Over the last year, I’ve heard a number of talks and seen a number of presentations relating to a new possible application for rotomolding – hydrogen storage tanks. These may be stationary (for intermediate gas storage) or mobile (on hydrogen powered vehicles and other equipment).
Like any other member of our community, a significant new application for rotomolding is something that I would celebrate. However, further thought and consideration has raised some questions, which I thought that I should share with you.
First of all, some background. Hydrogen is seen as the ultimate “green” fuel because, when you burn it, it only produces water vapour. No carbon dioxide produced- what’s not to like? In principle, it could be a possible substitute for both natural gas (heating) and gasoline (transport).
Unfortunately, as with most things in life, there are some big BUTS to contend with…
Firstly, hydrogen is very permeable. It’s the smallest molecule in the universe which means that, when you contain it in a vessel made of bigger molecules, it can creep between the inter-molecular spaces and eventually escape. When I worked in oil and gas construction, we were aware of a phenomenon called hydrogen blistering. We knew that we couldn’t easily contain hydrogen gas in a standard carbon steel pressure vessel. The hydrogen would permeate through the walls of the vessel, however thick, and create blisters on the outside surface. This sounds fantastical, but it really does happen! There were numerous other issues as well and hydrogen vessels had to be made from special alloys.
Hydrogen also permeates through plastics. The polymer we rotomolders love the most, polyethylene, presents a pretty poor solution. Much more expensive (and difficult to mold) polymers present a significantly better barrier, but none of them are that great. Nanocomposites may offer a workable solution, but only if we can rotomold them.
So… bottom line… I believe that we’ll need to do some serious polymer and process development if we are to participate in this new potential market.
There’s no doubt that hydrogen offers a lot of advantages as a replacement fuel, so the demand for hydrogen is likely to be sizeable. Which brings us to the next question: how will the world produce all the hydrogen it needs? You can’t drill a hole in the ground and extract it, you have to manufacture it in an industrial process.
One option could be to use “spare” renewable energy (from wind or solar), via electrolysis of water. This works technically, but is it sufficiently scaleable? Would we ever be able to generate enough renewable electricity to be able to generate all the hydrogen we would need? The “smart money” isn’t optimistic about this.
Enter the oil and gas energy industry, to the rescue. They already have a well-developed industrial process, called steam reforming, which can generate hydrogen on a large scale. The raw materials required are methane (ie natural gas) and water. So you can see the attraction to oil companies; they can carry on with their existing business model!
Unfortunately the by-products of steam reforming are carbon monoxide (an extremely poisonous gas) and carbon dioxide (the gas that’s creating most of the global warming problems in the first place). So utilizing this technology won’t be practical until we can operate carbon capture and storage (CCS) at scale. There is a lot of controversy whether this will ever be safe and workable. If CCS ever does become a practical reality, wouldn’t it be more efficient to simply burn the natural gas, rather than creating a new fuel out of it?
These are the key questions related to hydrogen, but there are others. Not least the fact hydrogen gas is highly explosive.
Unsurprisingly, these discussions generate a lot of argument and controversy and the future is not yet clear. However, if the rotomolding industry seeks to participate in hydrogen-related product niches, it pays to understand the drivers of the overall market.
I believe that there will be several presentations in our Atlanta meeting (November 7-9, 2022) that relate to the subject, which I’m really looking forward to.
I don’t claim any particular expertise in this area; I’m just an engaged observer keen to learn more. I would be very interested to hear the views of others, so please do send them in for us to share.
Happy rotomolding!
Dr. Nick Henwood serves as the Technical Director for the Association of Rotational Molders. He has 30 years-plus experience in rotomolding, specializing in the fields of materials development and process control. He operates as a consultant, researcher and educator through his own company, Rotomotive Limited, based in UK.
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