In the race to convert crops into energy, all eyes are on giant reed, a fast-growing and hardy grass species found throughout Texas and the southern United States.
Yet, the very qualities that make the species, also known as Arundo donax, attractive to the federal government as a renewable fuel source make it a noxious weed, capable of choking native plants, clogging rivers and streams, and draining wetlands.
Some scientists and environmentalists say the ecological and economic risks are greater than the reward and want the Environmental Protection Agency to reconsider a nearly finalized rule that would encourage farmers to grow giant reed and other invasive grasses for biofuels production.
“We think the idea of cleaner fuels is great,” said Janice Bezanson, executive director of the advocacy group Texas Conservation Alliance, “but we do not want to create a monster.”
The conflict illustrates the complexity involved in reducing the nation’s dependence on oil and gas with a new generation of biofuels that are made from algae, rice hulls, wild grasses and wood pellets rather than corn and other food crops.
The government also is counting on such fuels as a way to reduce emissions linked to global warming, a goal usually lauded by environmentalists.
This time, however, activists are warning that the use of invasive species could bring unintended consequences. Exotic species already cost the nation at least $120 billion each year, according to the National Wildlife Federation, and nearly half of the threatened or endangered plants and animals in the United States are at risk, in part, because nonnative pests have altered their habitats.
As benign and even lovely as it might seem, giant reed has menaced several states, including Texas, which classifies it as a noxious weed – a designation that means it cannot be planted in the state. Even then, the thirsty perennial, which can grow in dense stands as high as 30 feet, has taken hold, consuming large amounts of water from the Rio Grande and Pecos River and blocking the flow of the Nueces River.
The problem became so acute along a 30-mile stretch of the Nueces that landowners and other volunteers spent 11 weeks last year pulling sprouts by hand.
Giant reed is native to India and was introduced into the U.S. in the 1800s for erosion control. The plant can spread from a single underground stem or stalk fragments that grow roots and form new clones, typically along streams and irrigation canals.
Those opposed to the government’s plan to grow the wily weed say the plant could escape and overrun nearby farms and natural lands. Instead they want the government to encourage the use of native plants and grasses that also provide habitat for wildlife.
Climate change could contribute to the spread of giant reed and other invasive species, which might have a competitive advantage in places disturbed by droughts, floods and other extreme events that scientists say will increase in intensity and frequency as the planet warms.
Joshua Yuan, a plant pathologist at Texas A&M University, said growing giant reed as a biofuel crop still could be safe if introduced under the right conditions.
“There are legitimate concerns because there is no natural enemy to mitigate the growth of Arundo,” Yuan said. “How you manage the crop is important.”
The U.S. Department of Energy has awarded a $1.8 million grant to Yuan to create a tobacco plant packed with terpenoids, a hydrocarbon that can be used for fuel. If the project is successful, he will receive $2 million in additional funding to do the same with giant reed, a higher-producing species.