For sustainable society, the design philosophy of chemical processes will need to be changed from large-scale mass production systems to decentralized local-scale production systems so that chemicals and energies can be supplied from diverse biomass and other renewable resources. Supercritical water allows fast reaction rates, high selectivities and high-yield conversions of many biomass and biomass-related feedstocks and allows chemical transformations to occur with compact devices. Supercritical carbon dioxide allows selective separations, efficient transformations, and low-energy processing of many types of materials. in this overview, sustainability is examined with respect to available solar energy, UN Millennium Development Goals, the carbon cycle and competing factors that affect sustainable society. Through a general block diagram fora biomass refinery, material conversions of biomass and biomass-related compounds are discussed along with a proposal for using supercritical water oxidation (SCWO) with biomass boiler to produce energy and a biorefinery on a 100 ha land area. Supercritical fluid technology, especially water and carbon dioxide solvents, can provide the basis for decentralizing chemical processes and for achieving material recycles for sustainable society. (C) 2008 Elsevier B.V. All rights reserved.