Challenges, opportunities lie ahead for biomass energy production
Opportunities and challenges are evident as the biomass industry develops new and innovative methods of producing renewable energy across the U.S., according to Texas AgriLife experts.
Scientists from Texas AgriLife Research and the Texas AgriLife Extension Service recently discussed ongoing biomass production and logistical efforts in producing renewable energy from biomass at a conference in College Station.
Members of the Rural Alliance for Renewable Energy, which includes AgriLife Research, co-sponsored the event held at the Clayton Williams Jr. Alumni Center at Texas A&M University.
From a logistics standpoint, biomass crops such as sorghum and miscanthus can produce high yields, but removing moisture during harvesting and processing is a big challenge, the experts said.
Over the last four years, AgriLife Extension has evaluated more than 25 different biomass and sweet sorghum varieties and hybrids in the Brazos bottom and at additional locations throughout Texas.
In the Brazos bottom, sorghum seed was planted in mid-April. It was harvested for the first time in mid-July and for the second time in late October and early November. Annual yields in the Brazos bottom averaged between nine and 11.5 tons of dry matter, with the best hybrids yielding as high as 15 tons of dry matter per acre, said Juerg Blumenthal, AgriLife Extension agronomist.
"Plants at harvest contain 75 to 80 percent water and that means freshly harvested biomass contains as much as 30 to 35 tons of water," Blumenthal told attendees. "That presents some logistical issues."
Removing the water is a critical consideration once the biomass is harvested and ready for transportation, he said. The added water content adds to the load and increases transportation costs.
Another continuation of the research is looking at how long a sorghum crop can be left standing in the field during fall and winter. Blumenthal said they are evaluating how much lodging (falling down of the plant) takes place.
"We found the later in the season the more lodging you have," Blumenthal said.
Comparing the energy sorghum to corn for ethanol, Blumenthal said the 15.2 tons of dry matter as produced by the best sorghum hybrids is equal to all above-ground biomass (grain, cobs and stover) in a corn crop yielding 360 bushels per acre.
Steve Searcy, Ph.D., AgriLife Research engineer, discussed logistics methods for harvesting biomass in the field and delivering them for conversion. He discussed the limitations of using traditional hay harvesting methods for dedicated biomass crops, pointing out the need for handling large packages, as is done for international shipping.
There are issues to contend with, Searcy explained, and AgriLife Research has been experimenting with forming large packages of chopped biomass as an alternative.
"Our challenges are to minimize water when harvesting," he said. "We also need to minimize the dry matter loss during storage and develop logistics systems that can work from Beaumont to the Texas-Oklahoma border, meaning high rainfall to semi-arid regions."
Packaging is another area under study. First generation logistics are similar to hay harvesting.
"Current haying techniques can be used for biomass, but the costs will be high," he said. "Second generation logistics systems under development will combine capabilities from various systems to minimize cost and maximize the amount of dry matter available for conversion."
Searcy said AgriLife Research is studying and evaluating large packages, such as a 24- foot-long module of biomass.
"You can put two on a semi-trailer and haul it down the road," Searcy said. "We're looking to minimize labor and equipment."
Searcy said in his concluding remarks they have worked with four different commercial mower/conditioners and have yet to get the results they've wanted. More conditioning and drying is needed to remove water from the energy sorghum stalks quickly.
"It takes two or more weeks for it to dry to a level we consider safe for storage," he said.
But the integrity of the module has held up well when traveling on a truck up to 60 miles, he added.
For more information about AgriLife Research bioenergy activities, visit http://agriliferesearch.tamu.edu/corporaterelations/programs/bioenergy. For more information about the Rural Alliance for Renewable Energy, visit www.infinitepower.org/rare.