A fuel cell is a device that generates electricity by a chemical reaction. It converts hydrogen and oxygen into water, and in the process also creates electricity. Fuel cells provide many advantages, they are environment friendly as they don’t produce pollutants or greenhouse gasses, significantly improving our environment, high energy efficiency ( can be close to 80% where they generate both heat and electricity), scalable providing power from milliwatts to megawatts, and complementary i.e. readily be combined with other energy technologies, such as batteries, wind turbines, solar panels, and super-capacitors. There are many types of fuel cells, and each can operate in a clean manner using different fuels including hydrogen, natural gas, methanol, ethanol, biogas. In just the last two years, Toyota, Hyundai and Honda have released vehicles that run on fuel cells, and carmakers such as GM, BMW and VW are working on prototypes.
Fuel cells can also extend the operating range and mission of military systems by reducing the dependence on carbon-based fuel sources. They also save energy and reduce the operating costs associated with dependence on foreign oil. “As the U.S. moves to reduce its dependence on foreign oil and become more energy efficient, this technology may well define the future of power and energy for the war fighter,” writes ONR. According to US Military, the reductions in the Department’s need for energy can improve warfighting capabilities, such as increased range, better endurance, longer time on station, and reduced requirements for resupply. Improved energy performance also can reduce the risk and effects of attacks on supply lines and enable tactical and operational superiority.
While boosting the military energy readiness by actively promoting low-and no-carbon energy alternatives, the Defense Department is also working to reduce its use of fossil fuels and the resulting greenhouse gases being produced. Another driver behind the American military’s move to clean sources of energy is climate change – a threat that military leaders continue to warn policy makers is very real and will impact the military, whether it’s responding to natural disasters or responding to conflicts caused by scarce resources.
Hydrogen – the most common element in the universe – can be generated from several sources, and refueling a fuel-cell vehicle takes no longer than a gas vehicle, as opposed to the hours it takes to charge a battery-powered one. Hydrogen-powered military vehicles also could be used to generate power, and produce 2 gallons of water per hour.
“Fuel cells offer a highly efficient and fuel flexible technology that cleanly produces power and heat with low or zero emissions. Using renewably produced fuels such as hydrogen fuel cells can reduce our nation’s dependence on imported oil, leading to a secure energy future for America. With a multitude of end-uses—such as distributed power for backup, primary, and combined heat-and-power systems; automobiles, buses, forklifts and other specialty vehicles; and auxiliary power units and portable electronics—fuel cell applications hold potential to dramatically impact the 21st century clean energy economy,” writes the U.S. Department of Energy (DOE).
Consumer fuel cell vehicles from Toyota, Honda and Hyundai are for sale and on the road in California, which is home to about half of the 6,500 fuel cell vehicles sold between 2013 and 2017, supported by about three dozen refueling stations. General Motors has announced a deal to develop a fuel cell manufacturing plant with Honda, and has started testing the ZH2 with the Army, a highly modified Chevrolet Colorado pickup that runs on hydrogen.
There are many types of fuel cells, but they all consist of an anode, a cathode, and an electrolyte that allows positively charged hydrogen ions (or protons) to move between the two sides of the fuel cell. The reactions that produce electricity take place at the electrodes. Every fuel cell also has an electrolyte, which carries electrically charged particles from one electrode to the other, and a catalyst, which speeds the reactions at the electrodes.
Fuel cells are classified primarily by the kind of electrolyte they employ. This classification determines the kind of electro-chemical reactions that take place in the cell, the kind of catalysts required, the temperature range in which the cell operates, the fuel required, and other factors. These characteristics, in turn, affect the applications for which these cells are most suitable.
The six fuel cell types are : PEMFC, Proton Exchange Membrane Fuel Cell, DMFC, Direct Methanol Fuel Cell, PAFC, Phosphoric Acid Fuel Cell, AFC, Alkaline Fuel Cell, MCFC, Molten Carbonate Fuel Cell and
SOFC, Solid Oxide Fuel Cell.
