Environmental Health & Safety / Reaction & Synthesis / Energy Efficiency / Electricity

The Ball Keeps Rolling For Renewables

Significant progress is occuring in a number of key areas.

By Seán Ottewell, Editor at Large

Renewable raw materials are assuming ever-growing importance for chemical makers. New commercial-scale projects, advances in processing of second generation feedstocks and novel catalyst development exemplify efforts to extend the role of renewables.

For instance, bio-based ethanol is advancing on several fronts.

Vivergo Fuels, Hull, U.K. — a joint venture formed in 2007 by AB Sugar, Peterborough, U.K. (45%), BP, London (45%), and DuPont, Wilmington, Del. (10%) — has spent 6 years and £350 million ($550 million) to create a "biorefinery of the future." Full production — 420 million L/yr (110 million gal/yr) of bioethanol and 500,000 t/yr of animal feed — is imminent at the plant in Hull (Figure 1).

At its rated output, the plant will deliver about one third of the U.K.'s forecast demand for biofuel for gasoline. Under the European Union's Renewable Energy Directive, the U.K. government is aiming to have renewable sources account for 10% of the amount of energy used in transport by 2020, more than doubling the current 4% level.

The plant mills locally sourced feed-grade wheat into wholemeal flour. This is converted into a slurry and then treated with enzymes to break down its starch into fermentable sugars. Next, yeast converts the sugars into alcohol. The resulting beer contains 12% ethanol and goes to a distillation tower, which provides a 96%-ethanol product. Dehydration increases this concentration to 99.7%, producing fuel-grade ethanol that can be blended at around 5% in gasoline.

Evaporation concentrates the wheat protein and fiber residue, which then are dehydrated to create dried distillers grains with solubles and wet distillers grain, which are suitable for animal feed.

DuPont is building a biorefinery of its own, too. It has just broken ground in Nevada, Iowa, for a commercial-scale plant to use corn stover, an agricultural waste, to produce ethanol ("Biorefinery Beckons"). The 30-million-gal/yr unit should go onstream in 2014.

Meanwhile, BP Biofuels, Tampa, Fla., has begun a $350-million expansion of its sugar-cane-based ethanol plant at Tropical, Edeia, Brazil. The project, which includes the building of a new sugar cane mill, will double current cane-processing capacity to 5 million t/yr. When fully operational late in 2014 or early 2015, the expanded plant will be able to produce 450 million L/yr of ethanol. It also will be able to export an estimated 340 GWh/yr of electricity to the Brazilian national grid.

"Since we started operating in May 2011, we have been improving our operational efficiency and this announcement marks a further milestone in delivering our biofuels strategy," notes Mario Lindenhayn, CEO of BP Biofuels Brazil.

February saw the first commercial shipments by Amyris, Emeryville, Calif., of Biofene from its new plant in Brotas, Brazil. Biofene is the company's brand of farnesene, a long-chain hydrocarbon that can be used in a broad range of specialty chemicals such as flavors and lubricants and fuel products such as renewable diesel and jet fuel.

Amyris relies on a fermentation process in which proprietary yeast strains convert a sugar source into target molecules such as Biofene. The process can use any fermentable sugar.

"This initial shipment marks the successful completion of our startup activities. We have operated multiple tanks without contamination or surprises through several production runs during the first month of operation. We are now focused on ramping up Biofene production and delivering product to our customers, from renewable diesel for bus fleets in Brazil to squalane emollient globally and soon a range of specialty chemical applications," says John Melo, president and CEO.

Swiss specialty chemicals company Firmenich, Geneva, already has partnered with Amyris, funding technical development aimed at producing a sustainable, cost-effective and reliable source of key ingredients for the flavor and frangrance market. Japanese specialty chemicals company Kuraray, Tokyo, is using Biofene to replace petroleum-derived chemicals in the production of certain classes of high-performance polymers for the tire industry. In addition, Amyris and Total, Paris, are carrying out joint research and development into the production and marketing of renewable fuels.

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 sottewell@putman.net