Decarbonisation Technology - November 2021

dependence and stimulates trade. Amongst the range of clean energy vectors, such as low carbon hydrogen, ammonia, and methanol, all fall short of LNG when it comes to volumetric energy density, which is the important factor for long- distance shipping. Whilst the CO 2 emissions at the power plant from gas fired electricity generation are significantly less than coal, only a tiny amount of methane leakage would give the gas fired option an equally damaging greenhouse gas footprint. It is essential to consider the full lifecycle analysis of fuels production, distribution, and utilisation. Going underground CCS is also an established technology. In Europe, more than 20 years ago, Equinor commenced capture and sequestration of CO 2 on the Sleipner West field in the Norwegian sector of the North Sea. The components of a CCS scheme, from the absorption tower to the multi-stage CO 2 compressor with integrated drying system, are highly developed. Beyond Norway, CCS has also been used in Australia, Canada and the United States for many years. The use of safe, permanent underground CO 2 storage in saline aquifers, depleted oil and gas reserves for CCS schemes is an area where midstream and upstream operators can rise to the decarbonisation challenge. The expertise that has been used to explore and drill for oil and gas can be applied to developing CCS reservoirs. Furthermore, the associated pipeline transmission infrastructure is likely to be adaptable to become the backbone of a CO 2 disposal network. Most existing CCS schemes are point to point, meaning that one carbon capture location such as an ammonia plant SMR is connected to one underground geological CO 2 storage location. This simple model will transition to more complex ‘hub and cluster’ schemes where CO 2 will be captured from several plants and fed into a feeder network connected to a long-distance transmission pipeline. This will mirror the existing natural gas pipeline grids. Sub-surface technologies can also be used for mid-term and long-term storage of energy gases. To add flexibility to integrated energy systems in the future where reliance on variable renewable energy will increase, long-term, high-capacity energy storage will be essential to balance

focus on high emission sources. Delivering on the Pledge would reduce warming by at least 0.2°C by 2050. Major sources of methane emissions include oil and gas, coal, agriculture and landfills. Of these sectors, the greatest potential for short- term methane abatement by 2030 is within the energy sector. Oil and gas sector can rise to the challenge Energy usage in industrial, domestic and transportation is responsible for an overwhelming proportion of greenhouse gas emissions. The oil and gas sector is fundamentally an energy business, and it will therefore be integral to the transformation to climate neutral energy vectors and efforts to minimise the impact of fossil fuel usage. Conversion of natural gas to blue hydrogen and low carbon ammonia or methanol is one value chain that the midstream and downstream sectors are in pole position to lead. But methane emissions must ruthlessly be eliminated. Additionally, CO 2 released with methane from the reservoir and CO 2 generated from the energy requirements of gas processing and liquefaction must also be mitigated. Blue hydrogen relies on capturing the CO 2 that is released from the reforming process chemistry and capturing the post-combustion CO 2 emissions from the fired burner that is used to generate the heat energy, which is required to drive the reforming reactions forwards towards hydrogen production. Whether the CO 2 is then utilised or sent for permanent underground storage or mineralisation is of secondary importance – the first stage of the process relies on carbon capture. There may be latent concerns about classical CCS with underground CO 2 storage, but the idea of CCS as 'Carbon Capture and Something' begins to turn the focus towards capturing the carbon, thus leaving the next steps open. At the very least that approach may get some traction behind carbon capture, whilst the debate about the long- term storage mechanism can take place in parallel to constructive action. Displacement of coal fired power generation with pipeline natural gas or LNG is another area where the midstream sector will most likely be busy for the coming decades. LNG can connect energy producers and consumers. Through its transportability it creates international inter-