Alternative jet fuels put to the test

NASA and 11 other research groups are testing two non-petroleum-based jet fuels in the pursuit of alternative fuels that can power commercial jets and address rising oil costs. The tests, being run through Feb. 3 at NASA's Dryden Flight Research Center in California, are measuring the performance and emissions of two synthetic fuels derived from coal and natural gas using the Fischer-Tropsch process. These fuels have drawn attention because they have the energy necessary for commercial flight.

The Fischer-Tropsch process is a chemical reaction in which a synthesis gas - a mixture of carbon monoxide and hydrogen -- is converted into liquid hydrocarbons of various forms. The process produces synthetic petroleum for use as a lubricant or fuel.

The technology has been around for decades, but until now the high cost of building new plants to produce synthetic fuels has stymied interest. The United States does not have any Fischer-Tropsch plants, although synthetic fuel is produced using this process elsewhere in the world.

Some companies have tried out synthetic fuels in proprietary tests. Unlike those, the results of these NASA tests will be in the public domain because researchers are obtaining them with a NASA plane.

A DC-8 based at Dryden in Edwards, Calif., is the test vehicle because its engine operations are well-documented and well-understood. The airplane remains on the ground for the tests, which are using one fuel made from natural gas and one from coal. Researchers are testing 100 percent synthetic fuels and 50-50 blends of synthetics and regular jet fuel. Almost all previous testing has considered only blends. Researchers are looking primarily at engine performance and aircraft emissions.

"We’re starting to look at just what comes out of the tailpipe of a commercial aircraft [that is burning alternative fuels]," said Bruce Anderson, a scientist with NASA's Langley Research Center in Hampton, Va., who serves as project scientist for the Alternative Aviation Fuel Experiment, also known as AAFEX.

It is thought that synthetic fuels create fewer particles and other harmful emissions than standard jet fuel. If this is found to be true, use of synthetic fuels could improve the air quality around airports.

The tests are using sampling probes placed downstream from the DC-8's right inboard engine. Researchers examine the plume chemistry and particle evolution to compare it to that of standard jet fuel.

NASA is one of many organizations working to understand how non-petroleum alternatives may be used to satisfy the growing demand for less expensive, cleaner burning fuel for aviation.

"We’re still very much in the early research stage," said AAFEX project manager Dan Bulzan of NASA's Glenn Research Center in Cleveland. "[But] we know in the future these fuels are going to become important to aviation. Petroleum is dwindling and you're going to need to make fuel out of coal, natural gas and biomass."

The AAFEX tests are funded and managed by NASA's Fundamental Aeronautics Program, which is part of the agency's Aeronautics Research Mission Directorate in Washington, D.C. The participating research groups include three other government agencies, five companies and three universities.

1. Answer the following questions.

- What are NASA and 11 other research groups testing? Describe the tests.

- Can the use of synthetic fuels improve the air quality around airports?

- Why is it very important to understand how non-petroleum alternatives may be used to satisfy the growing demand for less expensive, cleaner burning fuel for aviation?

Green Skies: Engineer's Work May Reduce Jet Travel's Role In Global Warming

The text is taken from http://www.sciencedaily.com/releases/2007/10/071014174122.htm

1. Learn the following vocabulary.

Mechanical and Aerospace Engineering

To have a lofty goal

To end the nation's reliance on oil for jet travel

To advance the fundamental knowledge of jet fuels

To develop practical, innovative energy sources

To make alternative jet fuel sources feasible

To predict and evaluate

The refining process

Alternative energy sources

To reduce the amount of greenhouse gasses

Additional expertise

To present a major quandary to researchers

To develop feasible alternatives to petroleum

1. Read the text:

Princeton Professor of Mechanical and Aerospace Engineering Fred Dryer has a lofty goal: end the nation's reliance on oil for jet travel.

With potentially major benefits for energy security and the environment riding upon his success, Dryer is advancing the fundamental knowledge of jet fuels while developing practical, innovative energy sources.

"In order to make alternative jet fuel sources feasible, they need to be compatible with petroleum and produce similar combustion performance," Dryer said. "This will only be possible if we fully understand how both petroleum and alternative fuels burn and design engines based on this fundamental knowledge." Backed by government and industry grants, Dryer is leading two new research efforts to advance these technologies. The first, a major project funded by the U.S. Air Force, is focused on developing computational and kinetic models that accurately simulate the burning of jet fuel, a complex and poorly characterized mix of chemicals. At the same time, he is putting his basic understanding to use as he develops jet fuels with near-zero net greenhouse gas emissions in a project funded by NetJets, a leading provider of business jets.

