Hydrocarbon Processing - June 2022 - 74

Carbon Capture/CO2
TABLE 1. CO2
Mitigation
reduction by using renewable power vs. generation from fossil fuels
Kg CO2
/
Modern combined-cycle power plant (64% efficiency)
Natural-gas-fired, open-cycle peaking plant
at 34% efficiency
Coal-fired power plant (100 kg CO2/1 MMBtu coal)
at 34% plant efficiency
of power. Only 3% of the land is occupied
by turbines, leaving the rest of the land
for farming and grazing. The layout of the
wind turbines is critical to avoid secondary
air from nearby turbines.24
Land-based
wind turbines presently have a capacity of
3 MW, which will increase to 6 MW as
technology improves. With more favorable
winds, offshore wind turbines will
have a higher capacity that can be scaled
up to 17 MW by 2030.25,26
An offshore
wind turbine can have a rotor diameter
of 170 m. Large offshore wind farms are
being developed in the North Sea and are
planned for installation off the northeast
coast of the U.S. (i.e., Massachusetts, New
Jersey and New York). One beneficial factor
is that offshore oil/gas platform technology
can be applied to offshore wind.
Integrated oil and gas companies are investing
in both solar and wind generation.
Solar PV systems and wind turbines
are unable to supply all the green power
required, so there will still be a role for
nuclear power after 2035. Development
work on the next generation of nuclear
reactors is ongoing. For example, NuScale
is developing a small modular nuclear
reactor, which is a light water reactor
that does not need pumps for circulating
reactor cooling water. TerraPower is developing
its Natrium reactor, which is a
sodium-fast reactor combined with molten
sodium salt heat storage.
Oil companies are moving into the
generation and direct sale of renewable
electricity to customers. Electrification
of transportation vehicles-such as cars,
trucks and trains-is a key pathway for
reducing Scope 3 emissions resulting
from the burning of gasoline and diesel.
In the U.S., the Biden administration has
set a goal for half of all new vehicles sold
in 2030 to be zero-emissions vehicles,
including battery electric, plug-in hybrid
electric, or fuel cell electric vehicles
(FCEVs). By 2035, General Motors plans
to stop making internal combustion
cars. The installation of electric charg74
JUNE 2022 | HydrocarbonProcessing.com
MWh generated
283
532
1,040
steam venting with electric drives
CO2 for 100-MW
power plant, tpy
248,000
466,000
911,000
ing stations along major highways, and
at homes and workplaces, will be necessary
to achieve these goals-and accomplishing
this will constitute a major
capital expenditure.
According to the U.S. Environmental
Protection Agency (EPA), 1 gal of
gasoline contains 33.7 kw of energy and,
when burned, generates 8.87 Kg CO2
.27
If one person drives 20,000 mi/yr with
a 35-mpg car, they will generate 5 tpy of
CO2
renewable power, CO2
. If a subdivision has 200 EVs using
can be reduced by
1,000 tpy. Note: If green power is generated
and converted to H2
for use in an H2
FCEV, CO2 is reduced by only 42% vs. using
green power directly in a battery EV.
A battery EV will average 3.5 mi/kWh. If
a person drives 35 mi, 10 kWh of electric
power is used. If power costs $0.13/kWh,
this equates to $1.30. Driving 35 mi in a
gasoline vehicle would use 1 gal of gasoline
at a cost of approximately $3/gal. In
this example, using an EV would save the
driver $1.70.
TABLE 1 shows the CO2
reduction impact
of using renewable power vs. three
current methods of electrical generation.
Using 100 MW of renewable power will
reduce CO2
emissions by 248,000 tpy vs.
a combined-cycle power plant; 466,000
tpy vs. a natural-gas-fired, open-cycle
gas turbine peaking plant; and 911,000
tpy vs. a coal-fired plant. The impact of
phasing out coal and open-cycle natural
gas plants (which have no gas turbine
heat recovery) with renewable power
is clear. Blending 20% H2
(vol%) into
emissions by
natural gas as fuel for a combined-cycle
plant will reduce CO2
approximately 7%.
Industrial opportunities for electrification
to reduce Scope 1 and Scope 2
CO2
e emissions include:
* Switching condensing turbines
to electric drives, considering the
impact on steam and fuel balances
* Replacing old and inefficient steam
turbines that cause low-pressure
* Using electrically driven heat
pumps to upgrade unusable lowlevel
heat to a higher usable level
* Switching medium-temperature
fired heaters to electric power,
and switching out larger heaters
to use green H2
as a fuel
* Replacing open-cycle gas
turbine drives in LNG plants
with large electric drives
* Replacing the gas turbines on
offshore platforms with electric
motors that use renewable power
from offshore wind turbines and
land-based renewable power
* Electrifying ethylene plants,
using motor-driven cracked gas
and refrigeration compressors.
of CO2
Ethylene crackers are a large source
emissions. Replacing the large
thermally inefficient condensing steam
turbines with electric drives reduces the
need for steam generation. The cracker
furnaces are the primary source of CO2
emissions in an ethylene plant. Adding
air preheat and redesigning the furnace
to recover more of the heat in cracking
coils and to produce less steam in the
convection section can reduce furnace
fuel usage by 30%.28
Work is ongoing to
replace steam cracker furnaces with electrically
heated furnaces. Earlier this year,
pilot-scale testing began of a roto dynamic
reactor that could replace the cracking
furnace. The roto dynamic reactor uses
electrically powered rotor blades that
transfer mechanical energy into thermal
energy in just nanoseconds, thus reducing
the reactor residence time-this can,
in turn, increase ethylene yield.29
Renewable electricity can also be used
to produce green H2
, which can be used
can also be used to
to hydrogenate biofeedstocks to produce
biofuels. Green H2
make synthetic fuels or e-fuels with a low
carbon footprint through the e-chemistry
of Power-2-X (P2X) conversion technology.
P2X technology reacts green H2
with CO2
methane (CH4
captured CO2
to produce gaseous fuels [H2
)] or liquid fuels [metha,
nol,
synthetic fuels, sustainable aviation
fuel (SAF)] and chemicals [ammonia
(NH3
)]. The reaction of green H2
with
to produce syngas for use
in Fischer-Tropsch chemistry to make efuels
was discussed in Part 1 of this article,
which was published in the May issue
of Hydrocarbon Processing.
http://www.HydrocarbonProcessing.com
Hydrocarbon Processing - June 2022

Table of Contents for the Digital Edition of Hydrocarbon Processing - June 2022
