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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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NASA NTRS2009

Synthetic and Biomass Alternate Fueling in Aviation

Worldwide, aviation alone uses 85 to 95 billion gallons of nonrenewable fossil fuel per year (2008). General transportation fueling can accommodate several different fuels; however, aviation fuels have very specific requirements. Biofuels have been flight demonstrated, are considered renewable, have the capacity to become "drop-in" replacements for Jet-A fuel, and solve the CO2 climate change problem. The major issue is cost; current biomass biofuels are not economically competitive. Biofuel feedstock sources being researched are halophytes, algae, cyanobacteria, weeds-to-crops, wastes with contingent restraints on use of crop land, freshwater, and climate change. There are five major renewable energy sources: solar thermal, solar photovoltaic, wind, drilled geothermal and biomass, each of which have an order of magnitude greater capacity to meet all energy needs. All five address aspects of climate change; biomass has massive potential as an energy fuel feedstock.

Hendricks, R.C.↗

DOE OSTI2015

Data Driven Fuel Efficient Driving Behavior Feedback for Fleet Vehicles

Dependency of the transport sector on fossil fuels is encouraging a significant amount of research in to improving fuel efficiency in vehicles. Three primary techniques are identified for vehicle fuel efficiency improvement: 1) vehicle technology improvements such as drivetrain improvements, 2) traffic infrastructure improvements such as traffic flow management and route selection, and 3) driver behavior changes such as acceleration and deceleration profiles. Out of the 3 techniques, driver behavior changing has the least implementation cost and is able to provide immediate results. Thus, this paper presents a fuel efficient driving behavior identification and feedback architecture that is specific to fleet vehicles. The presented method utilizes historical data from fleet drivers on specific routes and generates fuel optimal velocity profiles that do not affect travel time. The identified velocity profile is the prompted to the driver via a low-cost plug-and-play style un-obstructive display. The display uses an intuitive and easily understandable visualization to prompt drivers on fuel efficient velocity. The presented architecture was tested on the Idaho National Laboratory (INL) bus fleet in real-world driving conditions and was shown to be able to increase the fuel economy by 9% and 20% in two different driving scenarios.

99 GENERAL AND MISCELLANEOUS↗

DOE OSTI2016

Win–Win strategies to promote air pollutant control policies and non-fossil energy target regulation in China

The rapid growth of energy consumption in China has led to increased emissions of air pollutants. As a response, in its 12th Five Year Plan the Chinese government proposed mitigation targets for SO2 and NOx emissions. Herein we have investigated mitigation measures taken in different sectors and their corresponding impacts on the energy system. Additionally, as non-fossil energy development has gained traction in addressing energy and environmental challenges in China, we further investigated the impact of non-fossil energy development on air pollutant emissions, and then explored interactions and co-benefits between these two types of policies. An extended Global Change Assessment Model (GCAM) was used in this study, which includes an additional air pollutant emissions control module coupling multiple end-of-pipe (EOP) control technologies with energy technologies, as well as more detailed end-use sectors in China. We find that implementing EOP control technologies would reduce air pollution in the near future, but with little room left to implement these EOP technologies, other cleaner and more efficient technologies are also effective. These technologies would reduce final energy consumption, increase electricity’s share in final energy, and increase the share of non-fossil fuels in primary energy and electricity consumption. Increasing non-fossil energy usage at China’s proposed adoption rate would in turn also reduce SO2 and NOx emissions, however, the reductions from this policy alone still lag behind the targeted requirements of air pollutant reduction. Fortunately, a combination of air pollutant controls and non-fossil energy development could synergistically help realize the respective individual targets, and would result in lower costs than would addressing these issues separately.

Air pollution↗

DOE OSTI2019

Bioconversion of renewable feedstocks by Rhodococcus opacus

The production of fuels and chemicals from renewable feedstocks is necessary for a fossil fuel independent economy. Lignin and other industrial wastes represent sustainable, non-food feedstocks that can be tapped for microbe-based bioproduction. Rhodococcus opacus is a gram-positive bacterium capable of catabolizing a broad range of feedstocks, and recent technological advances have further established its potential for lignin and industrial waste valorization. In the process of developing R. opacus as a platform for bioproduction, metabolic profiling has elucidated its native mechanisms of bioconversion, adaptive evolution has enhanced its tolerance towards inhibitory feedstocks, and genetic engineering has enabled it to produce novel products, such as wax esters, free fatty acids, and long chain hydrocarbons. Furthermore, we present recent examples of broad feedstock utilization and value-added chemical production by R. opacus , demonstrating its potential as an industrially-relevant strain.

