Renewing resources with waste management research
The adage "one man's trash is another man's treasure" captures the essence of the innovative work being done by AgBioResearch scientist Steve Safferman. He and his colleagues are developing new methods to minimize and treat waste, particularly animal agriculture waste and food processing and food service waste.
The research is timely because effective waste management systems have come to the forefront as the United States struggles to reduce greenhouse gases and global warming and protect freshwater resources. Safferman, an associate professor of biosystems and agricultural engineering, is director of the new MSU Anaerobic Digester Research and Education Center (ADREC).
"We believe MSU can play a very critical role in the waste management industry as it evolves in this country because of the resources we have, both in the faculty and staff members and now in the laboratory facilities," Safferman said. "Instead of waste being a burden on the environment, it can now be an asset and a very much needed commodity."
Anaerobic digesters are enclosed tanks that decompose animal manure, food waste and/or other organic material in an oxygen-free environment. The lack of oxygen allows the waste materials to decompose and produces methane that can be captured and used as fuel. When waste decomposes in open tanks or lagoons, the methane released into the atmosphere is an extremely potent greenhouse gas.
"Animal waste is a highly unstable product, and even if it's stored and properly handled in a lagoon system, there are still the issues of odor, greenhouse gas emissions, and handling and disposal to contend with," Safferman explained. "It's not efficient or economical to move liquid manure any great distance from where it's produced."
After digestion and separation takes place, what is left is virtually liquid-free phosphorus manure with the consistency of dirt. It can be easily and economically transported off-site to be used as a beneficial fertilizer. The separated liquid fraction can be spread on cropland as a nitrogen source.
The U.S. Environmental Protection Agency estimates that about 150 on-farm manure digesters are operating across the country, and that about 8,000 farms are good candidates for capturing and using biogas. If all 8,000 farms implemented biogas systems, methane emissions would be reduced by more than 34 million metric tons of carbon dioxide equivalent per year, which is roughly equal to the annual emissions from 6.5 million passenger vehicles. In addition, these projects could generate more than 1,500 megawatts of renewable energy.
"Investing in a digester is extremely expensive, but it leads to opportunities beyond just being able to manage manure more easily and protect the environment," Safferman said. "Methane is a valuable byproduct that can be used for energy. Excess energy can be sold for profit, and producers can earn and sell carbon credits and receive renewable energy credits."
Safferman and his colleagues are also researching how blending farm, food processing wastes and many other organic wastes together could ultimately lead to more economical and efficient energy production.
"There's great potential for putting multiple wastes together to produce so much more energy than either could alone; our biggest challenge is determining the right ratios to use," Safferman said. "This is a key piece of the puzzle, and we're still a long way from being able to consistently predict the digestibility of blends without first conducting laboratory and pilot-scale studies."
Another challenge that the researchers would like to tackle is to develop a centralized digester that can serve multiple producers of biomass residuals, including both large and small operations. For the time being, reducing the cost of investing in a digester is one of the most obvious challenges facing North American innovators.
"Digesters are a promising part of a diversified waste management system, but there is more work to be done," Safferman said. "I have no doubt that we'll come up with advancements to reduce installation and implementation costs, but how does one really put a price tag on providing for a healthier environment?"
For more information on the ADREC, visit researchgroups.msu.edu/adrec