Unformatted text preview: Copyright © 2010 American Institute of Chemical Engineers (AIChE). On the Horizon Gazing into an Energy
By mid-century, new energy sources
could be integrated into the existing
but additional research is needed to
ﬁne-tune the technologies and
improve efﬁciencies and economics. Vern W. Weekman, Jr.
Princeton Univ. I f we could look into an Energy Crystal Ball and get a
peek at the year 2050, what might we see? We would
certainly see growth in such non-CO2-producing energy
sources as nuclear, wind and solar, as well as growth in
CO2-neutral biofuels. We would also see that air transportation still depends on the jet engine and jet fuel; trains,
trucks and heavy construction equipment still need diesel
fuels; and ships are still powered mostly by heavy fuel oils.
Cars and light trucks may still need diesel and gasoline if
hybrid vehicles prove to be competitive with fuel-cell and
electric cars. At the same time, petrochemicals such as light
oleﬁns, benzene and para-xylene will continue to be essential raw materials for a wide range of products.
The crystal ball would also reveal that the new energy
sources have not displaced all of the existing fossil fuels.
Rather, some new equilibrium between the newer and older
sources will be established.
Many studies have explored the future use of speciﬁc
new energy sources and some small degree of integration.
However, few, if any, have considered how to accomplish a
broad integration of the old and new sources to achieve this
new equilibrium. The National Academy of Engineering and the National
Academy of Sciences recently completed the “America’s
Energy Futures” study (1). Administered by the National
Research Council and chaired by Harold Shapiro, president
emeritus of Princeton Univ., this study should facilitate
a productive national discussion of the nation’s energy
policy and energy future. The study’s ﬁrst phase consisted
of reports from three panels — one on energy efﬁciency,
another on electricity from renewable sources, and a third
on alternative liquid transportation fuels (2). This third
panel undertook a study of the economics of integrating chemical conversion technologies for biomass and
coal. The second phase of the National Academies’ study
focuses on strategic, tactical, and policy issues.
Shinnar (3) was among the ﬁrst to recognize the potential advantages of integrating alternative energy sources
with existing chemical-conversion technologies. Williams
(4) showed that synergies are possible in the cogasiﬁcation
of coal and biomass when coupled with Fischer-Tropsch
(FT) and catalytic (ZSM-5) processing.
Our energy crystal ball reveals the efﬁcient and economic integration of energy sources with chemical manuCEP June 2010 www.aiche.org/cep 23 On the Horizon facturing and processing illustrated in Figure 1. This article
suggests overall strategic paths that should be explored in
future energy studies in the hope of adding some clarity to
the picture. Using electricity to produce hydrogen …
Figure 1 demonstrates how electricity and hydrogen
can be made from a variety of sources.
The advantage of making electricity from nuclear, solar,
wind, and geothermal sources is that it is generated without producing CO2 emissions. Some of this electricity is
used for electrolysis to make H2, which in turn is used to
upgrade fossil fuels or employed in fuel cells to power
cars and light trucks. However, due to thermodynamic losses and process inefﬁciencies, the
electrolysis step consumes 20–25% of the
electrical energy. Making H2 from fossil
fuels may be cheaper, but the associated
CO2 emissions must be balanced against
the lower cost. The H2 fuel cell is about
60% efﬁcient, so the overall efﬁciency
(with the electrolysis step) is about
45–50%, which is similar to that of
an efﬁcient diesel engine (2).
Since a combined
electric motor and battery
is 80–85% efﬁcient, an
all-electric car may offer
more energy efﬁciency
than a car powered by a
hydrogen fuel cell. One
alternative is to feed this
electricity directly to the
grid to charge the batteries in
electric cars or plug-in hybrids.
An important future study should
determine whether the electric car or plug-in hybrid will
offer a lower-cost transportation system than H2 fuel cells,
since expanding the existing electrical grid may be cheaper
than building a new H2 infrastructure (5).
Fossil fuels are gasiﬁed and the resulting carbon monoxide and hydrogen can be water-gas-shifted to produce
more H2, although at the expense of more CO2 production. Cooper (6) recently explored the technologies and
economics of gasiﬁcation for simultaneously producing
electricity and methanol from coal. Natural gas is also
steam-reformed to produce CO and/or H2. Lighter fractions of crude oil (naphtha) are catalytically converted to
higher-octane components as well as H2. Finally, biomass
is gasiﬁed to CO and H2 or shifted to all H2. Biomass is
essentially CO2-neutral, because the resulting CO2 is balanced by increased growth of replacement plant material.
