H2Tech - Q2 2021 - 25

SPECIAL FOCUS: PATHWAYS FOR SUSTAINABLE HYDROGEN

Ready-now blue hydrogen leads the way
to decarbonization
E. CARTER and A. HICKMAN, Honeywell UOP, Des Plaines, Illinois

The urgency to limit global warming to 1.5°C is intensifying. Global leaders are developing decarbonization strategies to
meet the goals of the Paris Climate Accord. Climate modeling
indicates that to meet this ambition, rapid, aggressive decarbonization must start now, and global CO2 emissions must reach
net zero by 2050. This will require a multidimensional strategy,
employing cost-effective decarbonization tools including improved efficiency, circularity, deep electrification with renewable power, migration to low carbon intensity or renewable fuels and feedstocks, and carbon capture and storage (CCS).
One challenge is the so-called " hard-to-decarbonize " sectors, such as industrial, residential and heavy transportation.
Reducing emissions in these sectors requires either large-scale
and distributed deployment of CCS or switching to renewable or clean-burning fuels. Hydrogen is a promising fuel because it generates no greenhouse gas emissions at the point of
use. Demand for H2 is expected to increase up to 10-fold, from
75 MMtpy today, as it replaces natural gas, diesel and jet fuel.1
For H2 to be a critical vector for the energy transition in
the coming decades, its production must be decarbonized. Today, H2 is produced mainly from fossil fuels, resulting in 800
MMtpy of CO2 emissions-2% of total global CO2 emissions.
This traditional production scheme is called " gray " H2 and has
lifecycle greenhouse gas emissions of 9-11 kg CO2 equivalent
(CO2eq)/kg H2 , depending on the method of production and
transportation distance.2
Several methods exist to produce H2 with low carbon intensity, including the addition of CCS for so-called " blue " H2
(1.2-1.5 CO2eq/kg H2 at 90%-98% CCS rates), use of renewable feedstocks such as biogas or biofuels (1-3.3 CO2eq/kg
H2 ), or water electrolysis using 100% renewable electricity for
so-called " green " H2 (0.3-1 kg CO2eq/kg H2 ). Even 100% renewable electricity does not have zero lifecycle greenhouse gas
emissions because energy is required to produce wind turbines
and solar panels.
All three of these low-carbon-intensity H2 production pathways can achieve very low lifecycle emissions compared to gray
H2. Each will have a role in supplying the H2 demands of the future, as shown by the almost daily announcements of new blue
and green H2 commercial projects and studies around the world.
The lowest lifecycle emissions cited previously are for 100%
wind-powered electrolysis of water, coming in at 0.3 kg CO2eq/
kg H2 . Although multi-GW projects have been announced,
green H2 is an industry in its infancy, with the world's largest operating green H2 plant having an electrolyzer capacity of 20 MW.

To generate the same amount of H2 as a typical refinery steam
methane reformer (100 ktpy or 125 MMsft3d) with renewablepowered electrolysis of water, approximately 50 times that electrolyzer capacity would be required (1 GW), along with an equal
amount of installed renewable power.
This large amount of renewable power capacity is best used
in a strategic decarbonization pathway to replace fossil power
first, as it can have 2.5-6 times the decarbonization impact. Furthermore, despite significant cost reductions over the past 10 yr,
green H2 production remains expensive, at 4-6 times the cost of
steam methane reforming with CCS.3
In contrast, blue H2 can address the urgent challenge of decarbonization as the ready-now, commercially proven, and economic alternative to CO2-emitting processes. The H2 production and carbon-capture technologies that enable blue H2 are
commercially proven at scale and economical at CO2 prices that
are available in Europe and North America today. The technology is well-suited to serve existing and emerging H2 markets.
In the near term, decarbonizing H2 production of existing refining and chemical feedstock assets can be expedited with bolton carbon-capture revamps. Over the next decade, new low-carbon-intensity H2 plants will be built to meet the steep growth in
demand for clean H2 fuel.
The main infrastructure hurdle for blue H2 is the widespread
development of carbon-sequestration facilities for permanent
geological storage. Many worldwide projects are in various stages
of project lifecycles, amounting to approximately 40 MMtpy of
CO2 storage capacity. By 2050, if all H2 demand (550 MMtpy)
were met by blue H2 , then the CO2 generated will consume
< 0.02%/yr of current assessed global high- and medium-confidence underground CO2 capacity.4 Ongoing development of
CO2 infrastructure for transportation and sequestration is needed
in tandem with blue H2 and other CCS decarbonization projects.
Blue H2 plays an important role in leading the way to decarbonization. This article explores technology options for blue H2
production, including the revamp of existing assets and greenfield installations. Technology selection and operating parameters have a role to play in maximizing CO2 reduction impact
while delivering the H2 and CO2 products on spec and at the
lowest cost of production.
Existing SMR retrofit. Most existing H2 production plants for
refining, chemical and agricultural use employ a steam methane
reformer (SMR) to convert hydrocarbon feeds, such as natural gas and steam, into synthesis gas, which comprises H2, CO,
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H2Tech - Q2 2021

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