Drop-in JP-5 jet fuel replacement ‘invisible to user’
By Andrea Watters
The Secretary of the Navy’s energy vision came to fruition in September when the EA-18G “Green Growler” completed flight testing of a 100-percent advanced biofuel at Naval Air Station Patuxent River, Maryland.
From takeoff to landing, you couldn’t tell any difference,” said Lt. Cmdr. Bradley Fairfax, project officer and test pilot with Air Test and Evaluation Squadron (VX) 23, after the first test flight Sept. 1. “The information presented to us in the airplane is pretty simplified, but as far as I could tell, the aircraft flew completely the same as [petroleum-based] JP-5 for the whole flight.”
Using the Naval Air Warfare Center Aircraft Division’s (NAWCAD) Real-time Telemetry Processing System (RTPS) at the Atlantic Test Ranges, flight test engineer Mary Picard monitored the ground and test flights and confirmed Fairfax’s observations. “What we have seen is that the 100-percent bio-JP-5 appears to be basically transparent. It looks exactly like petroleum JP-5 in the airplane; it performs the same, and we haven’t noticed a difference.”
And that’s the technical premise of the Navy’s alternative fuels test and qualification program: the JP-5 produced from alternative sources must be invisible to the user, said Rick Kamin, Energy and Fuels lead for Naval Air Systems Command (NAVAIR). Kamin also leads the alternative fuel test and qualification program for the Navy.
Prior to the first test flight, the catalytic hydrothermal conversion-to-jet (CHCJ) process 100-percent alternative fuel performed as expected during ground test Aug. 30 at NAWCAD’s Aircraft Test and Evaluation Facility.
“Today is a further example of how the Navy and Marine Corps continue to lead in energy innovation, and in doing so, remain the greatest expeditionary fighting force the world has ever known,” said Secretary of the Navy Ray Mabus.
The fuels program supports SECNAV’s operational energy goal to increase the use of alternative fuels afloat by 2020.
“As the owner of the JP-5 aviation jet fuel specification, our job at NAVAIR is to make sure that whatever source our JP-5 is made from, we know it will work in our aircraft,” Kamin said.
“This is the first time we’ve looked at a process that can produce a fuel with all the properties and chemistry of JP-5 jet fuel without having to blend with petroleum-based JP-5,” said Kamin.
CHCJ is produced by Florida-based Applied Research Associates (ARA) and Chevron Lummus Global. ARA’s process uses the same feedstocks as the Hydroprocessed Esters and Fatty Acids (HEFA) 50-percent advanced biofuel blend previously approved by the Navy, but goes through a unique conversion process that provides a fully synthetic fuel that does not need to be blended, Kamin said.
Advanced Biofuel Production Processes
As part of its qualifications program, the fuels team evaluated five alternative sources for JP-5 and four F-76 sources since SECNAV kicked-off the program in 2009.
The biofuels were analyzed in the fuels lab and engine components were tested followed by aircraft ground and flight testing, with the ultimate goal of incorporating advanced biofuels into the military specifications.
The first biofuel process evaluated in 2010 was HEFA, which produces biofuel from oil seed plants, algae, tallow and waste oils. While not specified by the Navy, camelina seeds (Camelina sativa) were used to produce the test fuel. However, since the HEFA product did not have all the properties of JP-5—particularly aromatic compounds—it had to be blended 50/50, Kamin said.
CHCJ starts with feedstocks including algal oils, tallows and plant oils such as carinata (Brassica carinata), waste vegetable oils, canola oils and distillers’ grain oils. These feedstocks undergo a catalytic hydrothermolysis process, which uniquely converts the starting materials into a mixture that primarily contains the variety of hydrocarbons essential for jet fuel (aromatic, paraffinic and olefinic compounds). The final hydrogenation and fractionation steps convert or remove unwanted compounds from the intermediate process stream so that the finished product is an on-specification, fit-for-use fuel.
“We are excited to work with the U.S. Navy as it takes this important step toward the use of 100-percent drop-in renewable jet and diesel fuels in its aircraft and ships,” said Chuck Red, vice president of fuels development for ARA. “Our renewable fuels continue to prove their viability as 100-percent replacements for petroleum in diesel and jet fuel applications.”
JP-5 is exclusively used by navies because it is specifically refined with a higher flash point for additional safety at sea. A primary need is that all candidates must be drop-in replacements that meet the following criteria:
- No changes to Navy equipment
- No impacts to performance or operability
- No incompatibilities with current fuel stocks
- No changes for the end user
“The sources of the fuel can change, but not the fuel itself,” Kamin said.
