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Batteries or FCs

Page history last edited by Ulrich Bonne 12 years, 10 months ago

Electricity storage via electrolyzers and H2-fuel cells or batteries: Comparison of capital costs

Ulrich Bonne, Kailua-Kona, Hawaii, ulrichbonne@msn.com

18 July 2011


Abstract – Many of us consider the objective of becoming “individually or organizationally energy independent”, to be a worthy and noble one. We can put enough solar PV panels and even some new wind-turbines on our roofs to meet our household and maybe PHEV or EV needs[1,2]. But what about night-time, or several days of rain and no wind? Can batteries or H2-storage with fuel cells, or emergency generators or a combination of them help solve the electricity storage problem?

        This paper compares the economics of above storage options for off-grid operation of home communities and businesses. We conclude that the capital cost of batteries is 2-5x lower than the combination of water electrolyzers + fuel cells + H2-storage tanks (WE-FC-H2T), depending on the design-average of battery depth-of-discharge to achieve equal service life to that of a WE-FC-H2T system , even if we conservatively assume that the maintenance costs of battery and WE-FC-H2T systems are equal.  Because input solar and wind energy are free, the comparison then boils down to comparing the capital costs.

        For a nominal 500-kW(peak) & 200-kW(average), clean, off-grid power supply providing 4000 kWh worth of storage (20 hours at 200-kW), we find capital costs of 1.46 to 2.34 M$ for the battery system and 7.0 to 5.4 M$ for the WE-FC-H2T system. The 5.4 M$ lower cost of the latter assumes that it is practical to use the waste heat of the electrolyzer and fuel cell for water heating.

There is one H2-energy storage application, which may well be economically more attractive than even battery electricity storage: It is for a H2-consuming synfuel process, where H2-consuming equipment for steady 24/7 operation is already in place, and the only added cost is to add electrolyzer throughput, i.e. increase total electrolyzer electrode area and power, and add more H2 storage tanks.

     To read the full article,please click here

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