New Directions for Chemical Engineering (2022) / Chapter Skim
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From page 31... ...
To contribute to solutions for societal challenges in the coming decades, chemical engineers will need to become increasingly comfortable working across disciplines and as members of interdisciplinary teams. Indeed, this report highlights many areas in which chemical engineers will benefit from interdisciplinary collaborations.
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From page 32... ...
The global energy demand today is about 155,000 TWh, 82 percent of which is currently supplied by fossil fuels (32 percent petroleum, 23 percent natural gas, and 27 percent coal) and the rest by nuclear (5 percent)
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From page 33... ...
The chapter is organized from sources to end uses. Opportunities for chemical engineers are explored in energy sources; energy carrier production; energy storage; energy conversion and efficiency; and carbon capture, use, and storage.
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From page 34... ...
A notional average view suggests that in 2040, petroleum and natural gas will continue to play a significant role in the energy mix; coal usage will decrease significantly; energy carriers from nonbiogenic renewables (e.g., solar, wind, hydroelectric power) and biogenic sources (bioenergy)
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From page 35... ...
This section focuses on the recovery and conversion of energy and opportunities for chemical engineering with respect to the two primary energy sources -- solar and nuclear. The section on solar energy also includes opportunities for chemical engineers related to secondary sources (fossil fuels, biomass, and intermittent sources)
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From page 36... ...
into biomass. Biogenic sources have been used as energy carriers throughout history -- first soon after their formation as combustion fuels, but much more extensively in modern times as fossil fuels, well after geological chemical reactions have deoxygenated these photosynthetic residues and increased their energy density, forming natural gas, crude oil, and coal.
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From page 37... ...
These factories will produce heat, electrons, energy carriers, and chemicals as part of modular integrated systems designed to capture the largest possible fraction of the solar flux with high quantum efficiencies and convert it into useful forms of chemical energy. Direct photon capture and conversion to electrons as energy carriers.
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From page 38... ...
PSC devices have evolved rapidly in photon capture efficiency, from 4 percent in 2010 to >25 percent in 2019 (Grätzel and Milić, 2019; Figure 3-3)
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From page 39... ...
. Conversion of photons to H2, NH3, or organic fuels as energy carriers.
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From page 40... ...
that couple photovoltaic and electrochemical cells at the device scale to gen erate H2 from H2O, organic energy carriers or H2–CO mixtures from CO2–H2O reactants, or NH3 from N2–H2O mixtures (photoelectrochemical devices)
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From page 41... ...
These PEC devices for the synthesis of solar H2-based fuels, as well as their architectural analogs for artificial photosynthesis strategies for converting CO2–H2O mixtures to CO and organic energy carriers, remain at the proof-of-concept stage (Lewis, 2016)
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From page 42... ...
Systems-based integration, control, and design; reaction-transport formalisms; and knowledge of the catalytic properties of active surfaces and centers will play an enabling role in the design and selection of cost-effective devices for the direct generation of energy carriers from photons in a manner that avoids toxic and scarce elements, as well as containment and sustainability concerns (Montoya et al., 2017)
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From page 43... ...
. Electrochemical systems face similar challenges in meeting the scale required for impact: more efficient and robust electrodes based on earth-abundant elements; thinner and more selective membrane separators; higher-temperature electrolyzers; integration of electrocatalytic and thermocatalytic systems in sequence or within a single device to form more suitable energy carriers; and the development of supply chains to lower the costs of manufacturing and integrating the modular devices into molecular weight (MW)
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From page 44... ...
The expertise of chemical engineers remains essential in enabling a transition from the current energy landscape to one based on renewable and sustainable energy sources. However, most studies have concluded that fossil fuels will continue to play a key role in the energy mix at least until 2050, and in the meantime, the imperative is to reduce the carbon footprint of fossil fuels -- a key opportunity for chemical engineers.
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From page 45... ...
taking place in 2019; in contrast, the use of natural gas has increased dramatically since 1995, and the use of renewables has increased since 2005, albeit at a slower pace (Figure 3-5) .6 FIGURE 3-5 Annual electricity generation by different sources (natural gas -- dark blue; coal -- dark red; nuclear -- yellow; wind -- green; hydro -- light blue; all other sources -- gray)
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From page 46... ...
In the United States, natural gas is used primarily for electricity generation (power sector) and for heating (industry, residential, and commercial)
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From page 47... ...
, 1950–2019. A net increase in natural gas consumption occurred over this time period across all sectors.
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From page 48... ...
Chemical engineers have played a central role in the oil industry from its beginning, initially converting crude oil into useful products in small and simple refineries, and subsequently optimizing large and integrated refineries to address energy efficiency and environmental concerns in the manufacture and use of transportation fuels and chemicals. Chemical engineers have also worked closely with geologists to maximize the recovery of conventional and unconventional fossil resources.
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From page 49... ...
