Comparative Energetics and Economics of Alternative Pathways for Fuel Production

An alternative description of conventional fuels, biofuels, and future fuels is provided. The approach taken builds on the commonality of those fuels' origins and the relationship of those origins to their end use. The alternative pathways for fuel production are defined and represented in a logical, visual scheme. All the fuel pathways begin with the basic components of light (h upsilon ), water (H//2O), and carbon dioxide (CO//2) and through a variety of processes, result in a utilizable fuel. Detailed biofuels alternative pathways that integrate the production and conversion steps are defined. Future fuels pathways are direct routes to fuel in the sense that no living organism is required and only a synthetic system, such as a photoelectrochemical system, is used to produce fuels from the three basic components. The utility of the pathway approach for developing a perspective on the opportunities for fuels from biomass as well as future fuels is illustrated and can be applied with comparative mass and energy flows, economics, energy contributions, and production/conversion efficiencies.