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July 24, 2023
By
Kathryn Porter
Hydrogen, blue or green or beyond, cannot prevent the
looming renewable energy disaster
![](images/images_07_25_2023/pic25.jpg)
Probably history's most famous hydrogen explosion
CREDIT: AP
The Royal Society of Chemistry describes hydrogen
as “a colourless, odourless gas”. It’s up there at the top if the
Periodic Table: Group 1, Period 1. It is the most abundant gas in the
universe, but on Earth it is mostly found bound with oxygen in the
form of water – very little hydrogen gas is present in the atmosphere
as it quickly escapes the Earth’s gravity and floats away into outer
space.
Yet this ephemeral gas is touted as the solution to the great looming
problem of renewable power – carbon free energy storage at scale. The
obvious issues with relying on intermittent wind and solar energy can
be solved by using excess renewable energy on sunny, windy days to
produce hydrogen gas. This can then be stored for use on less windy
days, whether that be by direct combustion to generate heat, or to
generate electricity, or in other industrial uses.
The different ways in which this invisible element can be produced
have been assigned different colours: green, blue, brown, yellow,
turquoise and pink hydrogen. Also, white hydrogen. Helpfully, there is
no universal naming convention so hydrogen colour definitions may
change over time, or between countries.
Green hydrogen is the “best” hydrogen, made by using that surplus
renewable energy to electrolyse water, splitting it into its
components of hydrogen and oxygen, emitting zero carbon dioxide. Some
say yellow hydrogen if solar power is used. This is currently a very
expensive way to make hydrogen and represents less than 0.4 percent of
current hydrogen production.
Blue hydrogen is produced from methane – the “natural gas” currently
piped to our homes for heating and cooking – using a process called
steam reforming, which combines the methane with steam to produce
hydrogen but also carbon dioxide which then needs to be captured and
stored. The carbon capture part is the difficulty, with only one
percent of existing projects including this capability.
Grey hydrogen is essentially blue hydrogen but
without the carbon capture part. Almost all the hydrogen currently
produced is made by this method.
Black and brown hydrogen are made from coal (black) or lignite (brown)
and these methods emit even more carbon dioxide than grey hydrogen.
This type of hydrogen is obviously not going to form part of the net
zero pathway.
Pink hydrogen is generated through electrolysis powered by nuclear
energy – this is also referred to as purple or red hydrogen. Like
green hydrogen, this is zero-carbon but expensive.
Turquoise hydrogen is made using a process called methane pyrolysis to
turn natural gas into hydrogen and solid carbon. This relatively new
process is yet to be proven at scale, but the production of solid
carbon would obviously reduce the challenges associated with carbon
capture and storage.
Finally, white hydrogen is naturally occurring hydrogen, found in
underground deposits. It might perhaps be extracted through fracking,
a process already effectively banned in many places. It has been
talked up for decades but, according to the National Grid, there are
still “no strategies to exploit this hydrogen at present”.
Apart from the black and brown hydrogen this all sounds lovely. Quite
literally, one can picture a gleaming future where horrible, sooty,
carbon dioxide (because we all picture it as being sooty despite the
fact it’s also colourless and odourless) is replaced with a beautiful
rainbow of lovely, clean hydrogen, whose only byproduct on combustion
with oxygen is water.
However, it is far from being that simple, or that clean. To begin
with, hydrogen is one of the most explosive and flammable gases – the
airship Hindenburg was filled with it – but its real challenges relate
to the fact its molecules are very small and as a gas it has very low
density. This means that hydrogen is hard to contain and large volumes
of it are needed to generate much energy. You need around three times
the volume of hydrogen as compared to methane to get the same amount
of energy.
Tiny hydrogen molecules fit through tiny gaps, so structures designed
to contain methane such as pipes, joints, boilers and cookers, and gas
storage facilities such as tanks or geological formations (salt
caverns or depleted gas fields) allow hydrogen molecules to escape
where methane molecules would not. Tests suggest that the safety
concerns this creates are mitigated by the lightness of hydrogen which
means it quickly dissipates, but leakage also worsens the economics of
using hydrogen as an energy store.
Hydrogen is also hard to move around. To get gas to move through pipes
it has to be compressed and pushed along using compressors. This
process requires energy: the losses in moving hydrogen through pipes
are ten times greater for hydrogen than for methane: up to thirty
percent. In other words, you need to use up almost a third of your gas
just moving it from A to B.
Hydrogen can also cause the metals in pipes and storage equipment to
become brittle leading to material degradation and potential safety
issues. Special materials or coatings may mitigate these effects, but
they add further complexity and cost to an already complex and
expensive system.
In fact, all of this is expensive. The infrastructure for hydrogen
storage does not yet exist, neither for the most part do the
production facilities and they will cost billions of pounds to build.
Then the underlying cost of storing hydrogen is probably at least four
times that of storing methane. Huge amounts of energy are lost in each
stage of the process due to the fundamental properties of hydrogen.
Quite simply hydrogen is one of the worst substances you could choose
for this purpose, but, because you can burn it in air without creating
carbon dioxide, it has been hailed as the answer to net zero dreams.
Like its cousin, carbon capture, hydrogen energy storage is a backfill
technology – a silver bullet that will enable the otherwise unlikely
net zero target to be met, but neither actually exists yet. Both are
square pegs which people are desperately trying to force into round
holes.
Hydrogen of whatever colour is a hypothetical solution to the
challenge of net zero, and an extremely expensive one at that. And
this goes to the heart of the net zero problem: it relies on
developing a range of solutions that are easy to say but difficult and
expensive to do.
Who will be left to pay for all of this? We will.
Kathryn Porter is an independent energy consultant. She holds a
Master’s degree in Physics and an MBA, and is an associate member of
the All-Party Parliamentary Group for Energy Studies executive council
Green Play Ammonia™, Yielder® NFuel Energy.
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