Carbon Capture and Usage (CCU)
“CO2 use cannot replace CO2 storage in delivering the very significant emissions reductions needed to meet Paris Agreement ambitions. This reflects the expected smaller scale of many CO2 use opportunities, their very limited scope for negative emissions, and their early stage of technology and market development”
In our previous blog, Carbon Capture and Storage, I briefly mentioned two CCU niche applications, ammonia and ethylene oxide. These processes are perfect candidates thanks to the highly concentrated CO2 flows that are generated in the production process.
*Don’t forget hydrogen is used as feedstock for ammonia and methanol production, which covers the 70% of its current usage.
How can CCU be applied in ammonia and ethylene oxide production processes?
Ammonia: It is most commonly made from methane, water and air, using steam methane reforming (SMR) and the Haber process. Approximately 90% of the carbon dioxide produced comes from the SMR process. This process consumes a lot of energy and produces around 1.8% of global carbon dioxide emissions.
The best way to reduce carbon emissions when making ammonia is to use low-carbon hydrogen. In the short term blue hydrogen seems the most likely options, where the emissions from the steam methane reforming (SMR) process are captured and stored (CCS). Obviously, using green hydrogen using a power-to-X process would be the long term preferred option.
Urea is the most-used nitrogen fertilizer in the world. Urea’s production consumes roughly 53% of all the ammonia produced on the planet. Typically, the carbon in urea’s molecule is obtained from the CO2 emitted by natural gas or coal-based ammonia production. But if hydrogen is produced by electrolysis, the CO₂ has to be sourced from elsewhere. The CO₂ can either be captured and recycled from another emissions source, coupling sectors, or urea producers could make use of the CCS networks, or CO2 could even be extracted from the air.
Ethylene Oxide: A conventional hydrocarbon feedstock that could be of particular interest for CO2 Utilization is ethylene. In this case the technology change requires the implementation of CO2 conversion reactors allowing to retrofit an existing chemical process. The recycling concept is based on use of an electroreduction reactor, where CO2 is converted to chemicals; exploring the synergies between the established and emerging process can accelerate the decarbonisation of the chemical industry, and that more sustainable chemical production methods can be economically viable in the current market.
In the world there are an increasing number of facilities in operation, according to the IEA, the amount of facilities which put CO2 to use are increasing in the natural gas, fertilizers and hydrogen sectors. In the last years chemicals have not yet increase the number of facilities using these technologies, whereas in the power generation, bioethanol and steel sectors 2021 was the year where first projects took off.
Methanol seems to be an attractive option due to its versatile application, and exceptional physical and chemical characteristics...
If we focus on the chemical sector and if CO2 is catalytically synthesised with hydrogen it can form a variety of hydrocarbons, such as methane, methanol, higher alcohols, and liquid fuels. Amongst the several chemical compounds that can be synthesised from CO2 and H2, methanol seems to be an attractive option due to its versatile application, and exceptional physical and chemical characteristics.
Methanol is not only a fuel, but a base chemical.
However, raw materials prices, H2 and captured CO2, do not allow such process to be financially viable yet. In order to make the CCU plant financially attractive, the price of MeOH should increase in a factor of almost 2, or H2 costs should decrease almost 2.5 times, or CO2 should have a value of around 222 €/t. Production of methanol from biomass and from CO2 and H2 does not involve experimental technologies. Almost identical proven and fully commercial technologies are used to make methanol from fossil fuel-based syngas and can be used for bio- and e-methanol production.