The fuels team has evaluated five alternative sources for JP-5 and four F-76 ship diesel sources since SECNAV kicked-off the program in 2009. (See graphic above.) The team, however, was already researching biofuels in response to interest from the U.S. Air Force and the commercial airline industry in 2008.
Test Pilot Perspective
“There are several differences between test flying and fleet flying,” said Lt. Cmdr. Bradley Fairfax.
“First, flight test, especially propulsion testing, involves flying the aircraft to very exact flight conditions and collecting data via scripted maneuvers. By doing this around the edges of the flight envelope, we can evaluate the performance of the aircraft in worst-case scenarios, and feel confident that fleet aviators will have satisfactory performance when they employ the aircraft in combat.
Second, executing the scripted maneuvers usually involves flying the aircraft in non-standard or new configurations. For the biofuel testing specifically, we only performed the throttle transients on one engine at a time, but the engines are designed to be used as a single propulsion system. We also secured auxiliary systems, like bleed air circuits and generators, that are normally left operating for fleet flights.”
“We shot for this 100-percent drop-in fuel from the beginning,” Kamin said. “We wanted to know if a fully synthetic JP-5 from a non-petroleum source could work in our systems and we proved that it could!”
Assistant Secretary for Energy, Installations and Environment Dennis McGinn recognizes the fuels team’s due diligence.
“We didn’t just fill up the jet and fly it,” McGinn said of the Navy’s involvement over several years now. “We did an extensive amount of ground testing, a lot of measurements at every point along that jet engine, from going into the fuel tank to coming out the exhaust. It was done well, and we’re very confident that the 100-percent alternative works.”
Benefits of Alternative Fuels
“This is a continuation of a long Navy tradition,” Mabus said. “In the middle of the 19th century, we went from sail to coal. In the early 20th century, we moved from coal to oil. In the mid-20th century, we pioneered nuclear as a propulsion method. Every single time we moved to a new form of power, as we are doing now with alternative fuel, people had doubts; and every single time they were wrong.”
A 100-percent alternative helps with procurement and logistics, Kamin said. A blend requires the biofuel manufacturer to blend its biofuel with a petroleum-based JP-5 to produce an on-specification product, which requires more time and additional facilities, all with a higher cost.
“Having our platforms certified to operate on 100-percent alternative fuels gives us flexibility and, in the end, gives us both a strategic and combat advantage,” Mabus said. “It gives us options; options which are important now and will remain important in the future.”
And the Navy is not alone.
“The commercial sector is also working hard to incorporate alternative fuels into their supply chains, which will only increase our operational flexibility,” Mabus said.
The Navy fuels team is collaborating with commercial activities such as the American Society for Testing and Materials (ASTM), the owner of commercial fuel specifications, and the Commercial Aviation Alternative Fuels Initiative (CAAFI), which seeks to enhance energy security and environmental sustainability for aviation through jet fuel produced from alternatives to petroleum, Kamin said.
The technical fuels community is small but effective, sharing resources and information across the Navy, with other services and with the commercial airline industry.
“One of the government’s best kept secrets is the interagency cooperation among the Naval Fuels and Lubricants Cross Functional Team,” said Rick Kamin, energy and fuels lead for Naval Air Systems Command (NAVAIR). Kamin also leads the alternative fuel test and qualification program for the Navy.
The Naval Fuels and Lubricants Cross Functional Team is comprised of technical experts from across naval services, including the Naval Air Systems Command, Naval Research Laboratory (NRL), Naval Supply Systems Command Energy, the Naval Sea Systems Command, the Military Sealift Command, Marine Corps and the Coast Guard. The team’s mission is to provide a single source of fuels-related technical expertise, guidance and solutions to all levels.
Additionally, NAVAIR works with its counterparts in the Air Force, Army and Defense Logistics Agency as well our allies, original equipment manufacturers and industry.
As the technical authority, NAVAIR operates the Navy’s lead Fuels and Lubricants Laboratory, but relies on its in-house engineering expertise in propulsion, flight test, materials and airframes to evaluate the effect of biofuels on the aircraft in flight, Kamin said.
