Dow eyes ethylene from cellulosic ethanol

Dow is planning to plunge into biobased polyolefin production. The firm, the largest US chemical maker, has agreed to buy ethylene from New Energy Blue, which is planning a cellulosic ethanol plant in Mason City, Iowa.

The plant will convert corn stover—the stalks and other leftovers that remain after corn is harvested—into ethanol. It is designed to produce about 75 million L of ethanol per year from 275,000 metric tons of stover. New Energy Blue will convert nearly half of that ethanol into ethylene for Dow, which will use it to make plastics, such as polyethylene for packaging.

New Energy Blue unveiled the project in 2021, estimating its cost at $200 million. The company aims to eventually construct four more plants, and Dow will have the option of securing supply from them.

New Energy Blue acquired the rights to the technology it is using from the Danish firm Ørsted, which ran a demonstration plant in Kalundborg, Denmark, for nearly 5 years and distributed ethanol through local gas stations.

Dow wouldn’t be the first firm to make biobased polyethylene. Braskem has been producing it in Brazil for more than a decade from sugar cane-derived ethanol. In the late naughts, Dow itself had a plan to build an ethanol-based polyethylene complex in Brazil, but it didn’t materialize.

Manav Lahoti, Dow’s global sustainability director for hydrocarbons, says sustainable polymer production is more attractive now than when the company was considering the Brazilian project. “The demand has evolved with more focus on the need to transform towards circularity and decarbonization,” he says in an email.

Making ethanol and ethylene from cellulose instead of sugar is complicated. “There hasn’t been a whole lot of success at commercial scale with cellulosic ethanol,” says Doug Rivers, a project director for Lee Enterprises Consulting.

DuPont, Abengoa, and Poet all opened cellulosic ethanol plants in the US to great fanfare, only to shutter them after a few years of struggle.

Rivers says the problem is that crop residues are very abrasive on processing equipment, which complicates preparing them for enzymatic degradation into sugars that can be fermented into ethanol, he says.