Nomenclature

during the daytime to have enough storage for night operation. Second, as the weather input data were based upon tropical climate conditions, therefore, the system is oversized to have enough hydrogen generated to sustain during rainy period. This design summary is only for the mentioned location and the consumer load data. However, the main objective of proposing design methodology for standalone operation of CPV-Hydrogen system is achieved which can

Parameter description Units Value Total hydrogen consumption kg 630.55 Total oxygen consumption kg 2502.28 Total water production kg 2817.49 Hydrogen storage maximum kg 81 Oxygen storage maximum kg 319 Hydrogen storage maximum pressure bar 200 No. of hydrogen storage cylinders — 2 Maximum water storage tank kg 358 Hydrogen compressor rated power kW 1.13

In order for the renewable energy sources to replace conventional fossil fuel-based energy sources, there is need for them to provide steady power supply for any load demand. Due to the intermittent nature of renewable energy sources, energy storage system is needed for steady power supply. Among all renewable energy sources, solar energy has the highest energy potential. But it is only available during diurnal period, with unsteady intensity. In order for such a system to compete with conventional fossil fuel-based system, there is a need for it to operate in standalone mode with sustainable and long-term energy storage system. For such standalone operations, it is very

Photovoltaic system provides a most simple mean to convert sunlight into electricity and concentrated photovoltaic (CPV) technology provides the highest solar energy conversion efficiency among all photovoltaic systems. However, the entire photovoltaic market is dominated with conventional flat plate PV panels. In addition, the literature also focuses on the performance model and optimization strategy of conventional PV system, for its standalone operation. There is not even a single commercial software available which can handle CPV for the system performance analysis. Therefore, a detailed performance model and optimization strategy is proposed for standalone operation of CPV. For energy storage purpose, hydrogen is considered to provide a sustainable and long-term energy storage option than the conven-

be easily implemented for any load requirement and weather conditions.

Table 3. Summary of optimized CPV-hydrogen system design for standalone operation [17].

8. Summary of chapter

116 Advances In Hydrogen Generation Technologies

important to capture solar energy with high efficiency.

tional battery-based electrochemical storage.



Lmax maximum electrical load requirement (W)

Preq electrical power deficiency not supplied by the CPV (W)

IEC,max electrolyzer cell maximum current (A)

PEL,max electrolyzer cell maximum power (W)

Lmin Minimum Electrical Load Requirement (W)

Uo reversible voltage of fuel cell (mV)

Urev reversible voltage of electrolysis (V)

MH2 molar mass of hydrogen (g/mol)

n electrons requirement for water splitting

Pta instantaneous pressure of hydrogen tank (Pa)

PE pressure of hydrogen production from electrolyzer (Pa)

nta instantaneous number of moles of hydrogen gas in storage tank (mol)

)

Concentrated Photovoltaic (CPV): Hydrogen Design Methodology and Optimization

http://dx.doi.org/10.5772/intechopen.78055

119

CPH specific heat capacity of hydrogen (J/kg.K)

Tcom hydrogen compressor temperature (K)

r isentropic exponent of hydrogen R universal gas constant (J/mol.K)

ZH compressibility factor of hydrogen

nH number of hydrogen stage tank

tPF time for power failure (sec)

CAT total annual system cost (\$)

OMC operation and maintenance cost (\$)

CC capital cost (\$)

CCPV CPV total cost (\$)

Tta temperature of hydrogen storage tank (K) V volume of storage tank of hydrogen (m<sup>3</sup>

PH pressure of hydrogen storage tank (Pa)

PSFT power supply failure time factor (sec)

L2 maximum limit for cyclic hydrogen storage (kg) L1 minimum limit for cyclic hydrogen storage (kg)

F Faraday constant (A.s/mol)


STMO2 maximum oxygen storage capacity (kg)

ηDC/AC efficiency of DC to AC converter (%) Pexcess excess available power from CPV (W) ηEF Faraday efficiency of electrolyzer (%) PTr solar tracker power requirement (W) ηCDC efficiency of DC to DC converter (%)

Pcom hydrogen compressor power (W) ηFF Faraday efficiency of fuel cell (%) PMJC,max MJC maximum rated power (W)

ηcom efficiency of compressor (%)

TE electrolyzer temperature (�C)

IF fuel cell current (mA) IE electrolyzer current (A) AF cell area of fuel cell (cm2

AE electrolyzer cell area (m<sup>2</sup>

UF cell voltage of fuel cell (mV) UE electrolyzer cell voltage (V) NFC number of cells of fuel cell

NEC number of cells of electrolyzer

PFC,max cell maximum power of fuel cell (W) VEC,max electrolyzer cell maximum voltage (V)

PCPV CPV power output (W)

118 Advances In Hydrogen Generation Technologies

PLoad total load demand (W)

Pmppt solar cell maximum power point power (W)

ηOP optical efficiency of concentrating assembly (%)

ηmppt Efficiency of Maximum Power Point Tracking Device (%)

n•E,H<sup>2</sup> hydrogen production flow rate from Electrolyzer (mol/s)

)

)

n•F,H<sup>2</sup> hydrogen consumption flow rate from fuel cell (mol/s) n•E,O<sup>2</sup> oxygen production flow rate from electrolyzer (mol/s) n•F,O<sup>2</sup> oxygen consumption flow rate from fuel cell (mol/s)

