Alireza Arjomand

The electrochemical reduction of CO2 to formic acid presents a promising pathway for carbon utilization, yet its industrial-scale implementation remains limited. The main idea of the present article is evaluating the feasibility of integrating existing CO2RR cells with conventional industrial equipment to achieve commercial-scale formic acid production. So, this study develops a comprehensive process design for producing formic acid from biogas via CO2RR, with hydrogen generated as a co-product. It includes hydrogen generation with reforming of biogas, chemical carbon capture, CO2RR cells, auxiliary refrigeration cycle, and formic acid separation units. The result of comprehensive economic assessment showed that the CO2RR alone account for 78.7% of the total bare module cost, while electricity consumption dominates operating expenses at 54.3% of variable costs. Through systematic economic evaluation, this study numerically determines the required product pricing for economic viability: achieving a competitive 3-year payback period demands formic acid prices of $5.55/kg under reference hydrogen pricing or $5.90/kg when hydrogen is discounted by 50%. At current market prices ($0.94/kg for formic acid, $5.17/kg for hydrogen), the project yields a negative net present value of −$120 million, a 32-year payback period, and a −4% return on investment. The findings demonstrated that current CO2RR cells are not yet economically effective for industrial-scale application, and significant advancements in cell performance, particularly reduced capital costs, improved durability, and lower energy consumption, are essential prerequisites for this technology to become a viable CO2 utilization pathway.

In many industrial plants including petrochemicals and refineries, raw hydrocarbons (mostly flammable gas) are released during unplanned operations. These flammable gases (usually called flare gases) are sent to a combustor and the process is called flaring. Flaring wastes energy and produces environmental pollution. Consequently, recovering the flare gases is an important subject in these industries. In this work, an economical and technical analysis is presented for the production of valuable products, namely, liquefied natural gas and natural gas liquids from flare gas. The flare gas of Fajr Jam refinery, a refinery located in the south part of Iran, is selected as a case study. One of the issues in recovering flare gases is the nonconstant flow rate of these gases. For this reason, an auxiliary natural gas flow rate is employed to have a constant feed for the flare recovery process. The Poly Refrigerant Integrated Cycle Operations (PRICO) refrigeration cycle is employed for producing liquefied natural gas and natural gas liquids. In the PRICO cycle, the mixed refrigerant is used as the working fluid. The other issue is the existence of H₂S in the flare gases. The main idea is that the flare gas components, including H₂S, have different boiling points and it is possible to separate them. Consequently, flare gases are separated into several parts during a number of successive cooling and heating stages and passing through phase separators. It is shown that the proposed flare gas recovery process prevents burning of 12 million cubic meters of the gases with valuable hydrocarbons, which is almost 70% of the current flare gases. Furthermore, about 11,000 tons of liquefied natural gas and 1230 tons of natural gas liquids are produced in a year. Finally, the economic evaluation shows a payback period of about 1.6 years.