Hydrocarbon Processing - May 2022 - 24

Biofuels, Alternative Fuels and Green Petrochemicals
new H2 pipelines will be built, and some
pipelines.
Green H2 should first be used in the
for hydrotreating and desulfurizawith
green
footprints
must be used wisely, since it is proexisting
natural gas pipelines can be converted
to dedicated H2
chemical and refining processes that require
H2
tion, followed by its use in producing synthetic
fuels. Replacing gray H2
H2 will reduce the Scope 3 CO2
of refining and chemical products. Green
H2
duced by using renewable power at a 70%
conversion efficiency-there is a 30% loss
of renewable energy in the electrolyzer.
H2
moved by pipelines and trucks. It can also
be converted into green ammonia (NH3
converted (dissociation) back into green
H2
at its destination. H2
is an energy carrier that can be
)
or green methanol, and then transported
by pipelines and ships. Green NH3
into existing natural gas pipelines and can
be extracted from the H2
can be
can be blended
/natural gas mix
at an endpoint by using pressure swing
adsorption and membrane technology. A
new technology is liquid organic H2
riers, which bond H2
carto
organic liquid for
transport by pipelines. Since renewable
wind and solar power may be generated at
remote locations, converting power into
H2
for transport can help reduce future
demand on the electric grid. H2
for storage. The H2
can also
be used as storage for renewable electricity,
when grid power demand is low, by
converting excess renewable power into
H2
can be used or can
be converted back into electric power
when needed; however, there is an efficiency
loss in the H2
fuel cell.
An H2 fuel cell can convert H2
back
into electricity. There are PEM fuel cells
and solid-oxide fuel cells. The PEM fuel
cell takes H2
, which is oxidized at the anode,
and oxygen (from air) that is reduced
at the cathode and generates electricity
and water. The reaction in the fuel cell is
2 H2
+ O2 = 2 H2O + electricity. This is the
reverse of what an electrolyzer does-i.e.,
using electric power and water to make H2
and oxygen. A fuel cell has an efficiency
of 60%.10
Converting electricity to H2
then converting H2
and
back to electricity has
a double efficiency hit, resulting in only
42% (0.7 × 0.6) efficient use of the renewable
electric power.
H2
fuel cell electric vehicles (FCEVs)
will have an important role in reducing
transportation emissions of electric cars,
forklifts, trucks, buses and trains. Many
24 MAY 2022 | HydrocarbonProcessing.com
CO2 e-chemistry: Power-to-X (P2X).
P2X or CO2 e-chemistry uses renewable
electric power to produce green H2
reacts the H2
and
with captured CO2
low-carbon gaseous fuels (H2
the methanol-to-olefins
and CH4
to make
),
liquid fuels (methanol and synthetic fuels)
and chemicals [NH3
and olefins via
(MTO)
reaction].
Using renewable electric power to
make H2
" e " in the technology name. Green H2
acts with captured CO2
accounts for the " power " or the
reto
make syngas,
which is a mixture of carbon monoxide
(CO) and H2
. Using Fischer-Tropsch (FT)
chemistry, the syngas can then be converted
into organic chemicals and synthetic
fuels like methanol, ethanol, e-gasoline,
renewable diesel and SAF. The methanol
can then be converted to olefins by using
MTO technology or into e-gasoline by using
methanol-to-gasoline technology. The
synthesis reactions to produce methanol
from green H2
and CO2
+ CO2
are:
* Step 1 (reforming):
H2
* Overall reaction:
CO2
+ 3H2 = CH3
= CO + H2
* Step 2 (syngas F-T reaction):
CO + 2H2
O.
= CH3OH (methanol)
OH + H2
Synthetic natural gas (SNG) can be
produced by reacting green H2
tured CO2
tion is CO2 + 4H2 = CH4 (SNG) + 2H2
better use of valuable green H2
.
and cap.
The reaction is 80% efficient,
. The Sabatier reacO.
This
is referred to as carbon circularity.
The reaction consumes a lot of H2
, and a
is to make
synfuels or to use it in chemical and refining
operations that require H2
so it produces less energy than is put in
with the renewable H2
new forklifts are electrically driven by
using H2
fuel cells. Refueling H2
vehicles
takes half the time of electric vehicle battery
recharging. Battery manufacturers are
working to reduce charge times. Just as an
electrical recharge network along highways
is needed, there will also be a need
for H2
refilling stations for vehicles.
Ships can also use green NH3
as a fuel
for long-distance trips-Maersk plans to
launch the world's first container vessel operated
on green NH3
is made from green H2
in 2023. Green NH3
and green nitrogen
by the Haber-Bosch process. The air separation
unit providing nitrogen is driven by
renewable power. Coal-fired power plants
are also planning tests to evaluate burning
up to 20%-50% NH3
as a fuel.
valuable green H2
Producing synthetic fuels uses a lot of
and renewable power.
Dry reforming of methane is another
route to make syngas from CO2
forming of methane uses CH4 (not H2
react with captured CO2
and H2
. Dry re)
to
to produce CO
. The dry reforming reaction is
to convert
1 CO2 + 1 CH4 = 2CO + 2 H2. This reaction
does not require green H2
the CO2
(SDR) process is being developed, which
can react 3 moles of CO2
CH4. The SDR reaction is 1 CH4
= 2 H2O + 4 CO.11
going research to produce low-carbon
synfuels from captured CO2
+ 3 CO2
There is a lot of on.
Using gas
fermentation, CO can be converted into
ethanol; or by using F-T chemistry, syngas
is then converted into synthetic fuels.
Renewable fuels, biofuels and e-fuels:
The oil and gas industry's pathway
to reduce Scope 3 CO2
emissions.
For the oil and gas industry to reduce
Scope 3 CO2
emissions, it must transition
to becoming energy providers that produce
and sell less carbon-intensive fuels
like renewable power, green and blue H2
,
renewable fuels, biofuels and synthetic
e-fuels. The Low Carbon Fuel Standard
(LCFS), created by the California Air Resources
Board (CARB) in 2009, provides
attractive credits to producers of lowcarbon
fuels. California's goal is to replace
petroleum-based diesel with renewable
diesel by 2035.
Demand for petroleum-based gasoline,
diesel and jet fuel will decrease. Some energy
consultants have predicted that world
oil production will peak by 2031 and will
gradually decrease by 40%-50% by 2050.
Some refineries will shut down or reduce
crude throughput and will convert some of
their processing units (e.g., hydrocracker
and fluid catalytic cracking units) to hydrogenate
renewable feedstocks to produce
renewable diesel, bio-naphtha and SAF.
These low-carbon fuels will be required
in addition to the electrification of vehicles
(e.g., battery electric vehicles and H2
FCEVs) to meet the world's growing transportation
demand. Renewable feedstocks
have a high level of unsaturates and oxygen
requiring hydrogenation, resulting in high
H2
demand and high heat generation. Reand
may
fineries converting to processing renewable
feedstocks will need more H2
have to add additional heat removal capacity
or operate at reduced rates.12
into CO. The super dry reforming
with 1 mole of
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