D2.5 Advice on odorant choice for hydrogen

This report is part of HyDelta work package 2 “Odorisation”. The research question within this part of the HyDelta program was:

“what is the odor strength and odor characteristic of candidate odorants in hydrogen and how do these relate to the odor characteristic and odor strength in natural gas?”

With the results of this research, the studies that have been done before within this work package and a literature search on foreign experiences, an attempt has been made to provide preliminary advice on a suitable odorant for hydrogen.

The research into the smell of three selected odorants THT, GASODOR® S-free and 2-hexyne, shows that the smell of all three odorants in hydrogen is comparable to the smell in natural gas. This applies to the perceptibility of the odors, the perceived odor strength and the perceived odor characteristics. The same dosage of odorant can be used for hydrogen as is required for natural gas. Based on the findings from the HyDelta program Work Package 2, it is not yet possible to make a choice for an odorant for hydrogen for both the short and the long term. The three odorants studied each have specific advantages and disadvantages. Some properties are not yet fully known.

An important consideration will be whether the public recognizes and associates the odor with gas and whether the odor perception will lead to an action, such as turn off the gas supply.

If the use of fuel cell applications should increase strongly and no cleaning is applied just before the fuel cell, the choice of odorant is not yet clear. THT seriously affects the performance of polymer fuel cells, GASODOR® S-free also adversely affects the performance and the influence of 2-hexyne is not yet known. Several properties of 2-hexyne for an odorant have not yet been tested and it has not yet been investigated whether this odorant can be produced in an economical way.

For THT, the odorant that is already known to the public in the Netherlands, the alarming effect has already been proven and when fuel cells are only used very sporadically in the public gas supply and not all knowledge gaps can be filled in the short term, this seems to be the best choice for the first hydrogen projects in the public domain.