09 BIOMASS FUELS↗

DOE OSTI2021

The zero-emissions cost of energy: a policy concept

The energy sector generates over 70% of global greenhouse gas (GHG) emissions, but existing energy-climate policies do little to reduce GHG emissions to prevent climate change. We present a new carbon tax policy concept in which energy users would be taxed an amount equal to the cost of cleaning up the emissions that they create, wherein the tax revenues would be used to operate negative emissions technologies. The policy is based on applying the zero-emissions cost (ZEC) metric to energy prices, which includes the 'regular' cost of an energy source plus the cost of sequestering its emissions. Using the ZEC, (a) the energy sector would be emissions-neutral, (b) biofuels would be cheaper than petroleum fuels, and (c) renewable electricity would be cheaper than fossil-fuel electricity. We calculate the energy spending as a fraction of gross domestic product for 'regular' and ZEC cost scenarios. Implementing the ZEC carbon-tax policy would enable a monumental shift to a net-zero emissions energy sector, but carries a significant risk of causing an economic recession. The summary point of this commentary is to demonstrate a pathway to achieve net-zero GHG emissions from the US energy sector, and to contemplate the associated economic impacts on our society.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2018

An Electrified Future: Initial Scenarios and Future Research for U.S. Energy and Electricity Systems

As an energy source, Electricity benefits from a number of desirable characteristics: it can be transported at nearly the speed of light with transmission infrastructure, it has zero enduse emissions, it is highly flexible and controllable, it is now storable at rapidly declining costs, and it can offer improved service quality relative to conventional fuels. As such, electrification-the conversion of previously fossil-fueled end-use processes to electricity-has been identified as a key pathway to a clean, reliable, and secure energy future. Electric vehicles are the most widely cited application of electrification, but technology improvements in electrically driven devices for buildings and industrial end uses, including heat pumps for space and water heating needs, induction stoves for cooking, infrared or ultraviolet curing processes, and electric arc furnaces for process heating, could lead to more widespread electrification across these sectors.

24 POWER TRANSMISSION AND DISTRIBUTION↗

DOE OSTI2014

Greenhouse Gas emissions from California Geothermal Power Plants

The information given in this file represents GHG emissions and corresponding emission rates for California flash and dry steam geothermal power plants. This stage of the life cycle is the fuel use component of the fuel cycle and arises during plant operation. Despite that no fossil fuels are being consumed during operation of these plants, GHG emissions nevertheless arise from GHGs present in the geofluids and dry steam that get released to the atmosphere upon passing through the system. Data for the years of 2008 to 2012 are analyzed.

15 GEOTHERMAL ENERGY↗

DOE OSTI2018

Energy & Environmental Research Center (EERC)–U.S. Department of Energy (DOE) Joint Program on Research and Development for Fossil Energy-Related Resources