Individual fuel cells produce relatively small electrical potentials, about 0.7 volts, so cells are “stacked”, or placed in series, to create sufficient voltage to meet an application’s requirements. The energy efficiency of a fuel cell is generally between 40–60%, or up to 85% efficient in cogeneration if waste heat is captured for use.
Emerging Military Fuel Cell Applications
Fuel cell vehicles
FCVs represent a radical departure from vehicles powered by conventional internal combustion engines. Rather than relying on energy from an external source, FCVs could potentially self-generate more than twice the amount of energy of an internal combustion engine — without the noise or emissions. FCVs run on power generated onboard the vehicle through a chemical process using hydrogen fuel and oxygen in the air. FCVs offer a potentially sustainable energy source through the mixture of hydrogen and oxygen, with zero air emissions produced.
GM is believed to be using military applications to research and develop next-generation fuel cell technologies. If produced, the Silverado ZH2 would be at least the second military-specific pickup. The first was the fuel cell-powered Chevrolet Colorado ZH2, which the U.S. Army started testing in April 2017. GM has at least three other fuel cell initiatives for military use, including an auxiliary power unit for aircraft applications, an unmanned undersea vehicle and a multiuse platform called the Silent Utility Rover Universal Superstructure, or SURUS.
This concept vehicle is essentially a giant self-driving platform that can hold any kind of vehicle body — or even just cargo. Something like this could be useful in disaster zones or in conflicts, the automaker said.
Hydrogen power is particularly well-suited for military use, according to GM, because fuel cells produce very little heat. That makes them harder for enemies to detect. Additionally, hydrogen can be produced in the field from a number of different sources, which means that fuel for the vehicles won’t always have to be transported to the vehicles. U.S. military is testing a hydrogen-powered GM pickup called the ZH2 and the Navy began testing a GM-produced hydrogen-powered unmanned submarine.
GM and U.S. Army testing GM’s Extreme Off-Road Hydrogen Fuel Cell Chevrolet Colorado
General Motors and the U.S. Army Tank Automotive Research, Development & Engineering Center (TARDEC) have modified a Chevrolet Colorado midsize pickup truck to run on a commercial hydrogen fuel cell propulsion system and will expose the truck to the extremes of daily military use for 12 months.
The ZH2, based on a Chevy Colorado, has a reinforced body with a suspension built for off-road handling. It’s also powered by a fuel cell and a battery that’s quieter than traditional internal combustion engines and gives off less heat. This will help in situations where the Army wants to reduce sound and thermal signatures. The truck comes with a 50-kilowatt battery—charged by the fuel cell—that can be removed to power other applications. The ZH2 can also keep soldiers hydrated since the only byproduct from the fuel cell is pure water. The Army is in the process of evaluating the truck for potential use in military operations.
Fuel cell propulsion has very high low-end torque capability useful in off-road environments. It also offers exportable electric power and quiet operation, attractive characteristics to both commercial and military use. “FCVs are very quiet vehicles, which scouts, special operators and other specialties place a premium,” he said. “What’s more, fuel cells generate water as a by-product, something extremely valuable in austere environments.”
Hydrogen fuel cell propulsion technology helps address two major environmental challenges with automobiles today – petroleum use and carbon dioxide emissions. Fuel cell vehicles can operate on renewable hydrogen from sources like wind and biomass. Water vapor is the only emission.
Specifically, the Army intends to test the Colorado ZH2 fuel cells for quiet, silent watch operation; reduced acoustic and thermal signatures; high torque; low fuel consumption and water by-product for use in the field. GM is also applying that hydrogen fuel cell technology for US Navy unmanned undersea vehicles through a project with the ONR and is exploring a variety of aerospace applications.
