Researchers use methane, hemp to create wood

By Ryan C. Christiansen
Web exclusive posted March 19, 2009, at 6:00 p.m. CST

Researchers at Stanford University are using hemp fibers fused with a biodegradable plastic resin called polyhydroxy-butyrate (PHB) to develop a synthetic wood substitute that can be recycled to produce more of the same. The plastic resin can also be used to replace the petrochemical plastics used to manufacture disposable water bottles.

"This is a great opportunity to make products that serve a societal need and respect and protect the natural environment," said lead researcher Sarah Billington, an associate professor of civil and environmental engineering at the university. Billington and her colleagues are doing work that is funded in part by a three-year, $1.5 million grant from the California Environmental Protection Agency that was awarded in 2008 to develop biodegradable plastics for beverage bottles. The researchers originally received a two-year Environmental Venture Projects (EVP) grant from Stanford's Woods Institute for the Environment in 2004 to develop artificial wood that is both durable and recyclable.

The hemp-PHB composite material "is quite attractive looking and very strong," said collaborator Craig Criddle, a professor of civil and environmental engineering at Stanford. "You can mold it, nail it, hammer it, drill it, a lot like wood. But bioplastic PHB can be produced faster than wood, and hemp can be grown faster than trees."

The hemp-PHB biocomposites are stable enough to use in furniture, floors and a variety of other building materials, Criddle added. The material degrades in anaerobic environments and releases methane which can be captured and reused to make more PHB.

"It dawned on us that there are microbes that can make PHB from methane," Criddle said. "So now we're combining two natural processes. We're using microbes that break down PHB plastics and release methane gas, and different organisms that consume methane and produce PHB as a byproduct."

According to the researchers, their work has caught the attention of private investors and in the next few months, the group will form a new startup company.

In addition, the researchers have been awarded a 2008 grant from Stanford's Precourt Energy Efficiency Center to develop biodegradable foam for structural insulated panels. They also received new funding from the Woods Institute to explore the feasibility of using the polymers to manufacture "green glues" that make air quality in buildings less toxic.