About a year ago I made a video looking at ways to convert hydrogen into ammonia without
using the massively CO2 emitting processes that are currently required by the global
industries that use these two products. And one of the questions I get asked the
most in the comments section of this channel is whether I can do some sort of follow-up videos
on the technologies I've talked about previously to see if any of them actually make any progress
as we hurtle through arguably the most important decade of our lifetimes. And in this case it looks
as though some decent progress has indeed been made by one of the teams that I've featured in
last year's programme. So I figured now was as good a time as any to see what they've been up to.
Hello and welcome to Just Have a Think. The team in question is based at Monash
University in Australia and they reckon they've made a pretty useful breakthrough
that could finally eradicate the existing method of making ammonia - a process called Haber Bosch,
which is currently responsible for about two percent of global greenhouse gas emissions.
So why should we be interested in ammonia anyway? Well although it's one of those
chemicals that everyday consumers like you and I probably don't think about all that much,
and very rarely come into direct contact with, it's actually a very widely produced industrial
product used predominantly to make agricultural fertilizers but also for numerous other industries
including plastics and pharmaceuticals. According to this article in New Atlas
more than 230 million tons of ammonia is produced annually in a global market worth the best part of
a hundred billion dollars a year. And demand looks set to rise as research teams look for ways to use
ammonia as a replacement for fossil fuels. The way to get ammonia is to derive it from hydrogen. Now
as you probably know hydrogen is already a very good energy carrier so why not just use that as
a source of fuel? Well, currently there are a few reasons. The vast majority of hydrogen made today
is produced via a process known as steam methane reformation or SMR, not to be confused with the
other SMR technology which is small modular reactors. They're a completely different kettle
of fish which we looked at in this video. The methane reformation process pumps high pressure
steam into methane gas to liberate hydrogen atoms. But the by-product is a shed load of
carbon dioxide - about 6 tons of CO2 for every 1.1 tonnes of hydrogen produced, which we don't
want! The fossil fuel industry bods are promising they'll start capturing all that CO2 in a process
they call blue hydrogen, and that's something I had another little rant about in this video.
Anyway once it's been liberated hydrogen does carry a very high level of energy per unit mass
but it also has very low density at normal room temperature - about a third the density
of natural gas for example. So in order to store it and transport it
it has to be cooled right down to about minus 250 degrees Celsius to make it into a liquid,
or it has to be pressurized, and that reduces the process's efficiency by about 30 percent.
Once it's in that form though it carries about 40 000 watt hours of energy per kilogram.
Compare that to the 280 or so watt hours per kilogram
that the best lithium ion batteries can produce and you start to see why the energy industry
is keen on developing it. But hydrogen atoms are extremely small compared to other elements so they
have a nasty habit of leaking through the walls of whatever container they're being stored in.
And it's a very reactive element as well, so it can corrode the steel walls of pressurised
cylinders and pipelines, which is not ideal! And that's where ammonia comes into the picture.
This might sound a bit weird but ammonia is actually a better hydrogen carrier than hydrogen
itself. For the same volume ammonia contains 50 percent more hydrogen than hydrogen does. It
liquefies at only -33 degrees Celsius compared to the minus 250 odd degrees for hydrogen and it only
needs to be compressed to 10 times atmospheric pressure to make it practically transportable.
Plus it doesn't corrode steel or leak out of containers, so it has got great potential as
a high density green fuel for very large and very hard to decarbonize transport systems
like shipping and aviation. The Haber- Bosch cycle that I mentioned earlier compresses nitrogen and
hydrogen at about 250 times atmospheric pressure and temperatures of about 400 degrees Celsius
in tall narrow steel reactors where an iron catalyst helps to liberate the individual nitrogen
atoms so that they'll react with the hydrogen atoms in the right proportions to produce ammonia.
