How would you forecast the demand for electricity in Oman over the next ten years?
Well, the question is very broad, and would have liked some more information.
Basically, in order to project demand, you need to account for many things. Most important thing would be to calculate the Expenditure Elasticity of demand. For calculating this you may need large database on electricity consumption at different prices (per capita expenditure on electricity) You should also account for household caharecteristics while calculating the expenditure elasticity.
In the next step you can fit a appropriate model for projecting demand. I dont know exactly what data you have. Irrespective of that i would suggest you to go for AIDS model( Almost Ideal Demand System). Study the model in detail, know what you need and fit a model.