24 www.aiche.org/cep June 2010 CEP … for chemical conversion
The hydrogen produced by these methods is fed to a
variety of processing steps. In the Bergius process, ﬁnely
divided coal is liqueﬁed catalytically with high-pressure
H2, and the resulting heavy coal liquid is upgraded using
the high-pressure H2 and various catalysts. For example,
some of the same catalytic hydrocracking and catalytic
desulfurization and denitrogenation technologies widely
used to upgrade coal liquids to conventional fuels are also
employed to upgrade heavy oils and tar sands. However,
due to the high H2 pressure required, direct liquefaction
may be more expensive than the indirect route, i.e., gasiﬁcation followed by FT synthesis.
Coking, another conversion process, has
long been used extensively in petroleum reﬁning. Through a thermal soaking process,
it converts heavy fractions to lighter
oleﬁnic products and solid petroleum
coke. These lighter products must be
upgraded with H2 processing to reduce
the oleﬁn content and increase product
quality. The coke produced is either
gasiﬁed to CO and H2 or disposed of as easily sequestered
solid carbon. Since coking
with coke sequestration
competes directly with
gasiﬁcation, more work
is required to assess the
In shale retorting,
another thermal process,
shale is partially burned
to heat the petroleum-like
material locked in the rock
and then capture it as shale oil.
This liquid must be upgraded by catalytic H2 processing to
reduce its high nitrogen content and produce useful fuels.
The high-carbon spent shale can then be buried in landﬁlls
or in the mines where it originated.
In all of these routes, the product has a higher quality
and a higher H2 content, so it will create less CO2 when
burned as a fuel.
During the transition period, fossil fuels continue to
be used as the development of alternative energy sources
progresses. Some of the H2 produced from the non-CO2
sources is used to upgrade fossil fuels. These H2-upgraded
fossil fuels have a lower environmental impact because
they produce less CO2 and they are compatible with the
existing fuel distribution system. If H2 is made from fossil
fuels, then, stoichiometrically, using the H2 in a fuel cell or
to upgrade fossil fuels will result in the same overall reduc- Figure 1. Fossil fuel and alternative energy sources can be
integrated with chemical manufacturing and processing. Process Heat
Electricity To Grid
H2 Electricity H2 Electrolysis Catalytic H2
PV, Thermal Methanol
H2 Methanol Catalytic
Liquefaction Wind, Tides,
Processing Naphtha Conventional Fuels,
Light Oleﬁns Naphtha H2
Reforming Coke Fossil Fuels Gasoline,
Petrochemicals FischerTropsch Alcohols, Diesel,
Petrochemicals Coal, Heavy Oils, Shale Oil
Wood / Stalks Vegetable Oils
Algae H2 & CO
Oils CO2 Esterification/
Cellulosic Material Hydrolysis/
Fermentation Ethanol CEP June 2010 www.aiche.org/cep 25 On the Horizon tion in CO2 released to the atmosphere. Research is needed
to evaluate the overall economic impacts of H2-upgrading
of fossil fuels versus the direct use of H2 in fuel cells.
A large part of the transportation sector (i.e., over-theroad diesel trucks, heavy construction equipment, airplanes, and trains) still require H2-upgraded hydrocarbon
fuels. The manufacture of petrochemicals and polymers
also still requires the chemical conversion technologies
outlined above (3). lube oils, waxes, and petrochemicals, the combination of
FT synthesis and ZSM-5 processing plays a key role in
energy integration. The FT process, proven in large-scale
plants in Germany during World War II and subsequently
used in South Africa, Borneo and Qatar, yields very pure
products, because all impurities must be removed from the
H2 and CO feed to protect the FT catalyst. For example,
according to information gathered after the war, the FTbased fuels used in Germany’s zeppelins were so pure that
the exhaust-gas condensate could be used for showers and
dishwashing. FT diesel fuel has a very high cetane number
and no sulfur, making it an excellent blending stock for
Some of the methanol produced by the methanol
process goes directly to market, and some is converted by
ZSM-5 to high-octane gasoline and to oleﬁns for petrochemicals manufacturing. This methanol-to-gasoline
technology has been demonstrated in a large-scale plant in
New Zealand. FT products require fairly extensive upgrading using conventional petroleum reﬁning technology, so,
when only gasoline or diesel is required, part or all of the
FT efﬂuent can be fed to ZSM-5 processing for conversion
directly to high-octane gasoline or high-quality diesel.
