Techno-economic and social analysis of energy storage for commercial buildings

Techno-economical and social evaluation methodologies for energy storage systems applied for commercial buildings are presented in this paper. The demand analysis methodology is used to determine power rating and capacity. The technical and economical evaluations are described to analyze the techno-economic feasibility by the financial indices: net present value, internal rate of return, and initial investment payback period. Other benefits, including improved power quality/reliability, improved utilization of grid assets, and reduced greenhouse gas and air pollutant emissions, are estimated in a social evaluation. Finally, an illustrative example combining the measured load data and the current economic parameters is analyzed for three scenarios: 6.5 kW/12.7 kW h lead-acid battery, 5.4 kW/12.4kW h sodium-sulfur battery and 5.15 kW/10.4kW h lithium ion battery for the same peak shaving demand 4.9 kW and a two-hour discharge. The results and discussion of the abovementioned examples show that all three typical battery energy storage technologies are technically feasible, however, investment in sodium-sulfur and lithium ion battery for commercial buildings energy storage should be done with caution, as lead-acid battery systems are the more economic choice at this time. However, systems with lithium ion batteries provide the maximum social benefits due to their high cycle efficiency. Lastly, the standard discount rate with the largest absolute value of sensitivity coefficient has the biggest influence on the net present value through the sensitivity analysis.