For three generation facilities X$,$ Y and Z$,$ with details in Table $1,$ assume an interest rate of $7\%,$

and the possibility of choosing any generation capacity of the above technologies $($X$,$ Y and Z$).$

$($a$)$ Draw the annual cost curves for different types of fuel technology.

$(2)$

$($b$)$ Using the screening curve, determine the optimal type and capacity to supply the demand

characterised by the Load Duration Curve shown in Figure $1.$