Resources from Wastes: Benefits and Complexity

Abstract

The United States produces significant quantities of waste biomass from wastewater treatment, food production, food services, and landscape and wood debris. This waste contains essential resources, including water, carbon, and nutrients. Conversion of carbon to energy and recovery of nutrients and water have the potential to reduce the use of scarce resources, protect the environment, and save funds. Several established, demonstrated technologies that convert wastes to resources are available and are reviewed in this paper. Included are anaerobic digestion, direct combustion, biodiesel production, ethanol production, and particulate phosphorus and organic nitrogen separation using ultrafiltration, ammonia stripping, and reverse osmosis. Thermochemical technologies include pyrolysis, torrefaction, and gasification. Unlike solar, wind, hydrological (dams and pumped storage), and closed-loop geothermal renewable energy technologies, the transportation of biomass can be energy intensive. Therefore, a holistic evaluation of complexity, costs, and benefits of converting wastes to resources is mandatory to ensure a net-positive energy value and environmental protection. Several tools described in this paper are available to aid stakeholders when considering biomass waste-to-resource projects. Many of these tools have long been in practice and have been extensively covered in technical and popular literature. As interest in renewable energy resources increases, new tools are being developed to address the challenges posed by biomass projects. This paper discusses tools that combine waste biomass inventories with a geographic information system mapping platform and cost-benefit analysis that return environmental, economic, and financial assessments of selected feedstocks that can be used in planning, siting, and financing a biomass-to-energy project.