Depending on process conditions, the ZSM-5 step can Co-processing of biomass
and high-carbon fossil fuels
Figure 1 shows that the heavier fossil fuels (i.e., coal,
tar sands, heavy oils, shale oil) can be integrated with
biomass (i.e., wood, plant stalks) through gasiﬁcation and
water-gas-shift technologies. Larson, et al., (4) and Ramage
(2) have outlined comparative economics for co-gasiﬁcation of coal and biomass. All the feed materials are linked
to conventional fuels through the CO and H2 produced in
gasiﬁcation and subsequently converted in either the FT
process or the methanol process. Huber (7) presented a
comprehensive review of various routes to biomass fuels.
With the ﬂexibility to make a broad range of products,
including conventional fuels, alcohols and oxygenates, Numerous chemical-conversion processes can play a role in energy integration.
Process Feed Products Catalytic H2 Liquefaction Coal, biomass, heavy oils, tar sands, shale,
peat, H2 All conventional fuels Gasiﬁcation Coal, biomass, heavy oils, tar sands, shale,
peat, natural gas, oxygen, air CO and H2 Thermal Conversion (coking, retorting) Coal, heavy oils, biomass, shale, tar sands,
peat Coke, all conventional fuels, C1 to C3
gases, oleﬁns Catalytic Water-Gas Shift CO, H2, H2O H2 Catalytic Reforming of Natural Gas Natural gas, C1 to C5 gases CO2 and H2 Methanol Production CO and H2 Methanol Fischer-Tropsch Process CO and H2 Higher alcohols, parafﬁns, light oleﬁns,
diesel, gasoline, waxes, lubricating oils Conversion of Alcohols to Hydrocarbons
(ZSM-5) Methanol, ethanol and higher alcohols, raw
Fischer-Tropsch efﬂuents, bioalcohols,
biooleﬁns, biooils All conventional fuels, oleﬁns Catalytic Naphtha Reforming C5 to C20 hydrocarbons High-octane gasoline, H2, petrochemicals Fermentation Grains, cellulosic parts of plants, sugar
cane Ethanol Thermal and Catalytic Oleﬁns Production C2 to C40 parafﬁns C2 to C40 oleﬁns, petrochemicals, H2 Catalytic Methanation CO2, CO, H2 CH4, some higher hydrocarbons Catalytic Hydrocracking Heavy hydrocarbons, H2 Low-sulfur, high-H2-content conventional
fuels Catalytic Desulfurization and
Denitrogenation Fuels high in sulfur and nitrogen, H2 Low-sulfur conventional fuels 26 www.aiche.org/cep June 2010 CEP convert FT efﬂuent and methanol to light oleﬁns for use in
polymers and petrochemicals (8).
Vegetable oils and animal fats are upgraded to biodiesel by hydrogenation and puriﬁcation, or fed directly to
ZSM-5 processing for conversion to conventional fuels (8).
Upgrading these liquid biofuels is expensive, and it may
be more cost-effective to use the one-step ZSM-5 route to
produce high-quality conventional fuels.
Research to ﬁnd an economical way to ferment cellulosic material to alcohol indicates that gasifying this
cellulosic material and using the FT/ZSM-5 route to
produce fuels may make economic sense. Because ZSM-5
can convert almost any alcohol, oxygenate, or biodiesel to
conventional fuel, converting the bioalcohols to gasoline or
diesel and shipping the fuel via existing pipelines may be
more cost-effective and have lower environmental impacts
than transporting the alcohol cross-country by trains or
trucks for blending. In addition, it would allow an unlimited amount of alcohol or biodiesel to be used as a fuel
without affecting current engine performance. A path to the future
If we are to reach the new energy equilibrium predicted
by our energy crystal ball, where energy and environmental
needs are met simultaneously, it will be critical that we
integrate solar, wind, nuclear, and biomass energy sources
into our existing infrastructure for the chemical conversion
of fossil fuels. Doing so will translate into the most efﬁ- Literature Cited
1. 2. 3.
4. 5. 6.
7. 8. Shapiro, H. T., et al., “America’s Energy Future: Technology
and Transformation,” U.S. National Research Council, National
Academies Press, Washington, DC (2009).
