Shipping is one of the fastest growing sources of greenhouse gas , prompting shipyards and operators to look for environmentally friendly alternative propulsion systems. Researchers at Fraunhofer have joined forces with partners to develop the HyMethShip concept, in which hydrogen is obtained from methanol . This technology does not require carrying large hydrogen tanks , making it safer. In the future, it may also prove to be an attractive solution for cruise ships.
© Fraunhofer Figure
The top of the figure shows onshore methanol production. The bottom shows how the engine's hydrogen is obtained from the methanol in the reactor (blue arrow). The remaining CO2 is stored in tanks and reused in onshore methanol production.
According to the European Environment Agency, shipping accounts for more than three percent of the EU total carbon emissions. In 2019 alone, emissions reached 144 million tonnes of carbon monoxide. This may not sound like a lot, but shipping has been one of the fastest-growing sources of greenhouse gas emissions for years due to dramatic increases in trade volumes. As a result, shipyards and operators around the world are looking for environmentally friendly alternatives to traditional ship engines powered by fuel oil or diesel. Against this background, the focus is increasingly turning to green hydrogen as a clean energy source. However, carrying large, heavy-duty specialized tanks containing pressurized hydrogen on the high seas always involves some risk.
Researchers at IKTS, the Fraunhofer Institute for Ceramic Technology and Systems, have worked with partners to develop a technology that uses hydrogen as a zero-emission propulsion concept and avoids these disadvantages. The EU-funded HyMethShip project uses methanol as a liquid hydrogen carrier. In this concept, the ship is refueled in port with methanol. On board ships, hydrogen is obtained from methanol through a steam reforming process and used for ship propulsion. "This way, we kill two birds with one stone: the ship has an almost emission-free propulsion system and does not require large and potentially dangerous hydrogen tanks," explains Dr. Benjamin Jäger from the Catalysis and Materials Synthesis Group at Fraunhofer IKTS.
Fill up with methanol and burn hydrogen
The technical core of the system is the reactor. Methanol is mixed with water, then evaporated by heating and fed into a preheated reactor, where the methanol and water mixture is converted into hydrogen and carbon monoxide. 2. In terms of hydrogen separation and reactor engineering, Fraunhofer IKTS can contribute its many years of experience in membrane process technology. Fraunhofer researchers have developed a ceramic membrane coated with carbon. Hydrogen molecules escape through the membrane's extremely fine pores, while larger carbon dioxide gas molecules are retained. During this process, hydrogen reaches purity levels of over 90%. It is then fed into the engine, where it is driven by being burned in a conventional internal combustion engine - and produces absolutely no climate-damaging exhaust gases. The craft concept used in the
project includes two additional clever design elements that optimize the system. First, waste heat from the engine is used to heat the reactor, significantly improving system efficiency. Secondly, the remaining carbon dioxide is returned to the fluid state downstream of the reactor and fed into the empty methanol tank. When the ship arrives at the port, the CO2 is fed into a storage tank and can then be used in the next methanol synthesis process.
"Methanol is an ideal hydrogen carrier for transport. It has twice the energy density of liquid hydrogen , so methanol tanks on ships only need half the size. It can also be transported safely: even if the tank leaks, there will be no serious Environmental risks,” says Dr. Benjamin Jäger, an expert in the field at IKTS.
During development, one of the technical challenges was to expand the ceramic membranes so that they could be used for the propulsion required by ship engines. The researchers managed to extend the membrane from its original length of 105 millimeters to 500 millimeters, allowing the engine to reach 1 megawatt of propulsion. The mid-term goal is to develop propulsion systems of 20 MW and above.
© Fraunhofer Integrated membranes in the module for the reactor separate hydrogen from carbon dioxide.
Eco-friendly journeys for ferries and cruise ships
The zero-emission propulsion system is ideal for ferries sailing fixed routes between two ports, each with its own methanol bunkering station. However, the technology could also become an attractive future solution for container ships and cruise ships. Environmentally conscious passengers will be attracted to green cruise ships with zero greenhouse gas emissions and no large funnels to release soot from the combustion of fuel oil into the air.
In the EU-funded HyMethShip project, Fraunhofer IKTS collaborates with a number of partners. The Large Engine Competence Center (LEC) in Graz, Austria, is responsible for the overall coordination of the project, while the Innsbruck-based startup SES-HyDepot e.U. operates a small test facility to validate the potential technology process. Christian Mair, CEO of SES-HyDepot, is optimistic: "Tests have shown that hydrogen can be supplied on a basis of methanol. It offers medium-term prospects for ships and their huge electricity needs.
On the energy transition and the European Green Deal In 2020, the European Parliament called on shipping companies to significantly reduce emissions. With its zero-emission hydrogen propulsion system, the HyMethShip project can make an important contribution in this regard. There are also potential applications. The principle of generating hydrogen from methanol can also be applied to a range of scenarios in the chemical industry.
Original article: Powering ships with hydrogen from methanol (fraunhofer.de)
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