H2Tech - Q2 2021 - 28

PATHWAYS FOR SUSTAINABLE HYDROGEN

SPECIAL FOCUS

Feed
Fuel
Air or O2
Water

System optimization of
import/export heat, steam, and/or
electricity to maximize associated
CO2 availability for low-cost
capture and minimize overall
carbon intensity of H2
Conversion
(SMR/ATR/POX)

Syngas:
H2, unconverted CH4,
unshifted CO, CO2,
inerts, contaminants

CO2
H2 puriﬁcation and
CO2 separation Fuel and/or recycle

FIG. 4. New blue H2 unit landscape.

residential sectors where gas infrastructure currently exists. Today, about 2,000 Bm3 of natural gas is used for heat and power
in a highly distributed user base. A portion of this volume can
be substituted by H2 without major infrastructure modifications
while still using the distribution network for natural gas. Greenfield design of these H2-as-fuel plants can be customized to deliver the lowest cost of H2 production and the lowest cost of CO2
avoided. H2 is also expected to be used as an energy source in
the transportation sector. H2 can be used in a fuel cell to power
forklifts, cars, trucks and even locomotives, ships and planes.
Each of these end-use applications requires that the H2 meet
certain purity and pressure specifications (TABLE 4). In the refining industry, H2 is typically purified with PSA units that can deliver 99.9+% purity at more than 90% recovery for use in hydroprocessing, where catalysts are sensitive to CO poisoning. For use in
ammonia synthesis, the syngas typically is scrubbed of CO2 and
then methanated and washed with nitrogen, or purified by PSA.
In the emerging fuel cell markets, ISO 14687 sets specifications for H2 fuels for fuel cells requiring 99.97% H2 purity, 0.2
ppmv CO maximum and 5 ppmv O2 maximum. An industry
standard does not yet exist for H2 used in natural gas networks.
The Hy4Heat program in the UK conducted a cost-benefit analysis in 2019 and proposed an H2 purity specification for domestic and commercial heating applications of more than 98% purity, a CO max of 20 ppmv in line with short-term exposure limits,
and an O2 max of 0.2% to reduce corrosion rates and maintain
pipeline integrity.6
Similarly, the captured CO2 product must meet certain phase
and purity specifications based on its sequestration or utilization. CO2 pipelines for enhanced oil recovery require injection
pressures of 153 bar at ambient temperature, but only a fraction
of all CO2 capture sites will have direct access to a CO2 pipeline.
Many will need to transport the CO2 to injection sites-either
for pipeline transport or for geological storage. In these cases,
liquid phase ship transport of CO2 (7 bar and -50°C) is often
required. Some sequestration sites have adopted strict purity
specifications with ppm level limits on CO, O2 and H2S.
Blue H2 producers aiming for carbon intensities approaching that of green H2 will need to choose among SMR technology that is optimized to minimize radiant firing while using H2rich fuel, autothermal reforming (ATR) and partial oxidation
(POX). The latter two technologies offer a similar advantage to
the optimized SMR design of enabling more than 90% CO2 capture without costly, post-combustion capture, but they achieve
this by eliminating the furnace and its associated flue gas at the
expense of requiring pure O2 as a reagent and reduced production of H2 per mole of methane processed.
28

Q2 2021 | H2-Tech.com

In all three of these options, greater than 90% CO2 capture
can be achieved with a single capture step on a pre-combustion
stream. The CO2 capture technologies covered in the SMR retrofit analysis are equally applicable for new unit installations,
irrespective of reformer selection. The most appropriate precombustion technology for carbon capture and H2 purification
will depend greatly on the required phase, purity, pressure, storage and means of transport for both the CO2 and the H2 (FIG. 4).
Takeaway. Hundreds of companies and countries have com-

mitted to achieving net-zero emissions in support of the Paris
Climate Accord. Retrofitting existing SMR assets with carboncapture technology is a ready-now, commercially proven and significant step on the journey to net zero. With technology innovations such as the cryogenic fractionation system on the PSA tail
gas with additional H2 yield leading to a cost of carbon captured
as low as $20/t of CO2, these projects make financial sense today
in many areas with an established price on carbon.
As the decade progresses, new blue assets in the form of SMR,
ATR and POX will be built to realize the potential of H2 to address " hard-to-decarbonize " sectors. Escalating the carbon price,
coupled with emerging technological advances, will drive investment. Depending on the end uses of the H2 and CO2, the technology of choice for the syngas separation will vary. Through
thoughtful pairing of carbon capture and H2 purification technology, economic differentiation can be achieved, delivering a
significant step in the CO2 countdown to net zero.
LITERATURE CITED
Hydrogen Council, Study Task Force, " Hydrogen scaling up: A sustainable
pathway for the global energy transition, 2017, Online: https://hydrogencouncil.
com/wp-content/uploads/2017/11/Hydrogen-scaling-up-Hydrogen-Council.
pdf
2
Hydrogen Council, " Hydrogen decarbonization pathways: A life-cycle
assessment, " 2021, Online: https://hydrogencouncil.com/wp-content/
uploads/2021/01/Hydrogen-Council-Report_Decarbonization-Pathways_Part1-Lifecycle-Assessment.pdf
3
International Energy Agency, " The future of hydrogen, " 2019, Online: https://
www.iea.org/reports/the-future-of-hydrogen
4
Page, B., et. al, " Global Status of CCS 2020, " Global CCS Institute, 2020, Online:
https://www.globalccsinstitute.com/wp-content/uploads/2020/12/GlobalStatus-of-CCS-Report-2020_FINAL_December11.pdf
5
Jakobsen, D. and V. Åtland, " Concepts for large scale hydrogen production, "
Master's thesis, Norwegian University of Science and Technology, 2016, Online:
https://ntnuopen.ntnu.no/ntnu-xmlui/handle/11250/2402554
6
DNV GL, Department for Business, Energy and Industrial Strategy,
" Hy4Heat (WP2) Hydrogen purity and colourant hydrogen purity-Final
report, " No. 10123173, Rev. 05, 2019, Online: https://static1.squarespace.
com/static/5b8eae345cfd799896a803f4/t/5e58ebfc9df53f4eb31f7
cf8/1582885917781/WP2+Report+final.pdf
1

AMANDA HICKMAN is a Principal R&D Scientist at Honeywell UOP, where she leads
the development of breakthrough technology platforms. She joined UOP in 2011,
after receiving a PhD in chemistry from the University of Michigan. Since arriving
at UOP, Dr. Hickman has worked as a technical leader and project manager in
the refining and petrochemical industry, with experience in adsorptive separation
and contaminant removal, biodegradable surfactants and carbon capture for
low-emission hydrogen production.
BETH CARTER is the Senior Business Manager for Clean Hydrogen at Honeywell
UOP. In this role, she leads the commercialization of Honeywell UOP's hydrogen
and carbon-capture technologies as key enablers of the global energy transition.
She has been with UOP since 2008, spending her early career in field service
and engineering, followed by leadership positions in R&D focused on the design,
optimization and commercialization of new process technologies. Ms. Carter
received a BS degree in chemical engineering from Northwestern University in
Evanston, Illinois and is a licensed Professional Engineer in Illinois.

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