Decarbonization of Natural Gas at Pre-Combustion Stage

Decarbonization is becoming increasingly urgent because of the rise in global warming. Given the substantial utilization of natural gas by corporations in the US and Europe, this need has become notably more significant. Currently, the adoption of renewable energy sources stands out as the most relevant method for mitigating carbon emissions. However, limited availability of renewable energy supplies and declining levelized cost of energy (LCOE), has increased per unit cost of green energy, thereby compelling companies to sustain considerate consumption of natural gas. Companies can adopt other techniques for decarbonization, such as carbon capture storage/utilization (CCS/CCUS), as a feasible option to eliminate carbon dioxide content of natural gas. However, due to high costs associated with carbon capture and storage, evaluating certain other future ready techniques, such as methane processing, to decarbonize the balance usage of natural gas is necessary.

The extensive use of natural gas in the pre-combustion stage by companies in the US and Europe significantly contributed to their energy requirements and economic growth. However, considering the pressing global concern over climate change and the imperative to reduce greenhouse gas (GHG) emissions, exploring sustainable solutions for decarbonizing natural gas is crucial.

Currently, a company’s emissions are monitored under Scope 1, 2, and 3 GHG emission targets. These emission targets were introduced by “The Greenhouse Gas Protocol” in 2001 and are laid to differentiate between direct and indirect emissions and monitor the emissions levels that can impact the global temperature rise. Hence, to sustain manufacturing activity, companies are compelled to abide by the Scope 1, 2, and 3 GHG emission targets.

Scope 1,2 and 3 targets to control emissions

Scope 1 and 2 targets, which govern emissions controlled by a company, are framed to limit global temperature rise to 1.5°C over pre-industrial levels. While Scope 3 targets, which govern emissions caused by different activities by a company, are linked with the level of decarbonization required to keep the increase in global temperatures well below 2°C over pre-industrial level.

Since the contribution of scope 3 emissions, majorly coming from energy usage are higher in the entire value chain, it becomes vital for companies to take necessary measures to prioritize within different sources of energy sources available.

Renewable sources of energy and its limitations

Renewable sources of energy are a few of the most viable decarbonization options. Yet, a complete transition towards it is difficult due to limited availability. One of the main reasons for this constraint is declining LCOE of renewable energy due to phasing out (retire) of existing infrastructure.

Although renewable sources of energy would be considered as a promising option to decarbonize the energy streams in future, there is still dependence on fossil fuels (natural gas) for manufacturing processes. Therefore, companies would require feasible solutions to decarbonize the balance portion of natural gas in their energy stream.

Carbon Capture Storage (CCS)

CCS is being adopted by companies to generate a low-carbon economy by minimizing carbon dioxide emissions. Major CCS processes include capturing of carbon dioxide in the pre-combustion stage by introducing hydrogen in the stream, the mix of which can further be used to generate electricity and capturing carbon dioxide through absorptive solvents in the post combustion stage.

Carbon dioxide captured using CCS system is usually transported in gaseous form through pipelines to geological storage site, or in liquid form, using high pressure tanks, to end user sites. Alternatively, carbon dioxide is permanently removed from the atmosphere by storing it in geographical foundations such as gas and oil reservoirs, deep saline formulations, coal beds, shale basins, and basalt formulations.

Limitations of Carbon Capture and Storage (CCS) – High Cost

Many of the geological storage techniques for carbon dioxide (CO2) is prohibited under international conventions and regional agreements. Further, there are no major technological developments made toward long-term storage of CO2, due to which challenges, such as leakage from geological storage sites are yet to be addressed.

Long-term storage of CO2 is associated with higher costs (usually 2–8 USD/Ton, depending on the region). The major issue in transporting liquid CO2 is requirement of a pressurized and semi refrigerated carrier, which adds to the cost. 

Methane Processing: Alternate Way to Decarbonize Natural Gas

Although the availability of alternate decarbonization techniques is low, methane processing (sometimes referred to as methane pyrolysis) in the pre-combustion stage of natural gas is gaining popularity as an alternative to decarbonization the balance portion of the natural gas usage.

For instance, Monolith, a chemical and energy company, developed a methane processing process in which the natural gas is converted directly into hydrogen and solid carbon using renewable electricity. This is one of the cleanest technologies that claims to have zero CO2 emissions, low electricity consumption, and less land and water requirements. Additionally, gives solid carbon as an output which can generate an alternate revenue stream.

Conclusion:

Amid extensive Scope 3 targets for the manufacturing industry toward decarbonizing energy sources and constraints in securing renewable energy supplies for complete transition, methane processing technique can prove to be a viable option for decarbonization of natural gas stream.