The EERC teamed with the DOE National Energy Technology Laboratory to conduct complementary research and development under the Joint Program on Research and Development for Fossil Energy-Related Resources (Cooperative Agreement No. DE-FC26-08NT43291). This 10-year program merged two previous 10-year agreements—DE-FC26-98FT40320 and DE-FC26-98FT40321—into a single follow-on agreement. The Fossil Energy cooperative agreement between DOE and the EERC was initiated in 1983 when the EERC was defederalized. This dynamic 35-year partnership has evolved to further research in areas that address DOE Office of Fossil Energy program goals while serving the missions and exploiting the strengths of both organizations through this agreement and a new 5-year Fossil Energy-Related Resources cooperative agreement established in 2015. As the 10-year program has ended, the purpose of this report is to summarize the activity and significant outcomes that were accomplished by the EERC. This program is an excellent model for research, development, demonstration, and commercialization partnerships between government, industry, and the applied science and engineering communities to bring cutting-edge science closer to commercial application. The overarching goal was to support DOE Fossil Energy goals by advancing the scientific knowledge and technical development essential to ensuring future sustainable supplies of affordable energy and clean water, protecting and restoring the environment, and reducing dependence on foreign energy sources, thereby increasing U.S. energy security. The strategic objective was to advance continued use of domestic fossil fuels as a mainstay of U.S. energy production by making fossil energy systems nonpolluting and more efficient, capturing and sequestering greenhouse gases, and integrating the use of fossil and renewable energy sources into the energy mix. The research achievements from this partnership have exceeded the goals and objectives by contributing substantially to the development of science-based energy and environmental policy, educational foundations for science and technology, and commercialization and international marketing of energy technologies. The program comprised 75 individual projects, which included basic/applied fossil energy research projects involving no cost share and development, demonstration, and commercialization projects (many derived from applied research projects) that included nonfederal cost share of approximately 40% (the contractually required minimum level of cumulative nonfederal cost share was 29%). In all, 32,798,698 of federal funding was leveraged with industry cash and in-kind cost share of 21,697,129 from 80 nonfederal partners for a total of 54,495,827 of funded research that 1) advanced the development of unconventional tight oil resources in the Bakken Formation; 2) demonstrated the application of CO 2 Storage and EOR in tight oil formations; 3) developed advanced carbon capture technology; 4) addressed key application and infrastructure concerns for commercial deployment of CO 2 ; 5) demonstrated innovative, integrated water management strategies for energy development projects; 6) developed novel pollution control technologies for mercury and hazardous air pollutants; and 7) performed world-class outreach and dissemination of research results to industry partners and other stakeholders. These outcomes speak to the valuable return on the substantial investment in this program.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2018

Fluidized Bed Production of Surface Functionalized Powders for Solid Oxide Fuel Cell Cathodes

Fuel cells offer tremendous potential for highly efficient conversion of fossil fuels to useable electrical power. Solid oxide fuel cells (SOFC) are particularly attractive, due to their high efficiency and capability to utilize either hydrogen or hydrocarbon fuels. Presently, there is considerable incentive to develop medium temperature (600 C to 800 C) SOFC's, in order to reduce the material compatibility issues and the engineering challenges associated with higher operating temperatures. Developing cathode materials with viable performance at intermediate temperatures is presently one of the key challenges in commercialization of solid oxide fuel cells. Recent works have shown the advantages of using surface functionalized cathode materials to improve SOFC performance at intermediate temperatures. However, present techniques for surface functionalization are expensive and difficult to implement in commercial SOFC production. In this SBIR Program, Structured Materials Industries, Inc. (SMI), along with partners FuelCell Energy, Inc. (FCE) and the University of Connecticut (UConn), demonstrated a simple and economical process to produce surface functionalized cathode materials, based on fluidized bed technology. SMI has developed a variation on this technology, known as Fluidized Bed Chemical Vapor Deposition (FBCVD), and is presently implementing and commercializing FBCVD as an economical and scalable process to deposit coatings on powder materials. In Phase I of this Project, the SBIR team demonstrated technical feasibility of this approach for producing high performance SOFC cathode materials. In this Phase II Project, the SBIR team refined and optimized the FBCVD process and the surface functionalized cathode materials. Surface functionalized powders of various composition and morphology were produced at SMI using the FBCVD process. Electrochemical characterization of the powders was done at FCE under actual SOFC operating conditions. The results demonstrated the potential for significant improvement in SOFC performance. Long term testing at FCE showed the performance enhancement to be stable with time. Advanced materials characterization at UConn identified the composition and morphology of the materials. SMI's FBCVD processed materials represent a "drop in" replacement for present cathode materials, and should have minimal impact on SOFC production costs. SMI has designed a scaled up FBCVD system for high volume production of SOFC cathode materials, and is well positioned for future implementation and commercialization of the technology developed in this SBIR.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS1977

Technical and economic feasibility study of solar/fossil hybrid power systems

Results show that new hybrid systems utilizing fossil fuel augmentation of solar energy can provide significant capital and energy cost benefits when compared with solar thermal systems requiring thermal storage. These benefits accrue from a reduction of solar collection area that results from both the use of highly efficient gas and combined cycle energy conversion subsystems and elimination of the requirement for long-term energy storage subsystems. Technical feasibility and fuel savings benefits of solar hybrid retrofit to existing fossil-fired, gas and vapor cycle powerplants was confirmed; however, economic viability of steam cycle retrofit was found to be dependent on the thermodynamic and operational characteristics of the existing powerplant.

