Existing tankers, pipelines, cisterns and more could be used for hydrogen stored in liquid form using organic molecules. A new pre- study within the Swedish Transport Administration’s industry program Sustainable Shipping, which Lighthouse runs, will investigate the potential for the use of liquid organic hydrogen carriers in shipping.
A disadvantage of hydrogen is that it takes up a lot of space. To be stored more efficiently, it therefore needs to be cooled in liquid form or converted to other hydrogen carriers such as ammonia, methanol or methane – processes that require a lot of energy. However, there is another possible solution that researchers at IVL Swedish Environmental Research Institute
and Chalmers are looking into – hydrogen can also be stored with liquid organic hydrogen carriers, so-called LOHC (Liquid Organic Hydrogen Carriers).
“You can add and remove hydrogen from an LOHC without affecting it. The hydrogen carrier is always permanent. Previous studies show that LOHC has the same type of storage properties as liquid hydrogen without having to cool down, and should therefore be able to replace liquid hydrogen”, says Anders Hjort, researcher at IVL who leads the work with the Pre-study Hantering av vätgas i flytande form som LOHC.
Previous research has focused a lot on which materials are suitable as hydrogen carriers, especially with regard to the fact that it can be transported and stored, for example on board ships and in energy ports.
“On the other hand, we have not seen any studies on hydrogen stored as LOHC on vessels where the hydrogen after it has been released is also used directly to power them.”
If this were to work, space could be saved and risks possibly reduced compared to storing hydrogen as ammonia or as hydrogen in liquid or compressed form (ammonia is toxic and hydrogen is flammable during storage). The great advantage is still judged to be that existing infrastructure – tanks, pipelines, cisterns and other things on ships and in ports could be used.
“It could mean that you do not have to build completely new ships. Our hope is that tanks that store oil or aviation kerosene will also be able to store LOHC”, says Anders Hjort.
“In a larger perspective, the technology can be a way to transport hydrogen to Sweden from warmer countries with better conditions to produce cheap green hydrogen.”
However, the question is which type of LOHC is suitable. Some substances can be toxic while others require a lot of heat to release the hydrogen gas from the liquid.
“Often over 300 degrees is required, which complicates it. You therefore need to have access to a heat source, otherwise a lot of energy is used. When hydrogen is added to LOHC, heat of over 100 degrees is also emitted. Of course, you should take advantage of that. On a ship, one could generate electricity or clean seawater using the waste heat.”
The pre-study work that is ongoing throughout 2022 consists partly of a literature study and, when it is completed, a comparison with other alternative fuels.
“When we are done, we will know a lot about the potential of LOHC, while we will certainly have a lot of questions that require further research”, says Anders Hjort.