Optimization of Small-Scale Trigeneration Systems in Terms of Levelized Total Costs and Carbon Tax Using a Matrix Modeling Approach

Combined Heat and Power (CHP) systems have increasingly drawn attention in recent years due to their higher efficiency and lower Greenhouse Gas (GHG) emission. Input-output matrix modeling was considered here as one of the efficient approaches for optimizing these energy networks. In this approach, power flow and energy conversion through plant components were modeled by an overall efficiency matrix including dispatch factors and plant component efficiencies. The purpose of this paper is to propose a modification of the objective function presented in some previous studies. This procedure was performed by adding the parameters of plant component lifetime and environmental costs to the objective function. Thus, the optimization problem was formulated by minimizing the total system levelized cost instead of simply hourly energy cost. The study results revealed that producing the electricity by the trigeneration system led to achieving 1256 MWh annual electricity savings that otherwise must be purchased from the grid. The results also showed a significant reduction in annual CO2 emissions (703.31 tons per year). Furthermore, if the price of purchasing CHP electricity was considered three times more than the current ones, payback times would be less than 5 years.