This symposium is a sequel to the 2008, 2009, and 2010 symposia "The Global Nexus of Energy and Water,” “The Global Nexus of Food and Energy,” and “Algae for Food, Feed, Fiber, Freshwater, and Fuel.” The first two symposia discussed tensions between food, water, and energy, while the third discussed the possibility of algae as a solution. This proposed symposium continues the technical and policy discussion with an examination of waste as a globally abundant and renewable resource. Particular topics to include are the following: biofuels from waste, agricultural waste, nuclear waste (as a source of energy or neutrons for fusion-fission hybrids), waste carbon dioxide (as a feedstock for algae, drywall, concrete, and road aggregate), industrial waste that can be formed into by-products, and waste heat (60 percent of all the primary energy in the United States is lost as waste heat; novel technologies for harvesting waste heat could be a game-changing breakthrough at a global scale). Although waste is an appealing solution because it holds forth the potential to convert environmental liabilities into valuable commodities, many technical, economic, cultural, and policy barriers remain. In this session, leading intellectuals from government, industry, and academia will present their views on the state of the science, engineering challenges, industrial practicalities, policy barriers, and promising research and development pathways for using waste as a resource.