• Energy Research

We forecasted 82 GW of total geothermal capacity by 2045, reducing system capacity and costs by 40% and 8.6%, respectively.

Abstract Carbon capture and utilization (CCU) has gained great attraction as an alternative route of producing carbon-based chemicals, which also mitigates atmospheric CO2. This paper develops a numerical optimization model that utilizes experimental data pertaining to the CO2 hydrogenation reaction (catalyst type, conversion, selectivity, and space velocity) to guide engineers to pick the optimal industrial scale CCU process. Four carbon conversion pathways that produce value-added chemicals are assessed: conversion into methanol, methane, carbon monoxide, and dimethyl ether. This techno-economic analysis is founded on elaborate sizing methods and process design principles of heat exchangers, compressors, reactors, and separators. Based on the collected data reported in the literature, the state-of-the-art model incorporates and assesses feed and catalyst costing, plant sizing and costing, and revenues from the produced commodity chemicals at market price. A thorough optimization analysis is conducted to determine the optimal conversion pathway subject to corresponding constraints. The objective of this problem targets cost minimization with respect to various production constraints. The results of the model show that the optimal CCU path is associated with the CO2-to-MeOH/DME reactions, with the model almost strictly allocating the available CO2 mass at the different production rates to processes generating these products. This result is due to the processes’ high reaction selectivity, which has been at the forefront of research in CO2 hydrogenation, in addition to the relatively high market price of both these products. Such results reinforce the promise of George Olah's Methanol Economy. The optimization model thus presents a novel basis for a comprehensive and quantitative multi-variable CCU plant assessment, utilizing optimized carbon conversion reaction data.

The aviation industry is responsible for over 2% of global CO2 emissions. Synthetic jet fuels generated from biogenic feedstocks could help reduce life cycle greenhouse gas (GHG) emissions compared to petroleum-based fuels. This study assesses three processes for producing synthetic jet fuel via the synthesis of methanol using water and atmospheric CO2 or biomass. A life cycle assessment and cost analysis are conducted to determine GHG emissions, energy demand, land occupation, water depletion, and the cost of producing synthetic jet fuel in Switzerland. The results reveal that the pathway that directly hydrogenates CO2 to methanol exhibits the largest reductions in terms of GHG emission (almost 50%) compared to conventional jet fuel and the lowest production cost (7.86 EUR kgJF-1); however, its production cost is currently around 7 times higher than the petroleum-based counterpart. Electrical energy was found to be crucial in capturing CO2 and converting water into hydrogen, with the sourcing and processing of the feedstocks contributing to 79% of the electric energy demand. Furthermore, significant variations in synthetic jet fuel cost and GHG emissions were shown when the electricity source varies, such as utilizing grid electricity pertaining to different countries with distinct electricity mixes. Thus, upscaling synthetic jet fuels requires energy-efficient supply chains, sufficient feedstock, large amounts of additional (very) low-carbon energy capacity, suitable climate policy, and comprehensive environmental analyses.