[en] The benefits attributable to alternative energy R and D programs should be evaluated in terms of how well the technologies contribute as integral elements of the total United States energy system. Thus, the present model simulates the dynamics of the evolution of the total energy system by requiring both existing and new technologies to compete for introduction on a cost-competitive basis that considers the time phasing of (1) retirement of energy conversion facilities, (2) growth in end-use demands, and (3) escalation of the costs of extracting depleting domestic energy resources. This approach contrasts with a static model used by the Energy Research and Development Administration, wherein assumptions must be made for each future year of interest for (1) maximum capacity constraints for alternative types of conversion facilities and (2) the cost of energy resources. The present model is used to compare the relative consequences and merits of the technology products from the following three of ERDA's major energy R and D programs: (1) the liquid-metal fast breeder reactor (LMFBR), (2) synthetic fuels derived from coal and oil shale, and (3) improved efficiencies for end-use devices (e.g. space heaters). (author)