Methanol Production By H2 Generated from Water Using Integrated Ultra High Concentrated Solar Cells-Electrolysis and Captured CO2: A Process Development and Techno-Economy Analysis

Abstract

A novel hybrid process based on an ultra-high concentrated solar module and water electrolysis for the production of methanol is presented. This process utilizes captured CO2 and H2 produced by electro-catalytic water splitting. The electrocatalytic system is powered by high concentration photovoltaic modules during the day and from an electrical grid during the night. The system is called the Hybrid High Concentration Solar and Electrolyzer system (HHCSE). Aside from the highly concentrated photovoltaic (UHC-PV) water splitting unit, which is currently under development, the full system is based on well-established industrial processes and component designs. Here, we present an initial assessment of energy efficiency and economic viability of a 233 tonne/day industrial-scale methanol plant. The breakeven price of the methanol produced using the base case is 0.62 $/kg. A levelized selling price of methanol of less than 0.50 $/kg can be achieved using the integrated system with a solar to hydrogen efficiency (STH) of 30% which is comparable to the current market price (0.510 $/kg). For the base case with STH (20%), the price of electricity (0.05 $/kWh) and location in Tabuk, Saudi Arabia, the gross energy efficiency of the process is 18%. Importantly, the primary economic driver is the high capital cost of the H2 production plant associated with the solar concentrator unit. The electrocatalytic system and solar concentrators account for more than 83% of the hydrogen section capital expenditure. Moreover, the electricity price also has a significant effect on the final price of methanol. The analysis indicates that an alternate pathway of concentrated solar and electrolysis to fuels has significant potential. The sensitivity study points towards future research opportunities to increase STH of the solar modules, reduce the balance of system (BOS), and reduce the electricity cost to achieve lower priced methanol. As a final element, we compared the proposed process with other renewable methanol production routes from the literature to highlight the differences in electrochemical, photoelectrochemical and thermochemical approaches. Figure 1