Development of a methodology for long term hourly electrical load forecasting and assessment of gas requirement

Abstract

Continuous supply of electricity in meeting the consumers' demand is very crucial in every aspect of nation building activities. Therefore, a modern power system appears with the primary objective of providing electrical energy to its consumers at an optimum cost. However, the supply of electrical power at a reasonable cost is . directly linked with the availability and use of eco-friendly indigenous fuels of the country. Therefore, electrical power utilities. throughout the world, prepare economically acceptable and technically feasible long term generation expansion plan well ahead of time with a usual duration of 20 to 25 years primarily using the available indigenous fuels of the country. Bangladesh Power Development Board (BPDB) uses natural gas and liquid fuels to generate electricity. It has also hydro units. Presently, about 85% to 90% of the nation's demand is met by burning natural gas and rest 10% 915% from liquid fuels and hydro units. The liquid fuels being imported incur excessive generation costs. There is hardly any prospect of harnessing additional hydro power in the country due to its negative environmental impact on the society. Therefore, the only reliable and indigenous fuel of the country for the generation of electricity for a long term is the natural gas. Presently, electric power sector constitutes uniquely the major subsector consuming 46.66% of the total gas consumption in the country. This fossil fuel being non-renewable is depleted on use. The investigation on the forecasting of natural gas requirement in electric power sector of Bangladesh may provide a sensible picture of requirement of gas as input source in this sector for a long term. In turn, it may help the authority to conceive a realistic plan in utilization of gas for the betterment of the country. The appropriateness of the forecasting of gas requirement for a period in electric power sector depends mainly on the realistic forecasting of the electrical energy requirement for that period. It necessitates the forecasting of the electrical load of every hour of the duration. This thesis develops a methodology to forecast the electrical hourly load for a long term. It is based on the development of a mathematical relation between the forecasted hourly load and forecasted annual average load through mean values of load ratios. The annual average loads are forecasted on the basis of the historical annual average loads. Various load ratios (hourly, daily and monthly) and their mean values are calculated from the relevant historical load of appropriate durations . .-The total requirement of electrical energy is estimated from the forecasted hourly • loads of the period. The likely contributions of various energy sources other than gas (liquid fuels, hydro and coal) for the same period are assessed on the basis of published papers, reports, statistical data etc. The net energy requirement to be generated by gas fired units is estimated as 1179394 GWh from the total energy requirement and likely energy contributions from other sources for the duration under consideration. The average fuel consumption rate to produce unit electrical energy is estimated as 11.806 TCF/kWh on the basis of fuel consumption rate of individual units. Finally, the total requirement of gas in the electric power sector of Bangladesh for the coming 25 years (2004 to 2028) is estimated as 13.924 TCF from the projected total electrical energy and the average fuel consumption rate of the gas fired units. The gas requirement in electric power sector of Bangladesh as projected in this thesis is compared with the same as projected by other investigators. It is found that the result obtained using this methodology is meaningful.