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Rolls-Royce is developing mtu electrolyzers with a power output of up to 2 MW that can be scaled up to more than 100 MW.
Now the company has acquired a stake in Hoeller Electrolyzer, a specialized company that develops and manufactures the cell stack, the main component of the electrolyzer. The common goal of Rolls-Royce and Hoeller Electrolyzer is to develop a solution to produce hydrogen cheaply and on a large scale using green electricity. It is an ideal complement to an mtu microgrid. It creates the possibility to store and utilize solar and wind energy, thus making an important contribution to the energy transition.
Large-scale electrolysis works on the same principle as electrolysis experiments in physics and chemistry classes, in which two electrodes are suspended in a water bath: In an electrolyzer, water is broken down into its hydrogen and oxygen components by an electrochemical reaction. However, unlike the electrolysis experiment in physics or chemistry classes, here a membrane is used instead of electrodes. Current is passed through this membrane into the water, producing hydrogen at the negative cathode and oxygen at the positive anode. This process is carried out in a so-called cell, of which hundreds of units are stacked so that they produce the required amount of hydrogen as economically and efficiently as possible.
Why hydrogen?
“Because it contains no carbon and cannot produce harmful carbon dioxide (CO2) when powering fuel cells or hydrogen engines.” Sounds simple enough. The trick, however, is to ensure that no CO2 is produced during hydrogen production, as is partly the case when hydrogen is obtained from natural gas,” explained Armin Fürderer, head of net zero solutions at Rolls-Royce Power Systems.
This requires hydrogen to be “green” and produced without carbon emissions, which is where solar farms and wind turbines come into play, supplying the electrolyzers with CO2-free electricity. The hydrogen collected in the electrolyzers can be used in a variety of ways: In fuel cells, the hydrogen is used to re-generate electricity when needed. Or it is used to power hydrogen engines. Either way, the electricity can feed into the grid or be used to power vehicles or ships. On the other hand, green hydrogen can be used in industry and replace so-called gray hydrogen, i.e. hydrogen from natural gas.
Combustion engines operate in a climate-neutral way
Another possibility is to use more energy from renewable sources to produce methanol from hydrogen and CO2 in the air. If this methanol is used in a future mtu methanol engine, the CO2 is released again, but in quantities equivalent to those extracted from the air during methanol production, meaning that the whole process is “net zero carbon”. The synthesis of other sustainable fuels, such as e-kerosene or e-diesel, is also possible with hydrogen. Thus, other sectors such as heavy transport or aviation can also be decarbonized.
There is still work to be done to make this process profitable. Stefan Höller, CEO and the ingenious mind behind Hoeller Elektrolyzer, wants to change that. “With our stack, it is going to be possible to produce hydrogen so economically that it was previously thought impossible,” he says.
Anything but a dream
The first mtu electrolyzer will soon be producing hydrogen. The development of the first mtu electrolyzer with a Hoeller cell has been underway for some time. It is scheduled to go into operation at the Friedrichshafen Validation Center in 2023, demonstrating the role an electrolyzer can play in the overall architecture of a microgrid. A first customer project is already planned for 2024. “We will be launching electrolyzers with several megawatts of power from the outset. A total output of more than 100 MW is conceivable by combining several electrolyzers,” says Armin Fürderer.
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