COLORS OF HYDROGEN

Hydrogen can be made from several abundant sources such as natural gas (methane) or water. The colors of hydrogen were created to classify it by the type of process and energy used. This also enables the determination of whether it will be "low-carbon" or not.

In general,

• Green Hydrogen is produced via water electrolysis using renewable energy
• Blue hydrogen is produced using natural gas in a reforming process with a CCS system included
• Turquoise Hydrogen is produced by methane pyrolysis and has carbon black as a by-product.
• Pink Hydrogen is produced via water electrolysis using nuclear energy

In our Energy Transition 2021 coverage, we had one session regarding Green and one regarding Turquoise Hydrogen production, and we are planning to kick off next year with a blue hydrogen session, for which the objective here today is to give an introduction to blue hydrogen, briefly explain what processes can lead to its production and identify the main challenges faced by them.

WHY IS IT IMPORTANT TO SPEAK ABOUT BLUE H2?

The global green hydrogen market size was valued at 786.9 Million U.S. dollars in 2019 by the Grand Review Research's 2020 Report and is expected to grow at a compound annual growth rate (CAGR) of 14.24% from 2020 to 2027. Similarly, according to a Nov 2020 report from Emergen Research, the blue hydrogen market was valued at 816.5 Million U.S. dollars in 2019 and is anticipated to reach 2.48 Billion U.S. dollars by 2027 at a CAGR of 14.8%.

So far, both blue and green hydrogen are more expensive than grey hydrogen, but with significant differences. The H2 costs estimated for the EU are €1.5/kg for gray, €2/kg for blue and up to €5.5/kg for green. However, considering CO2 costs of $25/ton to $35/ton, blue H2 is actually starting to become competitive against gray, while green may still double that price.

WHAT ARE THE WAYS TO PRODUCE BLUE H2?

Considering that natural gas and CCS are used to produce blue H2, there are three main methods currently utilized:

SMR: Steam Methane Reforming

Accounting for ~60% of the blue hydrogen market, SMR is a proven catalytic technology widely applied for gray H2 production that exposes the natural gas in a rich-steam environment at high temperatures (800-900°C) and moderate pressure (25 bar). As a result, one obtains H2, CO, and CO2, and of course, depending on the fuel, there might also be NOx and SOx in final emissions.

The key advantage to SMR is that it is the most common production technology of hydrogen, for which there's currently a great amount of research and development. However, POX (Gas Partial Oxidation) and ATR (Autothermal Reforming) technologies are more cost-effective than SMR, so we are also seeing a good amount of development in that area.

POX: PARCIAL OXIDATION

Gas partial oxidation (POX) reactions occur when a sub-stoichiometric fuel-air mixture is partially combusted in a reformer, producing a hydrogen-rich syngas stream with a typical H2/CO ratio range of 1.6 to 1.8, which can then be put to further use, for example in a fuel cell.

Compared to SMR, POX technology saves money by maximizing the carbon capture efficiency and simplifying the process lineup, both of which offset the cost of O2 production. Additionally, it does not require steam as a reactant which reduces the need of a gas pre-treatment.

Compared to ATR, a key advantage is again that the POX reaction does not require steam as a reactant. Instead, high-pressure steam is generated by using waste heat from the reaction, which can satisfy the steam consumption within the blue H2 process, as well as some internal power consumers. Also, with no need for feed gas pre-treatment, gas POX technology has a far simpler process lineup than ATR. According to the Shell Blue Hydrogen Process, POX technology provides substantial savings compared with ATR – a 22% lower levelized cost of H2 that derives from lower CAPEX (higher operating pressure  smaller H2 compressor)

ATR: Autothermal Reforming

Autothermal reforming is the combination of the SMR and POX resulting in a net reaction enthalpy of zero. ATR uses O2 and steam with direct firing in a refractory-lined reactor with a catalyst bed.

The ATR reaction has several advantages compared to SMR:

• increased energy efficiency (more cost-effective)
• faster start-up times,
• faster response time to transient operation

And compared to POX:

• increased energy efficiency
• higher hydrogen production efficiencies

As a disadvantage, ATR requires a substantial feed gas pre-treatment investment as well as a large investment for an oxygen production plant. ATR would also be more suited for a pre-combustion carbon capture system.

The Darcy team has seen that the vendors within the blue hydrogen production have mainly been developing SMR and ATR technologies with less attention to POX but given Shell’s newest SGP (Shell Gas Partial Oxidation), there will surely be an increased technology development in this space.

There have also been some companies like Proton Technologies and Hydrogen Source, that have come up with novel technologies that should allow for hydrogen production in underground resources, combining production of hydrogen with carbon dioxide storage underground.

The Darcy team is currently meeting with many innovators in this space to get a great presenter for next year. Who would you like to see in a future session? Comment and let us know where you interests lie!

REFERENCES:

• Sbh4
• Science Direct
• Hydrocarbon Processing
• The Shell Blue Hydrogen Process
• Emergen Research
• World Economic Forum