Avjet Biotech, Inc. (ABI), a developer of small distributive refining systems in the 10 to 15 million gallon per year range and parent company of Red Wolf Refining, has licensed exclusive rights to a technology portfolio developed at North Carolina State University (NCSU) for producing drop-in diesel, jet and gasoline hydrocarbon fuels from triglycerides (fats), and for producing products from genetically modified marine microalgae (earlier post).
NCSU had earlier licensed the technology to Diversified Energy (earlier post). Diversified Energy’s license agreement was terminated, according to Dr. Terry Bray at NCSU’s Office of Technology Transfer.
Avjet Biotech will sell stock and use the funds raised to reimburse the university for its investment in patent applications, as well as allocate development capital to create a continuous production model for the biofuel refining system. The license agreement is global in scope and extends to 22 foreign countries where patents have been filed. Red Wolf, formed in 2010, is in the process of raising $3 million through an equity offering to commercialize the thermal-chemical catalytic process.
The Red Wolf Process (RWP) consists of three main steps: hydrolysis, deoxygenation and hydrocarbon reforming.
Hydrolysis. The first step of the RWP uses the well-established Colgate-Emery reaction (hydrolysis via high-pressure, high-temperature steam) to cleave the three fatty acid chains from the glycerol backbone of the triglycerides. This is accomplished by separately pumping steam and the feedstock oil at high temperature and pressures into a Colgate-Emery reactor. Two product streams exit this reactor, free fatty acids (mixed with water) and sweet water (glycerol mixed with water). Water is removed from the free fatty acid (FFA) stream prior to the next processing step: deoxygenation.
|Step 1: Hydrolysis. Click to enlarge.|
Deoxygenation. The free fatty acid (FFA) and low concentrations of hydrogen are fed into a deoxygenation reactor. This reaction has two steps: 1) remove any degrees of unsaturation from the FFA; 2) catalytically remove oxygen molecules from the FFA. This reaction step results in a saturated, straight chained hydrocarbon with one less carbon than the reacted FFA (i.e. a C18 free fatty acid yields a C17 hydrocarbon). These n-alkanes are a common component of petroleum (which has a wider distribution of alkanes as well as other types of hydrocarbons). The n-alkanes derived using the RWP from the fat-containing oils are in the ranges needed for diesel and jet fuel.
|Step 2: deoxygenation. Click to enlarge.|
Hydrocarbon reforming. This step converts the n-alkanes to the specifications necessary for jet, diesel and gasoline fuels. Two separate reactions (and reactors) are used to reform the n-alkane into the desired fuels: hydroisomerization and aromatization.
In the hydroisomerization reaction, the n-alkane is branched (no longer a straight chain). Within the hydroisomerization reaction, hydrocarbon cracking also occurs, which shortens the hydrocarbon branch size, which can be controlled to give the desired ranges for jet, diesel and gasoline fuels. Aromatization is a reaction in which the n-alkane is converted into aromatic (or cyclic) hydrocarbons. These aromatics formed are necessary to meet specifications for jet fuel and are also a common component in gasoline to raise the octane rating.
A parallel step to the fuel conversion is the separation of the by-product of hydrolysis, glycerol, from the sweet water. Then the glycerol is combusted to provide energy for the entire process. This step increases the energy efficiency of the process as well as minimizes waste streams.
|Step 3: Cracking and reforming. Click to enlarge.|
According to Red Wolf, the process produces low levels of CO2 relative to processes such as Fischer-Tropsch and coal liquefaction for the production of synthetic hydrocarbon fuels. Hydrogen consumption is minimal (up to an order of magnitude less); most of the hydrogen that is consumed is used to saturate any unsaturated fatty acids during the deoxygenation process. This hydrogen becomes part of the fuel molecule, increasing the energy density of the fuel. This is in contrast to hydrogenation processes where the hydrogen is used to deoxygenate the fat/oil/lipid, and thus ends up as water, Red Wolf notes.
Red Wolf says that modeling has shown economic viability for smaller plant sizes (10 MGPY and larger). Co-locating fuel processing plants near the feedstock-producing sites, rather than near oil refineries, is therefore advantageous in this schema. This mitigates transportation costs of both the feedstock and the produced fuel. Smaller plants require less land space and capital, and are optimized towards the most economical feedstock of the region.
A pre-pilot plant for continuous operation at 20 L/h is currently being designed at NCSU and is scheduled to be fully operational by the end of August 2012. While the pre-pilot plant is being constructed and going through shake-down operations, Red Wolf Refining will be securing the land and capital necessary for the next scale-up—a pilot plant designed for 400 L/h continuous operation. Ground-breaking for the pilot plant is anticipated in September 2012 and should be fully operational by July 2014. A similar effort of securing the land, capital and infrastructure for the full-scale production plant (10 million gallons/year) will occur starting in August 2014 with the first full-scale production targeted to begin in July 2016.