Biojet, Biogas & Biodiesel in Review

Biomass Magazine reviews sessions from the 2016 National Advanced Biofuels Conference & Expo held this summer in Milwaukee, Wisconsin.
By Ron Kotrba | August 22, 2016

For the first time ever, the National Advanced Biofuels Conference & Expo was colocated with the International Fuel Ethanol Workshop & Expo in 2016, a conference pairing that will become the norm for event organizer BBI International. The conferences were held in Milwaukee, Wisconsin, with sessions running June 21-22. NABCE included two tracks, with one focused entirely on cellulosic ethanol, and the second on biodiesel and other advanced biofuels. Track two, the focal point of this review, included presentations on biojet fuel, biogas and biodiesel.

Four biojet fuel technology positions were represented in a panel titled “Technologies Unlocking New Opportunity for Advanced Biofuels in Aviation Markets.” Tony Barnette, sales support manager at Honeywell’s UOP LLC said the recent Defense Logistics Agency’s 76 MMgy award for fuel containing 10 percent renewable F-76 Naval Distillate was given to AltAir Fuels, a converted oil refinery turned biorefinery in Paramount, California, which started production this year. Barnette said AltAir has delivered 1.3 MMgy of its contract as of June.

Barnette noted the International Air Transport Association’s goals of cutting net emissions by 50 percent by 2050, and achieving fuel efficiency increases of 1.5 percent per year through 2020. “Globally, there was an 80 billion-gallon demand for jet fuel in 2010,” Barnette said, “and this is growing at 3 to 3.5 percent per year. If biofuels can supply 6 percent of the jet fuel by 2020, this represents 7 billion gallons of renewable jet fuel and a reduction in carbon footprint by 5 percent.” Barnette recounted at least 20 commercial demonstration flights from 2008-’14.

UOP’s technology converts triglycerides and fatty acids to isoparaffins, long-chain molecules with a high cloud point, which are then isomerized and hydrocracked, followed by product separation.

Bin Yang with Washington State University discussed biojet fuel from lignin. He said lignin from biomass is currently used for electricity and steam production, but through a process of depolymerization and defragmentation followed by catalytic upgrading, the material is suited for jet fuel feedstock. The challenges to this are appreciable, however, and include lignin’s high molecular weight with uncertain reactivity; low oxidative and thermal stability of processed lignin; limited tools for quantitative characterization of conversion processes; mass transfer limits for catalytic processing; low catalytic selectivity; and low hydrocarbons yields. Simulated distillation showed lignin-derived biojet has a higher boiling point, Yang said, adding that analysis shows coproduction of jet fuel from waste lignin can dramatically improve the overall economic viability of an integrated process for corn ethanol production. The lignin can also be used to power the lignin-to-biojet process.

Vertimass LLC President and CEO Charles Wyman presented on using ethanol as a platform to biojet, since it’s relatively inexpensive and large-scale ethanol production is already in place. Wyman said Vertimass’ bolt-on technology has four issued patents and requires modest capital costs to install. The single-step conversion process uses a catalyst developed by Oakridge National Laboratory, for which Vertimass has exclusive rights. Ethanol and water are processed through the catalyst at 275-350 degrees Celsius at atmospheric pH and reaction conditions, and without addition of hydrogen, hydrocarbon blend stocks with high yield are obtained, Wyman said. This bolt-on technology can avoid use of molecular sieves and displace rectification at ethanol plants. He added that capital costs for the technology are similar to dehydration units.

He said last year Vertimass received $2 million in U.S. DOE funds, which will be used to scale up the technology. Vertimass chose Technip to perform pilot plant scale-up runs of its process. The company plans to launch its first commercial construction within two years acting as licensor with potential ethanol producers as owners and operators. First, he said Vertimass must complete Series B funding.

Gevo Agri-Energy President Chris Ryan rounded out the panel by discussing Gevo’s isobutanol-to-biojet process. He said it starts with fermenting the mash into isobutanol instead of ethanol. Ryan said Gevo has been producing hydrocarbons from isobutanol since 2011 in Silsbee, Texas, where it has 25,000 hours of operational experience. The plant processes 60 pounds an hour of isobutanol to biojet fuel. Once isobutanol is produced, the company uses dehydration to get to isobutylene. Oligomerization of isobutylene makes a distribution of C8-C16 hydrocarbons followed by hydrogenation and distillation. He said with oil at $65 a barrel and $4 corn, the net price of Gevo’s renewable jet fuel is competitive with petroleum-based jet fuel with a 20 percent return on investment.

