Evaluation of hybrid power system alternatives : A case study

Pursuant to executive and statutory policies, the National Park Service (NPS) has been evaluating the use of photovoltaic (PV) hybrid power systems for many of its remote, off-grid areas. This paper reports the results of a detailed technical and economic evaluation for one such area: the Needles District of Canyonlands National Park. The study evaluates the present power system and five alternative power generation configurations, four of which utilize PV. Projections are provided for the generator run-time and fuel use associated with each configuration as well as all initial and future costs. Included in the study are specific recommendations for energy efficiency improvements at the site. Results show that the generation system presently in use, two full-time diesel generators, has the lowest conventional 20-year life cycle cost (LCC) of the six systems evaluated. However, when emissions costs are included (per NPS guidelines), several of the PV hybrid alternatives attain a lower LCC than the diesel-only system. General discussion of the effects of initial versus future costs for PV hybrids as they compare with engine generator systems is presented.