Mobile Hydrogen Generation Providing Lifting Gas for Aerostats
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- H-‐Series Hydrogen Generator
- Capabilities Mission
- Coverage Area and Capabilities
- Operating Restrictions
- Operating Costs
- Table 1.
- Unlike natural gas, however, leaking hydrogen encountering an ignition source is far likelier to burn than explode, even inside a
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Mobile Hydrogen Generation Providing Lifting Gas for Aerostats Robert Schluter President Element 1 Corp There is considerable interest in adapting the benefits of Unmanned Aircraft Systems (UAS) and Lighter-‐ than-‐air (LTA) platforms proven in military applications, towards real world uses including precision agriculture, natural resource management, emergency response, and forest fire suppression. UAS have proven to be an excellent sensor platform where high mobility is desired. Alternatively, LTA platforms have been used to success as a tactical tower when low-‐cost, long-‐endurance, surveillance and communication is required. This white paper focuses on the benefits of using distributed hydrogen generation on a mobile platform to deliver lifting gas for LTA aerostats providing fire detection and monitoring. Why Aerostats? New generations of small aerostat systems are commercially available from a number of companies, and are an excellent platform for sensor packages, which show tremendous promise in solving real world problems. Mobile towers are height limited, providing only short-‐range coverage. Aircraft or UAS are expensive and have limited endurance. The new generation of aerostats provide coverage of a large area, comparable to aircraft or UAS, but with persistence of days and weeks instead of hours, at a fraction of the cost of Aircraft or UAS. Aerostat systems consist of a small specially designed tethered blimp, a launch platform mounted on a skid or single axel trailer, and a sensor or communications package. The launch system is comprised of a winch & powered tether, small electrical generator, and lifting gas for initial fill and “top off”. Depending on the size of the Aerostat the system is operated by a two or three person crew.
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2 The aerostat can be flown at several hundred to several thousand feet altitude, provides coverage 24 hours a day for up to two weeks without maintenance or downtime. Surveillance versions up to 1,000 feet can cover a 20-‐mile radius, depending upon terrain. An Aerostat with a communications relay payload at 4,000 feet altitude provides extended communication coverage up to 60 miles from its location. FAA Safety As a ground based system, aerostats do not require the complicated flight clearances needed for UAS deconfliction with manned aircraft. The FAA requires tether banners, lights and a system to automatically deflate the aerostat if the tether breaks. Simple “pop valves” which activate when an errant aerostat rises to a high altitude can meet this requirement. Aerostat Capabilities
Capabilities Mission *
Long-‐Endurance tactical sensor platform from 200 to 4,000 feet Mission Duration *
24/7 up to 14 days before a 60 minute "top off" is required Coverage Area and Capabilities *
Variety of payloads: surveillance, communications, NDVI (< 20 lbs.) *
Limited by camera resolution and mission. (1 < 10+ miles) *
Communications relay range limited by height, terrain (< 60 miles) Operating Restrictions *
No COA and minimal FAA restrictions allowing for rapid deployment *
No noise, unobtrusive, no danger of falling on civilians Deployment Requirements *
Rapidly deployed from either a truck, trailer or helicopter in under 4 hours
* Can launch and recover in low to moderate winds (<25 mph) * Can operate in challenging weather conditions (winds < 90 mph) Manpower *
Very simple operation with high reliability *
Only two or three person crews to launch and retrieve the Aerostat *
Communications and sensor operators can also serve as launch crew *
Lower level of skilled personnel required than UAS Acquisition Costs *
$50,000 (for smaller versions) to $250,000 (for midsize versions) *
Total costs depends on the payload and other options Operating Costs *
Minimal manpower costs. No pilot proficiency flying etc. *
Low operating costs with lifting gas produced from mobile hydrogen generator (<$35 per fill) High Cost of Helium is Limiting Adoption The Aerostat is made of a large fabric envelope that is filled with helium or hydrogen, which are lighter than air and provides the lifting force together with the aerostats lifting surfaces. Despite the success in military applications, widespread adoption of LTAs for commercial uses is limited without the availability of low-‐cost and easily transported lifting gas. Aerostats and other LTA platforms have historically been filled with Helium, an expensive gas that is in short supply. Helium must be drilled from a limited finite supply in the earth and is regulated by the US
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3 Government. In addition, because helium is a compressed gas, it is stored in heavy and bulky steel cylinders making transport of helium both difficult and expensive. Hydrogen as a Lifting Gas Hydrogen is a plentiful, cost effective, versatile, and safe (see Appendix) alternative to Helium. e1 has developed a small, portable hydrogen generator that is capable of filling aerostats with hydrogen at a much lower cost while overcoming the logistic challenges of handling compressed helium. A variation of the field-‐transportable hydrogen generator could also support fuel cell powered UAVs when they are commercially available in 2015. Benefits of Hydrogen Hydrogen is a plentiful, cost effective, versatile, and safe alternative to helium.
