Dow Pilots Plastics-to-Energy

• By Laura Williams
• Jul 25, 2011

No matter how dedicated you are to recycling, sometimes it can just be plain confusing. For a while, we were told to recycle only those plastics designated by specific numbers. And then we were told to disregard those numbers altogether and “check for the neck.” And now, who knows what slogan we’re supposed to follow?

The cause of these complexities is that certain types of plastics simply can’t be recycled efficiently enough to justify the expense and energy use. Rather than stuff landfills with these thin-film plastics, Dow Plastics is investigating whether it can convert them into something we all need more of: energy.

“You can think of plastics as a solidified form of energy,” said Jeff Wooster, Dow’s plastics sustainability leader for North America. “We take energy from oil and convert it into plastic – and now we’re going to convert that plastic to energy.”

The company’s initial foray into converting waste plastics to energy recovered 96 percent of the material’s energy potential. The plastic, waste sourced from Dow’s lab, was made of linear low-density polyethylene (LLDPE), a thin-film material typically used to make such items as grocery bags, plastic wrap, packaging, cable covering, and flexible tubing. The 578 pounds burned in the pilot had energy equivalent of 11.1 million BTUs of natural gas and was used to fuel an incinerator.

The trial is part of Dow’s overarching push to recycle 100 percent of its packaging, something Wooster said is important to the company’s customers.

“We need another use for our material when we or our customers are done using it,” he said. “We don’t like to send material of value to landfills. We’d rather develop more alternative uses for those materials at the end of their lives.”

Factories looking to replace natural gas with plastics need to meet a few requirements. First, they must have a furnace that workers can feed with bulk feedstock. A home furnace, for example, would not accommodate the switch from natural gas to plastic. Wooster said facilities also need to be able to accommodate the high fuel value per pound, as well as have the right control equipment and emissions control equipment.

As plastics are made from fossil fuels, burning them creates some amount of carbon emissions, though Dow would not say how those emissions compared with those of traditional fossil fuels.

In addition to studying other alternatives, the company is looking at the best way to implement plastics-to-energy techniques in its businesses. The trial, said Wooster, was a great first step.

“We’re really excited about this because it has twofold benefits: It keeps material out of the landfill and recovers the value in material we think of as resources,” he said.