Unmanned Aerial Vehicles (UAVs)
Unmanned aerial vehicles (UAVs) are typically used for military operations where manned flights would be too risky or difficult. They send back real-time imagery of activities on the ground and are usually powered by batteries that last up to 30 minutes before they need to recharge. Hydrogen fuel cells can increase UAV air time to approximately 8 hours and, after landing, can be refueled in less than 15 minutes. Also, there are no moving parts—meaning the fuel cell-powered UAV requires less maintenance and zero lubricants.
At InterDrone exhibition in Las Vegas, two FCHEA member companies showcased hydrogen fuel cell powerpacks for commercial UAVs. Doosan Mobility Innovation’s fuel cell powerpack is refueled using a single, detachable hydrogen container, and the powerpack can keep UAVs flying for two hours on a single charge of hydrogen.
Intelligent Energy’s new 800W Fuel Cell Power Module (FCPM) was shown with the company’s 650W model, which was unveiled at the 2017 InterDrone exhibition. The 800W FCPM is 10% more power dense than the 650W model, and multicopter UAVs will be able to carry one kilogram of cargo for two hours, or two kilograms for one hour. Intelligent Energy will also work with customers who have the capability to combine two of the 800W models to provide 1.6 kW of continuous power
Building on the success and interest in UAVs, FCHEA member Alakai Technolgies is going one step further, developing a hydrogen fuel cell-powered, four passenger, long-duration, all-electric vertical takeoff and landing (eVTOL) aircraft in 2019.
Unmanned Undersea Vehicles (UUVs)
In addition to UAVs, the development of underwater drones, Unmanned Underwater Vehicles (UUVs), has targeted various commercial, research, and military applications due to their ability to reach areas deemed too dangerous, expensive, or difficult for manned vessels. Untethered UUVs require an onboard power supply sufficient for propulsion while powering sensors, communication equipment, cameras, lights, and other auxiliary functions. Currently, lithium-ion batteries are used as this onboard power supply. However, as the vessels get larger and the desired ranges get longer, batteries are unable to meet the requisite power requirements. Hydrogen powered fuel cells provide the power density necessary to meet these requirements while also minimizing the impact on the marine environment with no emissions, noise, or vibrations.
US Navy has requirement for an air-independent advanced electric power source with high energy storage for unmanned undersea vehicles (UUV). Current battery systems can not meet mission requirements. Proton exchange membrane fuel cells (PEMFC) and solid oxide fuel cells (SOFC) are being investigated due to higher efficiencies and energy densities.
The United States Office of Naval Research and the U.S. Naval Research Laboratory have partnered with General Motors to develop fuel cell-powered UUVs.
The Navy started using fuel cells instead of batteries in UUVs to allow bigger payloads and longer runtimes. They recently completed an evaluation of a prototype at the Naval Surface Warfare Center in Carderock, Maryland. Because fuel cells are compact, lightweight, and reliable, they have the ability to run for long periods of time and support the Navy’s focus on energy technology for vehicles that need more endurance. Prototypes have passed the Navy’s tests, showing reliability, high energy density, and cost-effectiveness. Ultimately, the Navy wants the vehicle to be capable of operating for 60 days without refueling, which hydrogen powered fuel cells can provide.
Navy considering Fuel cells for Unmanned Underwater Vehicles to submarines
ONR and its partners across government, defense and private industry are exploring fuel cell power to expand warfighter capabilities — whether to reduce the size and weight of man-portable devices or to meet megawatt requirements for shipboard power. A fuel cell vehicle (FCV) uses hydrogen-powered fuel cell propulsion instead of a standard internal combustion engine.
The ONR under the Fuel cells program is exploring improved power generation capabilities within the critical weight and volume constraints of future systems that are designed for increased capability and agility, including all electric naval ships, unmanned (air, surface, subsurface, ground) vehicles, aircraft auxiliary power units and man-portable power applications.
Within the Navy and Marine Corps, ONR has long recognized that greater fuel efficiency can improve the effectiveness of U.S. forces. In the field, FCVs would increase mission endurance and stealth, while reducing logistical burdens and costs.
