Appraisal of the use of geothermal energy in state-owned buildings in Colorado

Abstract

An appraisal of the use of geothermal energy for space heating requirements for selected state-owned buildings in six communities in Colorado is presented. The appraisal addresses several components of a feasibility study for geothermal applications, including resource assessment, pipeline rights-of-way, well design and drilling program, conceptual engineering designs for retrofits of building heating systems, evaluations of economic feasibility, institutional requirements, and environmental considerations. Economic feasibility is determined from evaluation of four economic measures: a simple payback period in years; twenty-year annualized system costs (geothermal system versus conventional system); total twenty-year undiscounted energy savings; and total twenty-year present value energy savings. The results of the analyses of each feasibility component are finally ranked, using a weighting system, to arrive at an order ranking of the eleven state-owned buildings for overall feasibility. The relative total feasibility rankings and the absolute evaluations of economic competitiveness with the existing conventional-fuel heating systems show that several of the state facilities are likely candidates for conversion to geothermal hot water heating systems. The best candidate by far is the Colorado State Reformatory at Buena Vista. The geothermal resource at Buena Vista (Cottonwood Canyon and Chalk Creek) is a high quality resource with high water temperatures and a water quality adequate for direct flow through the building heating units.