*
Hydrogen lifting gas can be produced economically Easier Logistics *
Liquid feedstock is hydrogen dense and easily transportable Greater Lift *
Hydrogen has 12% greater lift capacity than Helium Hydrogen Generators for On-‐Site Production of Lifting Gas e1 is an Oregon Corporation dedicated to developing advanced hydrogen generators that are compact in size and affordable. Our H-‐Series hydrogen generators combine a chemical reactor with hydrogen purification—the product stream is >97% hydrogen. The standard product covers a range of sizes delivering up to 150 standard liters per minute (5.2 ft3/m) of purified hydrogen from a convenient, safe, biodegradable blend of methanol and water. Currently e1 offers a commercial version of its patent-‐pending hydrogen generator that is designed for telecom equipment cabinets. e1 is offering a mobile version of this hydrogen generator to support aerostat and fuel cell UAV’s. Benefits of Mobile Hydrogen Generator • Significant O&M cost savings vs. compressed gas cylinders • Stand alone operation • A higher degree of ruggedness (especially over-‐road shock and vibration) • Simple and safe manual user interface • Improved on/off cycling durability e1 hydrogen generators are currently undergoing field-‐testing in the U.S., China, Taiwan, Indonesia, and India, providing high-‐purity hydrogen to support the operation of fuel cells in critical backup power applications in the telecom industry. e1 has also produced a prototype military-‐specific version H-‐Series hydrogen generator, the AHG110 currently being tested by the US Army.
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4 A comparison of hydrogen versus helium as the lifting gas is presented in Table 1. Table 1. Lifting Gas Hydrogen Helium Fill Volume 969 cubic ft. 969 cubic ft. Payload (min., sea level, no wind) 41.4 pounds 38.4 pounds
Supply Method Hydrogen Generator Steel cylinders (qty. 4) Volume 1.2 cubic ft. (8.9 gal.) 13.5 cubic ft. Weight
Approx. 65 pounds Approx. 880 pounds
Cost
Initial fill $35.6 ($4.00/gal) $740 ($185/cylinder) Make-‐up (3% loss per week) Approx. $1.00 / wk. Approx. $23.00 / wk. Forest Fire Management Aerostats have the potential to provide valuable services in wildfire detection and monitoring as well as aiding communications in remote areas lacking cellular or IP coverage. Forest fires are highly complex, non-‐structured, difficult environments that cause billions of dollars in damage to property and the environment every year. The 2014 fire season is forecast to be severe with drought conditions existing in much of the western United States. To combat wildfires effectively, their early detection and continuous tracking is vital. Communications plus multispectral imaging are extremely important to early detection and reporting of wildfires, as well as managing the locations of fire-‐fighting personnel to maximize human safety and minimize property loss. Fire fighters need frequent and high quality information updates on the progress of fires to effectively and safely fight them. Piloted aircraft are expensive to operate, stressing limited fire fighting budgets. Fixed-‐wing and rotary-‐wing UASs have limited application in the near term until the FAA relaxes COAs for commercial applications. Aerostats can provide significant benefits to fire fighters, and are likely to see field adoption this year. Before the Fire Forest fire lookout towers are located on mountain summits or other high vantage points in order to maximize viewing distance, spotting early stage forest fires. Early detection is critical in retarding the spread of forest fires that cause tremendous damage. The disadvantage of ground-‐based lookout towers is they require constant manpower and provide incomplete coverage of the forest. Unmanned aerostats can be remotely deployed across mountaintops providing persistent high-‐resolution imagery and geo-‐mapped data back to a centrally manned location. This saves manpower expense while effectively extending and expanding the coverage of forest fire ground stations. Modern UAS automated sensor packages have enough computing power for early detection and assessment of wildfires, a key step in reducing risk to life and property loss.
