Step by Step towards Decarbonization: The Role of Hydrogen for Gas Turbine Upgrades

Climate change has emerged as one of the most pressing issues of our time, prompting a global shift towards low-carbon energy sources. Hydrogen (H2) has been identified as a promising energy carrier due to its zero carbon-emission combustion properties. As the world moves towards a cleaner energy future, the role of H2 co-firing in gas turbines has gained significant attention.

When planning new power plants, we can consider optimal solutions from the start. But new plants alone will not be enough to make the energy transition. We have a significant gas turbine fleet working around the world, and there lies tremendous potential in upgrading these turbines to include hydrogen in the fuel mix.

In some regions, for instance in Europe, the combined capacity of electricity generation from gas and from H2 is projected to peak early in the next decade, which is followed by a decreasing demand for the years until 2048. If we look at it this way, the capacity of the existing gas turbine plants might be almost sufficient to meet the overall capacity demand, when the majority of plants are modernized and upgraded to use hydrogen as a fuel.

The big question of H2 availability

Energy demands, existing infrastructure, political landscape, and strategies differ between regions. And it is only logical that different parts of the world also have and will continue to develop regional and national hydrogen roadmaps that are tailored to their specific needs and starting points, moving forward with differing speed towards their individual targets. In the end, the decision between fuels will be highly impacted by production costs and site-specific availability.

Another challenge will be the distribution – an enormous and complex field in itself, which will require strategic planning on cross-country level as well as big investments to then implement the necessary infrastructure. Currently, there are more than 4,500 kilometers of hydrogen pipelines around the world, but every region has its own program to ramp up. For example, Europe wants to install 28,000 kilometers of pipeline until 2030. An exponentially expanded distribution network is and will remain the biggest hurdle to mass adoption of H2 co-firing for the foreseeable future.

Why we cannot wait: Technological challenges

With all this in mind, one could ask why we should allocate R&D resources to a technology field where the availability of the energy source has not yet been clarified?

The answer is: We simply cannot afford to wait. We cannot wait for production capacity and distribution infrastructure to be in place, because switching from natural gas to hydrogen in gas turbines creates significant technological and design challenges. Compared to hydrocarbon fuels, hydrogen has different combustion characteristics, like higher flame temperature, faster flame speed and faster ignition. These characteristics make H2 a highly reactive fuel and create a number of hurdles for gas turbine combustion systems. When implementing H2 co-firing, several factors for full flexibility from pure natural gas to pure hydrogen firing must be considered, including flame flash-back, combustion stability, and emissions control. And these factors are not independent of each other, which contributes to the complexity of the whole system. Of course, the complexity does not stop with the gas turbine. Using H2 will also affect other components of the power plant, for which compatibility must be assessed and ensured, including the control system, the fuel gas supply system, fire/explosion protection system, electrical equipment, and the ventilation system.

With several years from project development until the start of operation and plant life cycles that are planned for at least 20-30 years, it is obvious that we need to invest now to be ready when the H2 supply will be available.

How can we drive the change?

Our target is to have our gas turbines capable of burning 100% hydrogen, and we are confident that we have the knowledge and capability to make it happen – but this change will not happen overnight. To drive this transition, there are several prerequisites:

1. In order to make the complexity manageable, we have to tackle it step by step. That is why we first test with burners in our Clean Energy Center, to see how a single component would react. Only as a second step, we have then tested co-firing in gas turbines to monitor reactions in the whole system.

2. We also have to start with lower levels of hydrogen, because we need to ensure for our customers that co-firing as well as fuel switch-overs work stably, depending on their regional and site-specific needs. Some countries even plan to blend hydrogen in general with their gas supply, so all engines must be capable of co-firing certain percentages. And again, we also need to see what impact higher levels of hydrogen have on combustion stability and emissions, to name just two of the factors we are monitoring and optimizing for.

3. Last but not least, we need courageous partners, who are eager to be among the frontrunners when it comes to driving the transition. Demand is high to take part in the energy transition and Siemens Energy already has multiple field applications for H2 co-firing.

Where do we stand today?

Together with our partners, we have already made good progress. Here are just a few of the many examples we have on real-world applications for H2 co-firing:

• In May 2023, we set an industry record by operating a SGT6-6000G gas turbine with 38% H2 co-firing. The site, which began operation more than 10 years ago, only needed a few minor modifications to perform the testing. This clearly proves that upgrading existing power plants is technically viable and has a huge potential on the way to a more decarbonized energy mix.

• As another example in summer 2023, Wien Energie, together with their partners, successfully started the test phase for running a SGT5-4000F gas turbine with a blend including 15% green hydrogen. The aim now is to look at increasing hydrogen levels to 30% and beyond in a second test phase.
• HYFLEXPOWER, a consortium between companies from France, the UK, and Germany, has proven in a first test that conventional gas turbines with Dry-Low-Emission technology – in this case, a SGT-400 gas turbine – can be operated with 100% hydrogen. Even better: the hydrogen needed for the gas turbine is produced by a Siemens Energy electrolyzer directly on-site. And very recently, Siemens Energy and Air Liquide inaugurated the Electrolyzer Manufacturing Plant in Berlin, with a planned manufacturing capacity of 3 gigawatt electrolyzer stacks by 2025.
• EnBW’s district heating power plant in Stuttgart, Germany, has even been constructed from the very beginning to be 100% H2-ready. In a first step, two SGT-800 gas turbines and a heat recovery system are replacing the oil-fired boilers, and in a second step the fuel switch-over from gas to hydrogen is planned.

With each of these projects, we are gaining more and more knowledge, which makes the next development steps even more efficient.

One last aspect to be considered is that local ESG standards and expectations towards decarbonization are becoming increasingly important in investment decisions. Some regions and countries have already installed laws and regulations favoring investments that are ecologically sustainable, like the Inflation Reduction Act in the USA, or the Taxonomy in the European Union. In some cases, governments are even funding projects and technological developments that drive decarbonization in the energy sector. H2 co-firing provides a good option for decarbonization while also taking advantage of the existing site infrastructure.

So, the path forward is clear. We cannot afford to wait, and for everyone who wants to drive the transition: Now is the time to make the next step.