Dr. ir. René Peters
- Offshore Energy
Hydrogen plays a key role in the energy transition because its use does not release any greenhouse gases into the atmosphere. However, green hydrogen is currently not available in large volumes and remains expensive. Blue hydrogen offers a cheaper alternative that prevents emissions because the CO2 released during production is stored underground. Blue hydrogen therefore paves the way for green hydrogen in the longer term.
In order to distinguish between different production methods for hydrogen, colours were assigned to the same molecule. Just as energy companies offer grey and green electricity, companies also produce grey and green hydrogen. Green hydrogen is produced by splitting water molecules (H2O) into hydrogen (H2) and oxygen (O2) via electrolysis. This is only called green hydrogen if the electricity required for it comes from sustainable sources.
As for grey hydrogen, natural gas (CH4) is split into hydrogen (H2) and carbon dioxide (CO2) using steam (H2O). The carbon dioxide released in the production of grey hydrogen currently escapes into the atmosphere. Storing this greenhouse gas underground prevents additional global warming. Hydrogen gas produced in this way is called blue hydrogen.
In principle, the production of blue hydrogen is no different from that of grey hydrogen. The industrial steam methane reformers (SMR) or auto thermal reformers (ATR) that currently produce grey hydrogen can also produce blue hydrogen. However, more efficient systems to separate synthesis gas are now available. One example is TNO’s SEWGS technology, which not only saves costs but also removes more CO2.
The SEWGS process combines two steps in one reactor: a water-gas shift reaction and CO2 capture with a solid absorbent. The combination results in a more energy-efficient conversion and almost complete CO2 removal.
TNO has already successfully demonstrated the SEWGS process on an industrial scale at SSAB in Sweden. In the European Union-supported STEPWISE project, a SEWGS installation processed 800 cubic metres of blast furnace gas per hour from one of the steel mills.
The biggest challenge for blue hydrogen is the transportation and underground storage of the captured CO2. This is also called carbon capture and storage (CCS). The CO2 is transported by pipeline to empty gas fields and injected into deep underground sandstone layers. The CO2 can also be used as a nutrient in greenhouses or as a raw material for chemical products and plastics. This is called carbon capture and use (CCU).
Currently, several parties are looking into the possibilities of blue hydrogen and CCS. For example, H-Vision (a joint venture between TNO and industry in Rotterdam) wants to quickly realise large quantities of CO2 reduction with blue hydrogen. Companies like BP, Shell and ExxonMobil want to make large-scale blue hydrogen production possible. Part of the plan is the Porthos project, which transports captured CO2 via an undersea pipeline to a gas production platform in the North Sea. From the platform, the CO2 is pumped into an empty gas field. Porthos was recently awarded a subsidy from the Dutch government that could amount to up to two billion euros.
In the North Sea Canal area, a consortium including TNO is also investigating the feasibility of CCS under the name Athos. Consortium partner Tata Steel can utilise blue hydrogen in the production of steel. The company can also make blue hydrogen from its own process gases, which are generated during the combustion of coke.
The H2Gateway Consortium also unveiled plans for a hydrogen facility, focusing on a blue hydrogen plant in Den Helder. The Port of Den Helder is also collaborating with the Port of Amsterdam and Groningen Seaports within Hydroports with the aim of contributing to the optimisation of infrastructure for the hydrogen economy.
Blue hydrogen currently holds the better cards for a fast and affordable energy transition. Green hydrogen is only truly sustainable if the electricity for the electrolysis process comes from renewable sources. For the time being, there is still too little green electricity available. Moreover, electricity is twice as expensive as natural gas. The high cost of the electrolysers that split the water also makes the technology less attractive for the time being.
Blue hydrogen remains cheaper than green hydrogen in all scenarios and is the only form of hydrogen that directly reduces CO2 emissions. There is enough natural gas to last for years and residual gases from refining or biogas, for example, can be split into hydrogen and CO2 in the same way.
However, as 2050 draws closer, it is expected that the supply of green electricity will increase while electrolysers will become cheaper through innovation and mass production. Until then, blue hydrogen is paving the way for a mature, affordable hydrogen market and infrastructure.