Ramage, M. P., et al., “America’s Energy Future — Liquid
Transportation Fuels from Coal and Biomass,” U.S. National
Research Council, National Academies Press, Washington,
Shinnar, R., and F. Citro, “A Road Map to U.S. Decarbonization,” Science, 313 (5791), pp. 1243–1244 (Sept. 1, 2006).
Larson, E. D., et al., “Co-Production of Synfuels and Electricity
from Coal + Biomass with Zero Net Greenhouse Gas Emissions:
An Illinois Case Study,” Energy and Environmental Science,
3 (1), pp. 28–42 (2010).
Ramage, M. P., et al., “Transitions to Alternative Transportation
Technologies — A Focus on Hydrogen,” U.S. National Research
Council, National Academies Press, Washington, DC (2008).
Cooper, H. C., “Producing Electricity and Chemicals Simultaneously,” Chem. Eng. Progress, 106 (2), pp. 25–32 (Feb. 2010).
Huber, G. W., “Synthesis of Transportation Fuels from Biomass:
Chemistry, Catalysis and Engineering,” Chemical Reviews,
106 (9), pp. 4044–4098 (2006).
Weisz, P. B., “The Remarkable Active Site: Aluminum in Silica,”
I&EC Fundamentals, 25 (1), pp. 53–58 (Feb. 1986). Integration of solar, wind, nuclear and
biomass sources with the existing chemicalconversion infrastructure for fossil fuels will
be key to reaching a new energy equilibrium.
cient and economical use of all of our energy resources and
ensure that the resulting liquid fuels will be clean-burning
with minimal CO2 emissions. Such integration could also
enhance the value of alternative energy sources, by promoting their use and increasing our energy independence,
while utilizing the sunk cost of the extensive infrastructure
of existing chemical-conversion technologies.
For instance, hydrogen obtained from sources that
do not produce CO2 may be used more economically
to chemically upgrade fossil fuels and biofuels. This
H2-upgrading route might signiﬁcantly reduce atmospheric
CO2 while reducing the need for a new hydrogen delivery infrastructure. In another example, biofuels may be
processed catalytically to conventional fuels, enabling their
unlimited use in current engines without incompatibility
problems in distribution systems.
The bottom line is that the integration of existing chemical-conversion technologies with various energy sources
will enable us to use our existing fuels, petrochemicals, and
engines more economically, while reaping the beneﬁts of
lower carbon impact from new energy sources, such as solar,
wind, nuclear, and biomass.
CEP VERN W. WEEKMAN, JR., has been a leader in the energy industry. He
began his career at Mobil Oil Corp., where he was actively involved
in establishing Mobil Oil’s international leadership position in the
catalytic processing of petroleum. He held positions as manager of
process research and development; president of Mobil Solar Energy
Corp.; and director of Mobil Oil’s Central Research Laboratory, where he
was responsible for all of the company’s basic and exploratory research
in both the upstream and downstream areas. He serves as an industrial
lecturer in the Chemical Engineering Dept. at Princeton Univ. Weekman
earned a BS and a PhD from Purdue Univ. and an MS from the Univ. of
Michigan, all in chemical engineering, and was awarded a doctorate
honoris causa at Purdue’s May 2007 graduation. He was elected to
the National Academy of Engineering in 1985, and as part of AIChE’s
Centennial Celebration in 2008 was named one of the 100 Chemical
Engineers of the Modern Era in recognition of his work in chemical
reaction engineering, modeling, and catalytic cracking. He has been
an active leader of AIChE, including chair of the Government Relations
Committee and terms as a director (1989–1992) and president (1998),
and is a director of the Chemical Heritage Foundation. His major awards
include AIChE Institute Lecturer (1978), Purdue Distinguished Engineering Alumnus Award (1980), AIChE Wilhelm Award in Reaction Engineering (1982), and Amundson Award in Reaction Engineering (2005). Acknowledgments
The author wishes to acknowledge the many helpful suggestions of colleagues on the AIChE Government Relations Committee, in particular Dave
Gushee, Pete Lederman, and Cawas Cooper, and the encouragement of the
GRC Chair, Otis Shelton. Former Mobil colleagues Mike Ramage, Jim Katzer,
and Jack Wise also made valuable suggestions. CEP June 2010 www.aiche.org/cep 27 ...
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