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Clariant bets big on cellulosic ethanol

Chemical maker breaks ground in Romania on $120 million waste-straw-to-ethanol plant

by Alex Scott
September 30, 2018 | A version of this story appeared in Volume 96, Issue 39


Photo of the site of Clariant's planned cellulosic ethanol plant in Podari, Romania.
Credit: Alex Scott/C&EN
In September, Clariant began construction in Podari, Romania, on a plant that will make ethanol from straw.

Michael Zavrel, a chemical engineer who heads development and biomanufacturing for Clariant’s biotech arm, remembers 2008. He was in the final year of his Ph.D. in biochemical engineering and had joined the Munich-based specialty chemical firm Süd-Chemie to work on a project, already a year or two old, to convert straw into ethanol.

The Sunliquid process

Efficiency was improved by designing each step to fit with the next, Clariant says.

1. Straw is pretreated to remove twine and stones.

2. Straw is fed into a hopper and chopped into pieces up to 4 cm in length.

3. Straw is subjected to steam under pressure, adding moisture and degrading the cellulose.

4. Enzymes degrade the straw into C5 and C6 sugars.

5. An engineered yeast ferments sugars into an ethanol-rich broth.

6. Broth is pressed to remove lignin, which is dried and used to power the plant.

7. The ethanol-rich liquid is distilled to a concentration of about 95%. The vinasse residue, which is rich in nitrogen, potassium, and phosphorus, can be used as fertilizer.

8. Molecular sieves remove more water from the ethanol, increasing purity to 99.5%. The separated water is reused.

“We used to work with these when I first started,” says Zavrel, waving a 96-well microplate for testing the effectiveness of biocatalysts in the ethanol process.

Much has changed since then. Clariant bought Süd-Chemie. Zavrel took up a management position and now works with about 80 colleagues on a range of projects rather than the small, focused team he joined in 2008. And the 96-well microplates have been mostly replaced by 1,536-well versions, which Zavrel and his colleagues hand over to a team of whirring robots.

The outlook for cellulosic ethanol processes—which run on cellulose from corn stalks, straw, and other biomass rather than the usual corn sugar—has also shifted during the project’s lifetime. The U.S. experienced the revolution of shale gas from fracking, driving down the price of fuel sufficiently to force several cellulosic ethanol plants to shut down.

Undeterred, Clariant is commercializing its technology, called Sunliquid. In the Sunliquid process, straw is shredded and steam treated to open its structure. It’s hit with enzymes that degrade the material into C5 and C6 sugars. In a fermentation step, a strain of yeast that Zavrel and his colleagues developed using directed evolution then converts the sugars into ethanol.

Given the risks, some companies might have shelved the project. But Clariant says it took the time needed to enhance the efficiency of the process, making executives confident that Sunliquid will be competitive.

Clariant is putting its money where its mouth is. The firm recently broke ground on a cellulosic ethanol plant in Podari, Romania. The Swiss firm is investing nearly $120 million to build the plant—including European Union subsidies of almost $30 million but on top of almost $50 million the firm spent developing the technology.

Scheduled to start up in 2020, the plant will convert some 250,000 metric tons per year of straw from farms up to 80 km away into about 50,000 metric tons of ethanol, largely destined for the fuel market.

If it gets this project right, the Swiss firm will be well placed to license Sunliquid to customers in Europe and beyond. If Clariant is unable to make fuel at a competitive price, though, it would be a major setback not just for the ethanol program but also the firm’s plan to use Sunliquid as a platform for a suite of biobased chemicals.

And plenty could go wrong between now and 2020, from raw material collection and quality issues to poor process efficiency at industrial scale. Some other cellulosic ethanol producers have found it a hard business to succeed in.

One of them is DuPont. The firm invested hundreds of millions of dollars developing a cellulosic ethanol business, but last fall it disclosed that it wants out. Its business includes a plant in Nevada, Iowa, that uses DuPont enzymes and yeast to turn corn cobs, stems, and leaves into ethanol.


Business isn’t any easier in Europe. Beta Renewables, an Italian cellulosic ethanol producer, is being sold to pay off debts from its bankrupt parent company, Mossi Ghisolfi Group. Beta Renewables’ plant in Crescentino, Italy, the world’s first large cellulosic ethanol facility, has reportedly been shut down for more than a year. Opened in 2013, the plant converted a variety of materials into ethanol using enzymes supplied by the Danish firm Novozymes.

