Green farming systems for the Southeast USA using manure-to-energy conversion platforms

In the southeastern USA, livestock operations face issues with both manure management and energy. Both issues can be advanced by implementing holistic solutions to manure treatment that involve (1) resourceful energy management and (2) green farming systems. In such systems, current and emerging waste-to-energy conversion platforms can contribute to renewable energy solutions, improved crop yields, and sustained natural resources. System-component technologies can manage both wet and dry manures to provide recycled nutrients to crops while minimizing air and water quality impacts. Relative to energy, anaerobic digestion (AD) is the prevalent biochemical platform. It is a mature technology that readily processes wet manure, and it is used on many levels of sophistication throughout the globe. Thermochemical conversion (TCC) processes with smaller physical footprints are versatile, capable of handling wet and dry feedstocks to yield multiple byproducts. They need (1) manure feedstock conditioning to lessen the effects of salts, metals, and sulfur and (2) heat recovery for energy conservation. Additionally, with appropriate downstream processing, the TCC gases and bio-oils can aid in farm energy management to include liquid fuel. The TCC processes also produce a reasonably transportable, nutrient-dense biochar. While AD provides a digestate suitable for land application, wastewaters within these systems can also be treated at different stages with solids-separation and nitrogen-phosphorous recovery technologies. This cleaner effluent offers more options for its use in meeting crop water needs via irrigation. Thus, through holistic thinking coupled with dynamic agribusiness, there are significant opportunities for future livestock farming systems to improve the sustainability of natural resources including energy.