Techno-Economic Metrics Of Carbon Utilization - Part 2

Explaining the technological and economical parameters of carbon utilization and how these vary widely depending on external as well as technology-specific variables

Joris Mertens, Mark Krawec and Ritik Attwal
KBC (a Yokogawa company)

Currently, there is a common misconception that carbon capture, utilization, and storage (CCUS) means carbon storage (CS) rather than carbon utilization (CU). The confusion between storage and utilization is understandable since they both help reduce carbon emissions. The difference between storage and utilization is that storage involves disposing of waste, whereas utilization involves the efficient use of resources. Since utilization is more expensive than storage, some utilization technologies need further development, which explains the current focus on storage.

To help curb carbon emissions, NEDO (New Energy and Industrial Technology Development Organization) entrusted Yokogawa, a leading provider of industrial automation and test and measurement solutions, to perform a strategic decarbonization study of the Goi industrial area in the Chiba Prefecture at Tokyo Bay, opposite the capital (Yokogawa, 2021). KBC carried out research related to carbon utilization for Yokogawa. This research aims to make the industrial area net carbon neutral by 2050, preferably using carbon utilization rather than storage.

Table 2 shows hypothetical price scenarios for green hydrogen and CO2 utilization in 2030 and 2050. Whereas the 2030 scenario assumes a high price for green hydrogen and a low price for CO2 utilization, the 2050 scenario speculates a much lower price for green hydrogen and a much higher price for CO2. The primary purpose of this comparison is to demonstrate the sensitivity of the carbon utilization economics with carbon and green hydrogen pricing.

Price estimates for the 2030 and 2050 scenarios have been established with a more rigorous market analysis for the other feeds (propylene, propylene oxide, slag) and the carbon utilization products. For most feed and product pricing, KBC relied on third-party market intelligence supplied by Argus Media. The investigation concluded that making hydrogen-intensive carbon utilization technologies available in a scenario depicting high-priced green hydrogen must impose either product mandates or high CO2 prices of USD 350/t.

Part 2 further develops the techno-economics of carbon utiliutilization by investigating the impact of the CI of green hydrogen, power, and fuel consumed. The capital expenditure for the different technologies is also compared.

Utility balance: impact of power, fuel, and steam imports on carbon emissions

The carbon utilisation units may import and export electricity as well as steam and/or fuel. However, the balance is primarily determined by the reaction heat, and the heat required for amine regeneration.

Exothermic processes have the potential to use the excess heat for steam generation and export. Synthesis processes using hydrogen tend to be highly exothermic. The methanation, Fischer-Tropsch (FT), and xylenes technologies indeed generate considerable amounts of reaction heat, ranging from 1.8 to 2.9 MWh of product for the xylenes and methane processes, respectively. However, this does not always translate into steam exports. Some technologies use medium-level and high-level heat above 120ºC for preheat, while the lower-level heat (<120ºC) is lost in cooling. The intermediatelevel heat (150-200ºC) is often used to produce the necessary steam to regenerate the amine solution, which is used to capture CO2. Carbon capture is used in the methanation, FT, and Oxo production processes. Capturing and recycling CO2 are required to avoid large purges of CO2. However, it requires a significant amount of relatively low-level heat for amine regeneration and electricity for the compression and recycling of captured CO2.

Ultimately, all technologies are net utility importers except the xylenes process. The xylenes process is a net steam exporter that assumes CO2 capture is optional, and the best technology available for heat integration has been considered, unlike other technologies studied. In addition, caution should be exercised with respect to the xylenes technology because it is still in its infancy. Consequently, the available yield information was limited. KBC anticipates that further improvements in product selectivity will be achieved once the technology matures.

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