Within 10 years, crop residue may be harvested - and processed - in the field for use as building material.
StrawJet, a production system developed by David Ward of Talent, OR, was introduced last year and won a national competition for inventors sponsored by the History Channel and the National Inventors Hall of Fame.
“It's a baler, a different kind of baler,” Ward says of the machine that binds residue in 2"-diameter cables compacted with clay and polyester string.
The former construction worker came up with the idea after developing chemical sensitivities to conventional building materials.
“I tried to make a continuous square bale,” Ward says, but that didn't work. Then he had the idea of joining round cables with plaster-like materials into planks or mats.
The StrawJet system is a multi-step process: Windrows of straw or stalks are baled into cables, then the cables are cut and weaved into mats. Next, layers of mats are bound with clay-based adhesives, stacked to dry and cut to create building panels. Another option is to layer cables with adhesives and shape them into beams plastered together like bricks.
The concept attracts Third World countries seeking low-cost and readily available building material. Simple versions of Ward's StrawJet system debut in Africa and India this year, mainly because those countries offer an immediate opportunity for his company, Ward says. He expects to see the first homes built from his plant-based cables in Chad.
At the same time, he's negotiating with a U.S. company to get his building material accepted for current building codes. Because the material is solid and encased in clay plasters, it meets fire standards as well as load-bearing requirements. It also has good thermal mass to hold heat or cold.
The material deadens sounds extremely well, Ward says, making it especially suitable for apartment complexes.
He anticipates that the harvesting/manufacturing system will cost about $200,000.
“It's economy of scale that makes this work,” he notes.
StrawJet harvesters would coordinate harvests where there is demand for the building materials. At this point, two developers have ap-proached Ward. One plans to build an entire resort town in Mexico; the other to create a retirement community in Nevada, building as many as 100,000 houses over 20 years. They are attracted by the material's cost savings and because it's environmentally friendly.
Ward, however, will leave building construction to others.
“Our first focus is to get the machinery out there,” he says. He expects to see U.S. operations set up within five to 10 years. California's Central Valley may be the most ideal starting point, he says. StrawJet harvesters could bale cables of rice straw after the crop has been combined with a stripper header.
Many crop byproducts are suitable. Tobacco and sunflowers work well, as do flax, hemp, cotton, bamboo and palm. Ward has worked extensively with wheat straw, the most plentiful in much of the U.S. Unfortunately, it decays easily and has not been as good as other materials. Ward and his team are working on additives and other techniques to make wheat straw more desirable.
For more information, visit www.greeninventor.org/strawjet.shtml.