Southwest Research Institute has been selected to receive a $1.5-MM contract from the U.S. Department of Energy (DOE) to evaluate the safety and efficiency of a full-scale compressor system for H₂-natural gas blends containing up to 20 vol% H₂. SwRI will collaborate with the Gas Machinery Research Council (GMRC) on this project.

“H₂ has been recognized as a viable alternative to natural gas fuel,” said SwRI Senior Research Analyst Sarah Simons. “However, a pure H₂ stream is not compatible with existing energy transport infrastructure because H₂ and natural gas have different characteristics. Using a blend of H₂ and natural gas can avoid the need to create new pipelines and other infrastructure while reducing greenhouse gas emissions.”

Before natural gas is delivered to homes and businesses for heating or cooking, it is pressurized by compressors to flow through gas pipelines. The SwRI-led project will utilize a full-scale reciprocating compressor loop at the Institute’s San Antonio campus to evaluate the safety and efficiency of pressurizing natural gas-H₂ blends for pipeline transport.

“Because H₂ molecules are so much smaller than natural gas, they can infiltrate materials resulting in embrittlement to piping and damage to infrastructure. The wide differences between H₂ and natural gas properties can change performance characteristics and also put various piping components, such as flow control valves, at risk for failure,” Simons said. “This project will evaluate the risks to the system and components associated with each tested percentage of H₂ and research technical solutions to enable safe, efficient compression of H₂-natural gas blends.”

Various compressor components have been evaluated separately for use with natural gas and H₂ blends. SwRI will build on that foundation by studying a complete compressor system with these components installed to ensure the system as a whole can operate safely and efficiently in the same environment. The team will also measure leakage and test gas meters for accuracy and compatibility with H₂-natural gas blends.

SwRI will initially make minor modifications to the compressor loop, updating some components for H₂ compatibility and upgrading capabilities for operation with a H₂ natural gas blend. Like most reciprocating compressors, the primary machinery is already compatible with H₂. SwRI will design and construct a blending skid to analyze blended H₂ in 5% increments from zero to 20 vol% concentration and evaluate a separation system to extract the H₂ from the process gas.

“The final task will be to take the lessons learned from this work, combine it with published research and develop a best practices document for pipeline operators to reference,” Simons said. “Appliances commonly installed in homes, such as natural gas stoves or heaters, as well as their connections to the gas pipeline, would require further evaluation to ensure they’re compatible with a H₂ blend.”