Someday trees could provide more than just shade, scenery and building materials. Purdue University researchers are studying how poplars might be turned into liquid fuel.

In May a team of researchers led by Rick Meilan, associate professor of forestry and natural resources, began a five-year study to determine the viability of poplar species as an ethanol feedstock and cash crop for Indiana farmers. The study includes trial plots at Pinney-Purdue Agricultural Center east of Valparaiso and Southwest-Purdue Agricultural Center just north of Vincennes.

Findings from the research could help propel the fledgling cellulosic ethanol industry, Meilan said.

"For biofuel production we're principally using the sugars in corn that are fermented to produce alcohol that's then blended with petroleum products," he said. "What we'd like to do is use cellulosic feedstocks, including not just corn stover but also wood chips."

Cellulose is considered the next frontier in ethanol production. The process involves extracting sugars from the cell walls of plant material, or what is commonly known as biomass. Because most plants contain so much more biomass than grain, cellulose potentially could provide more ethanol than grain. With trees, the biomass volume is even larger than it is with most row crops.

The Purdue study is looking at 69 varieties of poplar species within the genus Populus and how they perform under different soil and climatic conditions, disease and insect pressure, and fertilization and watering regimes. The varieties all are cottonwoods, not tulip tree or yellow poplar, which aren't true poplars.

Poplars already are used in energy production. Wood is burned at some power plants to create steam to turn turbines for generating electricity. Meilan said the trees also offer advantages over other species as a cellulosic ethanol feedstock.

"One advantage is that poplars can be vegetatively propagated," he said. "That is, we can take a stem segment and just shove it into the ground and it will spontaneously produce roots in the portion of the stick that's beneath the ground, and buds above ground will lead to the production of leaves and branches."

At both Purdue research farms, Meilan's team hand-planted about 2,000 poplar sticks on three-acre tracts. The sticks measured about 8 inches long and three-eighths inch in diameter.