A comparative technoeconomic analysis of renewable hydrogen production using solar energy

A technoeconomic analysis of photoelectrochemical (PEC) and photovoltaic-electrolytic (PV-E) solar-hydrogen production of 10 000 kg H 2 day −1 (3.65 kilotons per year) was performed to assess the economics of each technology, and to provide a basis for comparison between these technologies as well as within the broader energy landscape. Two PEC systems, differentiated primarily by the extent of solar concentration (unconcentrated and 10× concentrated) and two PV-E systems, differentiated by the degree of grid connectivity (unconnected and grid supplemented), were analyzed. In each case, a base-case system that used established designs and materials was compared to prospective systems that might be envisioned and developed in the future with the goal of achieving substantially lower overall system costs. With identical overall plant efficiencies of 9.8%, the unconcentrated PEC and non-grid connected PV-E system base-case capital expenses for the rated capacity of 3.65 kilotons H 2 per year were $205 MM ($293 per m 2 of solar collection area (m S −2 ), $14.7 W H2,P −1 ) and $260 MM ($371 m S −2 , $18.8 W H2,P −1 ), respectively. The untaxed, plant-gate levelized costs for the hydrogen product (LCH) were $11.4 kg −1 and $12.1 kg −1 for the base-case PEC and PV-E systems, respectively. The 10× concentrated PEC base-case system capital cost was $160 MM ($428 m S −2 , $11.5 W H2,P −1 ) and for an efficiency of 20% the LCH was $9.2 kg −1 . Likewise, the grid supplemented base-case PV-E system capital cost was $66 MM ($441 m S −2 , $11.5 W H2,P −1 ), and with solar-to-hydrogen and grid electrolysis system efficiencies of 9.8% and 61%, respectively, the LCH was $6.1 kg −1 . As a benchmark, a proton-exchange membrane (PEM) based grid-connected electrolysis system was analyzed. Assuming a system efficiency of 61% and a grid electricity cost of $0.07 kWh −1 , the LCH was $5.5 kg −1 . A sensitivity analysis indicated that, relative to the base-case, increases in the system efficiency could effect the greatest cost reductions for all systems, due to the areal dependencies of many of the components. The balance-of-systems (BoS) costs were the largest factor in differentiating the PEC and PV-E systems. No single or combination of technical advancements based on currently demonstrated technology can provide sufficient cost reductions to allow solar hydrogen to directly compete on a levelized cost basis with hydrogen produced from fossil energy. Specifically, a cost of CO 2