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Sobering Thoughts on Aviation Fuel

Fri, Feb 29, 2008 — David Evans

Briefs

What the aviation industry needs is a dramatic improvement in fuel economy if it is to remain a viable form of mass transportation in an era of diminishing petroleum reserves, according to a blog titled “Why Airbus and Boeing Will Soon Go Bust.” Extracts follow:“Kerosene is what powers turbofan or turboprop aircraft. A very sober jet like the Airbus A380 can fly 80 miles per gallon per passenger … imagine yourself checking-in with a couple of carts carrying two hundred 1-gallon cans of jet fuel (or alternatively sunflower oil if you are biofuel minded) for your Bombay-New York return trip, and you have a clue why air travel needs inexpensive fuel like rice crops need abundant water.

“I was an R&D engineer for future commercial aircraft projects. I was struggling to scrape 2% off the fuel burn of futuristic airliners. No need to have a Ph.D. in rocket science to see that this is absurdly inadequate. Oil prices rise by 2% each week, and we are trying to shave that much of an airline’s fuel bill five years from now. In 2008, the Boeing 787 Dreamliner will save 20% fuel burn compared to the aging 767. Now 20% is exactly how much  oil prices rose between January and May just [last] year – therefore, despite all its novelties, the 30-year younger 787 design will offset only five months worth of oil price [increases].

“If new designs cannot mitigate the issue, impending oil production decline and the resulting soaring oil prices are not compatible with sustained air traffic growth. …

“Now you might think that the industry should see this coming. They probably do, but admitting it would be telling their bankers that they are on the brink of major change. It is a very tricky situation. If hey launched the development of a revolutionary slow-flying, medium-size, medium-range turboprop to save 50% fuel burn (tat’s more like it), they would be confessing that they expect drastic turmoil in air travel models. As bankers hate turmoil, it might just hasten the fall. So they prefer to bury their heads in the sand, praying that this be just a temporary blip and that oil prices will soon nicely settle back to $30 a barrel and stay at this price for the next 30 years.” (www.wisemandarine.com/why-airbus-and-boeing-will-soon-go-bust)

“Now you might think that the industry should see this coming. They probably do, but admitting it would be telling their bankers that they are on the brink of major change. It is a very tricky situation. If hey launched the development of a revolutionary slow-flying, medium-size, medium-range turboprop to save 50% fuel burn (tat’s more like it), they would be confessing that they expect drastic turmoil in air travel models. As bankers hate turmoil, it might just hasten the fall. So they prefer to bury their heads in the sand, praying that this be just a temporary blip and that oil prices will soon nicely settle back to $30 a barrel and stay at this price for the next 30 years.” (www.wisemandarine.com/why-airbus-and-boeing-will-soon-go-bust)

Support for an era of petroleum scarcity comes from a website called The Oil Drum that specializes in forecasts. Its February 2008 update (77 pages of production and demand forecasts plus commentary) states that:

“World oil liquids production (Fig. 1) remains on a peak plateau since 2006 and is forecast to fall off this peak plateau in 2009. Increasing numbers of oil experts are forecasting peak production plateaus. According to the International Energy Agency (IEA), the current peak production of 87.2 mbd [million barrels per day] occurred on January 2008. As long as demand continues increasing, then prices will continue increasing. …

“World oil discovery rates peaked in 1965 and production has exceeded discovery for every year since the mid 1980s.” (www.theoildrum.com/node/3623)

Among many comments on the website, this one is salient:

“What the energy literate that pat attention to this site can agree on is oil is never going to be replaced. It is imperative that the West start now to create an economy that is far less energy intensive.”

Fig 1 – Total Liquids Supply & Demand to 2012

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Is future total liquids production likely to exceed the current peak of 87.2 mbd on January 2008? It might be possible but it appears unlikely. North Sea production continues to decline. Mexico’s production is also in decline. Former USSR production might increase by a small amount. Canada’s production should increase slowly, but the oil sands are experiencing production constraints and despite claimed reserves of up to 315 Gb (billion barrels), the oil sands will probably produce, at best, a maximum of only 2.5 mbd, according to the website. Biofuels production should also continue increasing.

One potential for increased energy efficiency in aviation may be unducted fan technology. Also known as propfan and also as ultra-high bypass (UHB) engines, the technology fits the blog call above for a revolutionary turboprop. Basically, a propfan is a modified jet engine, with the fan placed outside of the engine nacelle; the layout offers the speed of a jet with the fuel economy of a turboprop.

A propfan concept of the 1980s offered about a 30% improvement in fuel economy. The efficiency comes at a price: increased noise. However, the concept shown below met Stage III noise compliance and had low levels of interior noise and vibration. As Wikepedia, the free Internet encyclopedia, says, “With the current high price for jet fuel and the emphasis on engine/airframe efficiency to reduce emissions, there is renewed interest in the propfan concept for jetliners that might come into service beyond the Boeing 787 and Airbus A350XWB.” (http://en.wikepedia.org/wiki/Propfan)

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The General Electric GE-36 Unducted Fan (UDF) was flight tested in the 1980s, but the drop in oil prices in the early 1980s resulted in weak interest from the airlines and further development of the concept was discontinued.

Source: www.aerospaceweb.org/question/propulsion/q0067.shtml


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