SCOTT AIR FORCE BASE, Ill. –
As the Air Force worked to certify the B-52H Stratofortress for using an alternative fuel mix, Air Mobility Command's chief scientist saw his role in reviewing test data as a small one.
Now, Dr. Don Erbschloe has turned his attention to tests later this year for certifying Air Force C-17 aircraft to use the fuel mix, which is a 50/50 blend of a synthetic fuel and JP-8 aviation fuel. The C-17 tests will establish certification standards for all Air Force aircraft.
"There are extremely bright people in the Air Force who have been working this problem for many years," said Doctor Erbschloe. "Where I got involved was the B-52 tests -- I was asked to come in May to head up a team to do an independent review of the B-52 tests."
Doctor Erbschloe said his independent review team was comprised of world experts from AMC, industry, academia and government research labs in the areas of fuels, engines and logistics. He said the review team assessed how thoroughly the B-52 tests were conducted and concurred with recommendations to certify the B-52 for using the fuel blend. Doctor Erbschloe said his team also determined the blend certification process for the B-52 was "very methodical and grounded in solid systems engineering practices."
By 2010, the Air Force goal is to certify all its aircraft to use the fuel blend which mixes JP-8 with fuel produced using the Fischer-Tropsch process -- a process used to convert carbon-based materials into synthetic fuel.
German chemists Franz Fischer and Hans Tropsch developed the method at the Kaiser Wilhem Institute during the 1920s. The Air Force officially certified the B-52H Stratofortress to use a blend of Fischer-Tropsch synthetic fuel and JP-8, Aug. 8.
"Essentially, using a number of chemicals and catalysts, what (Chemists Fischer and Tropsch) were able to do was to reproduce in a laboratory what it takes the earth millions of years to do with organic matter," said Doctor Erbschloe.
Doctor Erbschloe said Fischer-Tropsch fuel can be synthesized from any carbon-based material.
"The process starts with carbon-based 'feedstock' -- this could be coal, natural gas or any other carbon-based material. Ultimately, it could be bio-mass or even trash," he explained. "The first step is to produce 'synthesis gas' or 'syngas' -- a mixture of carbon monoxide and hydrogen. During the catalysis of syngas, you're building up hydrocarbons, and you get a complex 'organic soup' very much like petroleum."
Doctor Erbschloe said a Fischer-Tropsch fuel mix has the potential to burn cleaner than JP-8.
"During the process of creating the organic soup, you don't introduce a lot of particulates and unwanted materials like sulfur compounds," he said. "Indications are that (Fischer-Tropsch fuel) doesn't leave sooty trails."
"In (the B-52 engine) tests, the use of the alternative fuel blend was found to reduce soot emissions by 30 percent at max power and by 60 percent at idle," said Dr. Tim Edwards, senior chemical engineer for the Air Force Research Laboratory's Fuels Branch. "Sulfur emissions were reduced by 50 percent. These emissions reductions are due to the very high quality of the Fischer-Tropsch fuel blend component."
Doctor Erbschloe said although the Fischer-Tropsch process generates excess carbon dioxide, he remains confident technologies will emerge soon to capture and store the carbon dioxide generated by the process. He said until more research is done, Fischer-Tropsch fuel is mixed with JP-8 to ensure the fuel contains adequate "aromatics" -- elements found in traditionally-produced fuels and lacking in Fischer-Tropsch fuel. Doctor Erbschloe said aromatics might be a factor in preventing fuel leaks.
"It turns out aromatics might help various seals and o-rings expand and seal properly in aircraft engines during operation," he said.
Doctor Erbschloe, a former deputy chief operating officer for the Department of Energy's Office of Science, said as fuel prices rise, synthetic fuel becomes economically viable with the potential to reduce dependency on foreign energy sources.
"The goal is to make the cost of synthetic fuel comparable to buying JP-8," he said.
Doctor Erbschloe said upcoming C-17 tests will be a stepping stone toward improving national energy security as well as toward prompting interest in commercial industry. He said commercial aviation already is working with the Air Force to certify more aircraft to use the fuel blend. The former Air Force command pilot with 3,900 flying hours said Air Force standardization efforts will help define the certification process.
"The C-17 tests will be important because it's a newer aircraft with newer materials and systems," said Doctor Erbschloe. "Our goal is to have a standard protocol -- a methodology to establish a military standard for the fuel. (The C-17 tests) will validate the methodology we'll use to certify other aircraft," he said.