Synthetic wood

Researchers at Stanford University in California have developed a synthetic-wood substitute that may one day save trees, reduce greenhouse-gas emissions and shrink landfills.

The wood is made from a novel biodegradable plastic that could be used in a variety of building materials and perhaps replace the petrochemical plastics now used in billions of 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.

In 2004, Billington and her colleagues received a two-year Environmental Venture Projects (EVP) grant from Stanford's Woods Institute for the Environment to develop artificial wood that is both durable and recyclable. The research team focused on a new class of construction material called biodegradable composites or 'biocomposites' - glue-like resins reinforced with natural fibres that are made from plants and recyclable polymers.

Billington's group began by testing a number of promising materials. The best turned out to be natural-hemp fibres fused with a biodegradable plastic resin called polyhydroxy-butyrate (PHB). 'It's quite attractive looking and very strong,' said EVP collaborator Craig Criddle, a professor of civil and environmental engineering. 'You can mould 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, flooring and a variety of other building materials, he added. To degrade, it must be kept away from air - for example, buried in a landfill - because its decomposition depends on micro-organisms that live in anaerobic environments.

Unlike wood scraps that can sit in landfills for months or years, hemp-PHB biocomposites decompose a few weeks after burial. As they degrade, they release methane gas that can be captured and burned for energy recovery or re-used to make more biocomposites.

The potential of producing low-cost, recyclable biocomposites has caught the attention of the private sector. In the next few months, the researchers expect to form a start-up company with venture capital funding.