Biomass gasification and the resulting production of “biochar” were among the topics addressed at the Texas Animal Manure Management Issues Conference Sept. 29-30 in Round Rock, north of Austin.
The conference was attended by about 175 beef, poultry and dairy industry producers, researchers, engineers, regulators and others involved in environmental, regulatory and energy related aspects of manure management.
During a technical session devoted to advanced manure conversion/bioenergy, Dr. Sergio Capareda with Texas AgriLife Research spoke about how animal manure and other biomass can be converted into useful energy. He also noted the commercial possibilities of the biochar which is produced from biomass gasification.
“On-site animal manure conversion into heat and energy is possible with the use of high-throughput fluidized-bed gasification system,” said Capareda, who works in the department of biological and agricultural engineering at the College of Agriculture and Life Sciences at Texas A&M University.
He said the gasifier can thermally convert relatively dry manure or other biomass into heat, synthesis gas or electrical power.
“The conversion process is endothermic – formed by the production of heat – so no external energy source is required, except during initial startup of the biomass gasifier," Capareda said.
According to its proponents, gasification also is an environmentally sound process because it produces clean air emissions and no water discharge. It also allows for the efficient disposal of animal waste and helps reduce odors emanating from agricultural operations.
“Biomass, like fossil fuels, contains a lot of carbon and hydrogen and can be a good alternative energy source,” Capareda said. “But while biomass produces less energy, unlike fossil fuels this is a renewable resource, and enormous reserves exist.”
Capareda, who has more than 20 years experience in biomass, biofuels and alternative energy, said his research on biomass gasification and biochar includes analysis of the various biomass “feedstocks.” Some of the feedstock material he has tested includes wood chips, poultry litter, dairy manure, sorghum crop residue, switchgrass and cotton gin residue.
He said his tests have shown that the “synthesis gas” produced by gasification of poultry litter and wood chips has produced a high-heating value, HHV, of about 150 British thermal units per cubic foot. A somewhat lower energy value was produced by manure gasification.
“Generally speaking, if an operation could just obtain a 15 percent efficiency in energy conversion from biomass, it could produce enough to be self-sustaining,” he said. “And any extra energy produced, depending on what form it’s in, could be sold back and put on the grid.”
Capareda added that biomass gasification also produces biochar, a carbon-rich product that can be used for many commercial applications. In agriculture, biochar has been shown to have a significant impact on replenishing soil, improving the growth rate of crops and reducing agricultural greenhouse gas emissions.
“Biochar is already known to be a useful soil supplement, especially around the Amazon rainforest, where its continued use creates what is called ‘terra preta’ or black earth,” he said. “This black earth allows crops to grow or crop production to increase by making nutrients more available through a type of carbon sequestration.”
Biochar from biomass gasification could be sold as fertilizer or soil amendment, or used as an ingredient in garden soil, he said. Many other possible commercial applications are still being analyzed and explored.
Much of the biochar being used today is the result of wood used as the fuel source, said Michael McGolden, president and CEO of Coaltec Energy USA in Carterville, Ill.
“Using animal manure in the gasification process will not only produce the carbon needed for nutrient uptake, it will provide many of the nutrients crops need as well,” he added.
McGolden said Coaltec has developed agriculture-based biomass gasification projects for the past five years, and has built on-site systems at poultry operations over the past two years.
“The main goal of these projects has been to make manure a valuable resource to these operations, even a key component of generating revenues,” McGolden said.
He added that different animal manures have been scientifically tested and proven to be a good fuel source for gasification, providing sustainable results.
“Potential revenue from biomass gasification can be derived from energy value, manure management cost reductions, mortality disposal, improved animal performance, environmental benefits, labor and cost reduction and the value of the biochar produced,” he said.
He also noted that while the marketing of biochar is still being fleshed out, it likely will provide producers with a significantly greater commercial potential than the value of the energy produced by biomass gasification.
“Along with other applications, biochar also has commercial possibility as a water filtration medium because the phosphorus in it also increases the ability to capture heavy metal particles,” he said.
McGolden added that other benefits of the gasification process may include disease control and biosecurity improvement, the potential for energy credits, and enhanced ability to increase operational capacity by improving manure-management capabilities.
To help prove the commercial viability of biomass gasification, Capareda is in the process of building a “mobile conversion system” at Texas A&M. The system, a portable biomass gasification unit that can be hauled to different locations, will be used to demonstrate the efficacy of biomass-to-energy conversion.
Capareda also is investigating how the synthesis gas combustible material can be removed from gasified biomass so the gas can be pumped through a pipeline in a manner similar to natural gas.
“The gas is combustible and may be cleaned and used to run internal combustion engines that are coupled with generators,” he said. “We’re also looking into condensing the gas to make what’s known as bio-oil or black oil, which looks similar to crude oil and can be used directly as fuel or converted into other valuable chemicals.” Capareda noted that while much research on biomass energy conversion remains to be done, his research shows it holds significant direct and spin-off commercial potential.
“Right now, we’ve just scratched the surface of the potential from the entire biomass energy conversion process,” he said.