Powering the U.S. Army of the Future (2021) / Chapter Skim
Currently Skimming:
3 Energy Sources, Conversion Devices, and Storage
3 Energy Sources, Conversion Devices, and Storage
Pages 23-54
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 23... ...
and volumetric energy density (function of volume) of the liquid and gaseous fuel sources that could be considered for battlefield deployment.
|
From page 24... ...
Liquid Energy Sources Liquid petroleum-derived fuels have more energy per unit volume (which determines the number of supply trucks) than any other transportation fuel.
|
From page 25... ...
As shown in Figure 3.3, cetane ratings for JP8 vary widely with the source, whereas DF1 and DF2 diesel fuel require 2 P.A. Muzzell, 2011, "Alternative Fuels for Use in DoD/Army Tactical Ground Systems," ARC Collaborative Research Seminar Series, U.S.
|
From page 26... ...
Muzzell, 2011, "Alternative Fuels for Use in DoD/Army Tactical Ground Systems," ARC Collaborative Research Seminar Series, U.S. Army Research, Development, and Engineering Command (RDECOM)
|
From page 27... ...
FIGURE 3.3 Jet propellant 8 (JP8) cetane ratings by source.
|
From page 28... ...
Although the rating variability is not a problem with turbine-operated aircraft (or the turbine-operated Abrams tank) , it can pose a problem for internal combustion engines, particularly in cold weather.
|
From page 29... ...
Higher cetane ratings are preferred in diesels to ensure reliable and consistent ignition and cold weather starting in the absence of a spark-actuated combustion event. 5 EIA, 2013, "Few Transportation Fuels Surpass the Energy Densities of Gasoline and Diesel," https://www.eia.gov/todayinenergy/detail.php?
|
From page 30... ...
Ethanol and methanol have 69 percent and 45 percent of the energy content per unit volume of JP8, respectively, making them impractical as a sole source of fuel for a military ground vehicle.9 NATO Single Fuel Forward Policy To date, the Army has relied heavily on JP8 as part of its "single fuel forward" policy -- one military fuel on the battlefield across all ground vehicle platforms. In addition to being an Army fuel for ground vehicles, JP8 is a fuel for turbine-powered aircraft and is specified by MIL-DTL-83133 and British Defense Standard 91-87.
|
From page 31... ...
GASEOUS ENERGY SOURCES Compressed Propane Compressed propane has roughly 73 percent of the energy content per unit volume of JP8 and roughly 14 percent better energy content per 11 Congressional Research Service, 2012, DOD Alternative Fuels: Policy, Initiatives and Legis lative Activity, https://fas.org/sgp/crs/natsec/R42859.pdf.
|
From page 32... ...
CNG has only 26 percent of the energy content per unit volume of JP8, making it impractical as a fuel source for military combat vehicles, where space is greatly constrained to provide room for ammunition, propulsion, cooling systems, and operators.13 Like compressed propane, a much heavier storage tank would be required and safety concerns abound. Lastly, the number of supply trucks required to transport an equivalent amount of energy to the battlefield would have to grow, putting more lives at risk.
|
From page 33... ...
Hydrogen is growing as a commercially available transportation fuel15 primarily for use in proton exchange membrane (PEM) fuel cells, with refueling stations planned across the United States and allied nations primarily for use in fuel cell–equipped vehicles.16 Hydrogen poses even greater transportation and storage challenges than natural gas, in that achieving practical handling densities requires that the gas be cooled (down to −253°C)
|
From page 34... ...
The most active consideration of hydrogen for tactical use involves usage with fuel cells. These energy-conversion devices will be discussed in further depth later in this chapter.
|
From page 35... ...
Because electrical energy is required for electrolysis, using JP8 to power an internal combustion engine to power a generator to power an electrolyzer to generate hydrogen to power a fuel cell has some inherent inefficiencies. In addition, as discussed above, using renewable energy sources (solar, wind, hydro, waste)
|
From page 36... ...
The Massachusetts Institute of Technology (MIT) Lincoln Laboratory has developed a method to produce activated aluminum beads that react in a similar manner, producing aluminum hydroxide, hydrogen, steam, and residual contaminants.24 As shown in Figure 3.5, a preliminary prototype design by the MIT Lincoln Laboratory has demonstrated the ability to generate 10 kW on an automotive application using a reaction chamber, conditioning system, and PEM fuel cell.
|
From page 37... ...
Fischman, and D Hart, 2020, Kilowatt-scale fuel cell systems powered by recycled aluminum, Journal of Electrochemical Energy Conversion and Storage 18(1)
|
From page 38... ...
However, a number of critical questions remain, including definition of the complete process to be used for each application. Recommendation: The Army should continue to explore the potential use of aluminum for onsite generation of hydrogen for use in proton exchange membrane fuel cells, not only for use in vehicles, but also for potential use in dismounted and base-camp applications.
|
From page 39... ...
