Currently there is worldwide interest in deriving energy from bio-based materials via gasification. Our objective was to assess the feasibility of wet gasification for treatment/energy conversion of both animal and municipal wastes. Wet wastes such as swine manure and raw sewage sludge could be processed directly via current wet gasification technology. Furthermore, these wastes generated high amounts of net energy based on reaction material and energy balances. Without use of an efficient heat recovery system, municipal solid wastes and unpaved feedlot manure would not generate positive energy return from wet gasification. Due to high sulfur content of the wastes, pretreatment to prevent the poisoning of catalysts is essential. The costs of a conceptual first generation wet gasification manure management system for a model swine farm were significantly higher than that of the anaerobic lagoon system. However, there are many significant environmental advantages of the wet gasification, e.g., BOD removal, odor elimination, and pathogen kill.