Hawaii is committed to replacing imported oil with indigenous, renewable energy resources to enhance the economic and environmental security of the state’s citizens. A case study of Hawaii’s fuel-energy balance by the end of the 21st century which features two scenarios, a ’Business-as-Usual’ energy system, based on imported fossil fuels, and a ’Renewable-Energy’ scenario, based on an alternative energy system consisting entirely of indigenous, renewable energy resources, is presented. In the year 2100, a projected total energy consumption of approximately 335 million gigajoules would be provided from a hypothetical renewable-energy system of approximately 13 gigawatts-electric of installed capacity. This system would feature methanol-from-biomass to meet liquid fuel requirements for surface transportation, industrial, commercial, and residential sectors; hydrogen via electrolysis in liquid form for air transportation and as a gaseous fuel for industrial purposes; and electricity generated from geothermal, ocean thermal, wind, and photovoltaic sources for all power applications. A comprehensive economic analysis, including capital costs, operating and maintenance costs, air pollution costs for the total fuel cycle of each energy system, and a local multiplier effect factor of 3.75 per dollar, indicates that between the years of 1987 and 2100 the ’Business-as-Usual’ scenario will have expended approximately $600 billion (1986 US dollars), and the ’Renewable-Energy’ scenario will have cost approximately $400 billion. By switching from imported fossil fuels to indigenous, renewable energy resources during this time period, Hawaii’s citizens could save approximately $200 billion to help preserve paradise.