6 Outotec SEAP Customer eNewsletter 1/2015

BRINGING BIOMASS TO THE MASSES WITH ETHANOL TECHNOLOGIESSome studies have stated that there are only 14,517 days, or about 40 years, left before the earth’s oil resources run out.

The growing need for transportation and the increasing-consumption of energy are generating severe pressure to develop alternative sources. One such source, ethanol, has been used for several decades as an addition to petroleum.

Modern biofuels – bioethanol, biodiesel, and biogas – are produced from renewable feedstock. Current develop-ments are focusing on fuels produced from nonedible feedstock because of their lower social impact.

From first to third-generation biofuelsThe biomass used as feedstock for modern biofuelproduction comes from the non-human food chain.Biomass consists of cellulose and hemicellulose thatcan be extracted as C6 (glucose) and C5 (xylose) sugarsrespectively. These sugars are fermented into bioethanolor fed to microbes to extract the oil, which is the rawmaterial for biodiesel.

Today, there are three generations of biofuels, each produced from a different feedstock: • First-generation (1G) biofuels are produced from

edible feedstock from the human food chain, which can lead to increases in food prices.

• Second-generation (2G) biofuels are produced from residues, biomass, waste, and non-edible plant mate-rial.

• Third-generation (3G) biofuels are primarily produced from microalgae.

For 2G biofuels, an average of four to five tons of straware required to produce one ton of bioethanol. One tonof dry biomass can produce around 300 liters of bioeth-anol. The main examples of 2G biofuels are bioethanoland biodiesel. Bioethanol is produced by hydrolysis and fermentation of lignocellulose, with a final stage ofethanol recovery.

Biodiesel is produced in two ways: from raw materialssuch as vegetable oil, waste fats, and microbe oil and fatsusing a hydrotreatment process, and through gasificationof biomass by Fisher-Tropsch synthesis. This secondprocess is also known as biomass-to-liquid (BtL).

Third-generation biofuels are a new approach to biofuelproduction using microalgae, yeast, or fungi. Growingbiomass contains hundreds of different microalgaespecies and can produce 150 tons/ha/year or more witha maximum oil content of 65 percent from dry mass,meaning an annual yield of 30–80 tons of biodiesel perhectare of biomass.

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The algae needs light, CO2, nutrients, and water in order to grow biomass and produce oil.

Continuous development and tailored process solutionsOutotec is continuously testing 2G and 3G biofuelsproduced from feedstocks such as sawdust, straw,bagasse (the waste from sugar production), giant cane,and forest residues. Ethanol and biodiesel productionprocesses involve between one and three filtrationphases. The most commonly used filtration applicationuses lignin slurry filtration, which in most cases includescake washing for sugars recovery before fermentation orprocessing in a bioreactor. In some cases filtration is doneafter fermentation, or at the latest after ethanol purifica-tion, when the slurry contains lignin, mash, and stillage.The counter-current filtration technology used in biodiesel production for microbe oil recovery uses a solvent, usuallyhexane. The goal of the filtration phase is to achieve thehighest possible oil recovery. The used filter cake can befed to cattle.

Outotec offers a wide range of filtration technologies,from vacuum to pressure methods and from continuous tobatch-operated filters. All of our process solutions can befully automated. For suspensions with low solids content,Outotec’s market-leading sedimentation technology,including clarifier and thickener equipment, can be usedto deliver a cost-effective filtration solution.

The product of continuous research and developmentand over 30 years of experience in filtration technology,Outotec Larox® PF (pressure filter) series filters set newstandards for reliability and efficiency in biofuel applica-tions. The PF series is fully automated, economical tooperate, produces good cake-washing results with lowwash-liquid consumption, and results in extremely drycake. Based on suspension testing and process data, wecan provide an operational and investment cost calcula-tion to demonstrate the savings compared to conventionaldewatering technologies.

“The industry standard for the biofuels process is centri-fuge and filtration. With a capacity of 50,000 t/a ethanol,Outotec Larox PF is the best solution for filtration due toits easy, reliable, and maintenance-free operation, as wellas its washing capabilities and exceptional cake-dryingperformance,” states Jason Palmer, Senior Manager,Outotec Filter Business Management.

Outotec Larox HBF (horizontal belt filter) filters areanother suitable option for biofuel production. They offergood cake-washing results, fully automated operation,and a wide range of options for cake drying, includingpress belt, steam hood, and infrared drying. “In caseswhere the goal is to minimize investment and labor costswhile maintaining good cake-drying results, Outotec LaroxFFP (fast-opening filter press) or FP (filter press) filterscan be used,” says Matti Luoma, Senior Manager, OutotecFilter Business Management.

Third-generation biofuels are a new approach to biofuel produc-tion. The biofuel production process is tailored according to theend-customer’s requirements, using Outotec’s processknow-how. Defining the most appropriate filtration tech-nology for the specific feedstock requires close collabora-tion between all stakeholders, including the enzymeproducers.

The Ethtec process

8 Outotec SEAP Customer eNewsletter 1/2015

Building a productive technology partnership with Ethanol Technologies LimitedBased on the banks of the Clarence River in Harwood,New South Wales, Australian company Ethanol Technolo-gies Limited, or Ethtec for short, has developed a pilotplant to investigate the commercial potential of its globallypatented 2G bioethanol production technology.

Ethtec has a worldwide exclusive license to furtherdevelop and commercialize patented, laboratory-proventechnologies for the production of ethanol from lignocel-lulosic materials such as pine chips, bagasse, cropstubble, and municipal green waste.

