Techno-Economic Study of an e-Methanol Production Plant Using Solar Energy and Carbon Dioxide Capture from a Cement Plant in Peru.

Methanol is a widely used raw material in the industrial and chemical sectors of many countries (Cieza & Ugaz, 2018). Despite its local demand, there is no industrial production in Peru that can meet it, so it is imported from countries such as the USA, Trinidad and Tobago, and China. A promising route for the production of e-methanol is the utilization of CO₂ from greenhouse gas emissions in cement plants in Peru, which account for 4-8% of total global emissions (INEI, 2021). These emissions are concerning due to their large volume and potential impact on air quality at local and regional scales (Yarlequé, 2022).

In this productive route, the use of hydrogen is required, and considering Peru's natural resources, green hydrogen produced with photovoltaic solar energy was chosen. This research aimed to economically and technologically evaluate the design of a green methanol production plant. With this objective set, the selection of the plant's location was initiated. The plant's location considers areas suitable for renewable energy sources (RES), specifically photovoltaic solar energy. The La Joya region has one of the highest solar radiation indices in the country, presents adequate atmospheric characteristics, and the energy resource averages 4.89 kWh/m²/day (SENAMHI, 2024). Regarding logistical aspects for the construction of the plant, its proximity to ports such as the Port of Matarani, located 90 km from the cement plant, its accessibility to major roads, and flat terrain were considered to ensure technical feasibility.

The capacity of our methanol plant is proposed based on the production of green hydrogen generated from a solar plant with 300 MW photovoltaic panels, which has a capacity similar to the San Martín project currently under construction in the La Joya region of Arequipa. The solar plant, the electrolyzer, the carbon dioxide capture plant, and the methanol synthesis plant were simulated using AVEVA Process Simulation Software.

The selection of the most suitable CCU technology began, with post-combustion technology chosen for its operational advantages and commercial maturity (Rodríguez, 2022). This technique can be classified based on the possible mechanisms employed: adsorption, absorption, membrane separation, and chemical reaction. Among these options, the most commonly used in the industry is the use of absorption/desorption towers. In these, a solvent, usually monoethanolamine (MEA), is employed (Mukherjee et al., 2019).

For the production of green hydrogen, photovoltaic panels with an installed capacity of 300 MW and an electrolyzer with a capacity of 196.4 MW were used, where water will be chemically separated into oxygen and hydrogen. Regarding methanol, according to Calo (2021), the chemical route for methanol production from CO₂ consists of a direct hydrogenation of the CO₂ molecule. At the same time, the reverse water gas shift reaction (RWGS) occurs. This reaction is undesirable and should be avoided as it consumes hydrogen. Therefore, a catalyst with high selectivity is needed, and copper (Cu) has been identified as the most suitable, promoted by another metal, mainly some zinc or zirconium oxide, or commercial preparations based on Cu/ZnO/Al₂O₃ (Duyar et al., 2020).

Considering all the aforementioned factors, the simulation resulted in an input of approximately 2,000,000.00 tons per year of flue gas, from which approximately 105,120.00 tons of MEA per year are required to capture 350,400 tons per year of CO₂ with a purity of 97.7%. Regarding green hydrogen, 36,226.5 tons per year were produced at a temperature of 80°C and a pressure of 8.9 bar. With the captured CO₂ and produced hydrogen, 179,600.00 tons of methanol with a purity of 75% were produced annually.

An economic analysis was conducted using CAPEX and OPEX variables, yielding values of 854.59 MUSD and 41.338 MUSD, respectively.

Although the process aims for the sustainability of green methanol production, aspects of the technologies used for transporting the generated hydrogen and its proper use should be considered. Additionally, based on the economic analysis and using variables such as WACC and TCI, the project is viable in the long term but not in the short term. Improvements in these economic aspects can be sought based on methanol production. Finally, possibilities for using methanol to produce various chemical compounds such as formaldehyde and methylamine should be explored.