Biofuels made from sugar and starch feedstocks have long been an important component of the world’s energy sources; however, the widespread availability and low cost of biomass residue make them a logical – and exciting – source of advanced biofuels. An increasing number of countries are working to capitalize on bioethanol’s potential to lower greenhouse gas emissions, provide energy independence, and spur economic growth. Through performance-enhancing product developments and strategic partnerships, the enzymes needed to produce commercially viable cellulosic ethanol are now available.
Biofuels are a key source of sustainable energy. Transportation is responsible for a quarter of global energy-related CO2 emissions (and this figure is steadily rising), and biofuel is the only existing renewable energy source for transportation that can effectively lead the world toward a lowcarbon future. Cellulosic ethanol can reduce CO2 emissions by up to 90% compared to conventional gasoline, a goal that many nations recognize as worth pursuing. The potential of this growing industry for meeting the demand for an alternative global liquid transport fuel is so well accepted that the US is requiring 16 billion gallons of cellulosic ethanol production by 2022, with other governments enacting similar mandates.
No longer “just around the corner”
“We made a promise to deliver commercially viable enzymes by 2010, and with the launch of Cellic CTec2, we have delivered,” says Cynthia Bryant, Global Biomass Business Development Manager at Novozymes. “But it’s not just about developing better-performing, lowercost enzymes. We also bring extensive internal research to our collaborations that result in developing a successful process our partners can use to manufacture and sell cellulosic ethanol.”
Cellic CTec2 is a novel cellulase complex that provides state-of-the-art cellulose conversion and the unmatched cost performance needed to take cellulosic ethanol to a commercial scale. Compared to Cellic CTec, launched in 2009, test results show a significant performance improvement across a range of feedstocks and process technologies when measuring glucose formation under relevant hydrolysis conditions (see Fig. 1).
Mads Torry-Smith, R&D Manager at Novozymes, explains: “Cellic CTec2 has been designed to provide maximum robustness toward feedstock and process variation. High levels of beta-glucosidase ensure continuous production of fermentable sugars. Research with our partner pilot plants over the past year has resulted in further process optimization that takes full advantage of this new enzyme system and allows for operation under commercially relevant conditions.”
To measure the performance increase, a variety of pretreated substrates were processed using both versions of the Cellic enzyme. Not only does the Cellic CTec2 enzyme complex deliver better performance improvement overall, but it provides an even greater performance benefit than Cellic CTec at higher total solids (TS) (see Fig. 2). Higher TS conditions permit processing of more cellulose and hemicellulose, resulting in higher ethanol titers and reduced capital and operating costs.
The potential of cellulosic ethanol
The world’s energy consumption is increasing, carbon emissions are having a visible effect on climate change, and usable oil reserves are diminishing. Clearly, one of our biggest challenges is the need for viable alternatives to petroleumbased energy sources. Novozymes has long been supplying enzymes for starch-based ethanol, recognizing that biofuels provide an answer to the search for a renewable and sustainable fuel.
Cellulosic ethanol – biofuel produced from feedstocks containing cellulosic biomass – is the most promising new contributor to the biofuel solution. The raw materials are many and varied, but there have been key technical and economic challenges in the quest to bring cellulosic ethanol to market. Despite the abundance of viable feedstocks, these substances are complex and can be difficult to break down and convert into ethanol. While traditional sugar- and starch-based processes rely on a few key crops and standardized technology, cellulosic ethanol production is much more complex.
With Novozymes Cellic® CTec2, it is now possible to produce ethanol from the cellulosic material found in everything from corn cobs to municipal waste.
High enzyme costs for the cellulosic process have been one of the biggest challenges. As a result, Novozymes has focused on how best to manage process integration and optimization while balancing capital and operating costs. Ten years ago, Novozymes was awarded US Department of Energy (DOE) funding to conduct extensive research and development on enzymatic cellulosic ethanol conversion. At the time, the cost of enzyme application for cellulosic feedstocks was too high, and few thought that it was possible to come up with a commercially viable process.
Powerful partnerships
Since 2000, Novozymes has consistently reduced enzyme costs, fueling excitement and promise in the future of cellulosic biofuels (see Fig. 3). Still, in order to achieve truly significant cost reductions, a more holistic approach was required. All aspects of the production process – from feedstock transport via pretreatment to operating expenses – had to be examined and improved. This realization of the need to combine better enzymes and process efficiencies has led to unprecedented endeavors toward both internal research efforts and valuable partnerships around the globe.
“A key component of Novozymes’ approach is developing strategic partnerships within the cellulosic ethanol industry. We recognize that it will take many different feedstocks and processes for cellulosic ethanol to reach its full potential. We have thus chosen to collaborate with a number of industry leaders in order to enable as many technologies as possible,” says Cynthia Bryant. “This has allowed us greater insight into the cellulosic conversion work currently underway across the globe – insight which we use in our continuing research and the development of enzymes and process improvements. We have achieved significant results in lab and pilot project work with many of our partners, including POET, Greenfield Ethanol, Inbicon, Lignol, ICM, and COFCO.”
Novozymes and its partners joined forces in order to capitalize on their different competencies. Understanding that the relationship between process mechanics and enzymes is critical, it was important to design processes that provide a suitable environment for the enzymes to do their job effectively. As a result, several of these collaborations have begun to achieve success through the reduction of process capital and operating costs, which has led to accelerated technical and commercial developments. When process improvements and new enzyme technology are combined, these partnerships have been instrumental in making the commercial viability of cellulosic biofuel a reality. There is much excitement that Cellic CTec2 is now globally available in commercial-scale volumes. With its proven performance, Novozymes has delivered on our promise of a commercially viable enzyme product in 2010. With the launch of our latest Cellic products, cellulosic ethanol is no longer “just around the corner” – it’s here now!