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5 During the Fire Fighting wildfires is a complex science, since the direction and intensity of the massive blazes can change in minutes. Additionally, spot fires can ignite behind fire lines when ambers carried into unburned fuel providing additional danger to fire crews. Aerostats can be rapidly deployed as mobile lookout towers behind fire lines to assist in the management of fires, gather information about changing weather and fire conditions, and help monitor for spot fires outside of fire lines, providing real-‐time alerts to fire crews. Communications Relay Another important function of aerostats is use as a voice and data communications relay. Firefighters are often sent out with tablets and smartphones so they can be updated about conditions. Internet-‐based tools can help calculate the risk of a fire reaching homes or other structures, and they can predict how fires may move, depending on the weather conditions. The aerostat will provide a wireless “hotspot” where ground service is weak or non-‐ existent, often the case as wildfires typically occur in rural areas where rough and remote terrain keeps firefighters out of signal range. After the Fire Even after a fire is contained and controlled, there will be areas inside the fire control line with active flames or smoldering materials. Aerostats can also be used for post-‐fire analysis to detect the presence of active fire embers during mop-‐up activities. Conclusion Aerostats have great potential to as a high-‐altitude platform for various communications relay concepts, local area security / surveillance and other missions. It can provide low cost, highly mobile platform with mission duration of a week or more. It can operate in weather conditions too severe for many UAVs or aircraft, and does so without endangering an aircrew. Perhaps the most compelling argument in favor of aerostats is in detection and fighting wildfires where persistent surveillance can lead to early detection of fires and, most importantly, protecting the fire-‐fighting crews who often work dangerously close to a rapidly moving (and unpredictable) inferno. However the adoption of aerostats will be limited due to the cost and logistic challenges related to using helium as a lifting gas. However, with training and adoption of standard industry precautions, hydrogen is a safe, cost-‐effective alternative as lifting gas for aerostats. Mobile, on-‐site hydrogen generators eliminate the logistical challenges related to using bottled gases and can provide a low cost source of hydrogen that will enable aerostats to reach their full potential in commercial applications.
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6 Appendix Hydrogen Safety
The hydrogen industry has an enviable safety record spanning more than a half-‐century. Any fuel can be hazardous and needs due care, but hydrogen’s hazards are different and generally more tractable than those of hydrocarbon fuels, like natural gas, diesel fuel, and gasoline. Unlike natural gas, however, leaking hydrogen encountering an ignition source is far likelier to burn than explode, even inside a building, because it burns at concentrations far below its lower explosive limit. In the vast majority of cases, leaking hydrogen if lit, will burn and not explode. And in the rare cases where it might explode, its theoretical explosive power per unit of volume of gas is 22 times weaker than that of gasoline vapor. Thus, with proper handling procedures and training similar to many of these common fuels, hydrogen can be safely deployed as a lifting gas. Hydrogen is extremely buoyant and diffuses rapidly • Hydrogen released into an open environment rapidly disperses up and away from its source • Hydrogen is 14.4 times lighter than air and thus dissipates quickly (45 mph; 20 m/s) • Hydrogen rises 2 times faster than helium and 6 times faster than natural gas Hydrogen is flammable only under specific conditions • Hydrogen must be contained to become a fire hazard • Hydrogen is flammable in air at concentrations between 4% and 74% • Optimal combustion condition is 29% H2-‐to-‐air ratio • Outside of optimal H2-‐to-‐air ratio, combustion profile is similar to other fuels A Fire Requires • Hydrogen gas leakage • Confinement of a hydrogen-‐air mixture at combustion ratio between 4% and 74% • An ignition source • Prevention focuses on avoiding these three conditions First Layer of Defense • Ventilation if hydrogen generator used indoors • Inert gas boundary bags • Lightning & static electricity protection • Electrical distribution safety systems • The safest approach to flammable gas handling is “keeping it in the pipe” Hydrogen Safety Resources • http://h2bestpractices.org/default.asp • http://www.arhab.org/pdfs/h2_safety_fsheet.pdf • http://www.hydrogenandfuelcellsafety.info/resources.asp • http://www.globalsecurity.org/military/world/airship-‐hydrogen.htm • http://www.rmi.org/Knowledge-‐Center/Library/E03-‐05_TwentyHydrogenMyths Download 56.9 Kb. Do'stlaringiz bilan baham: 
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