Bloomfield, H. S.↗

DOE OSTI2023

Renewable Diesel Production through Stand-Alone and Co-Hydrotreating of Catalytic Fast Pyrolysis Oil

Catalytic Fast Pyrolysis (CFP) of biomass followed by hydrotreating can be used for the production of renewable transportation fuels, such as sustainable aviation fuel and renewable diesel, which can reduce the dependence on fossil fuels and help achieve greenhouse gas reduction goals. Stand-alone hydrotreating of CFP oil and co-hydrotreating of the CFP oil with straight-run diesel (SRD) showed potential to produce high-quality diesel products in this study. Stand-alone hydrotreating of CFP oil produced a diesel fraction with oxygen content < 0.1 wt.% and an indicated cetane number (ICN) of 45. Co-hydrotreating of CFP oil and SRD using a 1:4 volumetric ratio produced diesel products with 0.1 wt.% of oxygen and ICNs of 42-45. Compared to CoMo/Al2O3, NiMo/Al2O3 was a more attractive catalyst for co-hydrotreating of two streams, leading to a higher carbon efficiency, a higher selectivity of cycloalkanes, a higher ICN, and enhanced desulfurization. Compared to stand-alone hydrotreating of CFP oil, co-hydrotreating with SRD could be achieved at a less severe operating condition and it produced hydrotreated products with a higher carbon efficiency. Synergy between CFP oil and SRD during co-hydrotreating process was suggested by the better experimental results in comparison with theoretical interpolation results. Co-hydrotreating gave high biogenic carbon incorporations of 91%-97% as determined by C-14 analysis.

biomass↗

DOE OSTI2024

Covalent Triazine-Based Frameworks with Ru-tda Based Catalyst Anchored via Coordination Bond for Photoinduced Water Oxidation

Light-induced water splitting (hν-WS) for the production of hydrogen as a solar fuel is considered a promising sustainable strategy for the replacement of fossil fuels. An efficient system for hν-WS involves a photoactive material that, upon shining light, is capable of separating and transferring charges to catalysts for the hydrogen and oxygen evolution processes. Covalent triazine-based frameworks (CTFs) represent an interesting class of 2D organic light-absorbing materials that have recently emerged thanks to their tunable structural, optical and morphological properties. Typically, catalysts (Cat) are metallic nanoparticles generated in situ after photoelectroreduction of metal precursors or directly drop-casted on top of the CTF material to generate Cat-CTF assemblies. Here, in this work, the synthesis, characterization and photocatalytic performance of a novel hybrid material, Ru-CTF, is reported, based on a CTF structure featuring dangling pyridyl groups that allow the Ru-tda (tda is [2,2':6',2'“-terpyridine]-6,6'”-dicarboxylic acid) water oxidation catalyst (WOC) unit to coordinate via covalent bond. The Ru-CTF molecular hybrid material can carry out the light-induced water oxidation reaction efficiently at neutral pH, reaching values of maximum TOF of 17 h -1 and TONs in the range of 220 using sodium persulfate as a sacrificial electron acceptor.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2017

Life-cycle analysis of fuels from post-use non-recycled plastics

Plastic-to-fuel (PTF) technology uses pyrolysis to convert plastic waste—especially non-recycled plastics (NRP)—into ultra-low sulfur diesel (ULSD) fuel. To assess the potential energy and environmental benefits associated with PTF technology, we calculated the energy, water consumption, and greenhouse gas emissions of NRP-derived ULSD and compared the results to those metrics for conventional ULSD fuel. For these analyses, we used the Greenhouse gases, Regulated Emissions and Energy use in Transportation (GREET®) model. Five companies provided pyrolysis process product yields and material and energy consumption data. Co-products of the process included char and fuel gas. Char can be landfilled, which, per the company responses, is the most common practice for this co-product, or it may be sold as an energy product. Fuel gas can be combusted to internally generate process heat and electricity. Sensitivity analyses investigated the influence of co-product handling methodology, product yield, electric grid composition, and assumed efficiency of char combustion technology on life-cycle greenhouse gas emissions. The sensitivity analysis indicates that the GHG emissions would likely be reduced up to 14% when it is compared to conventional ULSD, depending on the co-product treatment method used. NRP-derived ULSD fuel could therefore be considered at a minimum carbon neutral with the potential to offer a modest GHG reduction. Moreover, this waste-derived fuel had 58% lower water consumption and up to 96% lower fossil fuel consumption than conventional ULSD fuel in the base case. In addition to the comparison of PTF fuels with conventional transportation fuels, we also compare the results with alternative scenarios for managing NRP including power generation and landfilling in the United States.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2024

