H2Tech - Q3 2021 - 29

HYDROGEN INFRASTRUCTURE DEVELOPMENT
through the Haber process. The ammonia is further
converted into urea with the use of captured CO2
from
different sources. At present, the cost of green ammonia
is estimated at 2-3 times the cost of " gray " ammonia; by
2030, however, green ammonia is expected to be more
cost-competitive with gray ammonia. Middle East Gulf
countries are focusing on green H2
and export of green ammonia.
for the production
* Methanol: Green methanol can be produced using
captured CO2
other CO2
from a power plant, refinery or any
-emitting process plant. At present, the
cost of green methanol is estimated at 3-4 times
that of conventional " gray " methanol. The methanol
can be further converted into olefins, giving a more
comprehensive range of products.
The world is committed to keeping the global temperature
emissions. The reduction of CO2
. H2 has greater application when joined with
increase in this century well below 2°C. To achieve this goal, it
will be necessary to limit CO2
emissions is emphasized alongside the effective utilization of
captured CO2
CO2 capture, as shown in FIG. 4, for the production of synthetic
fuels like diesel, gasoline, synthetic natural gas, and synthetic
chemicals such as methanol and urea.
H2 production routes. Low-carbon H2
most requirement to establishing a sustainable H2
Various routes for H2
production is the foreeconomy.
production
exist or are under development
or study. Among these routes, steam reforming of natural
gas with carbon capture, biomass conversion and water electrolysis
are frontrunners.
SMR route. The most reliable and efficient H2
process is the steam reforming of fossil fuels.1
production
The SMR process
is widely divided into the following steps: feed pretreatment,
steam reforming, shift process, synthesis gas cooling
and purification (FIG. 5). The primary reaction of reforming is
strongly endothermic, meaning it requires heat to drive it forward.
That heat is usually supplied by burning the natural gas,
which produces CO₂. The carbon monoxide (CO) in the outSPECIAL
FOCUS
put stream from the primary reaction is generally converted to
CO₂ via the water-gas shift reaction (WGSR) for increasing H2
production, as shown in Eqs. 1 and 2:
CH₄ + H₂O + Heat } CO + 3H₂
CO + H₂O } CO₂ + H₂ + Heat
to maximize the H2
(1)
(2)
The reformed gas is cooled and routed to the shift reactor
content. The produced syngas is further
cooled, and the process condensate is separated out. The reformed
gas has a primary composition of H2
(7 mol%), CO (1 mol%) and CO2
(74 mol%), CH4
(18 mol%), which depends
on feed composition and the selected process scheme. The gas
is purified in the pressure swing adsorption (PSA) section to
remove CO, CO2
and CH4
The key to the success of blue H2
impurities and to produce gray H2
is selecting the right carbon.
capture
technology and carbon-capture location in the process.
There are varied technologies for capturing carbon. Carbon
capture through absorption technology is implemented in various
syngas plants. Overall carbon-capture rate is 53%-90%, depending
on the method used and the carbon-capture location.
FIG. 4. H2 can be integrated with CO2
range of chemicals and fuels.
capture and converted into a
FIG. 5. H2 production via SMR.1
H2Tech | Q3 2021 29
H2Tech - Q3 2021

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