With increasing global focus on the need to accelerate the transition to low-carbon energy to mitigate climate change, the expertise of chemical engineers is required now more than ever to help the oil industry minimize its carbon footprint. As discussed previously, the energy system is enormous and complex, and the transition to a low-carbon energy mix will take decades; in the near term, the need for petroleum and its derivative products will continue.
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From page 50... ...
. Areas in which chemical engineers can contribute to innovation in tight/shale oil production are described below.
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From page 51... ...
Chemical engineers can enable significant reductions in methane emissions by developing low-cost modular technologies for conversion of methane to liq uid products to replace venting; developing methods for using air instead of natural gas as the operating fluid for pneumatic controllers; improving techniques and developing smart sensors for methane leakage con trol and detection; and improving methods for deploying higher-efficiency compressors.
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From page 52... ...
Though reasonably mature today, starch- and sugar-based ethanol and biodiesel still pose challenges for chemical engineers in the areas of extracting value from by-products (e.g., glycerol in biodiesel production) , capturing and sequestering CO2 from ethanol production processes, and expanding the range of fuel products beyond ethanol at a scale of impact.
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From page 53... ...
The higher oxygen content of biofuels results in a lower energy content relative to fossilbased energy sources. NOTES: AA = acrylic acid; FDCA = furan-2,5-dicarboxylic acid; LAB = linear alkyl benzene; MEG = monoethylene glycol; NG = natural gas; PE = polyethylene; PEF = polyethylene furanoate; PET = polyethylene terephthalate; PP = polypropylene; PTA = purified terephthalic acid.
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From page 54... ...
The diversity of conversion pathways precludes a comprehensive review; therefore, this section focuses on the challenges and opportunities for chemical engineers to achieve cost-effective and sustainable biofuel production. In the conventional biochemical conversion pathways, thermochemical treatment processes increase the reactivity of biomass, mainly by improving physical access to polysaccharides.
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From page 55... ...
Ultimately, expensive, small-volume coproducts cannot serve as adequate justification for expensive biofuel production processes, and chemical engineers will play an important role in finding realistic, scalable solutions. It is important to note the annual scale of global petroleum production: 5.0–5.5 billion metric tons (100.69 million bbl per day)
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From page 56... ...
. Chemical engineers are involved in several areas of wind energy production (Veers et al., 2019)
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From page 57... ...
. Chemical engineers can potentially make contributions to marine energy through the development of materials capable of withstanding seawater corrosion; flexible materials capable of handling the fatigue loads imparted by waves with their fast cycles of 8–10 s; antifouling coatings for submerged equipment; and electroactive polymers -- polymers that generate electricity from mechanical stimuli (e.g., dielectric elastomers, piezoelectric materials, ionic polymer metal composites, and triboelectric materials)
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From page 58... ...
High-temperature reactors provide high-quality heat directly to industrial facilities, and the integration of this heat will require chemical engineers working within an interdisciplinary team that understands process safety, integration, and intensification. While existing as a separate discipline, nuclear engineering borrows heavily from physics, as well as from mechanical and chemical engineering.
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From page 59... ...
. The following sections describe the opportunities for chemical engineers to contribute to electricity generation and the production of low-carbon fossil fuels, hydrogen, and synthetic fuels; production of advanced liquid biofuels was discussed previously in this chapter.
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From page 60... ...
(Specific opportunities in these sectors were discussed earlier in this chapter.) Low-Carbon Liquid Fossil Fuels Liquid hydrocarbons from crude oil have been the preferred energy carrier for the transportation sector because of their high energy density, easy distribution and storage, low cost, and well-established and extensive infrastructure along the value chain.
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From page 61... ...
and "dirty" crude oils in the feedstock mix is maximized. Refineries will require significant reconfiguration not only to satisfy product demand and meet challenges associated with GHG emissions, but also to maintain low production costs for liquid fuels.
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From page 62... ...
Develop a hydrogen infrastructure for distribution and storage at scale to sat isfy demand. Globally, 96 percent of hydrogen is produced from fossil sources (48 percent natural gas, 30 percent liquid hydrocarbons, and 18 percent coal)
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From page 63... ...
Methane pyrolysis, or methane splitting of natural gas using renewable electricity to produce hydrogen and black carbon, is currently in the commercial demonstration scale.8 Many other routes to low-carbon hydrogen, such as thermochemical water splitting, direct photocatalysis, and biological production from microorganisms, are in various stages of R&D. It is generally accepted that hydrogen from fossil fuels without CCUS will remain the main source of hydrogen production.
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From page 64... ...
. Synthetic Fuels Synthetic fuels are produced by converting hydrogen and a carbon source into compounds that can be used as energy carriers, such as methane; methanol; ethanol; and such higher-carbon-number products as gasoline, diesel, and aviation fuel.
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From page 65... ...
Because many of these are mature technologies, chemical engineers have limited potential to impact some modes of energy storage, especially those involving mechanical energy, such as pumped hydropower and compressed gas storage. For energy carriers that involve electrons or chemical bonds, however, chemical engineers can play a critical role in the development and deployment of scalable and economical energy storage.
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From page 66... ...
