H2Tech - Q4 2021 - 15

SPECIAL FOCUS: FUTURE OF HYDROGEN ENERGY
Hydrogen on tap: Supporting decarbonization
by pipelining H2
to the point of use
O. PURRUCKER, Linde Engineering, Pullach, Germany and J. BALSTER, Evonik Fibres, Schörfling, Austria
H2 is set to play an increasingly important role in the world's
has the potential to graduis
being fueled not only by the promise
energy mix. As an industry feedstock, a source of heat and
power or a transportation fuel, H2
ally decarbonize large sectors of industry. As an energy vector,
it is increasingly being heralded as a way to unlock the potential
of renewable energy.
The appeal of H2
of " clean energy " during the transition to a more sustainable
energy economy. What makes this gas so compelling is its flexibility.
The multitude of H2
supports everything from conventional
production technologies has the
potential to support more rapid scale-up and market development,
as this variability can accommodate regional differences
in energy resources like natural gas, coal or wind and solar
power. Therefore, H2
(gray) production methods, through evolving lower-carbon
(blue) models leveraging carbon capture and storage (CCS)
technologies, to low-/no-emissions (green) options based on
the electrolysis of water powered by renewable energy.
Moving toward lower-carbon pathways. Today, most H2
of all H2
is
still produced by reforming natural gas and water (steam methane
reforming). This accounts for about 42%1
A similar share (around 41%1
cesses. Around 16%1
oxidation (POX) of coal. The remaining 1%1
produced.
) is attributable to byproducts
in many other production proor
coproducts of chemical processes. In fact, the chemical industry
goes on to use this H2
is made from the gasification or partial
is attributable to
renewable or low-carbon sources of energy, such as electrolysis
of water and biomass gasification. This share is set to rise
dramatically.
In the transition from gray through blue and toward green
H2, the energy economy needs gas generation and processing
companies that are capable of supporting the full production
spectrum. These companies must be able to produce and recover
H2
from a vast variety of feedstocks such as natural gas,
into blue H2
.
-rich offgases
liquid petroleum gas (LPG) and naphtha. Drawing on CCS
technologies, they can then convert this gray H2
Recovering H2 from a broad selection of H2
from refineries, ethylene plants or chlorine alkaline electrolysis
facilities, these companies should also be able to tap into
new H2
sources that were previously utilized mainly for heat
, made by electrolyzing water using electricity from solar or
.
generation. In addition, such companies should offer green
H2
wind power. This diversity of choice is essential for the widespread
adoption of low-carbon H2
Getting H2 to the point of use. Looking beyond the growing
diversity of production methods, H2
storage and transport are
equally important for cost viability and availability at the point
of consumption. Bulk trailer and cylinder deliveries are already
well established. As demand rises, however, more efficient highvolume
solutions will be required to deliver H2
safely and quickly
to different end users.
A dedicated H2
pipeline or delivery infrastructure would be
ideal. To date, however, the market has been deterred by the high
costs that would be involved in building such a pipeline from
scratch. So far, very few pure H2
pipelines have been realized
globally. Here, also, the answer lies in flexibility. The existing
natural gas infrastructure-disused pipelines, in particular-
could be repurposed to carry H2
newbuilds, could provide an innovative answer to the need for a
high-volume pipeline distribution infrastructure for H2
.
Blending H2
with natural gas. With this delivery scheme, H2
would be simply injected into the existing natural gas pipeline,
typically at concentrations between 5% and 30%, and delivered
to a wide range of endpoint applications. The idea is not new,
but it was previously hampered by the difficulty involved in
separating H2
from natural gas at the point of use. Now that
from the
was developed
challenge has also been resolved. The separation and purification
technologies required downstream to extract H2
pipeline or natural gas blend are available and mature.
This solution to separate and extract the H2
collaboratively by the authors' companies. The fully integrated
system combines pressure swing adsorption (PSA) technologies
with a custom-designed gas separation membrane
technology.
How do gas separation membranes work? Essentially, gas
separation membranes consist of asymmetric hollow fibers
made of polyimide with a nanometer-scale selective layer on
the fiber outer shell (FIG. 1). Polyimide is known for its excellent
chemical and mechanical properties, making it an ideal material
for membrane-based gas separation. When the H2
/natural gas
blend is applied to the membrane from the outside, the small H2
molecule permeates quickly through the wall of the membrane
to the pressure-less side. By contrast, methane (the major component
of natural gas) is a large molecule, so it stays outside the
membrane and is retained on the high-pressure side.
For H2
separation applications, the fibers are coiled in a
cross-counter winding pattern, forming a structured packing
H2Tech | Q4 2021 15
. This effort, complemented by

H2Tech - Q4 2021

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