Archive for April 24th, 2008
Sweet Sorghum Ethanol Association
The SSEA is a global organization whose purpose is to promote and develop the use of sweet sorghum, a renewable and sustainable resource, for processing into ethanol and other bio-derivatives.
Nebraska Sweet Sorghum
It looks like split-pea soup and tastes like sugar water with a vague vegetative twist. But never mind.
Ishmail Dweikat and John Rajewski don’t have their collective eye on Gatorade as the primary competition for the juice from the 12-foot long, one inch-thick stalks of sweet sorghum they’re harvesting from a University of Nebraska test plot.
Dweikat, leader of sweet sorghum research at UNL, and Rajewski, field manager and plant breeder, are more interested in using these plants rustling in the East Campus breeze as the raw material for future ethanol production.
“If you want a reliable source for ethanol,” Dweikat said, “corn would not be the one.”
Sweet sorghum’s advantages over Nebraska corn are many, he said.
It doesn’t need to be irrigated and goes into dormancy during drought periods. The ratio of energy consumed to energy produced is much higher than corn, and an acre of sweet sorghum can produce as much as 800 gallons of ethanol.
Corn’s ethanol yield is closer to 250 gallons per acre.
Despite what the UNL researchers see as sweet sorghum’s considerable promise, corn growers serving the ethanol market don’t need to leap out of the way just yet.
It will take another year or two to develop the right hybrid, Dweikat said. Harvesting equipment that can crush the juice out of the stalks as it moves through the field is also a work in progress.
“Back in the 1900s, sweet sorghum was used as a source of molasses,” he said.
In a new century, possibilities for what can happen with a plant traceable mostly to Africa are headed in an energy direction.
Can the crop be a major source of renewable fuel?
“It’s very likely it will be if we can get the mechanics worked out for it,” said Rajewski.
Dweikat said Texas and Oklahoma, neither of which is a major producer of corn, are further along in building distilleries to boil the water out of sorghum juice and convert what’s left to motor fuel.
But tall stands of sweet sorghum, which carry seed clusters at the very top, can be grown anywhere corn and grain sorghum can be grown.
In Nebraska, home to gusty winds early and late in the growing season, an adaptation is in the works.
“We’re trying to breed for tall, big stalks without seed,” Dweikat said. “If there’s nothing heavy on the top, it has a much better chance of standing the wind.”
Signs of success at UNL are not exactly taking the ethanol industry by storm. Preliminary checks with the ethanol establishment in other states failed to turn up anybody gushing with enthusiasm.
Brian Jennings, based in Sioux Falls, S.D., with the American Coalition for Ethanol, is among the less than overwhelmed. He sees corn and cellulosic ethanol made from the rest of the corn plant as dominant factors.
“I think corn will remain the centerpiece for years to come,” Jennings said, “and then we will see corn stover and corn fiber and other things like that kick off very soon.”
If sweet sorghum is a better choice, “that would be news to me.”
James Covey, ethanol advocate and state legislator from Custer City, Okla., said his state is moving toward building its first ethanol plant, but will use the same grain supply to make the finished product as plants elsewhere.
Sweet sorghum, said Covey, is “a different breed of pup.”
Dweikat and Rajewski are undeterred and lay out a future in which Nebraska farmers distill their own juice and store it in rubber bladders until it can be picked up by cooperatives and hauled off to make ethanol.
“Of course, economics drives everything,” Rajewski said, “economics and water availability. So we’ll see how that goes.”
The sweet sorghum research is being conducted on dryland plots at UNL’s High Plains Ag Lab near Sidney and at other Nebraska locations. UNL is looking at some alternative ethanol-producing crops for farmers who rely on dryland or limited-irrigation production, according to Drew Lyon, extension dryland crops specialist at the Panhandle Center. Growing dryland corn is risky in the Nebraska Panhandle. Sweet sorghum may be a crop that dryland farmers can grow more consistently and profitably.
In 2007, field studies were conducted at Sidney, North Platte, and Clay Center to determine theoretical ethanol yield from sweet sorghum, corn, and grain sorghum. This work was done by Lyon, in cooperation with other UNL experts, Ismail Dweikat of Lincoln, Charles Wortmann, extension, from Lincoln, and Bob Klein, extension cropping systems specialist at the West Central REC in North Platte.
