As I’ve written about hydrogen over the years, I’ve tended to avoid Hindenburg metaphors and allusions. Mostly that’s because I was mainly assessing its use in transportation, especially cars, where off-gassing tests indicated that it vented up and away very rapidly with little risk.
However, that’s not the case if it’s used in homes or commercial buildings, something I’ve written about a couple of times recently, indicating that its lack of efficiency meant it had no place in discussions of home heating, and calculating the rather absurd cost of it, over $100,000 more for a 15-year life-of-appliances span. And SGN in Scotland is preparing to put hydrogen appliances in 300 homes in Fife, in one of many desperate attempts by gas utilities to find a business model that isn’t disappearing rapidly (renewable natural gas features in many of these phantasms as well).
In homes and commercial buildings, hydrogen is much more challenging to make into a safe gas than natural gas is, which is saying something, given that the US National Fire Protection Association reports that an estimated 4,200 home structure fires per year started with the ignition of natural gas, causing an average of 40 deaths per year.
Recently, I’ve been talking to chemical processing engineering experts about hydrogen safety, and the clear message that’s coming back is that hydrogen is going to be a real problem for fire safety, and likely will have firefighting organizations, which are really fire prevention organizations with a crisis arm, seeing red. I recorded a lengthy podcast with Paul Martin recently — coming soon, so watch this space — about the mission of the new Hydrogen Science Coalition he’s a co-founder of. They are focused on bringing an evidence-based view into policy and press discussions related to hydrogen, something that’s been sadly lacking. Similarly, a chemical engineer, Neville Wood, who worked closely with hydrogen over his career around the world, reached out to share the same concerns Paul raised about safety in our discussion.
There are a few reasons to raise safety concerns when it comes to hydrogen for home or business heating that families, procurement staff, building code, and safety-oriented professionals need to be aware of.
The first is that hydrogen is a tiny molecule, much smaller than natural gas molecules. It leaks much more easily. It embrittles especially weld-connections on metal pipes, and permeates through many plastics. Any existing small leaks in pipes are much bigger leaks with hydrogen.
The second is that the distinctive smell of natural gas that gives humans warnings to get out isn’t innate to it, but an added odorant. However, there are no good odorants for hydrogen. The ones that exist make hydrogen fuel cells fail very rapidly, so a hydrogen network couldn’t be used for home combustion for heat, and also used for hydrogen fuel cell applications. Doubling the distribution network is unlikely.
For a bit of evidence, this is one of the many things SGN doesn’t have an answer for yet. It has a work package devoted to it, but having spoken to long-term professionals who have worked with hydrogen for decades, that’s quite probably a futile effort. What does exist and will likely be required are hydrogen detectors. They exist, so that’s a good thing. There’s a catch, however. A scan of hydrogen detector prices found that they cost hundreds of dollars each. And, of course, just like carbon monoxide detectors and fire alarms, they have to be tested regularly, as they are just as prone to failure. Given the propensity of hydrogen to leak, I would assume that they will be going off regularly in Fife homes, making the families deeply annoyed, leading to new entries in the delightful Scottish curses and insults lexicon. And, of course, leading to some people disabling the detectors so that they can get a good night’s sleep.
So hydrogen is much more likely to be leaking inside homes, and much less likely to be detectable. That’s not a good combination.
If hydrogen were less likely to catch fire or explode than natural gas, that might be okay. Unfortunately, it’s the opposite. For flammable gases, the thing to be aware of is the flammability range, which is the lowest and highest concentration of the gas in air that it can ignite in. Natural gas’ range is relatively small, 5% to 15%. Less than 5%, no boom. Higher than 15%, no boom.
Hydrogen’s flammability range is 4% to 74%.
Yeah, that’s much broader than natural gas. Get a big leak of natural gas in your home, it will stink and rapidly rise to the point where it won’t explode. Get a big leak of hydrogen in your home, it likely won’t smell, and it will be explosive over a very broad range of concentrations. And of course, the more of it there is, the more energy there is to go boom.
Hydrogen advocates like to talk up the energy density of hydrogen, but that comes with a downside when it explodes. One of the things most people don’t realize is that when a nuclear reactor actually experiences an explosion, as the Fukushima reactor 4 did in 2011, is that it is hydrogen buildup inside the containment unit. That twisted mass of concrete and steel didn’t get that way due to the radioactive material, but due to hydrogen. And that’s fairly common. The worlds newest and most expensive coal plant in South Africa blew up due to hydrogen in 2021. Similarly, the Callide coal-power station in Queensland Australia blew up in 2021, and hydrogen is the likely cause. These are professionally managed industrial sites with multiple engineers, detectors, and safety processes, all to no avail.
Of course, burning hydrogen in the home also produces nitrous oxides. One of them is a precursor to smog and is a leading cause of respiratory challenges. The other is a greenhouse gas with a global warming potential 265 times that of carbon dioxide. Oh, and hydrogen is an indirect greenhouse gas with a global warming potential 5.8 times that of carbon dioxide. If a Fife family signs up for the virtuous hydrogen for global warming reasons, they should think again. It’s not as bad as natural gas, but it would still be a problem.
If there were no alternatives to hydrogen for home heating — and if it was remotely economically sensible — there might be a case for working through these safety concerns to engineer a viable solution. However, there are alternatives: heat pumps and induction cooktops. These are vastly cheaper than the non-existing hydrogen appliances, don’t require multi-hundred-dollar hydrogen detectors and run off much safer electricity which is running into homes and buildings today. Heat pumps coefficients of performance run from 3 to 5, which means that every unit of energy put into them returns 3 to 5 units of heat energy. Gas and hydrogen have coefficients of performance of 1 (one). People who switch to induction stovetops rave about them, including professional chefs. Instant and accurate heat just like natural gas, but with a lot fewer concerns and maintenance.
So, to the families of Fife considering SGN’s offer of ‘free’ hydrogen appliances, be aware that you would be putting your loved ones at risk to perpetuate a disappearing business model for gas utilities. I personally don’t think that’s a good enough reason to do so. Pivot to electrification instead.
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