Methane Processing Techniques: A Promising Paradigm for Decarbonizing Natural Gas

Methane processing technique is being evaluated as a potential decarbonization process by various industries. Compared to commercially available CCS/CCU technique, this technique exhibits negligible cost of handling carbon content. Solid carbon forms derived from this technique are much easier to handle. Once implemented on a portion of natural gas stream, methane processing technique has a potential to form a feasible business case for companies adopting it as the solid carbon and hydrogen produced can be traded in various other end-use industries, including tire industry.

An effective way to decarbonize the natural gas stream in the pre-combustion stage is to process the methane content. During the process, methane is decomposed into hydrogen and solid carbon products, along with exhibiting 70–100% sequestration of the carbon content of the natural gas.

This technique is adopted by certain companies to decarbonize a portion of the natural gas stream. The hydrogen formed is re-titrated to the stream that reduces carbon emissions in the combustion stage, while keeping the net heating content of the energy feed same. Production of hydrogen also forms a business case for the companies as net sellers of hydrogen, as they can earn from the arbitrage of natural gas and hydrogen prices. Hence, companies can increase their natural gas input, and sequester a portion of that stream to hydrogen and achieve higher profitability. Currently, the per kg cost of natural gas is ~$0.65 whereas that of hydrogen is ~$2.0. The output of this technique is carbon dioxide in solid form; therefore, cost of capturing, storing, and handling carbon dioxide in gaseous form is eliminated, that is incurred in CCS/CCU method. The solid carbon is derived in forms of carbon black, graphite, or graphene, having high demand in tire, construction, steel, concrete industries, thereby generating alternate source of revenue to the companies.

Methane Processing Landscape:

Methane processing is broadly classified in three major techniques of decomposing the methane i.e., through plasma, through thermal breakdown or in presence of a catalyst. Among the three techniques, plasma is the most widely available technique and technology providers adopting it are in advanced stages of commercialization, while technologies based on thermal and catalytic processes are still in development or pilot stages.

Current Availability of Different Methane Processing Techniques:

Although methane pyrolysis process is broadly categorized based on plasma, thermal and catalytic-based methane reduction techniques. However, technology providers exhibit a high level of process innovation toward the technology working principle to maximize the CO₂ sequestration, alter the grade and purity of carbon products and H_2. Following are few of the developed methane pyrolysis techniques:

Pulsed Methane Pyrolysis (PMP): PMP pyrolysis uses thermal energy to break the methane molecules into solid carbon product and H₂. The process does not use any green electricity and the energy requirement is met by combusting a portion of natural gas in the presence of O₂.

Plasmolysis: This process relies on breaking methane molecules through plasma, generation of which is based on electrolysis concept, that uses a cathode and an anode connected to electricity source.

Thermal Plasma Electrolysis (TPE): TPE is based on breaking methane molecules through plasma, that is generated from the natural gas itself. While passing natural gas through the plasma torch, methane and H₂ are formed, that is fed into the main reactor for the initiation of methane cracking.

Microwave Energy Heating (MEH): MEH is based on conventional microwave heating of natural gas to form solid carbon products and H₂. In the process natural gas is passed over a fluidized bed reactor over which microwave heat is introduced.

Microwave Plasma (MP): MP is one of the most common methane pyrolysis, where microwaves are generated through plasma and is guided to the reactor containing natural gas for methane cracking.

Catalytic Pyrolysis (CP): CP is one of the emerging methane processing techniques where the methane is decomposed to solid form of carbon and H₂ in the presence of a catalyst. The process has low temperature requirement compared with other processes.

Level of Carbon Sequestration Achieved Through Different Methane Processing Techniques

Limitations

Currently, methane processing technique is not widely adopted by companies on their complete natural gas stream as through this technique overall new energy source i.e., hydrogen is formed. In case the plant equipment, such as boilers, furnaces, or other machinery are incompatible to run on hydrogen or hydrogen titrated natural gas, certain major modifications would be required in the existing equipment setup.

In addition to this, methane processing technique forms 1 part of hydrogen against 4 parts of natural gas (solid carbon forms the balance 3 parts). Thus, there is a stepdown in energy availability to run the power systems, making titration of hydrogen back to natural gas stream vital to compensate the feed losses. Alternatively, companies can form a business case as hydrogen seller for additional costs incurred by marginal increase in natural gas inputs. However, switching over to low energy consuming systems can aid in minimizing the incremental natural gas input.

Current Adoption of Methane Processing Technologies

Current adoption of methane processing technique is majorly localized within European and North American region, that have strict decarbonization targets for the industries. Apart from this few of the APAC countries such as Japan, South Korea, and Australia that has significant reserves of natural gas and subsequent decarbonization targets are emerging as a potential market for methane processing techniques.

In the current state, methane processing techniques are being piloted by various commodity, automotive, utility, mining companies such as Birla Carbon, Cabot, Jaguar Land Rover, Fluor, Centrica, Egas, etc. In addition, existing hydrogen suppliers are also evaluating methane processing techniques, to replace existing high carbon emitting steam methane reforming technique of hydrogen production.

Conclusion:

Although not proven to be used on the entire natural gas stream, utilization of methane processing technique on a portion of natural gas stream can aid in narrowing the gap between decarbonization target and efforts. The potential of attaining 70–100% sequestration of carbon content highly impacts the net carbon emissions of the companies that are reliant on natural gas for their energy needs. Moreover, the derivative products i.e., hydrogen and solid carbon (carbon black, graphene, graphite, etc.), have high demand in various end-use applications. Thus, the technique has the potential to incubate new business verticals for the companies adopting it.