The next generation of fuel ethanol

Good progress is being made towards converting biomass to ethanol in an economical way. But even though the cost of suitable processes and enzymes has been cut, there is still some way to go.

A major R&D effort is in progress at Novozymes to find enzymes to economically degrade lignocellulosic feedstocks such as straw into sugars.

Some obstacles still need to be overcome before a fully commercial process is developed, and so far biomass has only been converted into ethanol in a few pilot plants. However, this could be the humble beginnings of a huge new branch of industry that could grow to become even bigger than the existing first-generation fuel ethanol industry. ‘First-generation’ is used to refer to the conversion of sugar crops and cer­­eals that are rich in starch, for example corn (maize). ‘Second-generation’ refers to the conversion of lignocellulose, more commonly known as biomass - a very abundant substrate found all over the world.

The high cost of enzymes for converting lignocellulose into sugars was once considered one of the main obstacles to commercialisation, but costs have been reduced. In 2001, the US Department of Energy awarded a three-year research contract to Novozymes worth USD 14.8 million to reduce the cost of enzymes by tenfold. By the end of the government-sponsored research in 2004, the cost had been successfully reduced to the target level.

	Corn stover is a prime candidate for conversion into ethanol, but Emmanuel Petiot of Novozymes predicts that it will take another four to five years to develop and commercialise the enzymes for biomass conversion.

“Enzyme cost is no longer the dominating economic barrier to producing ethanol from biomass,” comments Joel Cherry, Director, Biotechnology/Bioenergy, who led the biomass research project at Novozymes’ research centre in Davis, California. The research work is continuing there under his leadership, and he predicts that even more efficient enzymes will be developed and process optimisation will take place at partners with whom Novozymes has allied.

Major opportunity
“The conversion of biomass to ethanol is not yet a commercial industrial process, but it is likely to be a very interesting opportunity for Novozymes in the future,” predicts Emmanuel Petiot, Global Business Development Manager for biomass applications at Novozymes. “This is an industry in the making. We believe it will take another four to five years to develop and commercialise the enzymes for this new field.”

Even if commercial sales of enzymes have not started, the conversion of biomass-to-ethanol is already receiving full attention at Novozymes, where efforts are being increased significantly within R&D, Marketing and other areas. In fact, the search for high-performance cellulases and hemicellulases represents a global mobil­isation of Novozymes’ research resources and expertise in this field. Novozymes also engages actively in key conferences on the subject and is seeking more government funding to speed up developments across the globe. Biomass research is being conducted at Novozymes’ laboratories worldwide, while biomass marketing is headquartered at Novozymes North America led by Emmanuel Petiot.

Pilot partnerships
Novozymes has a long history of mutually beneficial partnerships. The partnerships that Novozymes is entering into are visible signs of the research efforts. Implementing and fine-tuning Novozymes’ enzyme processes through collaborations with industrial partners that are bringing the technology to the pilot-scale testing phase is the current focus of biomass R&D.

For example, in June 2006 Novozymes signed a three-year research agreement with China Resources Alcohol Corporation (CRAC) on the development of biomass for biofuel in China. CRAC is a business area within China National Cereals Oils & Foodstuffs Corporation (COFCO) and has interesting technologies within the production of biofuel. CRAC has set up a pilot factory for the production of ethanol from corn stover in Zhaodong in Heilongjiang province.

In the long term, China is expected to become an important market for biofuel. The consumption of fuel has increased significantly in recent years in line with the increasing number of cars, and this has brought a focus on sustainable energy, especially biofuel.

It is commonly agreed that the production of first-generation ethanol based on food crops will not grow very much in China in the coming years because China largely imports corn and other cereals as foodstuffs. In contrast, China is expected to focus on the development of non-food crops such as cassava and sweet sorghum, and on second-generation biofuel from biomass.

In the USA, Novozymes has recently signed a partnership with Broin with the aim of taking the next steps needed to bring cost-effective ethanol derived from corn stover to market. The collaboration is an extension of the close partnership between the two companies; it is an opportunity for Novozymes to put its unique biotechnology platform to work and for Broin to aim for fast commercialisation.

These are just two examples of what is happening in the drive to bring biomass-based ethanol into the commercial arena.

Integrated approach
The production of ethanol from biomass can be broken down into the steps shown in the diagram. For a successful commercial process, all these steps need to be looked at in a holistic way because there is a complex interplay between them.

Lignocellulosic fibres are composed of three major fractions: cellulose, hemicellulose and lignin. Enzymes are able to attack the polymeric sugar chain in the cellulose and hemicellulose fractions, releasing monomeric sugars for fermentation. Pretreatment is needed to open up the fibres and make the lignocellulosic substrate accessible to enzyme action. Obviously the enzymes need to match the substrate. If a dilute acid pretreatment is used, most of the hemicellulose is degraded and a hemicellulase will not be needed. However, if an alkaline or neutral pretreatment is used, the hemicellulose still needs to be hydrolysed and hemicellulases will be needed. For researchers or companies that want to test enzymes in the laboratory, a Novozymes Biomass Kit is available with small samples of enzymes.

Another challenge is being faced at the fermentation stage because the 5-carbon (C5) sugars produced by the degradation of hemicellulose are not fermented by the yeast currently in use. Research is proceeding to develop organisms that can effectively utilise these sugars in order to increase ethanol yields and make the whole process more economical.

Collection of feedstock is a logistical challenge. Corn stover, which has been the subject of most research in the USA and China, is often not collected and is left in the fields to decompose. Systems of collection need to be established. That is why trials with biomass are often based on what are known as ‘captive streams’ - existing residues or by-products from first-generation ethanol plants. Corn fibre left over after the processing of corn starch and bagasse left over from sugar cane processing are examples of lignocellulosic raw materials that are readily available for conversion. Wood chips and wood trimmings could also be used.

Renewable fuel
Biomass provides a renewable feedstock for producing biofuel as an alternative to petrol (gasoline). With rising oil prices and strong government incentives, producing ethanol from biomass is becoming more viable step by step. With a growing awareness of global warming, biofuels could have a bright future. With political, economic and environmental factors favouring biofuels, there is now a strong will in certain countries to develop the conversion of biomass to ethanol.

Novozymes is engaged in an unprecedented research effort to find the cellulases and hemicellulases that the second-generation fuel ethanol industry will need in order to succeed.