Publication date: 31st March 2013
Solar to chemical energy storage is one of important technologies to establish stand-alone renewable energy system. Considering the system totally, solar energy is one of energy sources like wind and water energies. Thus, we proposed direct connection of conventional concentrated photovoltaic (CPV) and polymer electrolyte electrochemical cell (PEEC), which was named concentrated photovoltaic electrochemical cell (CPEC) system [1]. The CPEC system cost is estimated in this report because it is important for the feasibility.
While the CPEC system is able to be used as a large renewable energy plant, the cost has been estimated for the house-scaled system. The estimation was performed at present and at about 10-year after using the cost prediction of the devices [2-4].
The system requirement was calculated from the house located middle-latitude area like Japan. The daylight hours were estimated to be about 1000 hrs/year available to use for photovoltaic power generation. The average daylight hours for a day are calculated to be about 3 hrs/day, and are moderate number compared with that for Sunbelt area. The necessitated total energy for a house was assumed to be 21 kWh/day for the calculation from the average house energy consumption in Japan. In addition, all of energies were assumed to be used the route of; electricity generation by CPV, converting to hydrogen by PEEC, storage in tanks, and electricity generation for usage by fuel cell (FC). The energy conversion efficiency of CPV, PEEC, and FC were estimated to be 0.20, 0.70 and 0.40 at present and 0.25, 0.70, and 0.40 for 10-year after, respectively. The costs for the gas tank for 3-day energy storage and controlling system were also included in the calculation. The gas tank was assumed to be maximum pressure of 1 MPa due to elimination of the energy to make high pressurized gas. From these preconditions, the CPV area was obtained to be 125 m2at present and 100 m2for 10-year after.
The total manufacturing cost for the CPEC system were calculated to be 147500 USD at present, and 41500 USD for 10-year after using these assumptions. Even this system, 60% of the costs is CPV. When we assume the energy cost of 0.22 USD/Wh, the payout time is about 25 years using 10-year after cost. The cost is not unrealistic considering with the moderate assumptions. From the results, unit energy cost reduction is important for the system realization.
Fig. 1 Schematic system diagram of concentrated potovoltaic electrochemical cell (CPEC) for the calculation use and the cost calculation results at present and 10-year after.
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