Decarbonizing power and heat in Austria’s capital

By Florian Bayer

Next to the majestic blue Danube and adjacent to the green Lobau national park, the Donaustadt thermal power station is located on one of the main approaches to Vienna. With its 395 megawatts of electric power and 350 megawatts of thermal energy capacity, the power station – opened in 2001 – provides energy and heat for the greater Vienna region.

And the next breakthrough is happening right now: In 2023, the power plant will run in a trial for the first time not only on natural gas, but also on blended hydrogen, a much cleaner energy source. Siemens Energy has already completed most of the hardware changes and adaptations required for this transformation. Less than a year from now, the first hydrogen field tests will be conducted in the Donaustadt plant. It is one of the first such upgrades of a major heavy-duty gas turbine in commercial operation. The lessons gained here will help with other such adaptations in the coming years. 

With 15vol% hydrogen usage, 33.000 tonnes of CO₂ emissions could be avoided every single year. “We are happy to conduct such a major modernization”, says Alexander Kirchner, Division Manager “Asset Operations” at Wien Energie. “It is a huge step towards carbon neutrality in Austria’s energy and heat production.”

For this big project involving dozens of experts and engineers and a €10m budget, Siemens Energy and the plant operator Wien Energie are closely working together with their partners, Germany’s RheinEnergie and Austria’s VERBUND Thermal Power. By powering up and testing the upgraded plant, the engineers and specialists will gain valuable real-world knowledge about how to implement and run a major gas- turbine blended with hydrogen. With its venture into hydrogen burning, the Donaustadt power station is pioneering a change that many plants will undergo in the coming years. 

This change is part of a larger shift, prompted by the EU’s commitment to become entirely carbon-free by the year 2050 at the very latest. Even in Austria, where more than 75 percent of the nation’s electricity is already produced by hydro, wind, photovoltaic, and biomass systems today, there is a need for backups of heat and power grids. Since renewable energy sources inevitably involve fluctuations of supply, combined cycle power plants will be required as a reserve in the future, too.

Burning natural gas, however, has a significant CO₂ footprint. In order to achieve carbon neutrality, it will be absolutely essential to stop burning natural gas, coal, and oil. Hydrogen, on the other hand, emits no CO₂ emissions at all when burnt.

The most sustainable option is green hydrogen, which can, for example, be produced with surplus renewable energy (“power-to-x”) such as wind and solar panels, ensuring that the carbon footprint of hydrogen use drops to nearly zero. With hydrogen playing an ever-large role in political roadmaps and legal frameworks, more and more fossil-powered thermal plants will want to make the shift from burning gas to firing green hydrogen – especially due to the fact that with increasing availability, hydrogen will also become more attractive financially.

Siemens Energy, of course, has many decades of experience in maintaining and modernizing gas turbines. And there has been an enormous amount of research in the field of hydrogen. Nevertheless, upgrading such a large gas turbine as in Donaustadt is a first even for Siemens Energy’s experienced engineers. 

Aleš Mrvar, the Vienna-based project manager at Siemens Energy, expects no problems at all, but looks forward to important lessons on how best to implement and run a blended power plant. “We are excited to see how everything will work out in practice. So far, we have only been able to conduct such large trials in the lab,” says Mrvar.

He also emphasizes that the current goal of burning 15 volume percent hydrogen is not the limit of what is possible – not by far. “With smaller gas turbines, we will operate with up to 100 percent hydrogen already in 2023,” says Mrvar. “For larger power plants, however, also due to the lack of a hydrogen infrastructure and sufficient quantities of hydrogen, we have to increase the hydrogen share step by step.” That is exactly what will happen close to the Danube, and potentially in many more power plants. More than 115 Siemens Energy 4000F turbines – the same model as the one installed in Donaustadt – are in use across Europe.

Wien Energie’s Alexander Kirchner is also convinced that burning hydrogen will increasingly replace burning other fossil fuels in the future. “We are consistently following our path to full decarbonization. The Donaustadt trial is an enormous step in reaching that goal,” says Kirchner. “The insights gained will help us to conduct green upgrades in other power stations as well. These lessons are important for us in Vienna, but also in all of Austria and beyond.” As a positive side effect of the modernization, the improved Donaustadt power plant also will have a higher level of efficiency than ever before.

Burning hydrogen for energy and heat production is not only becoming an increasingly important issue on the political agenda. Hydrogen combustion is also becoming more feasible and attractive for power providers. As a consequence, its role will grow in the years to come. With this in mind, upgrades like in the Donaustadt station are the best investment in a greener future. 

October, 2022

Florian Bayer is a freelance journalist based in Vienna, Austria, where he has written for Zeit Online, Der Standard, and Wiener Zeitung.

Combined picture and video credits: Wien Energie, Siemens Energy, Florian Rainer