What is carbon capture and storage

Carbon capture and storage (CCS) is the process of extracting carbon dioxide (CO2) from industrial emissions, then transporting it (via ship or pipeline) for permanent storage. The aim of CCS is to help tackle global warming – not by reducing or offsetting emissions – but by capturing them at the source and stopping them from entering the atmosphere in the first place.

There are three steps to the CCS process:

• Capture the CO2
  The CO2 is separated from the other gases which are also produced during industrial processes.
  
• Transport the CO2
  The CO2 is compressed and transported to a storage site via pipelines, road and/or ship.
  
• Store the CO2
  The CO2 undergoes any steps required to prepare it for permanent storage. These steps will vary depending on the storage method chosen.

 

In this article, we provide a comprehensive overview of CCS, including what it is, how it works, and more specifically what it means for global shipping.

 

What is carbon capture?

 

Carbon capture is the first stage in the three-stage carbon capture and storage process. It involves using sophisticated technology to capture CO2 emissions from large-scale industrial processes, such as: 

• Biomass power plants
• Coal-fired power plants
• Integration gasification combined cycle (IGCC) power stations
• Global shipping
• Refinery, steel, ammonia and cement plants
• Natural gas processing plants

 

By preventing the emissions from entering the atmosphere, carbon capture plays a role in addressing climate change.

 

What is carbon capture storage?

 

Carbon capture storage involves storing the CO2 which has previously been collected during carbon capture. There are a few different ways in which captured CO2 can be stored, including:

• ‘Unmineable’ coal
  Some coal is too difficult to mine, however this makes it suitable for use for carbon capture storage. If the coal is permeable, it can absorb CO2 and be used to store the gas instead of it going into the atmosphere. As an additional bonus, this process also releases methane from the coal, which can be captured and used as fuel.
  
• Saline aquifers
  Saline aquifers are deep rock formations that have concentrated brine (salt water) in their pores. These can be used during carbon capture and storage to act like big sponges that can absorb CO2 that has previously been captured.
  
• Mineral storage
  Mineral carbonation is a naturally-occurring process during which CO2 reacts with the iron, magnesium, and calcium naturally found in rocks and turns into a solid carbonate. This process prevents the CO2 from being released back into the atmosphere and, as such, is a viable long-term storage solution for CO2 which has been captured.
  
• Enhanced oil recovery (EOR) 
  Captured CO2 can be injected into depleted oil and gas reservoirs for storage. This option has the added benefit of helping to increase oil production, making EOR an attractive option for CO2 storage because the cost can be offset by the money made from selling the additional oil.

 

How does carbon capture work?

 

The main aim of carbon capture is to stop CO2 that is produced during industrial processes from making its way into the atmosphere. There are three main points at which carbon capture can be used to help to do this:

 

• Post-combustion
  This process involves removing CO2 after burning the fossil fuel. During post-combustion carbon capture, CO2 is captured from the exhaust and then transported and stored.
  
• Pre-combustion
  Pre-combustion carbon capture is when the CO2 is captured before burning the fossil fuel. This process involves partially burning the fossil fuel in a gasifier to produce a synthetic gas, which is mainly a combination of CO2 and hydrogen. It is then relatively easy to separate the CO2 and hydrogen. Once separated, the CO2 is transported and stored and the hydrogen is used as an alternative fuel.
  
• Oxyfuel combustion
  Oxyfuel combustion involves burning the fossil fuel in oxygen instead of air. This process results in mainly just CO2 and water vapour being produced. As a result it is seen as a more environmentally friendly process as the water condenses and the CO2 can be captured, transported and stored.

 

Why is CCS important for global efforts to reduce carbon emissions?

 

We have seen widespread concern about the need to curb greenhouse gas (GHG) emissions in a bid to tackle climate change. As part of this, the 2015 Paris Agreement set an ambitious target to limit future temperature increases to 1.5°C. It will take a global effort across all industries to achieve this, meaning the call for more environmentally friendly operations is a high priority for all. CCS is one of a range of initiatives to address global warming and is playing a growing role in international decarbonisation strategies.

 

How does carbon capture impact shipping?

 

Global shipping is responsible for approximately 3% of global carbon emissions. So as international efforts to curb GHG emissions ramp up, so too are the requirements being placed on the shipping industry. The International Maritime Organization (IMO) has introduced a target to reach net-zero GHG emissions by or around 2050. In addition, a range of new regulations and legislations have been introduced across the maritime and offshore sectors, as well as a general move towards renewable energy as part of the wider energy transition. These include the EU ETS (Emissions Trading System) and the Carbon Intensity Indicator (CII). 

Carbon capture supports international decarbonisation strategies and offers a valuable tool in the fight against climate change. As a result, it is of increasing interest to the maritime and offshore sectors and carbon capture is impacting shipping in a range of ways, including:
 

• Encouraging the development of new carbon capture technologies ahead of predicted widespread deployment in the future.
• Influencing ship design as the need to integrate onboard CCS systems with other onboard systems grows impacts the design and layout of vessels.
• Reducing shipping’s carbon footprint without the need for alternative fuels. This makes CCS a viable route for helping the shipping industry become more sustainable in the short-term.
• Helping achieve decarbonisation targets by installing onboard carbon capture technology offers a relatively fast way to reduce CO2 emissions across the shipping industry, helping stay on track to reach ambitious goals.

 

What is onboard carbon capture and storage on ships?