change coal to energy
add an additional function that allows the input of the energy source (coal, hydo etc)
have all the calculations carried out with energy as the variable name (this will then point to the function that will have the specific energy source/ excel spread sheet value etc.)
change coal to energy add an additional function that allows the input of the energy source (coal, hydo etc) have all the calculations carried out with energy as the variable name (this will then point to the function that will have the specific energy source/ excel spread sheet value etc.)