The process brings distinct environmental advantages,particularly in terms of its low greenhouse gas emissionsand the production advantages over other ethanolprocesses. “Although the process has been in existencefor over 30 years, we only started working with it in 2007,when biomass became available from the local sugarindustry and there was sufficient demand for ethanolproduction,” explains Dr Tony Banks, Senior ResearchChemist at Ethtec. “Initially, the government approachedus and requested an investigation to find out if the processwas economically feasible, but now we are mostly fundedby the sugar industry,” he continues.

“First-generation biofuels typically convert food cropsinto ethanol and this can have a dramatic effect on foodprices,” adds Andrew Reeves, Senior Research andDevelopment Engineer at Ethtec.” The Ethtec processprovides an opportunity for farmers to value add to theirexisting farming practices by converting their by-productsinto a liquid fuel,” he continues. “There is the potential forat least 30–50 ethanol plants to be established on the eastcoast of Australia as the raw material is there. There areapproximately 30 sugar refineries and plants using woodin the region,” he explains. It seems that the industry is crying out for a viable, sustainable process and there is no simple solution – otherwise it would already have been developed. “When we are ready to take this process from pilot scale to industrial scale, our customers will be farmers and individual sugar plant owners. There is more than enough biomass available for feedstock. We have agreed on the national level here in Australia to the E10 fuel mandate, yet the supply of ethanol is still lacking,” Reeves points out. “A robust process such as this would be able to meet fuel demand.”

Developing the next-generation of bioethanolThe plant is capable of converting approximately twotons of second-generation feedstocks into ethanol everyday. The four-phase process uses a unique hydrolysisconversion method, with the entire cycle designed to bringenvironmental and economic benefits that far surpassthose offered by current ethanol production.

“We are quite confident in our process and we have already overcome the biggest risks and challenges,” says Reeves. “We are producing very clean sugars for conversion to ethanol. The process is very sustainable. We are able to dispose of waste, we recycle all the acid we use in the process, and we use the heat generated by the boiler as an energy source. We also have a water purification system in place to recycle process water.”

The biofuel production process and OutotecscopeIn phase one of the process the feedstock is milled anddried before being mixed with sulfuric acid. The acid func-tions as a catalyst and therefore no enzymes are needed.After the reaction time, the solution is mixed with waterand then fed to phase two of the process, which is solid–liquid separation.

Outotec was contracted to provide basic and detaileddesign, delivery, and support services for phase two of theprocess, which included their filter technology. Illustratedon the left, this phase involves lignin and acid separation,both of which are recovered for reuse along with recyclablewater.

Selecting the best technology For feedstock filtration, Outotec recommended its provenPF filter technology with feed-grade polypropylenefilter plates that would be capable of dealing with theharsh acidic cellulosic processes. Because the filtrate isreturned to the process for sugars concentration and acidrecovery, clear solutions are required. An Outotec LaroxLSF polishing filter was selected to clean the solution andprevent solids from fouling the ion exchange media.

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“We have not experienced any blinding issues, eventhough the filters use a fabric without a pre-coat. Both ofthe filters are working well and are ready to be scaled upfor the commercial plant,” says Reeves. “When choosingthe equipment for the process, I have to say that in manycases we took a risk and chose equipment straight offthe shelf as we had no reference projects or processes tomodel ours on. We are on a tight budget and have had toconceptualize and build our own equipment. We’ve beenforced to modify things along the way, but the processis all our own design work and is the first of its kind,”explains Banks.

Close collaboration delivers great resultsIntegrating the filters into the four-phase flowsheetrequired close collaboration between Ethtec and itspartners. As well as developing innovative methods toovercome new process challenges, the Outotec team alsohad to ensure successful integration with all the othertechnologies used in the process.

In phase two of the process, lignin and acid are separatedfrom the sugars, which are then fermented in phase threeto produce ethanol. The separated lignin is recovered forenergy production, and the recovered acid is used in thehydrolysis phase. This process enables liquids and energyto be recycled via the innovative closed-loop recoveryflowsheet, resulting in lower energy costs and reducedwater usage.

Outotec Larox filters occupy relatively small footprints.The high flow rates – up to 600 m3/hr – are handled bya single unit, which greatly simplifies the process. Theunits are designed to be expandable in order to providea cost-effective solution for capacity increases andachieving biofuel filtration targets of maximum sugarrecovery, minimum water usage, and maximum dry solids.

Perfecting the processSince the lab scale plant was commissioned in 2012, andits performance has been closely monitored and analyzedby Outotec engineers on site. The team was able to opti-mize the process according to variations in the feedstocks,slurry, and amount of washing required. This real-timeoptimization enabled critical data to be gathered for futuredevelopment on a larger scale.

The results for both the pressure and polishing filterswere highly favorable. The pressure filter produced alignin cake thickness of 16–19 mm and acid removal ofgreater than 90 percent. The filtered cake has a moisturelevel of as little as 35–40 percent, which is exceptionallylow.

The PF filter produces very clear filtrate that is fed tothe polishing filter. The solution is then fed to a chroma-tography system to concentrate the streams prior tofermentation and recycling of acid back to the reactor.The polishing filter filtrate is very clear, with less than 5ppm of solids, helping to ensure reliable operation of theprocess.

“The filters perform very well even without optimization.We have two different feeds coming into the filter andwe have not experienced any problems with either,” saysReeves. “Our process is quite robust, and even whenmixing the feed the process streams have not changed,”he continues. “We haven’t had to spend much timeworking with the filters – we just leave them there andthey do their job,” Banks explains. “The few issues we hadat the commissioning phase were solved, and we havereceived good support from Outotec. It is very valuable tohave their knowledge and support readily available in casewe do face any problems. It’s a very productive partner-ship,”he concludes.

FOR FURTHER INFORMATION PLEASE CONTACT:

JASON.PALMER@OUTOTEC.COM

“Outotec’s knowledge and support is invaluable.”