Philippe Mengal, executive director of Bio-based Industries Joint Undertaking (BBI JU), an agency that provided Clariant’s project in Podari with the $30 million of EU money, acknowledges that Clariant’s project is risky. But BBI JU’s detailed analysis showed that it is “absolutely” a risk worth taking, says Mengal, who headed to Podari in September to be at the plant’s groundbreaking ceremony.

BBI JU is funding the project because it sees it as a landmark opportunity for Europe. The project has the potential to generate value, provide jobs, and enhance sustainability in a rural community in Romania—one of the poorest countries in Europe—while supporting high-tech jobs in Switzerland, Mengal says.

Clariant claims its technology is fundamentally different from the ones that have failed. Perhaps the biggest difference is on-site production of the enzymes that degrade the straw, says Markus Rarbach, head of biofuels and derivatives for Clariant. This cuts out substantial transportation and stabilization costs, Rarbach says. The Swiss firm will provide its licensees with a starter batch of an organism for making the enzyme, which then reproduces on-site.

Another advantage of Sunliquid over many competing processes, Clariant says, is that the firm has fine-tuned each step so it is optimized with the next, including tailoring the design of the enzymes to work with a specific feedstock. This is different from many cellulosic ethanol processes, which may combine enzymes made by one company with a technology from another firm, Rarbach says.

Additionally, by-products are managed efficiently in the Sunliquid process. Lignin, a natural glue that holds plant fibers together, is removed as a solid by filtration. The lignin is then dried and used to provide enough heat and electricity to power the entire ethanol plant.

After the lignin is removed, the ethanol is distilled. The remaining nutrient-rich solution, dubbed vinasse, can be used as fertilizer. Because the Clariant process uses steam—and not chemicals—in its pretreatment phase, the vinasse contains no toxic residues, Rarbach says.

Clariant has been improving its process at a pilot facility in Straubing, Germany, about an hour and a half northeast of Munich, since 2012. The pilot plant mimics a commercial operation, down to the engineering design, and even has 24-hour production shifts to mirror activity at a commercial-scale plant, Rarbach says. This attention to detail is one of the reasons why the company is confident Sunliquid will be competitive at industrial scale, he adds.

The company has chosen not to design any new equipment for the process but rather focus on getting the biotechnology right. “When it comes to equipment we have not redesigned the wheel,” Rarbach says.

Clariant predicts that the Podari plant will produce ethanol at 60–70 cents per liter, a cost similar to that of sugar-based ethanol.

The technology is of interest in Europe, Rarbach says, because of the region’s drive to be more sustainable. EU regulations require that 3.5% of Europe’s transportation fuel be so-called advanced biofuels—those that don’t compete with the food supply—by 2030. This is equivalent to 10.5 million metric tons per year of cellulosic ethanol.

Romania—known more for its tales of Count Dracula than any industrial prowess—is an ideal location for the first commercial Sunliquid plant because it is a low-cost country with a strong agriculture sector and plenty of straw, Clariant says.

The firm will employ 100 local Romanians to be trained at the pilot facility in Straubing. It estimates the plant will also create about 300 jobs in the supply chain.

Some 500 million metric tons per year of straw are available in Europe, of which 200 million metric tons “realistically” could be collected, Rarbach says. Globally, there is enough cellulosic feedstock to produce over 700 million metric tons of ethanol, including 37 million metric tons of ethanol in Europe.

“Five years ago I would have said the business will start in North America or Brazil,” Rarbach says. But in that time, the cost of producing fossil fuels in the U.S. has fallen, while Brazil’s economy has floundered.

Clariant already sold its first Sunliquid license to the European ethanol maker Enviral. At the same time that Clariant is building its plant in Podari, Enviral will use the technology to convert a sugar-based ethanol plant in Slovenia to run on cellulose.

The Enviral plant will be an opportunity for Clariant to demonstrate Sunliquid’s effectiveness in converted traditional ethanol plants. Still, the plant in Podari is needed to show the market that Clariant is serious about its own technology, Clariant board member Christian Kohlpaintner says. “Don’t underestimate the importance of putting up your own money.”

Although ground was just broken in Podari, Clariant is also developing processes that use feedstocks other than straw, as well as processes for making nonfuel chemicals from ethanol or directly from C5 and C6 sugars.

Clariant’s most advanced Sunliquid project after ethanol involves a partnership with the French industrial biotech firm Global Bioenergies to develop polymer for cosmetics starting with biobased isobutene. The partners are almost one year into testing their technology at a demonstration facility in Leuna, Germany.

Zavrel and his colleagues will again be looking to ensure that the process is economically viable. “It takes time,” Rarbach says. “But that is the name of the game. It’s better to be patient than introduce a technology that doesn’t work.”


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