Chemical engineers have opportunities to significantly lower the cost of conversion before export and reconversion back to hydrogen in the case of LOHCs, and before consumption or the direct use of ammonia as fuel. Vast sectors of the global energy system rely on liquid or solid energy carriers, such as gasoline and coal.
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From page 67... ...
Tackling this challenge will require structural shifts in the transportation of people and freight, much larger gains in energy efficiency, major advances in technology, effective government policies, significant levels of investment in infrastructure for low-carbon energy carriers, and the manufacture of low-carbon and zero-emission vehicles. No single energy carrier can, in the foreseeable future, satisfy the requirements across all segments of the transportation sector (EPA, 2021a)
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From page 68... ...
The lithium-air battery has faced battery life and energy efficiency challenges. The lithiumsulfur battery has shown more promise than the lithium-air, but it, too, has been limited by life and volume concerns because of its low energy density.
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From page 69... ...
The stack is rated by maximum power output. The key challenges and opportunities to which chemical engineers are contributing in this domain are as follows:
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From page 70... ...
Without a breakthrough, vehicle manufacturers would be unlikely to opt for these alternatives in the foreseeable future because of the need to develop additional technologies and/or fueling infrastructures to accommodate them. Internal Combustion Engine Powertrain Vehicles For both heavy- and light-duty ICE powertrain vehicles, chemical engineers can play important roles in advancing technology for increasing fuel efficiency, thereby re
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From page 71... ...
GHG emissions could be reduced in ICE-powered heavy-duty vehicles by the use of low-carbon liquid fuels. Codevelopment of more efficient fuels and vehicle engines is a major collaborative opportunity for chemical and mechanical engineers, with chemical engineers bringing expertise in reaction mechanisms and transport and mechanical engineers bringing expertise in transport, computational fluid dynamics, and engine design.
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From page 72... ...
The following sections focus on opportunities for chemical engineers in the cement, steel, and chemical production subsectors, as well as cross-cutting approaches for decarbonization of the industrial sector. Cement Production More than 70 percent of the energy used in the U.S.
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From page 73... ...
Key technologies needed to decarbonize the steel industry include improvements in energy efficiency; a switch to low-carbon fuels; use of green hydrogen instead of natural gas in direct reduction of iron (DRI) ; production of iron by electrolysis of iron ore using only renewable electrical energy; postcombustion CCUS (such as top-gas recycling in BFs)
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From page 74... ...
The challenges for chemical engineers are clear: to identify top catalyst and catalyst-related process opportunities for these 18 and other chemicals. Key technologies for decarbonization of the chemical industry include energy systems engineering; fuel switching; novel catalytic processes (e.g., olefin production via catalytic cracking of naphtha or renewable methanol)
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From page 75... ...
Resolve waste management issues for selective membranes, including mem brane washing/cleaning, and drive step-change advances in separations, in cluding the use of ceramic membranes.
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From page 76... ...
Further RD&D is critical for these technologies, and chemical engineers can make contributions to advance synthetic fuel synthesis; integrate biofeedstocks; scale up technology for conversion of CO2 and H2 to hydrocarbons with lower electricity consumption; improve chemical separations with lower energy demand for selective mem branes; apply advanced modular nuclear reactors for low-temperature steam genera tion; and improve electric heating to achieve high temperatures and large scales effi ciently and economically. Food and Beverage Industry The food and beverage industry is the third-largest consumer of energy in the United States; its energy consumption is dominated by mechanical systems, compressed air, refrigeration, and process heat in the moderate-to-low temperature range.
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From page 77... ...
Although some decarbonization technologies are commercially available, further RD&D is needed in such areas as shifting from steam and fossil fuels to electric and solar heating technologies; demonstrating and certifying alternative processing technologies to reduce GHG emissions while maintaining product safety and quality, and reducing degradation in the supply chain; using waste to produce bioenergy; and adopting fuel switching and expanded implementation of energy efficiency. Cross-Cutting Approaches for Decarbonization of the Industrial Sector To achieve the net-zero emissions goal for industry, five broadly applicable decarbonization pillars require vigorous pursuit in parallel over the next decades: demand reduction, energy efficiency, fuel switching and electrification, transformative technologies in sectors, and abatement.
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From page 78... ...
To contribute to significantly reducing energy use in the commercial and residential sectors, chemical engineers will need to work closely with other engineers, including mechanical and civil engineers, who are more closely affiliated with these sectors, in the
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From page 79... ...
Although systems for refrigeration and air conditioning are ubiquitous, improvements in their efficiency and sustainability will require overcoming key technological challenges. Chemical engineers can play a pivotal role in the development of new heattransfer fluids that are nontoxic and nonflammable and lack the very high GHG intensity of many chlorofluorocarbons (CFCs)
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From page 80... ...
. Of these priorities, chemical engineers could contribute in the following areas: Capture -- designing high-performance solvents and developing environmen tally friendly solvent processes, designing sorbent materials and integrated processes, developing membranes and related processes, and producing hy drogen from fossil fuels with CO2 capture.
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