Green hydrogen is often proposed as a climate-friendly alternative to natural gas for energy production. However, the infrastructure for a green hydrogen economy is still in its infancy and may take years to fully materialize, if it happens at all. To bridge this gap and sustain small natural gas power plants in the interim, the German Aerospace Center (DLR) and power-plant service provider Power Service Consulting (PSC) have tested micro-turbines capable of running on hydrogen, natural gas, or a combination of both.

Peter Kutne, head of the Gas Turbines Department at the DLR Institute of Combustion Technology, emphasized the cost and time benefits of retrofitting gas turbines for hydrogen compatibility. Building a new 15-megawatt gas turbine power plant typically requires six years and costs approximately $31 million (€30 million). In contrast, retrofitting an existing plant takes just 1.5 years and costs about a tenth of that amount.

In a significant breakthrough, DLR and PSC have developed what they claim to be the first commercially viable retrofit of a gas micro-turbine, enabling it to operate on both hydrogen and natural gas. This innovation is designed to prepare for a future where green hydrogen becomes widely available. However, adapting turbines for hydrogen use poses significant technical challenges. Hydrogen burns hotter than natural gas and has a lower flash point, making it fundamentally incompatible with traditional gas turbine designs. Without proper adjustments, these differences can cause severe damage to the combustion chamber due to intense heat and shockwaves.

To address these challenges, engineers at DLR developed a jet-stabilized burner optimized specifically for hydrogen. Unlike traditional designs, this burner features air and fuel injectors arranged in a ring, which creates a backflow in the combustion chamber. This backflow mixes exhaust gases with the incoming air-fuel mixture, effectively lowering combustion temperatures, reducing nitrogen oxide emissions, and stabilizing the flame.

By recycling exhaust gases, the system reduces the temperature in the combustion chamber, producing fewer nitrogen oxides and enhancing overall stability. The design is also scalable, making it adaptable for various turbine sizes and types.

The new system has been tested in a pilot plant in Lampoldshausen, operating on pure hydrogen for approximately 100 hours. DLR researcher Martina Hohloch highlighted the challenges posed by hydrogen’s high chemical reactivity. “We were eager to see how the turbine would perform with the new combustion chamber system outside the laboratory environment. The tests have shown that we can start up with pure hydrogen without any problems and that the system achieves the full operating range from partial to full load,” she explained.

These advancements mark an important step toward a cleaner energy future, demonstrating that retrofitting existing power plants for hydrogen compatibility is a viable and cost-effective solution as we transition toward greener energy sources.

By Impact Lab