SECOND GENERATION FEEDSTOCKS
In a further boost to Brazilian bio-based production, the country's state development bank plans to invest R$600 million ($294 million) in bioenergy firm GraalBio's cellulosic ethanol plant, which is slated to open in early 2014. The plant in Alagoas will have a capacity of 82 million L/yr. It will be the southern hemisphere's first ethanol unit to rely on second-generation feedstocks (i.e., non-edible plant materials). Initially, the plant will use sugar cane bagasse and straw. The plan eventually is to switch to a new type of biomass known as energy cane, a hybrid of sugar cane and specially selected types of grasses.
In another second-generation development, Renmatix, King of Prussia, Pa., in January, commissioned at its headquarters a BioFlex Conversion Unit (BCU), a multiple-feedstock processing facility (Figure 2). The unit will put a range of non-food plant materials through the company's water-based Plantrose process. The technique involves two steps, thereby preserving the C5 sugars that otherwise would be rapidly destroyed during cellulose dissolution.
In the process, a biomass slurry, composed mainly of hemicellulose, cellulose and lignin, is created and then pumped into a fractionation reactor. Hemi-hydrolysis — solubilizing hemicellulose into a C5 sugar stream — occurs in a matter of minutes. The cellulose and lignin remain as solid particles. A simple solid/liquid separation stage splits off the C5 stream. The solids then are mixed with water and sent to a cellulose hydrolysis reactor where supercritical water — at 374°C and 221 bar — is the primary solvent. This solubilizes the cellulose into a C6 sugar stream in a matter of seconds. The lignin remains as solid particles. A second simple solid/liquid separation stage then recovers the C6 sugar stream from the lignin.
"Because we use no enzymes and no solvents, our consumable costs are very small. Then there are the capital costs. By its nature our reaction is very, very fast and the reactor needed is very small, so there is a small capital footprint, too. Effectively the process occurs in seconds — it's really major process intensification. So much so that we will achieve the production of second generation cellulosic sugars at lower cost than first-generation food-based sugars such as corn and cane at our first commercial facility," explains Fred Moesler, CTO.
The company will start by converting four locally available feedstocks: perennial grasses, agricultural residues, softwoods and waste streams.
Renmatix is in discussions with its multiple partners, which include BASF, about moving the technology to commercial scale, both in the U.S. and elsewhere. Over a dozen organizations are currently testing the technology. Moesler expects to break ground on at least one commercial-scale unit within the next two years.
Meanwhile in Brussels in early February, the CEOs of seven leading European biofuel producers — including Chemtex, Tortona, Italy; Chemrec, Stockholm, Sweden; and Clariant, Muttenz, Switzerland — and European airlines launched an industry initiative to speed up the development on the continent of second-generation biofuels.
Together the companies will address national and international policy makers with the aim of accelerating research and innovation into emerging biofuel technologies, including algae and new conversion pathways. They also will establish financing structures to facilitate the implementation of sustainable projects, and publicly promote the benefits of advanced sustainable biofuels.
The National Renewable Energy Laboratory (NREL), Golden, Colo., of the U.S. Department of Energy (DOE) for the last couple of years has promoted its Integrated Biorefinery Research Facility as a resource that can help industry scale up its technology ("Biofuels Development Gets A Boost"). Now, NREL is partnering with global specialty chemical company Johnson Matthey, London, in a five-year, $7-million effort to economically produce drop-in gasoline, diesel and jet fuel from non-food biomass feedstocks.
As part of the cooperative research and development agreement, Johnson Matthey is to supply and develop innovative catalytic materials to upgrade pyrolysis vapor to biofuel components.
"The goal is to find catalytic systems that can produce biofuels cost effectively at scale," notes Mark Nimlos, NREL's research supervisor for molecular sciences, who will serve as principal investigator.
The non-food-derived feedstocks for producing the biofuels will range from fast-growing poplar or pine trees to switch grass to forest and agriculture residue and municipal solid waste.
"The best outcome would be, in five years, to have a new catalytic process which can make gasoline, diesel, and jet fuel at a price range that is better than, or competitive with, the cost of existing fuels," he says.
Meanwhile, researchers at the DOE's Lawrence Berkeley National Laboratory, Berkeley, Calif., have modified a century-old chemical process to produce advanced biofuels. Using the bacterium clostridium acetobutylicum, the team fermented sugars found in biomass into acetone, butanol and ethanol (ABE) products. Then, via a palladium catalyst, they converted the ABE products into high-mass hydrocarbons that are precursors to gasoline, diesel or jet fuel.
"By catalytically upgrading ABE fermentation products we're able to exploit highly efficient metabolic pathways and achieve near theoretical yields of transportation fuel precursors," explains researcher Dean Toste. "With our technique, we can obtain about a gallon of fuel from 16 pounds of the sugars that can be derived from lignocellulosic biomass."
"You can tune the size of your hydrocarbons based on the reaction conditions to produce the lighter hydrocarbons typical of gasoline, or the longer-chain hydrocarbons in diesel, or the branched chain hydrocarbons in jet fuel," he says.
"A hybrid method, combining microbial production with chemical catalysis, might provide a pathway to more efficient production of these advanced biofuels," adds researcher Harvey Blanch.
Seán Ottewell is Chemical Processing's Editor at Large. You can email him at firstname.lastname@example.org