As a NAVAIR fuels engineer and project engineer for F-76 fuel ship engine testing, Andy McDaniel has witnessed the powerful technical collaboration this program has fostered. “The knowledge sharing from such a variety of specialists and decision makers has been fascinating, and has strengthened everyone’s technical understanding of fuels as well as the systems they affect.” “It’s been amazing watching the technical community get a stronger sense of what the information is telling them about their systems, and how that’s driving us to higher levels of confidence and better methods for testing and analysis,” McDaniel said. —Andrea Watters
For example, General Electric, which makes the engines for the F/A-18, also makes engines for commercial aircraft. “It’s a big community of military and commercial activities sharing information and working together to make sure that everyone has what they need to allow qualification to proceed,” Kamin said. “We, the Navy, are a customer and our role is to qualify processes that we can use, regardless of where the fuel source originated.”
The fuels team will continue to look at safety and interoperability with the commercial airline industry, Kamin said. “We’ll look at opportunities to qualify processes for the Navy in the future,” he added. “This is the way of doing business in the future as multiple sources are qualified, and as the demand increases, competition should bring the costs down.”
Kamin points out that, like any new product in the early stages of development, it takes time for markets to develop and the industry to be built and grow. Take the cell phone, for example. The first handheld cellphone, Motorola’s DynaTAC 8000X, cost $3,995 in 1984, and despite the cost, it became a business necessity with demand exceeding expectations.
“Look at where we were six years ago; we only knew how to use petroleum. Now we know how to use many other sources to make our ship and aviation fuel. More importantly, we set the benchmark and the strategy is in place to look at alternatives in the future,” Kamin said.
The 100-percent alternative biofuel is also good for the environment, said Andy McDaniel, fuels engineer with NAVAIR’s fuels and lubricants department and project engineer for the F-76 ship engine testing.
“One notable difference between CHCJ and petroleum-derived fuels is the absence of trace-contaminants and sulfur compounds,” McDaniel said. “The sulfur, nitrogen and oxygen-based compounds which naturally exist in fossil fuels are not present in the biological feedstock. Thus, you don’t see them in the final finished product.”
Flight test evaluates whether the aircraft system operates as expected throughout the flight envelope on a nonpetroleum-based JP-5 fuel.
“We are looking to make sure the engine operates properly on the biofuel and that it doesn’t affect engine operation in any way,” said Picard.
Picard develops the test plans and coordinates the test and evaluation at Naval Air Warfare Center Aircraft Division facilities at Pax River. She works closely with her military counterpart, Lt. Cmdr. Fairfax, and VX-23, which owns the EA-18G used in testing.
Fairfax was also a test pilot for the 50/50 blends of Alcohol-to-Jet and Synthetic IsoParaffins in 2014-2015. While Fairfax flies the EA-18G with test points on his kneeboard, Picard monitors the ground and flight tests at RTPS. She then analyzes the data and writes the report on how the biofuel performed.
Picard has been involved in the flight test of the biofuels program since 2010 and led the effort for the first biofuel testing of the Legacy Hornet in 2010.
“When we first started we had no idea what to expect. The engineers on the fuels side told us it was going to be exactly the same as JP-5, but until you go out there and give it a try, you are never completely sure,” she said.
“Since the HEFA 50-percent blend was the first biofuel tested, we evaluated more test points,” Picard said. “In the last several years, we have developed historical knowledge of biofuels, and reduced the number of test points on the blends. The test matrix, however, was expanded slightly since this fuel is a 100-percent biofuel,” she said.
In-flight, the flight test team added a higher altitude subsonic functional check and an additional supersonic functional check along with a few more airstarts to more thoroughly investigate the operation of the engine throughout the flight envelope, Picard said.
Flight test starts on the ground, and the 100-percent alternative fuel was no exception. In fact, an additional test—an acoustic ground test—was required, Picard said.
“When GE conducted the test originally the baseline with JP-5 was performed on a warmer day than the testing with CHCJ. The results showed, after taking temperature into account, that the CHCJ had higher vibration levels or ‘rumble,’” she said.
“To address that, the NAVAIR fuels team requested we perform the test installed in the aircraft on similar temperature days to reduce that variable. We conducted the baseline JP-5 test and CHCJ tests on similar temperature days and observed there was not a significant difference in vibration levels between the two fuels,” she said.
“We try to wring out the engine and the control system on the ground by doing several throttle transients similar to the ones we do in flight. Once we get up in altitude things are going to change, but we check it out on the ground, making sure everything looks good. Once we are happy with the results, then we can proceed with flight test,” she said.
