The Invisible Flame

Prof. Paschereit at his test stand, © TU Berlin

The hope for future power plants has a name: BlueStep. A prototype at the Technical University of Berlin burns hydrogen and oxygen with the help of wet air – or, in other words, with the help of wet steam. The project’s predecessor, Greenest, which was launched with the same intention of advancing the development of low-emission plants, also injected steam into the combustor of a gas turbine. This so-called “wet combustion” can increase gas turbine efficiency by up to 15 percent, not to mention that the renewably produced hydrogen will severely cut plant emissions.

Panagiotis Stathopoulos is developing the future of the gas turbine. He is project leader of BlueStep and Greenest at TU Berlin’s Institute of Fluid Dynamics. A very narrow and steep staircase leads up to the fourth floor. When arriving at his office, visitors are rewarded with warm sunlight entering through the big windows. Here, Stathopoulos is working meticulously on a process that will enable the utilization of excess green power stored in hydrogen inside a gas turbine or steam plant without leaving many traces, many emissions. The project’s name stands for: Blue Combustion for the Storage of Green Electrical Power.

“Theoretically, the hydrogen flame is invisible,” Stathopoulos explained during a tour through the laboratories. The researcher born in Athens, Greece, has worked in Berlin for two years after receiving his doctorate from the ETH Zürich. This may explain his slight Swiss accent. In practice, however, the flame would, most of the time, contain other gases besides hydrogen, which would indeed make it visible to the eye, he continued. And the right combination of gases in the mixture is precisely what he has been searching for in collaboration with fellow researchers.

New BlueStep technology

Burning hydrogen with the help of oxygen still presents a technical challenge, as there hasn’t been any material able to withstand the extreme temperatures resulting from the process. The new approach uses steam to dilute the mixture considerably. The steam is available as a byproduct of the combustion inside the turbine at every steam plant. Now, this steam should be recovered and fed back into the steam cycle to increase plant efficiency. To do that, Stathopoulos and his fellow researchers have investigated different strategies and intake quantities.

Theoretical proof prompts award


More steam to the rescue

Combine with electrolysis-generated hydrogen


Energy lab of TU Berlin

The laboratory building was inaugurated in late fall of 2013 at the Faculty of Experimental Fluid Mechanics. The grey, massive complex was put on five decoupled foundations to lessen the impact of vibrations transmitted through the ground. On an area measuring altogether 125 m², there are four labs, which contain four combustion test stands. The automation of the test stand‘s technology alone required close to ten …

Author: Niels Hendrik Petersen

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