Biogas took center stage at NABCE during the breakout session titled “How and Why Biogas Producers are Winning Market Share in Advanced Biofuel Markets.”

Digester Doc President Will Charlton said every digester is unique and individual, and each digester should be treated as such. Charlton said microbial enhancement is the act of bringing in nutrients and additives that allow the native populations to thrive in the environment they exist. This often also means introducing new populations that are more geared toward any issue the system might have.

Charlton said a list of protocols used to test system health include mineral toxicity tests, pH and temperature ranges, fatty acid breakdown and solids content. Items that need to be monitored and checked in digesters, he said, begin with temperature. Then, an operator should find out what methanogens are prevalent in the digester and allow them to dictate the temperature zone within which the digester operates. Solids content must be determined, and if it’s too high without the right mechanical accommodations or the right biology, this can be a problem. Finally, operating pH must be known as most methanogens—95 percent of them—prefer to operate between 6.8 and 7.8. He said mineral packages may be important, but noted that not enough may be as bad as too much. “Run extensive and ongoing tests to see what’s needed to find that balance,” he said.

Jeff Tocio, Pentair national sales manager, discussed his company’s technology to capture carbon dioxide (CO2) from biogas production. He said most biogas operations produce 55 percent biomethane (CH4) and 45 percent CO2. Pentair uses multimembrane technology to separate the gases. “The discharge from the membrane, the retentate, contains mainly CH4 as the CO2 has been pushed through the membrane surface,” Tocio said. “The CO2-rich gas leaves the membrane on the low-pressure side of the membrane.” He said that to separate the CO2 and CH4, the impurities must be removed with activated carbon. “With a two-stage membrane system and a cryogenic system, no methane slip is achieved,” he said, “along with the recovery of two valuable products—biomethane and 100 percent liquid CO2.”

Pentair’s CO2 recovery system is a bolt-on technology that can be deployed at existing biogas plants, Tocio said. The company has 450 systems installed globally. The food-grade CO2 can be sold for greenhouses, fire extinguishers, welding gas, dry ice, refrigeration, and food and beverage applications. Tocio said typical upgrading costs from biogas to biomethane and liquid CO2 run about 14 to 18 cents per normal cubic meter (Nm3) of biogas, wherein one Nm3 of biogas gives 0.58 Nm natural gas and 0.7 kilograms of liquid CO2.

Integrating biogas production at ethanol plants was the focus of a presentation by Lars Holm, CEO and managing director of Renew Energy A/S. In Renew Energy’s biorefinery concept, residue streams from ethanol plants are converted to energy, clean water and fertilizer fractions. Energy is produced by anaerobic digestion of stillage using continuously stirred reactor tanks, and fertilizer products and clean water are produced in a post-nutrient recovery process. Both energy and clean water are utilized by the ethanol plant. 

Holm said high biogas production is secured through good temperature control, optimal digester mixing, feed management, and design and maintenance of the digester, all of which should lead to a stable digestion process with no shutdowns for 20 years. While Holm mentioned many challenges for aneorobic digestion of stillage, including low energy costs, animal feed competition, and a relatively high investment cost—up to $3 million per megawatt of power—the benefits of codigestion are evident. These include the potential for a tipping fee of the substrate, production of biogas, and the potential to form regional collaborative partnerships on waste management issues, to name a few.

Jennifer Aurandt, R&D program manager with Valicor Inc., also discussed the challenges for thin stillage digestion. The relatively long hydraulic retention time needed for feasible gas production combined with the stillage high-water content leads to vast requirements of digester size. Also, the high sulfur content in stillage can lead to inhibition of the anaerobic digestion process. High sulfur content leads to high concentration of hydrogen sulfide in the biogas and its high protein content could lead to ammonia inhibition of the process when used as a monosubstrate, she noted. Digestion of a monosubstrate leads to a lack of essential trace elements in the digester, she said, resulting in a malfunctioning process with low gas production and continuous process disorders. Valicor’s Selective AD can help address those challenges, she noted. Valicor’s commercial prospectus for a 40 MMgy ethanol plant using its Selective AD process can convert roughly 6 percent of its wetcake solids to biogas, producing more than 181,000 million Btu in a 200,000 to 400,000 gallon reactor with estimated capital costs at $2 million to $4 million. 