The process uses huge amounts of energy and because the reactors are typically operated
continuously to prevent damaging the catalyst they can't easily be powered by intermittent
renewables like wind and solar, which means they're invariably run on fossil fuels,
which of course means more CO2 released into the atmosphere. The process is also responsible for
nitrate pollution of groundwater and it emits large quantities of another greenhouse gas,
nitrous oxide, into the atmosphere. The team at Monash University have been running their ammonia
project for some time now looking for ways to produce ammonia using the abundantly available
renewable wind and solar energy that Australia has to offer combined with electrolysis of water.
In fact I referenced an article on the subject in last year's video written by Professor Doug
McFarlane of Monash University. Their latest breakthrough is a process involving an electrolyte
that's very familiar in lithium-ion batteries. The team dissolved nitrogen gas into that electrolytic
solution so that when a current was applied across the cell a compound called lithium nitride was
produced at the cathode. But the team also added a hydrogen ion carrier to the solution in the form
of phosphonium salts. More specifically, for those of you with a hankering for complicated scientific
nomenclature, it was a solution of tetraethyl phosphonium cations. These phosphonium cations
are attracted to the cathode which is covered with the highly reactive lithium nitride. As
each one arrives it releases a hydrogen ion which displaces one of the lithium atoms in the lithium
nitride molecule before diffusing away leaving the coast clear for another phosphonium cation
to come in and displace another lithium atom. Once all three lithium atoms have been displaced
the lithium nitride is transformed into an ammonia molecule which then diffuses away from the cathode
leaving the lithium ions in place ready to form new lithium nitride molecules. The depleted
phosphonium cations are now neutral compounds which for reasons that I'm sure are perfectly
rational in the world of science are called Ylides. The Ylide compounds move back across to
the anode where they pick up new hydrogen ions to replenish themselves back into tetraethyl
phosphonium cations to start the reaction all over again in a process that so far the team
have been able to run continuously for up to four days. As long as it's powered by renewable energy,
which is eminently achievable in Australia, then the whole thing has a negligible carbon footprint.
Producing ammonia via direct electrolysis at ambient temperatures
has been something of an elusive holy grail for some years now. According to the most recent
paper submitted by the Monash team to the online journal science, previous attempts have yielded
ammonia production rates of less than one nanomole per second per square centimetre, which I suspect
means very little to the majority of us lay folk, but I'm reliably informed it's at least two orders
of magnitude lower than current industrial targets. This new process has apparently
achieved production rates of around 53 nanomoles of ammonia per second per square centimetre,
which while still not on a par with Haber-Bosch, is certainly a big step in the right direction.
And the process has the major advantage of not requiring any hydrogen to be produced beforehand,
either by steam methane reformation or by electrolysis. That means an entire step
has been removed from the supply chain which of course brings the overall energy consumption
and costs down significantly. Professor McFarlane explains that their system is massively scalable
right up to an industrial level, or it could be produced by something the size of an iPad
to provide small amounts of ammonia to run things like commercial greenhouses or hydroponics
operations. And if ammonia can be produced in this kind of distributed way where local production
meets local demand then of course you'd do away with a lot of the expense and emissions
of the transport system currently karting product all over the world. The Monash
team has now patented their technology and even reached the stage of creating a start-up business
called Jupiter Ionics which has already attracted 1.8 million US dollars of seed investment to get
them going. Now for completeness I should say that there are several other research teams around the
world working on potential alternative ways to generate ammonia without using the Haber-Bosch
method and although the Monash team's latest development is very promising and clearly one that
they believe can be commercialized, there's no guarantee that they'll be the first to market or
have the most cost-effective process. All of that remains to be seen as the concept gets properly
scaled up to production levels, which as many of you good folks point out to me on a regular basis
is usually the part of the process where many great ideas come unstuck.
So I'll keep my eye on progress down under and keep you posted with any further developments.
In the meantime if you're one of those people working in this development field and you've
got some useful insights you can share or if you've got views on these technologies in general
then why not dive down to the comments section below and leave your thoughts there. That's it
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