Global Logistics … Warfighter Focus 635th Supply Chain Operations Wing

USAF Use of Biodiesel Blends (B20)

Ben Curtis, DirectorProduct Support DirectorateAir Force Petroleum Office

Cleared for Public Release 88ABW-2017-0599

Global Logistics … Warfighter Focus 635th Supply Chain Operations Wing

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Docosane, C22H46 - common diesel fuel component

Methyl behenate, C22:0 – saturated FAME

What is Fatty Acid Methyl Ester (FAME)?

Polar end attracts water

Non-polar molecule

There will be a quiz on molecular structures at the end

Non-polar end

FAME (biodiesel) is made from vegetable oils or animal fats. It is mixed with dieselfuel at a 20 volume % concentration to create a biodiesel blend (B20). Because oftheir similar chemical structures, FAME will combust like diesel fuel. The oxygenmolecules attract water creating issues not seen with petroleum-based diesel fuel.

Global Logistics … Warfighter Focus 635th Supply Chain Operations Wing

Timeline

n 2001 – USAF 1-year B20 Demonstration at a Midwest Basen Only 1 soybean oil feedstock used, good quality product, no technical issues seen

n 2002-06 – B20 implemented at many AF Bases to reduce foreign oil dependence and reduce carbon emissions

n 2005-17 – Increased frequency of bulk tank cleaning versus diesel fueln 2007 Winter – Multiple Bases (northern & southern) affected by Cold

Weather Filter Plugging (CWFP) during extremely cold weathern Most vehicles using B20 would not start, clogging of dispenser filters

n 2008 – ASTM B100 spec added new requirements to address CWFPn Reduced number of CWFP occurrences by cold filtering trace contaminants

n 2008-09 – ESTCP TRIPOL Project to determine if B20 use could increasen Mixed results, orange deposits seen at multiple locations in vehicles

n 2012-17 – AFRL investigating fungal growth in B20 bulk tanks

AF B20 consumption 1.8 million gallons/year, largest single user in US

Global Logistics … Warfighter Focus 635th Supply Chain Operations Wing

2007 Cold WeatherFilter Plugging (CWFP)

30 gallons of B20 at this location passed through 6 spin-on filters which yielded several pounds of solids

Filters have the appearance of having been rubbed with lard

The AFPET began analyzing B20 in the winter of 2007 when CWFP restricted operations at many Bases during an arctic blast.

Global Logistics … Warfighter Focus 635th Supply Chain Operations Wing

B20 Bulk Storage

n AF Research Labs have identified fungal growth as the cause ofincreased B20 tank cleaning, Automatic Tank Gauge (ATG) and waterprobe failures, and loss of product

n See Dr. Goodson’s briefing

Global Logistics … Warfighter Focus 635th Supply Chain Operations Wing

Microbial Growth

n Biodiesel is easily metabolized by fungi and microbesn Water and biomass is a result of microbial fuel metabolism

n ATG and water probes can fail once growth establishedn Floats hampered by fungal growth and biomass accumulation

n Primarily a southern Base problem but seen at northern Bases intanks with water management issues

Global Logistics … Warfighter Focus 635th Supply Chain Operations Wing

Stability of B20in Vehicles

n The thermal and oxidative instability of B20 has been shown to leave heavy deposits on the fuel-wetted parts of vehicles

n These deposits form on fuel tanks, pumps, injectors and valves impeding their operation, deposits also seen post engine as well as EGR and emission controls

n Vehicle deposits found at northern and southern Air Force Basesn B20 use voids the warranty of many vehicles, B5 is generally OEM accepted n The design of the vehicle also determines if these deposits will formn The cost of cleaning and replacing these parts is substantial

Global Logistics … Warfighter Focus 635th Supply Chain Operations Wing

n The oxygen molecules in FAME attract water, encourage microbialgrowth, and cause thermal and oxidative breakdown products whichdamage vehicles

n In 2nd generation biofuels, such as renewable diesel and Hydro-treatedVegetable Oil (HVO), manufacturers remove the oxygen from FAMEyielding a molecule that is identical to the ones found in diesel fuel

n These fuels have been used in blends of up to 50% providing better energysecurity and lower carbon emissions

n AFPET and VSCOS (AF Vehicles) to conduct a demonstration of anHVO blend at a southern Base experiencing major microbial issues todetermine if it will perform better than B20

Quiz

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Global Logistics … Warfighter Focus 635th Supply Chain Operations Wing

Conclusions

n B20 Biodiesel was adopted to reduce our dependence on foreign oil andreduce carbon emissions

n But there were substantial hidden costs and unintended consequences withB20 use

n HVO and renewable diesel can be used in concentrations up to 50%,reducing our dependence without consequences

n Some NATO Allies already successfully using 50% HVO blendsn There are bio-based diesel fuels under development that can be used at

100% concentrations using HVO mixed with synthetic bio-based aromatichydrocarbons

n Time has come to move away from B20 to 2nd and 3rd generation biofuelsto reduce costs and improve mission readiness

Global Logistics … Warfighter Focus 635th Supply Chain Operations Wing

Questions?