Something old can be made new again. At AURI’s coproducts lab in Waseca, we take what once was called waste — vegetable peels, corn stalks, animal manure, ash, other leftovers — and help entrepreneurial businesses turn it into mulch, pelleted fuel, hog mats and a myriad of other value-added products.
The mission of AURI’s Coproducts Utilization Program is to develop new uses for ag processing leftovers, plant and animal coproducts and agricultural biomass that present environmental and economic opportunities. Coproducts are used in fertilizers, sorbents, renewable fuels, animal feeds, soil amendments and biodegradable products.
There are several opportunities that will receive considerable research and development attention in the months ahead.
Enhanced anaerobic digestion
Anaerobic digestion is not new, but its potential is just being scratched. While digesters are primarily fed by livestock manure, more and more communities are considering ag processing waste. Besides their energy value, using waste from local facilities could help solve waste handling issues. As we learn more about how various feedstocks react in a digester, “recipes” will be developed to maximize gas production. Also, there will be increased efforts to clean up biogas so it is pipeline quality.
Among ag-coproducts’ emerging uses are identifying lower-cost energy and protein sources for livestock feed. As producers reduce costs, ag-processing leftovers such as glycerin, solubles and other materials may take the place of traditional ingredients. There are also opportunities to develop fibers and chemical extractions from ag residues.
As the price of fertilizer climbs, natural fertilizers are likely to gain momentum. Using processing leftovers such as ethanol solubles, ash and other products may be a reasonable alternative. That also requires identifying and developing technologies for handling biomass-derived ash and biochar for fertilizer and soil amendments. In the future, carbon may be sequestered using agricultural coproducts and practices.
Solid biomass fuel production
Using crop residues, specialty energy crops or processing leftovers as solid-fuel sources continues to be an active coproduct utilization focus. Scientists are developing densified fuels, such as pellets or briquettes, for gasification systems, direct combustion or for co-firing to produce heat or steam. Key factors for developing biomass fuel include biomass harvesting, densification technology, ash content, chlorides and economics.
Biomass fuel equipment improvements
Many of today’s combustion systems were not designed to run on agricultural biomass. Technology improvements, including feedstock handling, burn pot performance and overall efficiency, will play a role in the long-term viability and development of solid biofuels.
Drying and densification improvements
Among the biggest challenges of using coproducts, particularly biomass, is handling. Most ag residues are light, bulky and wet. New drying technologies and small, portable densification technologies could make biomass handling more efficient. As with most technologies, economics is key to their success.