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capturing a greener future – The importance of green gases in decarbonising the energy system

given that industry may pursue fuel FIGURE 1 HYDROGEN DEMAND BY REGION
switching or technologies that could
significantly reduce the demand for
CO₂ pipeline capacity. For example,
if a major steel plant switched from
blast furnaces to electric arc furnaces,
or a blue hydrogen production facility
were replaced by green hydrogen,
CO₂ transport demand would drop
dramatically.
Transporting relatively pure CO₂ as
either a liquid or a gas is preferable
to managing a pipeline flowing a
two-phase, less pure mixture. It is
preferable to transport CO₂ either in
the gas phase at about 35bar or as a FIGURE 2 WORLD CCS CAPACITY BY REGION
dense liquid phase above 100bar. This
must be carefully modelled to avoid
CO₂ phase changes along the pipeline
by ensuring the CO₂ is maintained at
optimum pressure and temperature
range.
Contaminants and the need to
avoid phase change in pipelines
transporting CO₂ make metering
and monitoring in CO₂ pipelines
just as important as for traditional
hydrocarbon pipelines.
CO₂ flows are unlikely to be steady,
so metering and pipeline monitoring
will be essential for both single and FIGURE 3 WORLD HYDROGEN PRODUCTION AS ENERGY CARRIER BY REGION
multiphase flows. Further modelling
and metering developments are
needed to both forecast impacts
and adequately monitor operating
conditions.
HYDROGEN IN THE PIPELINE
As opposed to CO₂, which can be
considered as a waste stream, hydrogen
is a valuable energy carrier and
feedstock with a variety of applications.
The purity requirements of the end
application can have a significant
impact on pipeline design parameters.
For pipelines that are to be repurposed
for hydrogen, the original construction decarbonised future is often not well Crucially, these technologies are
and maintenance records are required understood, building these systems and interconnected. For example, one
to avoid detailed and time-consuming vastly increasing CCS network capacity cannot predict green hydrogen uptake
additional inspections. will significantly increase the demand without understanding developments
In its pure state, hydrogen has unique for pipeline expertise. in renewable sources of power,
properties and when combined with and an understanding of CCS is not
some impurities the corrosion risks CONCLUSION complete without considering technical
can increase dramatically; certain The world needs to act urgently on requirements for pipelines transporting
impurities, on the other hand, may be multiple fronts: increasing renewables, enormous quantities of CO₂.
beneficial. Many metallic materials, further improving energy efficiency, and
including steels (especially high- developing CCS. Existing competitive
strength steels), stainless steel, and technologies, such as solar and wind References
nickel alloys, suffer embrittlement in power, need to take full advantage of
hydrogen gas environments. As we the virtuous circle where cost decline 1. www.globalccsinstitute.com/wp-content/
uploads/2020/12/Global-Status-of-CCS-
move through the energy transition, both causes and is caused by the Report-2020_FINAL_December11.pdf
and both industrial and domestic growing number of unit installations. 2. www.iea.org/reports/net-zero-by-2050
consumers convert from methane to For less mature technologies,
hydrogen, both old and new systems like green hydrogen, scaling from 3. www.iea.org/commentaries/is-carbon-capture-
too-expensive
will need to operate side by side. prototype to a commercially investable
Though the role of pipelines in a level is critical. 4. eto.dnv.com/2020

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