As the rush for the production of green hydrogen begins, which is considered by most energy companies as the fuel of the present and the future free of the carbon footprint, it is necessary to highlight the important role of blue hydrogen in helping to stimulate the implementation of green hydrogen but also to significantly decarbonize the production and marketing chain of natural gas by sequestering CO2 generated during the production of blue
• Blue Hydrogen offers a line of sight for immediate decarbonization, but only with the activation of capture and sequestration technology.
• There are several key trapping mechanisms that make it possible to permanently trap CO2, generated through the production of blue hydrogen, to inject it thus reducing the carbon footprint from the production chain to the marketing of natural gas.
• There are more than enough underground reservoirs in the world for CO2 sequestration.
• Subsoil modeling is essential to predict and monitor CO2 movement in formation, understand risks and uncertainties; it is an integrated underground engineering and geoscience effort.
What is Blue Hydrogen? What is it?
Blue hydrogen is produced from the reforming, by steam or autothermal, of methane. Steam reforming of methane accounts for 95% of the hydrogen currently produced in the world. This process usually produces 9 tons of CO2 per 1 Ton of hydrogen.
Blue Hydrogen offers natural gas producers and suppliers the opportunity to significantly decarbonize life-cycle emissions from the energy product they sell through the sequestration of the CO2 produced.
Indeed, capturing the CO2 produced by one of the existing technological means, mainly in the hydrocarbon industry, will substantially decarbonize the entire natural gas production and marketing chain.
Blue Hydrogen now offers the opportunity to establish the hydrogen supply chain on a large scale and partially decarbonize industries that are struggling to reduce their carbon footprint.
Blue hydrogen also plays a very important transitional role in helping to stimulate market development while the great development of the Green Hydrogen economy is established in the longer term.
CO2 sequestration using Blue Hydrogen
The reforming process converts natural gas into a gaseous mixture of hydrogen and CO2. Hydrogen is separated, the remaining CO2 is packaged and compressed for storage for permanent sequestration.
CO2 is heavier than air. The molar mass of air is 29 g/mole while that of CO2 is 44 g/mole. It can be up to 8 times more compressible than methane. It dissolves in water and oil. It becomes miscible in certain qualities of oil. Solubility in water increases with pressure, decreases with temperature and salinity.
By its characteristics, CO2 is generally sequestered in deep geological formations where it is contained by various trapping mechanisms such as:
• Structural Depleted oil and gas reservoir,
• Residual Deep saline aquifers,
• Solubility Deep layers of coal
• Minerals Shale, Basalts.
Also, several innovative uses of CO2 are already being implemented, we can mainly mention:
• Improved crude recovery in hydrocarbon tanks (Enhanced Oil Recovery),
• The mineralization of CO2 that is set to react with magnesium oxide and calcium oxide to produce stable solid carbonates that will be used in the building.
• The use of CO2 in geothermal energy as a working fluid for the production of electrical energy.
• Food storage, use in soft drinks and medicine,
• The production of microalgae biofuel or methanol fuel,
CO2 Sequestration Tanks
Several tanks or supports are identified for the sequestration of CO2 generated during the production of blue hydrogen. The following essential supports for CO2 injection can be mentioned:
• Deep and unexploitable coal layers after possible production of the associated methane because adsorption improves trapping,
• Deep saline aquifers, which have the largest storage capacity but not enough data available to allow the evaluation of the mechanism. CO2 dissolved in water forms carbonic acid and possibly bicarbonate.
Over time, this dissolved CO2 reacts with rock minerals to form solid carbonate minerals, resulting in permanent trapping. Very slow reaction, thousands of years.
• Oil and gas fields exhausted to return CO2 from which it comes with an assured trapping mechanism, and at acceptable pressure due to tank depletion.
Physical capture of CO2 due to geological structure, such as the anticlinal (dome) and/or fault offset makes it possible to trap the largest amount of CO2 in the smallest space.
• Depleted organic Shales after fracturing and methane production.
It should be noted that for example, 69 Million tons of blue hydrogen require about 600 to 700 Million tons of CO2 sequestration. There is more than sufficient geological storage capacity in oil and gas fields to sequester them.
Geological CO2 storage resources in saline formations are hundreds of times larger than the resources of oil and gas deposits.
Tank Modeling
CO2 sequestration requires basic modeling of the receiving reservoir of what is likely to happen and identifying and studying the main risks and uncertainties to help mitigate or reduce them.
These simulations will make it possible to select the CO2 injection area, estimate the storage capacity, the number and location of injector wells, injection flows and pressures, the design of surface facilities, monitoring during and after injection, prediction of the pressure and movement of injected CO2 and detect possible leaks from formations as well as risk assessment.
By MESTIRI Yassine