– Dr. Aparna Deshpande
Hydrogen is proposed to be an effective alternate fuel with low greenhouse gas emissions. The calorific value of hydrogen makes it more energy efficient as compared to lithium-ion batteries. But when it is released in air it has a warming effect in the atmosphere. A new study done by UK government revealed that hydrogen has 11 times more global warming potential than CO2. The chemical dynamics for hydrogen acting as a green-house gas is by its interaction to form methane. The hydroxyl radicals present in the atmosphere manage to clean up methane but in the presence of hydrogen they will react with it leaving the bare methane pollutant in the air which is the most potent green-house gas. Also, hydrogen tends to increase the concentration of both tropospheric ozone and stratospheric water vapor, boosting a “radiative forcing” effect that also pushes temperatures higher.
The source of hydrogen release in the atmosphere are leakages during electrolysis, compression, refuelling, and during the process of conversion back into electricity through a fuel cell. Store hydrogen stored in a compressed gas cylinder has a leak proportion of between 0.12 – 0.24 percent of it every day. It’ll leak out of pipes and valves if you distribute it that way, losing some 20 percent more volume than the methane gas that’s now running through municipal pipelines – although since hydrogen is so much lighter than methane, this larger volume equates to just 15 percent of the weight. Where hydrogen is transported as a cryogenic liquid, boil-off is unavoidable, and you can expect to lose an average of about 1 percent of it per day. Currently, this is vented to the atmosphere leakages as venting and purging operations are currently common across the hydrogen life cycle. So overall around 1-1.5 percent of all hydrogen will be emitted into the atmosphere, with transport emissions playing the major part followed by production and consumption end. But with these numbers one must not jump to a conclusion and restart the traditional outmoded fuel option usage. The paybacks from CO2 emission reductions significantly outnumber the disbenefits arising from H2 leakage but controlling H2 leakage will be the parting shot.
Please see the following news Source(s) and original reference(s) therein: