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Researchers Develop Process for Aviation Biofuels

Centia
Centia biofuels process. Click to enlarge.

A new biofuels technology developed by North Carolina State University engineers has the potential to turn virtually any lipidic compound—e.g., vegetable oils, oils from animal fat and oils from algae—into aviation fuel or other high-value fuels.

The technology, called Centia, which is derived from “crudus potentia,” or “green power” in Latin integrates a sequence of three thermocatalytic-reforming processes that are either extensions of current commercial processes or based on recent laboratory breakthroughs. Centia can also be used to make additives for cold-weather biodiesel fuels and holds the potential to fuel automobiles that currently run on gasoline.

NC State received provisional patents to use the process to convert fats into jet fuel or additives for cold-weather biodiesel fuels. The technology has been licensed by Diversified Energy Corp., a privately held Arizona company specializing in the development of advanced alternative and renewable energy technologies and projects.

Dr. William Roberts, professor of mechanical and aerospace engineering and director of the Applied Energy Research Laboratory at NC State, developed the biofuels process with NC State’s Dr. Henry Lamb, associate professor of chemical and biomolecular engineering; Dr. Larry Stikeleather, professor of biological and agricultural engineering; and Tim Turner of Turner Engineering in Carrboro, N.C.

We can take virtually any lipid-based feedstock, or raw material with a fat source—including what is perceived as low-quality feedstock like cooking grease—and turn it into virtually any fuel. Using low-quality feedstock is typically 30% less costly than using corn or canola oils to make fuel. And we’re not competing directly with the food supply, like ethanol-based fuels that are made from corn.

—William Roberts

Centia is based on a three-step thermal, catalytic, and reforming process:

  • Hydrolytic conversion. The feedstock is heated under pressure to separate free fatty acids from glycerol in the triglycerides in the feedstock. Centia accomodates any lipidic compound without modification to the production process.

  • Decarboxylation. The free fatty acids and solvent are heated, pressurized, and passed through a catalyst in a reactor.

  • Reforming long-chain alkanes. The resulting alkanes—straight-chain hydrocarbons of 15-17 carbon atoms—are reformed into branched alkanes and ring structures. The process is optimized to maximize C10 through C14 iso-alkanes.

The fuel output is capable of meeting strict aviation specifications and acting as a biodiesel additive for cold weather operations, according to NCSU. In addition, the basic process may also be extendable to produce any other hydrocarbon fuel, including conventional gasoline.

The developers claim an end-to-end energy efficiency for the process of up to 85%, with roughly one-half the external energy of other conventional biofuel processes. This translates into higher yields and lower costs.

Centia does not require the addition of any form of fossil fuel as a component of the biofuel produced, and the production process itself can be designed to operate without consuming fossil fuels as a heat source.

Steps one and three are direct extensions from the commercial marketplace, step two builds upon recent NCSU-DEC laboratory results validating the science. Centia is ready for an end-to-end demonstration and commercialization.

Resources:

Comments

Brad

yay! Now they just need to make engine's that will run it, or make it run on current engine's and we're set.

Rafael Seidl

Brad -

the whole point of the second and third steps is to produce alkanes of the the same length as kerosene or diesel fuel. Unlike regular biodiesel, the compounds are chemically identical to those found in fuels derived from petroleum. All you need to do is get the mix to match the official fuel composition requirements, e.g. wrt to aggregate density.

NesteOil out of Finland has a process that works along similar lines, taking triglyceride-rich feedstocks and turning them into middle cut alkanes.

marcus

I think this is indeed good news. We could always electrify ground transport, the question in my mind was what to do about aircraft.

Cervus

Apply this to algae oils and we're well on the way to a petroleum replacement.

JJ

This is the sleeper app we've been waiting for. Biodiesel, as good as it is, tends to gel in colder weather and this stuff is good to -70 below!!! This really is a wolf in a sheep's clothing and it's a real game changer. Can anyone shed any light on the 85% end-to-end process efficiency -- is that a good number??

Aussie

It needs to be pointed out that animal and vegetable fats have unseen fossil fuel inputs, are vulnerable to climate and can't possibly replace more than a fraction of petroleum. Just to take the first remember that chicken was fed on grain grown with synthetic fertiliser delivered in trucks.

I'd prefer biofuels to come from weeds and trash.

Engineer-Poet

It'll just be different biofuels, Aussie.