The Air Force program is one of the Defense Department's highly competitive Multi-disciplinary University Research Initiative (MURI) grants. One of only ten such projects supported by the Air Force this year, the collaboration involves researchers from four institutions -- Princeton, Case Western Reserve University, Pennsylvania State University and the University of Illinois-Chicago. The award, with an overall value of up to $7.5 million, will provide support for three years with the option of a two-year extension. Research began in July and the kick-off meeting for the project will be held Sept. 17 in Princeton.

Dryer and his MURI collaborators, including Princeton Associate Professor of Mechanical and Aerospace Engineering Yiguang Ju, will develop methods to predict and evaluate how jet fuels will behave in actual engines and characterize the emissions they will produce. While current guidelines specify some overall properties of jet fuels, they do not spell out the actual chemical composition. Depending on the source and processing method, jet fuel typically consists of hundreds to thousands of molecular structures that behave in a variety of ways.

The models developed by the team will represent and characterize the behavior of this broad range of jet fuel species using only a few types of molecular structures as surrogates for the larger whole. Dryer previously developed similar "surrogate fuel" models to represent gasoline, which are now being used for engine design by the automotive industry.

"The composition of fuels changes with the geographic source, the refining process and even with the season," Dryer noted. "Since we have an energy security problem, we need to be sure that alternative fuel sources are going to work and, in order to do that, we need to understand exactly how petroleum-based fuels work alone and in combination with alternative fuels."

Alternative energy sources, if designed appropriately, also could significantly reduce the amount of greenhouse gasses released in creating and burning jet fuel. According to the U.S. Department of Transportation, aviation is responsible for around 10 percent of the greenhouse gas emissions from transportation in the nation, or roughly 2.7 percent of the country's total greenhouse gas emissions. The second research program, supported by NetJets, augments Dryer's fundamental MURI work and brings in additional expertise from the Princeton Environmental Institute to develop "greener" alternative fuels.

"NetJets is pleased to be working with the engineers and scientists at Princeton to develop new jet fuels with near-zero net greenhouse gas emissions," said NetJets Chairman and CEO Richard Santulli. "Princeton has a longstanding history of leadership in aerospace science. We feel they will make great strides with this research."

The NetJets-funded research project provides the opportunity to make substantial progress toward the launching of green technologies not only for corporate jets, but also for commercial aviation and transportation in general, according to Robert Williams, a senior research scientist at the Princeton Environmental Institute and member of the NetJets-sponsored research team. At Princeton, the team also includes Ju and Eric Larson, a research engineer at the Princeton Environmental Institute. In addition, the work will involve collaboration with researchers at the Institute of Transportation Studies at the University of California-Davis.

Two alternative fuel sources that are the subject of much investigation in the aviation field -- coal and biomass -- present a major quandary to researchers attempting to develop low-emissions jet fuels. Coal, a relatively cheap and readily available source of energy, has an emissions profile at least as harmful as petroleum. Biofuel -- fuel made from plants -- presents an attractive alternative because the carbon dioxide emitted from burning biomaterials will be removed from the atmosphere by a new generation of plants during photosynthesis. The production of biomaterials, however, requires the intensive use of land, limiting the feasibility of widespread production of biofuels.

To take advantage of the positive characteristics of each of these sources, the Princeton researchers will center their efforts on the synthesis of jet fuels from a combination of coal and biomass. A key component of their solution is isolating and storing the carbon dioxide produced during the production of so-called synfuels. This technique, called carbon capture and sequestration, is a promising strategy being investigated intensively by Princeton's Carbon Mitigation Initiative, among other research programs.

An "especially attractive feature" of processing coal and biomass together to make synfuels is that it requires only half the amount of biomaterial as pure biofuel production, while still making fuels with near-zero greenhouse gas emissions, Williams said.

The ultimate success of the research efforts will depend on how well the synfuels compare with traditional fuel sources, in terms of fuel characteristics, costs and environmental and safety issues, the researchers said.

"There is no doubt that developing feasible alternatives to petroleum for the aviation industry will be a long and expensive process," Dryer said. "And success, in the form of an enduring solution, will be priceless."

1. Answer the following questions.

- What kind of goal has Princeton Professor of Mechanical and Aerospace Engineering Fred Dryer?

- Is Dryer advancing the fundamental knowledge of jet fuels while developing practical, innovative energy sources?

- What should researchers understand in order to make alternative jet fuel sources feasible?

- What kind of two new research efforts is Dryer leading to advance these technologies?

- What will the models developed by the team represent and characterize using only a few types of molecular structures as surrogates for the larger whole?

- Why is it important to understand exactly how petroleum-based fuels work alone and in combination with alternative fuels?

- Why are two alternative fuel sources the subject of much investigation in the aviation field -- coal and biomass -- present a major quandary to researchers attempting to develop low-emissions jet fuels?

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