“In-flight, we will perform a series of throttle transients, where we move the throttle to and from specific power settings in order to stress a particular limit of the engine,” she said.
For example, throttle chops from a mid-power range to idle power can use up some of the flameout margin the engine has built in, she explained. “If all of the margin is used, then the combustor will flameout. We test this to ensure the CHCJ does not have a greater effect on flameout margin than we expect.”
After six days of flight test, CHCJ 100-percent biofuel demonstrated that it is indeed a drop-in replacement, Picard said.
Updating Military Fuel Specifications
The final step in qualifying a drop-in replacement is the incorporation of the alternative in the standardized military specifications for both JP-5 in aircraft and F-76 in ships, Kamin said.
The specification change is the culmination of all the testing efforts, McDaniel said. “At that point, all Navy stakeholders have reviewed test data and agreed that the fuel is fit for use in naval operations.”
The fuels team anticipates completing the qualification for the 100-percent alternative in the first quarter of fiscal year 2017. “We’ve demonstrated that we have developed the protocols to evaluate multiple alternatives and that we have the team to do it,” Kamin said.
Andrea Watters is the editor of Naval Aviation News and a public affairs specialist with Naval Air Systems Command.
Great Green Fleet Demo
The Rim of the Pacific (RIMPAC) 2012 Great Green Fleet trial provided operational validation of the laboratory, test stand and controlled platform test results conducted by the Navy’s alternative fuel qualification program.
The unanimous opinion from the shore facility, ship and aircraft personnel was that the 50-percent bio-based JP-5 and F-76 was operationally similar to the petroleum-based JP-5 and F-76 used both prior to and after the biofuel testing.
During the Great Green Fleet RIMPAC 2016, the Navy used 11.2 million gallons of a 10-percent alternative fuel blend of beef tallow mixed with marine diesel.
“We’re at a 10-percent blend now, depending on price and availability,” said Dennis McGinn, assistant secretary for energy, installations and environment. “Then we’ll start seeing blends for marine fuel and jet fuel at 20 percent biofuel, 30 percent, as we continue building up.”
Shipboard: Navy Tests Diesel F-76 100-Percent Renewable
The U.S. Navy has more than 100 different diesel engine makes and models in its inventory along with gas turbine engines and boilers, all of which run on F-76 diesel fuel.
A program similar to the one used to evaluate aviation JP-5 fuel alternatives is also designed and used to qualify diesel F-76 fuel alternatives, which serves as a primary fuel for maritime vessels, said Andy McDaniel, fuels engineer with the Naval Air Systems Command’s (NAVAIR) Fuels Team. NAVAIR manages the Navy’s alternative fuels test and qualification program.
McDaniel has worked with all of the alternative fuels tested since SECNAV established his energy goals in 2009, and is currently the project engineer for the 100-percent advanced biofuel—catalytic hydrothermolysis conversion to diesel (CHCD) qualification. CHCD was developed by Applied Research Associates (ARA) and Chevron Lummus Global, as a drop-in replacement for petroleum-based F-76 marine diesel.
“We work closely with industry experts, Navy subject matter experts within the Naval Surface Warfare Command and the United States Naval Academy, and the technical warrant holders at the Naval Sea Systems Command to ensure the tests we conduct meet technical expectations,” McDaniel said.
Like JP-5 alternatives, the F-76 fuels produced from alternative sources must also be invisible to the user, McDaniel said. And while the qualification protocols for F-76 alternatives are similar to those of JP-5, they place a greater testing emphasis on diesel and marine gas-turbine engines, he said. “We have a lot of ground to cover since there are so many types of hardware that use F-76.”
After the boiler, gas-turbine, diesel engine test results confirmed that the CHCD performed similarly to conventional F-76, successful shipboard trials were conducted in June aboard the ex-Paul F. Foster, now the Self Defense Test Ship.
Navy engineers monitored the performance of the gas-turbine engines and generators while running on petroleum F-76 prior to taking on the CHCD to establish a baseline for comparison, McDaniel said.
“While operating on 100-percent biofuel, the ship successfully completed multiple engine starts and speed changes, and there were no mechanical, operational or qualitative differences during operations,” he said.
NAVAIR and the Navy’s fuels team continue to look at ways to improve data sets and conduct testing more efficiently, McDaniel said, “whether it’s extracting more information from the tests we currently run or refining the quantity and types of tests conducted as we continue to learn.”—Andrea Watters