This paper reports on an application of the RFF/SEAS modeling system to a set of specified questions and assumptions about the economic, energy, and environmental consequences of alternative scenarios with respect to the U.S. during the next fifty years. These scenarios are not meant to portray what we consider to be the most likely situations to be faced by the U.S. but rather to explore the way the economy, as reflected in this modeling system, might behave in cases where it is difficult to satisfy energy requirements. purpose four basic scenarios were developed. For this Two involve cases incorporating substantial increases in energy prices but in which capacity to satisfy demands at those prices is relatively unconstrained. The other two add stringent re strictions on the use of coal, shale, imported oil, and nuclear power, the last being phased out completely by 2010, and assume that the price for new energy systems (for example, solar, biomass conversion, and sophisticated ways of increasing recovery rates for petroleum and natural gas) which can replace other non-electric sources would be substantially higher than in the first two cases. Within each set, the runs differ only with respect to the degree to which the economy can substitute other inputs for energy, the low substitution cases assuming a long-run price elasticity of demand for energy of -0.25 and the high substitution cases assuming -0.75.