Southwest Research Institute Enhances Hydrogen Engine with Turbocharger

Southwest Research Institute (SwRI) has made significant advancements in hydrogen-powered heavy-duty transportation by upgrading its hydrogen internal combustion engine (H2-ICE) with a state-of-the-art turbocharger. This enhancement has notably improved the engine’s performance, making it competitive with traditional long-haul diesel engines that prioritize fuel economy while achieving near-zero tailpipe emissions.

In 2023, SwRI converted a conventional natural gas engine to operate solely on hydrogen fuel with minimal modifications. This conversion was integrated into a Class-8 truck as part of the Institute’s ongoing H2-ICE project. The aim is to showcase a cost-effective hydrogen-fueled engine that provides a viable option for zero-tailpipe carbon dioxide emissions in heavy-duty transportation.

By incorporating the new turbocharger, the truck’s peak torque has increased from 1,494 to **1,760 lb-ft**, while peak power has risen from **370 to 440 horsepower**. These figures align closely with the performance metrics of modern long-haul diesel engines, which typically offer torque ranging from **1,450 to 1,850 lb-ft** and power outputs between **400–500 hp**.

Chris Bitsis, assistant director of SwRI’s Powertrain Systems Engineering Department, emphasized the importance of the turbocharger upgrade. “Upgrading this driven turbocharger gave us the airflow needed to continue improving the engine’s performance,” he stated. He noted that the engine’s peak efficiency has reached **44.0%**, setting a new benchmark for spark-ignited engines. The improvements in torque and power ratings position this hydrogen engine as a competitive alternative to current diesel trucks that prioritize fuel economy.

Hydrogen engines often face challenges in maintaining the necessary airflow during rapid acceleration, which can lead to preignition and increased nitrogen oxide (NOx) emissions. To address this issue, SwRI collaborated with a commercial supplier to engineer a turbocharger that meets specific performance requirements. The turbocharger shaft is mechanically linked to the crankshaft through a variable drive, enabling on-demand boost pressure for optimal performance.

“This is a significant milestone in the history of SwRI’s hydrogen combustion engine program and provides further evidence of the technology’s readiness,” Bitsis added. The Class-8 demonstration vehicle was developed as part of the H2-ICE consortium, which aims to assist the automotive and transportation sectors in overcoming technical challenges related to clean and efficient hydrogen vehicles.

Daniel Stewart, Vice President of SwRI’s Powertrain Engineering Division, expressed pride in the team’s achievements. “I am proud of our team at SwRI for demonstrating that there is a high-efficiency, zero-emission transportation solution available to help reduce CO2 and criteria pollutants,” he stated. Stewart also noted that the United States possesses the engine factories and supply chains necessary to bring this technology into production without delay.

As SwRI continues to advance its hydrogen combustion engine technology, the completed Class-8 H2-ICE demonstration vehicle offers the long-haul trucking market an innovative option for reducing greenhouse gas emissions and promoting a more sustainable future in transportation.