Miniature and portable devices employing radioisotope decay will be discussed in further depth in Chapter 5, "Dismounted Soldier Power and Light UAVs/UGVs." Nuclear reactor studies were advocated by the 2016 Defense Science Board report Task Force on Energy Systems for Forward/Remote Operating Bases and will be discussed further in Chapter 7, "Forward Operating Base Power."27 Approaches to address safety and regulatory concerns are covered in Appendix M Box 3.1 describes the challenges and opportunities of nuclear isomer energy storage.
|
From page 40... ...
They operate at 60°C to 120°C and require pure hydrogen as the fuel. If the use of a hydrocarbon fuel is desired, it will first have to be reformed to produce pure hydrogen containing no CO or sulfur, because each easily poisons the platinum-based catalysts that reduce molecular oxygen and oxidize the fuel in PEM fuel cells.28 However, reformation of hydrocarbon fuels such as JP8 or diesel to produce hydrogen with no CO and sulfur is extremely complex and should be further investigated regarding its applicability for onsite or on vehicle reformation.
|
From page 41... ...
Wang, and S Tao, 2018, Advances in reforming and partial oxidation of hydrocarbons for hydrogen production and fuel cell applications, Renewable and Sustainable Energy Reviews 82, Part 1:761–780.
|
From page 42... ...
In addition, the committee recognizes that small, flexible roll-up solar panels and small solar trailers, which are now commercially available, can provide expeditionary personnel with a fallback battery charger or power source for laptop computers and radios. As part of a 2016 report on energy systems for forward and remote operating bases, the Defense Science Board examined the availability, technical maturity, and operational considerations of alternative energy sources, including solar, wind, hydrokinetic, geothermal, and ocean thermal power (see Table 3.2)
|
From page 43... ...
Madia, and W Schneider, 2016, "Task Force on Energy Systems for Forward/Remote Operating Bases," Defense Science Board, Under Secretary of Defense for Acquisition, Technology, and Logistics (USD(AT&L)
|
From page 44... ...
and the kinetics at which electrons are released from or returned to the active materials in the two electrodes (walking the line between controlled delivery of electrons versus a bomb)
|
From page 45... ...
That demand places the performance metrics of an electrical energy-storage device in unoccupied territory -- up and to the right on the power versus energy Ragone plot -- where neither present-day electrochemical capacitors (ECs) provide sufficient energy nor batteries provide sufficient power.
|
From page 46... ...
program manager supporting battery research has noted they found little had changed when returning to battery science and technology (S&T) reviews after stepping away for 15 years.35 In keeping with that observation, note the first recommendation in the 2004 National Academies report Meeting the Energy Needs of Future Warriors,36 which assessed power and energy needs for the Army using the land warrior as its focal point: Recommendation 1: The Army should focus on batteries with a specific energy of 300 Wh/kg and higher for insertion into future versions of the Land Warrior (LW)
|
From page 47... ...
SOURCE: L.M. Toomey, 2020, "Combat Vehicle Energy Storage," U.S.
|
From page 48... ...
38 Battery500 goals include development of next-generation Li-metal anode cells deliver ing a threefold increase in specific energy to 500 Wh/kg. See Department of Energy, 2020, "Battery500: Progress Update," Office of Energy Efficiency and Renewable Energy, May 19, https://www.energy.gov/eere/articles/battery500-progress-update.
|
From page 49... ...
Using solid ceramic electrolytes to minimize growth of Li metal dendrites from extensive charge–discharge cycling is achieved currently by operating at loads of approximately 1 mA cm−2. This limit is likely to be overridden in the field to obtain necessary pulse power, one of the key conditions that favors the growth of dendrites, which then launches the accompanying safety concerns inherent to Li chemistry.
|
From page 50... ...
, the capacity of the active materials and thus the battery can be drained to manufacturer-rated levels of energy density. Power performance out of the same electrode structure cannot be ensured because electron flow from the current collector to the distributed active material relies on surface contact of the active material with carbon agglomerates.
|
From page 51... ...
The second is demonstrating that well-wired, nanoscale-textured active materials increase surface-to-volume ratio to innately allow surfacebased, capacitive charge/discharge at high load without decrementing the total charge stored or released at low-to-moderate loads. Combining the two redesigns affords power performance commensurate with an electrochemical capacitor while retaining the energy density designed into the battery.
|
From page 52... ...
The issues with respect to even the available generation of Li-based batteries, including the logistics complications surrounding ensuring that transport of Li-batteries occurs at less than full state-of-charge, emphasizes the practicality of optimizing aqueous-based or all solid-state–based energy storage for the Army. The following energy-storage systems offer other means to deliver both power and energy using safer chemistries and advanced electrode designs.
|
From page 53... ...
To match the innate capabilities of architected Zn electrodes -- a two-electron anode versus the one-electron Li-based anode -- further research and development will be required to optimize complementary positive electrode compositions and structures, including identifying multi-electron active materials (e.g., Ag/AgxO, potentially MnO2 and NiOOH, and trifunctional air-breathing
|
From page 54... ...
For the Army, fast rechargeability is an important objec tive that enables expeditious tapping into the vast supply of electricity available from generators and microgrids, as well as unmanned and manned combat vehicles.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.