If we're going to have reasonable aviation, we're going to need some kind of hydrocarbon fuel.  If lipids from whatever source can be turned into suitable hydrocarbon chains (repeating nature's half-billion year process in a few minutes), that's one possible route.  The best, or even good enough?  We'll see.

Cervus

Note that "Aquaculture" is one of the potential feedstocks listed. Algae are going to be the best high yeild, high volume source of lipids for this process. That it could also create straight gasoline and diesel is a plus. Is this tech a silver bullet? Maybe. We'll see how fast they can commercialize it.

Scott

Cool. Now for the million dollar question: How much does a gallon of bio-jet fuel using this process cost?

Rafael Seidl

Scott -

production cost is probably 2-3 times that of dinokerosene, which at present is not subject to fuel taxes due to long-standing international treaties on aviation.

The EU is considering tearing up those treaties that apply to intra-EU flights and then expanding taxation to flights into and out of the EU as well. It's entirely possible that renewable alternatives to conventional jet fuel will be taxed more lightly, just as on-road biodiesel is taxed more lightly in e.g. Germany. Note that GTL and CTL are alternatives but not renewable - indeed, they generate even more CO2 well-to-wheels than the regular distilled stuff.

Also note that LNG is not a viable aviation fuel today because of the geometry of modern commercial aircraft. Future BWB designs could accommodate a large spherical cryotank for this alternative fuel.

tom deplume

The Centia website mentioned a cost of $2/gal. Avgas currently retails for $3.85/gal and JetA is $3.79/gal.

Mark R. W. Jr.

Hmm, wasn't there talk of using hydrogen as a replacement for fossil-fuel based jet fuels?

And also I remember reading years ago about zeppelins making a comeback possibly powered by nuclear sources. That could be an option.

Paul Dietz

Hmm, wasn't there talk of using hydrogen as a replacement for fossil-fuel based jet fuels?

The size of the cryogenic fuel tanks becomes a problem, and they can't be placed in the wings anymore.

Engineer-Poet

The required volume of liquid methane wouldn't be all that much larger than kerosene (I calculated that you'd need tip tanks), and as long as you're burning it faster than it boils off you don't have to worry about insulation too much.  On the ground, you might want to run an APU and use it to power a chiller.

Methane could be used to run a much more efficient turbine engine, because of two features:

  1. It's a cryogenic liquid and can be used to cool the compressor blades, allowing higher pressure ratios for a given turbine-inlet temperature.  This shrinks the engine and reduces the compressor back-work.
  2. It can similarly be used to recuperate heat from the exhaust nozzle, regenerating energy that would otherwise be lost.
Combined with the greater energy per unit weight, liquid methane could make a better airplane all around.

Al Dozier

Why is everyone ignoring DME. It will the fuel for the future. It is Non-Toxic, Biodegardable can be made from any carbonaceous feedstock including MSW, sewage sludge, all forms of Biomass. coal, lignite and manures. It's infastructure is the same as propane and it is already a comercially proven technology.

Everything you do with Natural Gas you can do with the SynGas that is produced from these feedstock to make DME. DME is a direct substitute for diesel fuel with minor modifications to the gas tank and fuel injectors. Emission from a diesel engine are 83% reduced when using DME.

The USEPA designed an engine that runs with a 64% efficiency when using DME as its fuel. This efficiency is higher than fuel cells that cost more to make and have higher operating cost.

Japan & China are completely focused on Dme as their fuel of the future. China has aurthorizes $128 Billion for DME manufacture and already produces more than 144 Million gallons per Year. Japan has mobilized the entire contry, industry, government and the population to move from fossil fuels to DME.

Why are we trying to follow Brazil using Ethanol to reduce our dependence on foreign oil??. DME could be used in our homes for cooking, hot water heating and HVAC with a 31% savings in GHG emissions over Natural Gas. The same is true in the production of Electric Power while inproving the efficiency of fuel use and reducing GHG.

Large Plants can produce DME for less than $1.00 per gallon when using farm waste, MSW, wood waste and other feedstock as input fuel.

WHY ARE WE FOCUSED ON ETHANOL & HYDROGEN AND NOT DME????? Is it because the oil companies and farm lobby control congress and DME will substantially reduce their product sales and profits???

When will the USA begin to move toward DME the answer to our ENERGY and ENVIRONMENTAL PROBLEMS ????????????

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