H2Tech - Q2 2022 - 17

SPECIAL FOCUS: HYDROGEN INFRASTRUCTURE DEVELOPMENT
CO2 compressor technology
for a decarbonized energy economy
K. BRUN, Elliott Group, Jeannette, Pennsylvania
Because of H2
's potential in the context
of developing a decarbonized energy
infrastructure, technologies for efficiently
producing, transporting, storing
and utilizing it have attracted significant
investment.
Of the three H2
production processes
commonly used on an industrial scale
(steam reforming, partial oxidation gasification
and electrolysis), two require hydrocarbons
for feedstock and emit significant
amounts of carbon dioxide (CO2
)
as a byproduct-the outlier is electrolysis,
which requires only water and an electric
power source and can be powered by
renewable energy. Steam reforming and
partial oxidation gasification, by contrast,
are complex chemical processes that
convert a fossil fuel (natural gas or coal,
respectively) into H2
, carbon monoxide
(CO) and other compounds.
Due to the low cost of fossil fuels and
corresponding plant process equipment,
98% or more of H2
now produced is deis
a proven,
would still be
rived using one of these two methods.
Converting natural gas to H2
relatively inexpensive process, particularly
in North America where natural gas is
abundant; even if gas prices were to rise,
the conversion of coal to H2
both commercially viable and less expensive
than electrolysis. Therefore, the most
realistic path to decarbonization involves
the sequestration of CO2
the H2
production process, rather than its
elimination. As such, three important gas
streams must be managed, even in a decarbonized
economy:
1. The production of natural gas,
followed by its transportation
to a site where it can be converted
into H2
2. The transport of H2
to its end-use
site, either an industrial facility or
a power plant
Compressor
Pump
CO2 out 2,100psia
Electric motor
Cooler
FIG. 2. Intercooled centrifugal barrel compressor feeding a dense phase pump.
H2Tech | Q2 2022 17
CO2 in 30 psia
(Q= 32 kg/s)
emitted during
3. The transport of CO2
to
an appropriate geological
sequestration and end-storage site.
These gas streams will require substantial
compression. As the complexities
of both natural gas and H2
compression
have been extensively covered elsewhere,
this article is chiefly concerned with solutions
for the compression and transport
of CO2
. While CO2
compression has
been successfully undertaken for many
years as part of acid/sour gas injection
and enhanced oil recovery projects, the
scale-up required for carbon separation
and sequestration in a decarbonized H2
scenario would challenge even technologies
now considered state-of-the-art. Because
of this, a need exists for new CO2
compression applications for separation,
transport and storage injection.
CO2 compression: An overview. The
pressure of CO2
newly produced H2
gas separated from the
is strongly dependent
on the type of separation process utilized:
as such, it can vary from only slightly
above atmospheric pressure to several
hundred psi. Additionally, significant
Cooler
FIG. 1. Compression start and endpoint
on CO2
pressure-enthalpy diagram.
Cooler
uncertainty surrounds geological formation
injection pressure, since it depends
strongly on the type of formation and its
drilled depth of injection. The generally
accepted rule, however, is that for each
km of depth of injection, ~1,150 psi of
gas pressure is required. Since many of
the geological formations presently under
consideration for CO2
storage are relatively
shallow, injection pressures below
2,000 psi should be expected to occur frequently.
A typical carbon separation and
storage pressure application requires CO2
to be compressed from below 50 psia to
above 2,100 psia, as shown in FIG. 1.
Gear
H2Tech - Q2 2022

Table of Contents for the Digital Edition of H2Tech - Q2 2022
