Story by: Tyler Campbell, Managing Editor, H2Tech
The energy transition will require various innovations, such as sustainable aviation fuel, automation and hydrogen (H2). Although much attention has been given to green H2, blue H2 development will be crucial and may make more sense depending on the sector (e.g., refining). At Honeywell Users Group 2023, Naved Reza, Director, Business Development Sustainable Technology Solution for Honeywell UOP, delivered a presentation titled “Powering the CO2 countdown with blue H2.”
Honeywell UOP has been developing H2 processing solutions for decades. The company does not make electrolyzers but does produce catalytic-coated membranes for the electrolyzer stack. However, this presentation is focused on UOP’s blue H2 production methods, coupled with carbon capture and storage (CCS). According to Reza, of the 40 million tons (MMt) of CO2 captured, 15 MMt (approximately 38%) were captured by UOP's technology. The company intends to be carbon neutral in its operations by 2035.
Today, about 50 billion tons per year (Btpy) of greenhouse gas (GHG) is emitted. Nearly half comes from power generation, refining, steel and cement. CCS has the potential to decarbonize these hard-to-abate segments. According to the International Energy Agency, by 2050, 660 MMtpy of H2 will be needed, accounting for approximately 22% of the global energy demand. Gray H2 is currently the primary type of H2 produced, but Reza notes a McKinsey study predicting that by 2050 there will be no gray H2, and the energy mix will be dominated by blue (approximately 300 MMtpy) and green H2 (approximately 200 MMtpy).
To meet these projections, UOP has several blue H2 production processes highlighted in the presentation revolving around steam methane reforming (SMR) and autothermal reforming (ATR). “Today, SMR is the primary method for producing gray H2,” Reza said. “However, we see that for new projects like the ExxonMobil Baytown project, they will use ATRs for H2 generation, and decarbonize it using carbon capture, resulting in a very low carbon intensity (CI) H2.”
SMRs contain two streams for the CO2 to come through. One is the CO2 produced during combustion, about 40% and 60% is present in the synthetic gas (syngas)—carbon monoxide (CO) and H2. SMRs have pre and post combustion—pre combustion is the heat generated, enabling the process to occur. In ATR, the methane (CH4) is combusting with oxygen in a controlled environment. In this circumstance, all the CO2 produced comes through one stream.
UOP has multiple SMR and ATR processes that are slightly different. In the first ATR configuration, the syngas—40%−50% H2, the remainder is CO2—goes through a H2 pressure swing adsorption (PSA) system, removing the H2 and pushing the CO2 through the tail gas. The CO2 is then compressed, dried and passes through UOP’s CO2 fractionation system, removing the CO2, liquefying it and sending it to the pipeline for storage or utilization.
According to Reza, the process will have some off-gas. “There will be CO2 and CH4, and you will recycle it and go through the same process,” he said. “At the end, you should be able to capture most of the CO2.” The ATR has a preheater upstream that uses CH4 as fuel to burn. The ATR-fired fuel contains a small amount of H2 and will be sent to the preheater to be used as fuel for the combustion process, further reducing the CI and purging the argon and nitrogen.
In the second ATR configuration, the ATR-fired fuel extracts the H2. This process has no CO2, so the CI is very low, enabling only 0.1 kilograms (kg) of CO2 per kg of H2 produced. The process is mostly the same as the first configuration; however, the capital expenditure (CAPEX) is 2%−5% greater due to a much larger PSA. Concurrently, 5%−10% less syngas is required to produce the same amount of H2. The ExxonMobil Baytown facility is using this configuration.
Regarding the SMR processes, the natural gas steam H2 production is present, with syngas exporting, then going through the water gas shift (WGS) process. The WGS process produces H2 and CO2, and the polybed PSA removes them. Once again, UOP’s CO2 fractionation system recycles the CO2 and CH4 into the system. In this process, 90% of the H2 in the tail gas is captured and added to the main H2 stream, resulting in an additional 20% H2 yield with about 99.9% purity.
In the second SMR process presented, the H2 purity is not as high, at about 95%; however, according to Reza, it has the lowest CAPEX and operational costs (OPEX) of all systems previously mentioned. The 90%−98% of CO2 recovered from the PSA tail gas in this process results in a 50%−60% CO2 emissions reduction compared to existing SMR processes.
The amine guard is the third solution for CO2 capture that UOP offers. Everything in this system is the same, except the CO2 exported from the WGS reactor is passed through an amine guard, where the CO2 capture takes place—the H2 is separated with the polybed PSA.
The final SMR solution is the advanced solvent for carbon capture. According to Reza, more than 95% of CO2 can be captured with this process. In this process, the CO2 and CH4 in the tail gas are recycled into the H2 production process. This results in 50% of the CO2 being fed, with 40% of the post combustion in the flue gas.
“All the CO2 is passed through the flue gas, and we put our advance solvent carbon capture solution to capture the CO2,” Reza said. “With this, greater than 95% of carbon capture is possible in an SMR, whereas in the previous examples, it was about 50%−60%.”