Currently, two ONR-sponsored FCVs operate at the Marine Corps Base at Camp Pendleton. These vehicles provide instant torque from the start without a drop of oil, only emitting water vapor. FCVs require no pistons or cylinders. Because they have no transmission, FCVs relieve drivers of manual shifting. Acceptance of the technology is widening by users who find them fun, clean and “green” to operate.
GM collaborating with Navy for fuel cells in Unmanned Underwater Vehicles
Hydrogen fuel cells convert high-energy hydrogen efficiently into electricity, resulting in vehicles with greater range and endurance than those powered with batteries. Under the ONR’s Innovative Naval Prototype program for Large Displacement UUVs (LDUUV), energy is a core technology in the Navy’s goals for vehicles with more than 60 days endurance. The Navy plans to test the LDUUV in the open sea this year and could field a first squadron of the robotic submarines by 2020.
The Naval Research Laboratory recently concluded an evaluation of a prototype unmanned underwater vehicle equipped with a GM fuel cell at the heart of the vehicle powertrain. “Our in-water experiments with an integrated prototype show that fuel cells can be game changers for autonomous underwater systems,” said Frank Herr, ONR’s department head for Ocean Battlespace Sensing. “Reliability, high energy, and cost effectiveness — all brought to us via GM’s partnering — are particularly important as Navy looks to use UUVs as force multipliers.”
“GM’s fuel cells are compact and lightweight, and have high reliability and performance. Lower cost is achievable through volume production. These attributes match the goals of the Navy to develop reliable, affordable systems,” claims GM. In future submarines could be power by Hydrogen Fuel Cells, The advantage of a fuel-cell system aboard submarines is their air independent operation.
Wearable Power Systems
Ideal equipment weight is 30% of a person’s body weight, but some soldiers have to carry more than 100 pounds. To lighten the load, the Army is looking into replacing lithium-ion batteries with fuel cells for power generation—decreasing battery weight by 50%. These “wearable power systems” for the dismounted solider can produce 20 watts (W) of continuous output and 35W of peak power. To aid this effort, the U.S. Department of Energy (DOE) is working to drive down the cost of aluminum hydride—a promising material that can be used for storing hydrogen to utilize in these portable fuel systems.
Scientists at the U.S. Army Research Laboratory observed an unexpected result when combining urine with a newly engineered nano-powder based on aluminum. It instantly releases hydrogen from the urine at much higher rate than with ordinary water. The research team announced earlier this summer that a nano-galvanic aluminum-based powder they were developing produced pure hydrogen when coming into contact with water. The researchers observed a similar reaction when adding their powder to any liquid containing water.
“We have calculated that one kilogram of aluminum powder can produce 220 kilowatts of power in just three minutes,” said Dr. Anit Giri, also an ARL researcher. Making use of urine as fuel source may result in tremendous benefits for Soldiers, officials said.
Fuel cells for soldiers
“Today’s challenge for our dismounted infantry Soldier is basically weight, so we have situations where some Soldiers are carrying in excess of 100 pounds. Ideally you want to be at a thirty percent body weight, so you want to carry like 30 pounds,” Dr. Tony Thampan, a chemical engineer in the Army’s Communications-Electronics Research, Development and Engineering Center, or CERDEC, said. “Before they would just limit the missions, and that takes away capability.”
Thampan modeled, designed, and developed a Soldier wearable power system that can cut a Soldier’s weight burden by up to four times. He did this by using a fuel cell membrane made of Aluminum hydride, or AlH3, which provides a better energy density than the common Li-on battery used today.
“Now that these solutions have increased energy density systems, you can go out on longer missions and keep the weight manageable,” Thampan said.
The wearable power system powers individual Soldier devices or all of a Soldier’s ensemble devices — such as worn radios and end user devices — through a power distribution system. It consists of a power unit with an internal starting battery, fuel gauge and fuel cartridges.
