FUEL EFFICIENCIES, ALLOCATION OF FUELS AND FUEL COSTS FOR POWER AND DESALINATION IN DUAL PURPOSE PLANTS - A NOVEL METHODOLOGY

The top management or the owners of a company are mainly interested in the overall economics and productivity of their industrial plants, and are always on the lookout for analyses which should be able to guide them in their decision and policy making processes. They usually like the overall outputs to be compared to total inputs in terms of quantities and costs, are generally not bothered about the intricacies of individual plant/unit efficiencies and the technicalities, and therefore they are always looking towards simple and easier ways to assess their operations, plant effectiveness and economics. For the owners of a cogeneration power plant producing power and water, it is just another industrial plant which should produce two saleable products, from burning the fuel and processing the sea water. Cost-wise this should be economical and balanced. The Water and Electricity Department (WED), Abu Dhabi, has been using various types of hydrocarbon fuels as the main source of energy inputs for its power and desalination plants. The experience in fuel control has resulted in development of a proposed novel methodology for the analysis of combined power and desalination plants as a single unit, as far as fuel efficiency, the allocation of fuels to power and desalination and the relevant specific fuel costs for power generation and water production are concerned. The paper presents the idea of using a heat value for potable water produced from desalination of sea water. It discusses the use of overall fuel efficiency of the system for fuel allocation to power and desalination, and balancing the energy input against the output of power and desalination plants in the WED network, based on its own data.