The linear programming framework of the model comprises an objective function to minimize total energy system cost year by year subject to a number of constraints
including those on service demand, energy resource availability, existing device stock, maximum allowable quantity of devices and emissions. The total cost comprises
of annualized fixed cost of recruited devices during that year, variable operating cost (operation and maintenance cost of devices, and fuel cost), cost of installing removal
devices (flue gas desulfurizers for pulverized coal fired power plants, etc.) and cost of emissions taxes (carbon tax, energy tax, etc.). The formulation also provides functions to consider the existing device quantities in the starting year of the planning horizon and to calculate the retirement of the devices at the end of its life time