Open Access Article Originally Published: May 11, 2007
Commercial aviation is an essential component of the global economy. The cost of aviation fuel is directly determined by the prevailing world price of oil. It accounts for a major proportion of airplane operating costs. Several airline companies now add a fuel surcharge to the ticket cost of a commercial flight to compensate for the recent rapid rise in fuel costs. World oil prices are expected to remain high for several years. The prospect of sustained high aviation fuel prices could propel airline companies to seek alternative aviation fuels. Seeking alternative fuel could become become paramount for the airline industry should the peak-oil phenomena actually occur. The commercial aviation industry would likely compete for fuel and energy in a market of scarcity and escalating fuel prices.
Breakthroughs and Research
It may become possible for supercooled liquid hydrogen to eventually be used as an alternative fuel for some types of commercial airline service. Extensive research will be needed to resolve the numerous logistical problems that are related to its use as an alternative aviation fuel in supersonic and hypersonic aircraft. Other alternative fuels may include high-density energy-storage technologies that result from breakthroughs in research in the areas of nanotechnology and in high-temperature superconductivity.
Sporadic and significant breakthroughs periodically occur in both fields. High-temperature superconductivity holds great promise for use in high-density energy-storage technology. A coil formed into a torus and made from "high-temperature" superconductive material could theoretically store enough energy to enable a full-sized commercial airliner to undertake an extended trans-oceanic or trans-continental flight. Advances in nanotechnology could enable superconductive materials to eventually be manufactured at a cost that could justify their application in airliner propulsion.
Electrical Storage and Propulsion
Energy stored in a superconductive storage technology could power electric motors that drive the identical propulsion fans that are found at the front-end of modern, "high-bypass" turbo-fan aircraft engines. Such fans provide up to 90% of the propulsive thrust of the turbo-fan engine. Each electrically powered propulsion fan may be driven by multiple (induction) lightweight electric motors during take-off. Some electric motors would "cut-out" under reduced power demand at cruising altitude so that the remaining motors will operate at higher efficiency (electric motors have poor part-load effciency).
Coanda fans may propel subsonic commercial aircraft that use high-density electrical storage technology. Such units were originally developed by physicist Henri Coanda and can operate at comparable efficiency and at comparable flight speeds as turbine-driven propulsion fans. Electrically powered aircraft that use either turbine propulsion fans or Coanda fans could be flown in thinner air at higher altitude (up to 65,000-feet) to reduce energy consumption (less drag on aircraft) on extended flights. The cooler air found at such altitudes could assist in keeping the superconductive energy storage systems functioning properly.
Superconductive energy storage systems used in future commercial aircraft would likely be cooled by liquid nitrogen. Both systems would need to be frequently recharged. Commercial aircraft that operate long-haul service usually undergo cleaning and servicing in hangars after long flights. It is during such service periods when the energy storage and cooling systems could be recharged, a process that would likely be both energy-intensive as well as time consuming.
It may be possible to design the energy storage systems along with their cooling systems to be removed and replaceable during shorts layovers. Such technology may be possible and could help reduce the turn-around time of the aircraft. The introduction of superconductive energy storage systems in commercial aircraft in the long-term future would require that future airport terminals be equipt with power generation technology at or near the premises.
Short-haul/Commuter Aircraft
Aircraft turbine engines are very flexible in the kind of fuel that they can burn. Short-haul and commuter airline companies that operate routes of under 500-miles would be the most likely candidates to use alternative aviation fuel. Their fleets are mainly powered by turbo-prop or by turbofan engines and may likely have sufficient capacity in the fuel tanks to carry a cheaper fuel with a lower energy content. They may use such fuel if its cost per BTU undersells fossil aviation fuel. Breakthroughs in electrical storage technology could see a future generation of short-haul and commuter aircraft being propelled by electric motors driving propellers or propulsion fans.
Low-Altitude Flight
Ground-effect aircraft use a specialized wing design that generated a cushion of air between the wing and the surface over which it flies. Large and heavy versions of such aircraft could be flown at moderate speed over water and carry passengers and freight between coastal centres of up to 500-miles apart. Eliminating the need for take-off to at least 10,000-feet would cut fuel costs. The performance of such craft can be enhanced by a recent development from Britain that has been successfully tested in a scale model aircraft.
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7 comments so far...
11-May-2007
56165
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It 'may' be possible that Mr. Valentine is a real nutcase. It is certainly 'likely' that this is nothing more than a utopian vision to get the base salivating over energy storage technology that doesn't/won't exist. Some nice ideas; But, I like Heinlein's vision better: travelers are stuffed into a ballistic shell which is electromagnetically hurled into the lower atmostphere and then drops altitude right over the target airport.
Anyway, here is how aviation will likely play out:
1. Short term - If the public does not change its driving habits then aviation fuel will probably NOT rise all that much. Airliners will need to spend more money for inventory systems and buy larger proportion of fuel during the refinery off season when American motorists aren't driving insatiable demand.
2. Medium term - SynGas. We have loads of coal to make the stuff. Engines will be adapted to run on the stuff.
3. Long term - Either SynGas or Hydrogen. (depending on which is more politically correct). GE already does a ton of research on combusting H2.
In any event, the move to migrating airport service vehicle fleets to non-regular gas is underway.
Posted by: Tom Hamilton
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12-May-2007
56174
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Buy local , live local and save a billions times the energy of this futuristic dream. We don't all have to fly around the world. High spped video and fiber optics are light fast and very efficient.