The system is flexible and can be worn in a pouch on the side of a Soldier’s vest. It has passed government ballistic testing requirements and is rated safe for Soldier’s to wear.
SAFCell Inc. Awarded Enhancement Grant from US Army to Produce a 50 Watt Fuel Cell Power Unit
SAFCell and UltraCell have commenced the design and fabrication of a 50 watt, propane-fueled power unit based on the use of SAFCell’s proprietary Solid Acid Fuel Cell stacks in UltraCell’s world-leading military portable power systems. This first-of- its-kind ultra-light power unit will reduce by half the total battery weight burden on the modern soldier, up to 44 pounds for a three-day mission, enabling them to carry more mission critical equipment and ammunition.
Commenting on the Enhancement award, SAFCell’s CEO and President Dr. Calum Chisholm said: “This award enables us to demonstrate the advantage of using our fuel-flexible Solid Acid Fuel Cell technology in UltraCell’s ultra-rugged, portable power system design. The portability, fuel-efficiency, and silence of the final unit will make it ideal not only for military use, but for commercial applications as well.”
SAFCell announced that it has won a competitive $3 million award from the U.S. Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E). SAFCell will use this funding to develop a solid acid electrochemical hydrogen compressor (EHC) that converts ammonia directly into high purity, high pressure hydrogen.
The solid acid EHC unit will enable onsite hydrogen generation and compression from renewable, energy-dense carbon-neutral liquid fuels (CNLF), such as ammonia and bio-methanol. Such one-step hydrogen generation and compression would enable low cost, wide-scale storage and delivery of renewable energy for use in both stationary and transportation sectors.
This award enables us to demonstrate that our fuel-flexible Solid Acid technology can generate hydrogen from any of the commercial fuels that our fuel cell systems run on, and in particular, we can run on renewable fuels like ammonia.
Fuel cells for Military bases
The U.S. Army Corps of Engineers is powering stateside installations as well as bases in forward operating locations with fuel cells—electrochemical cells that convert fuel sources into electric currents. The efforts result in money savings, a reduction of the dependence on foreign oil, essentially unlimited power generation and a cleaner environment.
For backup power, installations can connect fuel cells to a grid so the energy sources will kick in during an emergency without a disruption in electrical services. This ensures the continued operation of mission critical resources such as computer rooms, telephone switching equipment, command centers, hospitals and emergency centers.
Nick Josefik, a mechanical engineer at the ERDC-CERL, says that over the years the laboratory has installed more than 200 fuel cells in various sizes. These range from 500-watt models that back up a few computers to 250- to 500-megawatt systems that can power entire subdivisions, hospitals or industrial buildings. The fuel cell installations are split almost evenly between prime power and backup power use. Through this work, CERL is helping the military meet its goal to reduce energy usage 25 percent by 2015.
Ultra-clean CHP-capable fuel cell power plants
The beauty of fuel cells is that they can also be integrated with other forms of renewable energy generation, to store energy or to produce electricity and heat later. No other distributed energy source can duplicate this kind of flexibility.
Combined heat and power (CHP) is gaining increased recognition as a cost-effective solution for meeting growing energy needs while reducing the environmental impact of power generation. Reliable on-site power generation improves power reliability and energy security, attributes valued at various U.S. military bases with DFC power plants.
Ultra-clean Direct FuelCell® (DFC®) power plants, unlike traditional reciprocating engines and gas turbines, produce virtually no nitrogen oxides (NOx), sulfur oxides (SOx), or particulate emissions (PM). While the average fossil fuel power plant in the USA produces nearly 25 pounds of these emissions per megawatt hour, the DFC fuel cell produces just 0.1 pounds of these emissions.DFC power plants also emit dramatically less carbon dioxide (CO2) than combustion-based power generation, a significant reduction of greenhouse gas emissions, particularly when configured for CHP applications.
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