Propelling sustainable energy: Multi-omics analysis of pennycress FATTY ACID ELONGATION1 knockout for biofuel production

Abstract The aviation industry’s growing interest in renewable jet fuel has encouraged the exploration of alternative oilseed crops. Replacing traditional fossil fuels with a sustainable, domestically sourced crop can substantially reduce carbon emissions, thus mitigating global climate instability. Pennycress (Thlaspi arvense L.) is an emerging oilseed intermediate crop that can be grown during the offseason between maize (Zea mays) and soybean (Glycine max) to produce renewable biofuel. Pennycress is being domesticated through breeding and mutagenesis, providing opportunities for trait enhancement. Here, we employed metabolic engineering strategies to improve seed oil composition and bolster the plant's economic competitiveness. FATTY ACID ELONGATION1 (FAE1) was targeted using CRISPR-Cas 9 gene editing to eliminate very long chain fatty acids (VLCFAs) from pennycress seed oil, thereby enhancing its cold flow properties. Through an integrated multiomics approach, we investigated the impact of eliminating VLCFAs in developing and mature plant embryos. Our findings revealed improved cold-germination efficiency in fae1, with seedling emergence occurring up to 3 d earlier at 10 °C. However, these alterations led to a tradeoff between storage oil content and composition. Additionally, these shifts in lipid biosynthesis were accompanied by broad metabolic changes, such as the accumulation of glucose and ADP-glucose quantities consistent with increased starch production. Furthermore, shifts to shorter FA chains triggered the upregulation of heat shock proteins, underscoring the importance of VLCFAs in stress signaling pathways. Overall, this research provides crucial insights for optimizing pennycress seed oil while preserving essential traits for biofuel applications.

Rasoul, Amira (ORCID:0009000714290175)↗

DOE OSTI2015

Semiconductor-electrocatalyst contacts: theory, experiment, and applications to solar water photoelectrolysis

Semiconductor photoelectrodes coated with electrocatalysts are key components of photoelectrochemical (PEC) energy conversion and storage systems. Such systems could provide a way to convert the energy in sunlight directly into energy stored in a fuel like hydrogen gas to power our modern society without using fossil fuels. Despite an intense effort aimed at optimizing these materials, there has been little systematic work focused on the semiconductor-electrocatalyst (SC|EC) interface. The SC|EC interface is important because it is responsible for collecting the photoexcited electron-hole pairs generated in the semiconductor. During the performance period we initiated a fundamental effort to understand interfacial electron transfer between electrocatalysts and bulk semiconductors. We developed an experimental technique, dual-working-electrode (DWE) photoelectrochemistry, allowing for direct electrical measurement of the SC-EC interface in situ. We also developed the first theory of the SC|EC interface and applied the theory through numerical simulation to explain the measured interfacial charge transfer properties of the SC|EC junction. We discovered that porous, ion-permeable, redox-active catalysts such as Ni-(Fe) oxyhydroxides form so-called “adaptive” junctions where the effective interfacial barrier height for electron transfer depends on the charge state of the catalyst. This is in sharp contrast to interface properties of dense ion-impermeable catalysts, which we found form buried junctions that could be described by simple equivalent electrical circuits. These results elucidated a design principle for catalyzed photoelectrodes - high-performance photoelectrodes with direct SC|EC junctions use soft deposition techniques that yield ion-permeable catalysts. This work thus provides a foundation for the development of improved photoelectrodes that are practically relevant because they provide a mechanism to directly convert and store solar energy in the form of hydrogen gas, a renewable chemical fuel.

