Koloma, an American cleantech company founded in 2021, develops technology to extract natural or geologic hydrogen from subsurface reservoirs while sequestering carbon dioxide underground permanently.
Challenges: hydrogen fuel
Green hydrogen
It is now more important than ever to switch to energy sources that are better for the environment. The switch to clean electricity sources, like renewables, and electrifying end uses will be two of the most important parts of this transition. However, gaseous fuels may be needed for some end uses, especially in heavy industry and shipping, because they are more reliable and have a higher energy density. Having a carbon-free chemical energy carrier may also help people get energy in the winter.
Hydrogen (H₂) has been widely proposed as a fuel that can meet these needs with minimal greenhouse gas emissions. Hydrogen can decarbonize hard-to-abate industries, such as steel manufacture, long-distance transportation, shipping, and aviation. It can also be used to store renewable electricity seasonally and as a chemical feedstock.
Today, more than 95% of hydrogen is produced using natural gas in steam methane reformers (SMRs). The carbon intensity of hydrogen production using SMRs without carbon capture is 10.4 tons of CO2 emitted for each ton of hydrogen produced.
Green hydrogen can be produced via electrolysis of water, pyrolysis of hydrocarbons, or solar heating using renewable energy sources such as nuclear, solar, and wind. To see which startups and understand how they work on green hydrogen technologies, you may become a member and check out our research on green hydrogen startups.
Natural hydrogen
Natural hydrogen (or “gold hydrogen”) is produced by drilling and stimulating iron-rich rock. It has been identified in many source rocks and areas beyond the sedimentary basins where oil companies typically operate. For example, large accumulations of natural hydrogen have been discovered in places like Bourakebougou, Mali, Rukwa, Tanzania, and Cauca-Patia Valley of Colombia.
The potential for natural hydrogen as an energy source is significant. It is continuously produced by geological processes and has a short retention period in geological traps. This makes it a dynamic system that could expand our use of hydrogen as a source of energy, not just as an energy carrier.
The commercialization of natural hydrogen is being developed in various regions, and it is being considered a potentially abundant source of truly green and inexpensive hydrogen.
Koloma Technology
Koloma has developed technology to produce natural or geologic hydrogen by injecting a hot reactant mixture stream into an injection well within iron-rich rocks and extract produced hydrogen from a recovery well. The hot reactant stream contains water, supercritical CO₂, and dihydrogen sulfide (H₂S). They react with iron-rich phases of rocks and increase the natural hydrogen production rates. These reactions not only produce natural hydrogen, but also mineralize sulfur and CO₂. Therefore, Koloma’s technology can produce low-carbon or even carbon-negative hydrogen.
How Koloma discovers natural hydrogen
There are many existing wells extending into subsurface rock formations around the world. Many of these wells have available well logs, which include information on the geophysical characteristics of the rock matrices and contents. However, most of these well logs only focus on finding one type of fluid, such as oil.
Koloma uses the following method to identify and quantify the subsurface hydrogen.
The method includes the following processes:
- Examine geophysical well logs and identify the geologic area of interest.
The interesting geologic area typically has iron-rich rock, mafic igneous rock, olivine- or pyroxene-bearing igneous, or other types of iron-rich rocks. The rock formation should be porous, faulted, or geologically or incipiently fractured. This is one of the key factors that limits natural hydrogen production and extraction.
- Determine a rock matrix type of a rock formation from the well logs.
The well logs include image logs, resistivity, acoustic measurement, or gamma ray readings. Software can process such data to determine the type of rock matrix.
The rock matrix type infers the rock matrix density. However, the bulk density measured from a geophysical logging tool is usually different from the rock matrix density. This is because rocks develop porosity via chemical weathering. Water or brine (salty water) initially fills these pores during weathering processes. Later, other fluids such as oil, natural gas, hydrogen, helium, or carbon dioxide displace water, as they migrate through that rock in the subsurface. Therefore, the bulk density measured from a geophysical logging tool is a combination of the rock matrix density and the pore fluid density.
Knowing the rock matrix type and bulk density logs, we can infer the properties of the rock formation and pore-filling contents.
- Determine the porosity of the rock formation.
Since the pores of rocks hold water, oil, natural gas, hydrogen, helium, or carbon dioxide, the porosity determines the quantity of these pore-filling contents, especially hydrogen. The porosity data can be obtained directly from geophysical well logs. Porosity is used to calculate the pore-filling fluid acoustic and density responses based on the properties of commonly found rock types and pore-filling fluids. This can identify and quantify the subsurface hydrogen.
- Determine a fluid density of a fluid within the pores of the rock formation.
A computer program uses the data in geophysical well logs to automatically calculate the fluid density at the corresponding subsurface interval. If the fluid density is much less than 1.00 g/cm³, such as less than 0.8 g/cm³, the fluid is likely in the gas phase, leading to the options of methane, hydrogen, helium, nitrogen, mixed hydrocarbon gasses, dihydrogen sulfide, or carbon dioxide.
- Determine an acoustic slowness of the fluid within pore space.
A computer program uses the data in geophysical well logs to automatically calculate the acoustic slowness of fluid at the corresponding subsurface interval. Hydrogen or helium can be easily distinguished from methane, nitrogen, or carbon dioxide in the gaseous or supercritical form.
- Determine the fluid type of the fluid within the pore pace
By comparing the bulk fluid density and acoustic slowness values of the corresponding rock matrices (e.g., rock matrix type and porosity) with the known bulk fluid density values and acoustic slowness values corresponding to known fluids, the subsurface hydrogen within the pores can be identified.
For example, if the calculated acoustic slowness value is less than 250 μs/ft, then the fluid is identified as water if the calculated fluid density is close to 1.00 g/cm³ or as hydrogen if the fluid density is less than 1.00 g/cm³ by one order of magnitude.
If the calculated acoustic slowness is in the range of 500-750 μs/ft and the density is much less than 1.00 g/cm³, then the fluid is identified as methane.
If the calculated acoustic slowness is in the range of 750-1,000 μs/ft and the density is much less than 1.00 g/cm³, such as less than 0.8 g/cm³, the fluid is identified as nitrogen.
If the calculated acoustic slowness is greater than 1,000 μs/ft, the fluid is identified as carbon dioxide.
- Flagging the determinations of hydrogen.
How Koloma extracts natural hydrogen
The extraction of natural hydrogen from the subsurface on a large scale is not possible without proper conditions, such as key reactants and suitable high temperatures. It also requires an economically viable method to produce natural hydrogen.
Koloma has developed a technology of sulfur-carbon mixture-enhanced hydrogen production to produce natural hydrogen gas, as shown in the diagram below.