H2Tech - Q3 2022 - 13

SPECIAL FOCUS: PATHWAYS FOR SUSTAINABLE H2
Power-to-X and green fuels:
Fruit from the decision tree
F. GRUSCHWITZ, MAN Energy Solutions, Augsburg, Bavaria, Germany
There is no doubt that green hydrogen (H2
) is a crucial element
on the path to decarbonization. Unsurprisingly, green H2
and Power-to-X have gained much popularity and public attention.
These technologies will not be a flash in the pan.
Strong programs1
come a serious priority, and many countries have already published
ambitious H2
strategies.
Mature technologies like efuel production are available and
enable the use of existing infrastructure. However, much remains
to be done to create more viable business cases that will
show how derivative fuels (efuels) can successfully complement
green H2
the ramp-up to a green H2
One thing is clear-elemental green H2
will not be a onesize-fits-all
solution. Instead, we will have a multi-option scenario
where pragmatic approaches will aim at maximum efficiency
while ensuring a solid base and ramp-up path are created
for a long-term transition to green H2
.
It is helpful to look at the topic from two perspectives to get
the complete picture. First, by viewing Power-to-X in the context
of how it can play a key role in reaching decarbonization targets.
Second, by looking at the main hurdles and success criteria
in ramping up a green H2
economy at a global level.
If we agree that decarbonization is an underlying imperative
to save the planet, then a policy comprising four elements can
be identified:
* Replacing fossil-fuelled power generation
with renewable energy sources
* The use of green H2
* Employing efuels (based on green H2
)
* Carbon capture and storage for hard-to-abate industries.
These four elements may be viewed as a decision tree-
when addressing an application that acts as a significant carbon
source, all four means of decarbonization must be assessed in
the order shown to find the best fit to achieve decarbonization
considering all boundary conditions.
Decarbonization is reliant upon the availability of an abundant
amount of renewable energy. Accordingly, extending the
capacity of renewable energy generation is of paramount importance.
The first question in our quest for decarbonization
becomes: Is direct electrification possible? This means, first,
replacing all fossil-fuelled power generation with renewable
energy. However, natural-gas-fuelled power plants, for example,
may be tolerated as back-up or peakers, as they facilitate
the maximum use of renewable energy in the grid while simulin
its elemental form and be an important enabler in
economy.
underline that decarbonization has betaneously
ensuring maximum reliability and grid stability.
Besides electrical energy, heat generation is another of the
most significant contributors to carbon emissions. Heat pumps
will undoubtedly become successful and can fulfill the demand
for heating buildings, but it is no secret that heat-demanding
industrial processes are another large contributor to carbon
emissions. Direct electrification with heat pumps powered by
renewable energy could be an optimal solution in many cases.
Large-scale heat pumps that can achieve temperatures rising to
hundreds of degrees Celsius are already on the market.
Continuing through the decision tree for applications that
cannot be electrified directly, many examples exist of how the
use of green H2
Pareto principle, some prominent areas particularly suited for
decarbonization are identifiable. For example, using green H2
instead of coal for steel production would considerably cut carbon
emissions.
Another good example of a sector ripe for decarbonization
is within processes that already require substan.
Grey H2 is used and produced by steam
tial amounts of H2
reformation with natural gas. One example is fertilizer production,
where ammonia as the primary feedstock requires copious
amounts of H2
.
In the third stage of the decision tree, when neither direct
electrification nor the use of green H2
as a molecule are possible,
efuels may be a solution. Efuels are carbon-neutral fuels
based on green H2
, including synthetic methane, methanol e.
or
as a green feedstock for green amkerosene
or ammonia produced from green instead of grey H2
As such, efuels could play an extremely significant role, acting
as a bridge technology and replacing its fossil twin as a carrier
medium for green H2
monia for fertilizer production. One of the great advantages of
efuels is its direct applicability.
However, even if we picture a fully electrified, green H2
and
efuel-powered world, we must not forget that there are still applications
or processes that intrinsically emit larger amounts of
carbon. One prominent example is cement production. Large
amounts of carbon dioxide (CO2
) chemically bound within
limestone are released during the calcination process. Pilot
projects have already demonstrated that these carbon emissions
can be captured, liquefied and stored in subsea locations to
reach the target for atmospheric emissions of net-zero. Another
method of achieving net-zero would be to use this CO2
duce methanol as a chemical feedstock; the carbon can then be
bound again as part of a cycle.
H2Tech | Q3 2022 13
could be a good option. However, following the
with green H2
to pro
H2Tech - Q3 2022

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