IEEE TRANSACTIONS ON ENERGY CONVERSION, VOL. 23, NO. 2, JUNE 2008
Analysis of the Cost per Kilowatt Hour to Store Electricity
Piyasak Poonpun, Student Member, IEEE, and Ward T. Jewell, Fellow, IEEE Abstract—This paper presents a cost analysis of grid-connected electric energy storage. Various energy storage technologies are considered in the analysis. Life-cycle cost analysis is used. The results are presented in terms of the cost added to electricity stored and discharged, in US dollar per kilowatt hour. Results are compared with wholesale and retail electricity costs and with the cost of conventional pumped hydro storage. Index Terms—Batteries, economic analysis, energy storage, ﬂywheels.
SUCU Unit cost for storage units (US$/kWh). TCC Total capital cost (US$). y Lifetime of energy storage (year). I. INTRODUCTION
NOMENCLATURE Annual storage unit replacement cost (US$/kWh). Annualized capital cost (US$/year). Annual energy production of storage system (kWh/year). ARC Total annual replacement cost (US$/year). BOP Total cost for balance of plant (US$). BOPU Unit cost for balance of plant (US$/kWh). C Number of charge/discharge cycles in life of storage. COE Cost added by storing electricity (US$/kWh). CRF Capital recovery factor. D Annual operating days for storage unit (days per year). eﬀ Efﬁciency F Future value of replacement cost (US$/kWh). Length of each discharge cycle (h). HO ir Annual interest rate (%). n Number of charge/discharge cycles per day. Fixed operation and maintenance cost (US$/kW· OMf year). OMC Total annual ﬁxed operation and maintenance cost (US$/year). P Rated power output capacity of energy storage system (kW). PCS Total cost for power electronic (US$). PCSU Unit cost for power electronic (US$/kW). r Replacement period (year). SUC Total cost for storage units (US$). A AC AEP
Manuscript received February 6, 2007; revised July 25, 2007. Paper no. TEC00027-2007. The authors are with the Wichita State University, Wichita, KS 67260 USA (e-mail: firstname.lastname@example.org; email@example.com). Color versions of one or more of the ﬁgures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identiﬁer 10.1109/TEC.2007.914157
HERE are about 90 GW of electric energy storage, almost all pumped hydro, operating in the world today , which is 3% of total generating capacity. New pumped hydro installations are limited by availability of sites. Siting concerns are reduced if other storage technologies are located in smaller units on the distribution system. This concept is known as distributed energy storage (DES). The DES may, in the future, be more important, and be present in much higher penetrations than distributed generation (DG) . The DES technologies may include batteries, ﬂywheels, and electrochemical capacitors (“super” or “ultra” capacitors), of which batteries and ﬂywheels appear to be the most promising for bulk storage. Compressed air energy storage and pumped hydro storage are usually large and have special siting needs, and superconducting magnetic energy storage are short-duration devices used for uninterruptible power supplies and other power quality support, making them less suitable for the DES. The beneﬁts of electricity storage are well known and include the following : 1) Support of renewables: Storage can reduce ﬂuctuations in wind and photovoltaic (PV) output, and allows sale of renewable energy at high-value times. 2) Reliability and power quality: Storage will allow loads to operate through outages. 3) Reactive power control, power factor correction, and voltage control: Power electronic interfaces provide the ability to rapidly vary reactive as well as active power. 4) Load leveling: Storage is charged during light-load periods, using low-cost energy from base-load plants, and discharged during high-load times, when the energy value is higher. The beneﬁts are improved load factor, deferred generation expansion, and reduced...
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Piyasak Poonpun (S’06) received the Bachelor’s degree from the King Mongkut’s Institute of Technology Ladkrabang, Bangkok, Thailand, in 1997, and the M.S. degree in electrical engineering in 2006 from Wichita State University, Wichita, KS, where he is currently working toward the Ph.D. degree. He is currently a Graduate Research Assistant at Wichita State University.
Ward T. Jewell (M’77–F’03) received the B.S.E.E. degree from Oklahoma State University, Stillwater, in 1979, the M.S.E.E. degree from Michigan State University, East Lansing, in 1980, and the Ph.D. degree from Oklahoma State University, in 1986. He has been with Wichita State University, Wichita, KS, since 1987, where he is currently a Professor of Electrical Engineering. He is the Site Director at the Power System Engineering Research Center (PSerc), Wichita State University. His current research interests include electric power quality and advanced energy technologies.
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