A Grand Challenge: Carbon Capture, Utilization, and Storage

_ This is the fifth in a series of six articles on SPE’s Grand Challenges in Energy, formulated as the output of a 2023 workshop held by the SPE Research and Development Technical Section in Austin, Texas. Described in a JPT article last year, each of the challenges will be discussed separately in this series: geothermal energy; net-zero operations; improving recovery from tight/shale resources; digital transformation; carbon capture, utilization, and storage; and education and advocacy. _ Net global anthropogenic greenhouse gases (GHG), mainly CO2 and CH4 emissions, reached nearly 60 Gt CO2-eq in 2019, with energy-related emissions contributing the largest amount at nearly 40 Gt (IPCC 2022). The fugitive emissions from coal, oil, and gas industries are about 5. 8%. Fig. 1 shows the global emissions from energy-related sectors; the use of coal, oil, and natural gas contributes the major share to GHG emissions. In the past 15 years, electricity production from renewable sources (solar, wind, and hydroelectric) has increased significantly. However, renewable energy accounts for only about 15% of the primary energy generation now. Almost 80% of the primary energy comes from fossil fuels: coal, oil, and natural gas, and about 5% comes from nuclear fission. In the next 30 years, the US Energy Information Administration (EIA) projects that renewable energy will grow from 15% to about 27. 6% (Fig. 2) but cannot meet human consumption by itself. Fossil fuels would still contribute about 68. 5%. How do we use fossil fuels and at the same time reduce CO2 emission? Fossil fuels can be used only if the associated CO2 can be captured and stored or reused. Hydrogen has been envisioned as the clean fuel for the future, but all of the needed hydrogen cannot come from electrolysis (for lack of renewable energy capacity) ; most will come from fossil fuels which, again, have to be supplemented with carbon capture in the net‑zero economy. CCUS has three components: carbon capture, transportation, and storage/utilization. The scale of needed CCUS dictates that the three components need to be developed simultaneously for successful deployment of this technology. For example, a power plant cannot install a carbon capture unit until transportation and storage/utilization are in operation. CO2 Capture Carbon capture processes separate CO2 from gaseous streams emitted from industrial sources (point sources), e. g. , power plants, steel plants, and steam methane reformers (SMR). The concentration of CO2 is about 4 to 12% in power plants, 20% in steel plants, and 15 to 45% in SMR. There are also emerging capture techniques to separate CO2 from air (with a concentration of 0. 042%) called direct air capture (DAC). As the CO2 concentration decreases, it takes more energy and cost (per CO2 amount) to separate.