Feasibility of Hybrid Retrofits to Off-Grid Diesel Power Plants in the Philippines

Research output: Contribution to conferencePaper


The Strategic Power Utilities Group (SPUG) of the National Power Corporation (NPC) in the Philippines owns and operates about 100 power plants, mostly fueled by diesel, ranging in energy production from about 15 kilowatt-hours (kWh)/day to 106,000 kWh/day. Reducing the consumption of diesel fuel in these plants, along with the associated financial losses, is a priority for SPUG. The purpose ofthis study is to estimate the potential fuel and cost savings that might be achieved by retrofitting hybrid power systems to these existing diesel plants. As used in this report, the term 'hybrid system' refers to any combination of wind turbine generators (WTGs), photovoltaic (PV) modules, lead-acid batteries, and an AC/DC power converter (either an electronic inverter or a rotary converter),in addition to the existing diesel gensets. The resources available for this study did not permit a detailed design analysis for each of the plants. Instead, the following five-step process was used:; 1. Tabulate some important characteristics of all the plants. 2. Group the plants into categories (six classes) with similar characteristics.; 3. For each class of system, identify one plant thatis representative of the class.; 4. For each representative plant, perform a moderately detailed prefeasibility analysis of design options. 5. Summarize and interpret the results. The analysis of each representative plant involved the use of time-series computer simulation models to estimate the fuel usage, maintenance expenses, and cash flow resulting from various designs, and to search thedomain of possible designs for the one leading to the lowest life-cycle cost. Cost items that would be unaffected by the retrofit, such as operator salaries and the capital cost of existing equipment, were not included in the analysis. Thus, the results are reported as levelized cost of energy (COE) savings: the difference between the cost of the existing diesel-only system and that of anoptimized hybrid system, expressed in units of U.S. dollars per kWh (US$/kWh) of energy production.
Original languageAmerican English
Number of pages12
StatePublished - 1999
EventWindpower '99 - Burlington, Vermont
Duration: 20 Jun 199923 Jun 1999


ConferenceWindpower '99
CityBurlington, Vermont

NREL Publication Number

  • NREL/CP-500-26927


  • petroleum
  • power transmission and distribution
  • solar energy
  • wind energy


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