Economic feasibility of combined cooling, heating, and power (CCHP) systems considering electricity standby tariffs

Abstract

This study examines economic viability of combined cooling, heating, and power (CCHP) systems when applied to the Department of Energy (DOE) reference large office building in three locales in the U.S.: San Francisco, Boston, and Miami. For realistic power generation unit (PGU) sizes, annual, monthly, and hourly operation costs are estimated using local utility tariffs and compared to those of conventional separate heat and power systems. The results show that compared to conventional systems, CCHP systems reduce operation cost by 0.11–0.42 million $/y in San Francisco and Boston, whereas they increase the cost by 0.16–0.29 million $/y in Miami. The cost savings are mainly attributed to electricity savings; therefore, be maintained unless electricity costs drastically decrease. Considerable cost savings are attributed to both energy and demand charges if tariff structures estimate demand charges as much as energy charges (e.g., San Francisco). Under time-of-use rates, the largest cost saving occurs during peak periods because of high utilization of PGUs that significantly reduces energy and demand charges. Although a larger PGU capacity yields a greater cost saving, an over-sized PGU decrease profitability. The results suggest that for regions with relatively expensive natural gas and low electricity cost, CCHP systems would not be profitable.