Biodiesel was represented on the big stage at NABCE as Anne Steckel, vice president of federal affairs at the National Biodiesel Board, participated in a general session panel with other biofuel leaders. “One of the biodiesel industry’s biggest strengths is feedstock diversity,” Steckel said. “Roughly 17 percent of our feedstock comes from corn oil extracted at ethanol plants.” EPA has proposed a 100 million gallon increase in the federal renewable fuel standard’s biomass-based diesel renewable volume obligation for 2018, up from 2 billion gallons in 2017. The NBB is calling on EPA to boost this volume so the domestic biodiesel industry, which Steckel said is only running at 60 percent, can produce greater volumes. Steckel also said she anticipates Congress will replace the $1 per gallon blender tax credit with a domestic production credit for next year, curbing $670 million in foreign production subsidies.

Colocating biodiesel production at ethanol plants was the focus of a session featuring Bernie Hoffman with KCoe Isom, Jatrodiesel President Raj Mosali and Rabbi Abraham Juravel with the Orthodox Union. Hoffman said ethanol plants can stay relevant in the industry by incorporating bolt-on technologies to produce biodiesel. Mosali said biodiesel at ethanol plants makes sense because it’s a big market and there is no blend wall for biodiesel. He added that the current 100 MMgy growth schedule in RFS could provide opportunity for 10 new 10 MMgy biodiesel plants per year. Juravel stressed the importance of kosher certification for any ethanol plants producing biodiesel—particularly when demulsifiers are used—to expand market opportunities for glycerin.

Biodiesel technology enhancements was the focus of two sessions at NABCE. Industry pioneer and producer Russ Teall presented on Biodico’s new 20 MMgy plant, Biodico Westside, in California’s San Joaquin Valley, and its Zero Net Energy Farm project with Red Rock Ranch. Biodico was recently selected by the California Energy Commission to receive a $1.2 million grant to develop a ZNEF. He said the grant will run from 2016-’18. Teall said Biodico Westside is entirely energy self-sufficient—the first such liquid biofuels plant. “Using the systems developed for the plant, our intent is to make a 1,400-acre portion of Red Rock Ranch energy self-sufficient using solar cogeneration, wind, anaerobic digestion and gasification,” Teall said.

Kurt Holecek, CEO of Austria-based Energia Tech s.r.o., discussed expanding and enhancing biodiesel production on a budget. His company has built five large biodiesel plants on three continents. Holecek promoted continuous flow processing over batch, and said biodiesel economy of scale is best in the two-digit range (e.g., at least 10 MMgy). He said Energia Tech can convert a 4 MMgy biodiesel plant to 20 MMgy for just $476,000. However, the addition of methanol recovery, glycerin treatment, increased storage tanks, additional utilities, building improvements and engineering costs would boost the total cost of the expansion to roughly $4.5 million.

Dehua Liu, a professor and director at Tsinghua University in China, presented on enzymatic biodiesel processing and the integrated production of 1,3 propanediol from glycerin. Liu said the lipase are easily deactivated and unstable in the presence of methanol and glycerin, so TU improved the process rather than the enzymes. He said TU’s novel technology greatly eliminated the negative effect of methanol and glycerol on enzyme activity. TU’s technology is in use at a 50,000-ton biodiesel plant in China. He said more than 40 patents have been filed with 20-plus granted for TU’s glycerin-to-1,3 propanediol technique.

University of Minnesota doctoral candidate and Superior Process Technologies Lab Manager Erik Anderson gave a technical presentation on a novel process for low-sulfur biodiesel conversion from scum. The process has been proven at a wastewater treatment facility in St. Paul, Minnesota. The “white mud” scum is heated to 150 degrees Fahrenheit,  and the usable portions of the oil are liquefied, filtered, acid hydrolyzed to release metals and nonmetals, put through cosolvent extraction to improve separation, glycerolysis and finally reactive distillation. Anderson said nearly 22,000 publicly owned wastewater treatment facilities in the U.S. could benefit from this process, saving money on landfilling and generating revenue through fuel production.

Finally, Larry Sakin, CEO of FYT Fuels, presented on FYT Fuels’ patent for sodium glyceroxide as a replacement catalyst for sodium methoxide in base transesterification. Sakin said the catalyst is recoverable and the use of crude glycerin is just as effective as distilled product. He said the cost of sodium glyceroxide is one-tenth that of sodium methoxide, which could lead to increased profits of $600,000 to $1 million per year at a 10 MMgy biodiesel plant, with capex costs of only $300,000.

Author: Ron Kotrba
Senior Editor, Biomass Magazine