen Energy Earthshot (Hydrogen Shot) in June 2021 to reduce the cost of clean hydrogen by 80% to $1 per 1 kilogram in 1 decade ("1 1 1"). While promising, hydrogen is highly flammable, and in the presence of oxygen, it can form explosive mixtures. Therefore, understanding leak scenarios is essential for evaluating and mitigate the safety risks associated with potential hydrogen leaks. An increased understanding of leak behavior and having tools to model leaks can help assess how hydrogen would disperse in different environments, influencing emergency response plans and safety measures, identify potential issues with materials, and design systems that can withstand the challenges posed by hydrogen. Recently, researchers have attempted to study hydrogen leaks for the development of risk management strategies. However, the focus has been on closed or semi-closed spaces like storage rooms, vehicles, garages, and fueling stations—all promising locations for future hydrogen infrastructure. In this presentation, the modeling environment extends research further by modeling hydrogen leak in an outdoor, open space. We will present the key challenges with modeling hydrogen leaks in an uncontrollable environment, how they were handled, and how modeling results informed sensor selection and placement.

A hydrogen research facility at the National Renewable Energy Laboratory (NREL) served as a case study to model hydrogen leaks (specifically, the NREL Advanced Research on Integrated Energy Systems; see https://www.nrel.gov/aries/). In the future, hydrogen wide area detection methodologies will be developed and tested at this site to monitor for unintended and operational hydrogen releases. A predictive model to detect hydrogen leak location based on the concentrations measured by sensors in this open space will be developed from the data generated by this model. Furthermore, the facility was also chosen because controlled hydrogen releases can be performed.

A computational fluid dynamics (CFD) based modeling approach was taken to model hydrogen releases.  The full-scale hydrogen facility was modeled with a large ambient domain. The electrolyzer at the facility can produce a controlled release rate of 27 kg-H₂/hr. The model used site-specific atmospheric and weather condition data, including wind direction, wind speed at various altitudes, and temperature, as inputs. To capture the variability of weather conditions, a subset of the weather conditions experienced during daytime hours without precipitation over the course of three months was generated; using established data clustering techniques, a total of 100 condition sets were chosen.

The results show statistical distributions and ranges of hydrogen concentrations at locations throughout the domain. These distributions will be compared to experimental data from a constant mass flow, controlled hydrogen release at the facility. The stochastic wind conditions of the release make direct validation difficult, therefore, statistical comparison approaches were necessary. Wind conditions had a significant impact on the release behavior, including direction and concentration. Sensor selection and placement is proposed for the facility and is now based on release behavior predicted for the facility given its weather patterns; this is much more informed than without the modeling results. The methodology and analysis procedure can be translated to other facilities using modified geometries and site-specific weather conditions.

Hydrogen holds great promise as a renewable energy fuel, but ensuring safety in its production, storage, and use is paramount. Studying potential leak scenarios in an open space will help develop sensors to detect hydrogen on a large spectrum of concentration and eventually build a smart distributed monitoring system.

Presenting Author: Jeffrey Gifford National Renewable Energy Laboratory (NREL)

Presenting Author Biography: Jeffrey Gifford is a postdoctoral researcher at the National Renewable Energy Laboratory after completing his Ph.D. in the Advanced Energy Systems program at the Colorado School of Mines in May 2023. His dissertation research answered key questions about long-duration, particle-based thermal energy storage systems using a multi-method approach, including computational fluid dynamics, dynamic integrated system modeling, and mixed-integer linear programming for design and dispatch optimization. His overall research interest is energy storage systems for economy-wide decarbonization but mainly focuses on component, system, and techno-economic modeling of particle-based thermal energy storage for industrial heat and grid electricity applications. He has also worked on modeling hydrogen electrolysis and leakage.

Authors:

Jeffrey Gifford National Renewable Energy Laboratory (NREL)
Munjal Shah National Renewable Energy Laboratory (NREL)
William Buttner National Renewable Energy Laboratory (NREL)
Zhiwen Ma National Renewable Energy Laboratory (NREL)