08 HYDROGEN↗

DOE OSTI2015

Development of Kinetic Mechanisms for Next-Generation Fuels and CFD Simulation of Advanced Combustion Engines

Predictive chemical kinetic models are needed to represent next-generation fuel components and their mixtures with conventional gasoline and diesel fuels. These kinetic models will allow the prediction of the effect of alternative fuel blends in CFD simulations of advanced spark-ignition and compression-ignition engines. Enabled by kinetic models, CFD simulations can be used to optimize fuel formulations for advanced combustion engines so that maximum engine efficiency, fossil fuel displacement goals, and low pollutant emission goals can be achieved.

30 DIRECT ENERGY CONVERSION↗

DOE OSTI2023

Turboexpander for Direct Cooling in Hydrogen Vehicle Fueling Infrastructure

Hydrogen fuel cell electric vehicles (FCEVs) have been identified as one of a few options for zero carbon emissions transportation. A major advantage of FCEVs is that they can fuel quickly and follow a familiar fueling behavior to hydrocarbon-fueled vehicles. Whether light duty or heavy duty, the goal for a hydrogen dispenser is to fuel a vehicle in the same amount of time as the fossil fuel equivalent. When hydrogen is dispensed into the vehicle storage system, however, the temperature rises due to the Joule-Thomson effect and the heat of compression. Typically, vehicles store the compressed hydrogen in composite overwrapped pressure vessels that have a polymer liner with an operational temperature limit of 85°C. This temperature limit can be exceeded during fast fueling if hydrogen is not precooled. Precooling allows for a dispenser to fuel a vehicle at a faster flow rate by preventing the storage tank on the vehicle from overheating. Fueling protocols and requirements are presented in SAE J2601 Fueling Protocols for Light Duty Gaseous Hydrogen Surface Vehicles [1]. A heavy-duty equivalent is under development with similar requirements for precooling. Currently, conventional precooling for light-duty vehicle refueling uses a heat exchanger and chiller to cool the hydrogen gas to -40°C before entering the vehicle. The precooling system represents a significant part of the station capital and operating costs, so if the cost of the precooling system can be reduced by improving its efficiency, the overall station capital and operating cost can be reduced. In this project, National Renewable Energy Laboratory (NREL) and Sandia National Laboratories (SNL) researchers teamed up to investigate the turboexpander precooling application. A turboexpander is a device that places a turbine in a flow path where a pressure differential can be attained. This expansion device will extract work and lower the temperature of the fluid as the pressure reduces. While initial calculations based on established principles showed potential for a turboexpander to generate cooled gas, much work needs to be done to prove the concept. Turboexpanders typically work best under steady state conditions, while the dispenser is a very dynamic flow system. Dynamic turboexpander systems have been proven, such as a turbocharger on a gasoline vehicle. The inlet pressure at a dispenser is also much higher than any other known turboexpander system but should behave similarly to higher density fluids at lower pressures. Having both performed initial calculations, NREL and SNL researchers teamed up to investigate the turboexpander precooling application further. A project was soon built around the idea with SNL performing system modeling using previously proven capabilities and NREL performing hardware characterization with established station capabilities. Creare LLC was contracted as the turbomachinery expert to design and build the concept device. Part way through the project, however, contracting issues with the funding partner caused the project to terminate early before building and characterizing the concept device. While the project could not continue, many key findings were already learned. This paper is a summary of those findings.

08 HYDROGEN↗

NASA NTRS1973

The use of hydrogen for aircraft propulsion in view of the fuel crisis

Some factors influencing the technical feasibility of operating a liquid hydrogen-fueled airplane are discussed in light of the projected decrease of fossil fuels. Other sources of energy, such as wind, tidal, solar, and geothermal, are briefly mentioned. In view of projected decreases in available petroleum fuels, interest has been generated in exploiting the potential of liquid hydrogen (LH2) as an aircraft fuel. Cost studies of LH2 production show it to be more expensive than presently used fuels. Regardless of cost considerations, LH2 is viewed as an attractive aircraft fuel because of the potential performance benefits it offers. Accompanying these benefits, however, are many new problems associated with aircraft design and operations; for example, problems related to fuel system design and the handling of LH2 during ground servicing. Some of the factors influencing LH2 fuel tank design, pumping, heat exchange, and flow regulation are discussed.

Weiss, S.↗