Preliminary findings indicate that, compared to corn and grain sorghum, sweet sorghum does not produce more ethanol yield per acre, but does produce greater net energy. This results in a net reduction in CO2 emission compared to corn or grain sorghum, and much more energy produced per energy invested. Approximately 250% more energy is produced than invested for sweet sorghum, compared to 50% more produced than invested for corn or grain sorghum. Sweet sorghum produces more net energy because it produces sugar, rather than starch. According to Lyon, less energy is needed to make ethanol from sugar than from starch. Sweet sorghum may require less nitrogen fertilizer input than corn, and may be more water-use efficient than corn.
Some potential problems with sweet sorghum include harvest challenges — for example, what to do with all the biomass and where and how to extract the sugar. The plants are very tall, and seed production is low. Questions also remain about how to feed sugar into a corn ethanol stream.
Sweet Sorgum
Oklahoma State University’s sorghum-related biofuels research is taking a localized approach, with the aim of making possible the effective production of ethanol in the farmer’s own field.
Sweet sorghum can be grown throughout temperate climate zones of the United States, including Oklahoma. It provides high biomass yield with low irrigation and fertilizer requirements. Corn ethanol, in contrast, requires significant amounts of water for growing and processing.
Best of all, producing ethanol from sweet sorghum is relatively easy, said Danielle Bellmer, biosystems engineer with the OSU Division of Agricultural Sciences and Natural Resources’ Robert M. Kerr Food and Agricultural Products Center.
“Just press the juice from the stalk, add yeast, allow fermentation to take place and you have ethanol,” Bellmer said. “Unfortunately, the simple sugars derived from sweet sorghum have to be fermented immediately.”
Throw in the expense of constructing and operating a central processing facility that would only operate the four to five months of the year when sorghum would be available in Oklahoma and the challenge multiplies.
The beginnings of a possible solution presented itself when entrepreneur Lee McClune, president of Sorganol Production Co. Inc., approached FAPC scientists seeking their assistance in testing his newly designed field harvester capable of pressing and collecting juice from sweet sorghum. His proposed Sorganol process involved using the harvester, large storage bladders for fermentation and a mobile distillation unit for ethanol purification.
OSU’s initial involvement in the project was to look at the feasibility of fermenting the juice in the field.
“We’re examining such things as juice extraction efficiency, whether or not pH (acidity) or nutrient adjustment of the juice is needed and various environmental factors,” Bellmer said.
The goal is to make production of ethanol from sweet sorghum economically viable by using an in-field processing system that minimizes transportation costs and capital investment.
Equipment such as the harvester and other technology could be owned individually or cooperatively with a number of producers sharing and possibly helping one another process ethanol from sweet sorghum.
In Oklahoma, the potential processing scenario might look like this: Plant sweet sorghum around mid-April, and then stagger plantings for two to three months. This would provide a harvest window of August through November.
“Ethanol yields in Oklahoma could range from 300 gallons to 600 gallons per acre, depending on biomass yield, sugar content and juice expression efficiency,” said Chad Godsey, biofuels team member and OSU Cooperative Extension cropping systems specialist with the department of plant and soil sciences.
Godsey said the team is working to determine the maximum possible harvest window for sweet sorghum in Oklahoma.
“Obviously, the longer the harvest window, the more ethanol state farmers will be able to produce,” he said.
OSU Biofuels Team researchers also are studying environmental parameters that may affect the feasibility of on-farm fermentation. A producer must be able to ferment the juice in the field during Oklahoma’s harvest season for sweet sorghum, which occurs in the fall when temperature extremes are highly possible.
“Temperature can speed up, slow down or derail the fermentation process,” Godsey said.
Weather data for Oklahoma indicate an average low temperature of about 44 degrees Fahrenheit and an average high temperature of approximately 98 degrees Fahrenheit during the August-through-October period over the past 10 years.
Six test plot sites are maintained at Oklahoma Agricultural Experiment Station facilities across the state, allowing OSU scientists to conduct research on sweet sorghum under local conditions.
“We would like to do with sweet sorghum what the Brazilians have done with sugar cane: In Brazil, sugar cane ethanol provides a large percentage of their fuel needs,” Bellmer said.
The idea of using sweet sorghum for commercial ethanol production is not new. The reason sweet sorghum is not as popular as corn in terms of being a source of ethanol in the United States has been the need to ferment its simple sugars immediately and the high costs associated with a central processing plant that is operated only seasonally.
“By determining a process by which agricultural producers can create ethanol in the field from sweet sorghum, that barrier is removed,” Bellmer said. “Producers will then have a much higher value product to sell.”