Posted by: jim stack
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12-May-2007
56172
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Carbon-neutral and even carbon-negative jet flight is here now. Biomass to Liquid using waste cellulose (wood chips, sawdust, crop residue, etc) makes a product with a sizable kerosene fraction. Choren of Germany does this. Another company [Eprida] and others use the remaining charcoal from the pyrolysis of the cellulose to make a potent fertilizer turning a soil into Terra Preta [black earth] and sequestering the carbon.
Posted by: Matt McAdoo
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12-May-2007
56180
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Mr. Valentine:
Great article! These are the kinds of ideas I dream about, and to hear someone else verbalize them actually gives me hope for the future! In a hundred years, I'm sure the idea of combusting anything will seem as quaint as the notion of a hunter/gatherer lifestyle. Everything you mentioned is inevitable, and we already have operating hydraulic/pneumatic and flow battery energy storage systems gaining popularity. If only we could have it sooner, rather than take the big oil/coal route.
Posted by: Mick Smith
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18-Jul-2009
67362
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I would just like say that this idea is a great and very good idea and is possible, i have had many dreams and visions of this happening so much that I have begun scteching and brainstorming ways to make this possible using a nitrogen cooled eletric feild with the combanation of magnatisim to create a vortex of air to propell a commercial airplane
Posted by: timothy moe
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21-Jan-2010
80382
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Seriously, what if I could show you a electrical power system that needs no charging, no fuels, and can power any thing., no matter the size. Pattented and built, not just on paper? Who do I contact?
Posted by: James Brummett
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15-May-2007
56202
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Because airplanes have a very long lifetime, they are probably going to fly on oil for many more years. But change is coming there to. Virgin plan to use biodiesel on it's transatlantic jets and the Cryoplane has already explored the use of liquid Hydrogen.
Hybrid airplanes can make use of a strong motor to move the propeller or the electrofan while taking their electricity from surge power devices like a supercapacitor or a battery. That device can on it's turn be recharged continuously by a generator that has only 65 % of the motor power. The result is higher reliability because the motors are less failure prone then engines and high surge power capability. This is particularly interesting in the case of a ground effect aircraft where the take-off is easily taking five times the power required to maintain it's standard flight. Motor driven propellers can give a boost to 180 MW and then continue the flight on only 30 MW. This is very important because motors are not so much larger when they get more powerfull and the generator supplying the constant energy to the surge power unit can be limited to 33 MW. With this system a 10000 tons ekranoplane becomes possible.
The same story is true for a follow on V22 Osprey. The engines can be replaced by two motors able to provide the surge power that is needed for the vertical take-off phase. Normal flight of the V22 is again only a fraction of the maximum power.
Actually the defunct smaller Duo-Treck is now more at reach then ever thanks to this new hybrid technology. A small generator, two ducted electrofans and a surge power device to accommodate vertical take-off.. I don't say it's easy but it is easier with an hybrid configuration then with an oversized thermal engine.
For an airliner like a 777 hybridization is still interesting despite the fact that take-off power and flight power are much closer. The advantage here is that the 777 could be safer and more efficient in the same time. The aircraft would be propelled by to electrofans receiving power from turbogenerators. The power surge device in between, would permit take-off power and would also be a reserve for a safe landing. The turbogenerators can be located just behind the electrofans or in the aircraft tail in the form of an enhanced APU. Like for the Prius a planetary gear system could also allow direct transmission of force between the turbogenerator and the fan. A very early form of hybrid 777 could be like a Honda Insight with a motor on the shaft of a otherwise standard turbofan. It could already provide some surge power at take-off and even transmit power from one turbofan to the other in case one of the turbofan engine fails in flight. This would allow continued double fan operation and re-equilibrate the airplane.
In the case of supersonic flight, once electricity is made available on board by a superconductor device a conventional turbogenerator or a fuel cell, it can be put at work in a much more interesting way then fans or other mechanical devices. We can make use of MHD or Magneto Hydro Dynamics, the science that was first established to study electromagnetic propulsion in water but that was later extended to include propulsion in air. An MHD device takes profit from the fact that charged particles moving in a magnetic field experience a resulting force on them. In sea water the charged particles are the Chloride and Natrium ions of the salt contained in the water. That's why MHD propulsion ships can only operate in the sea and not in fresh water. In the air there are no ions present so they must first be created. A spark device can be used for that, or a photonic activation by light, a base flame or micro waves. Anything that will cause electrons to separate from Oxygen or Nitrogen molecules. Once the air is ionized the same can be made then in the case of seawater. A magnetic field can be applied to create a strong force on the ions. That force will move the ions to the back of the aircraft and the reaction force will push the aircraft forward. The main difference with
a propeller or a fan is that there is almost no limit to the speed that can given to the ions and thus to the aircraft. As a result, supersonic aircrafts can be made but also hypersonic aircrafts up to the liberation speed. Once in space the air must be replaced by an on board gas though to be able to generate the ions needed to the MHD. The pleasant thing is that the energy used on a London Sydney flight would be smaller then the energy used in a conventional 777. That's because once the Mach 25 speed is reached the aircraft is in space with no drag on it for most of the flight. The landing is also energy free. Better it is even possible to regenerate energy by putting the MHD device in reverse. This time creating a strong current from the braking of the ions in the MHD engine. Of course the ions don't need to be generated this time since the re-entry into the atmosphere will be doing that for you more then enough.
An intriguing engineering thing to notice is that in the case of an electrical energy storage in a superconductor coil, the optimum 777 shape becomes that of a flying saucer. A large round energy storage coil, a cabin on top and the most efficient MHD engine that is an external conformal full body engine. In short the saucer shape. Even if ET was never observed for real, the observations stories somehow describe a perfect fit with what would be top engineering.
Posted by: Patrick Leonard
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