What is Carbon Capture and Storage?

What is carbon capture and storage?

CCS stands for ‘carbon capture and storage’ and is a method used to reduce carbon emissions from industrial processes that create a lot of carbon dioxide (CO2). Sometimes called ‘CO2 capture’, it involves three main stages: capturing the carbon, transporting it, and safely storing it underground. The goal is simple: prevent harmful gases from entering the atmosphere and contributing to climate change.

In 2022, CO2 emissions exceeded 36.8 gigatonnes (equivalent to 36,800,000,000 tonnes), a record level that highlights the growing challenge of tackling global warming. A few years earlier, the Paris Agreement saw nearly 200 countries commit to actions that limit long-term global temperature rise to 1.5°C above pre-industrial levels. However, extremely high levels of CO2 are still entering the atmosphere, and at the current pace, we could pass the 1.5°C threshold as soon as 2030.

By storing carbon underground, we ensure that the CO2 doesn’t get released into the atmosphere and contribute to the warming of the planet. This means industries can continue producing energy and goods while reducing their carbon footprint and supporting the UK's efforts to reach its net-zero targets.

If you're curious about how these emissions affect the planet, you can read more in our guide on greenhouse gases.

How does carbon capture technology work?

Carbon capture technology focuses on removing carbon dioxide from emissions of industries like power plants and factories. Here’s a breakdown of the three main steps involved.

Capture

The first step is capturing the CO2. There are several different methods to do this, including:

• Post-combustion – CO2 is captured after burning fossil fuels, often from exhaust gases.

• Pre-combustion – CO2 is separated before fuel is burned by turning the fuel into gas.

• Oxyfuel combustion – Oxygen is used in the combustion process, creating a concentrated CO2 gas that’s easier to capture.

Transportation

Once the CO2 is captured, it needs to be transported to a safe storage site. This is usually done through pipelines, which are long, pressurised tubes that securely carry the CO2 over long distances.

In some cases, carbon dioxide can also be transported by ship or lorry, especially if the storage site is located a distance away from the source of the emissions. However, pipelines are the most common and efficient way to transport gas as they have large capacities and can operate continuously without needing as much manual supervision or energy requirements compared to other transport options.

CO2 is also compressed before being transported, turning it into a liquid or dense gas that takes up less space and can be moved more easily.

Storage

The final step is storing the captured CO2 deep underground in secure geological formations. These locations are chosen because they are stable and unlikely to allow the CO2 to escape back into the atmosphere.

Some common storage sites are:

• Depleted oil and gas fields – These are areas where oil and gas have already been extracted, and they ideally need to be 1km or more underground. Since the CO2 is stored in rock formations that once held oil or gas, these sites are ideal for preventing leaks.

• Saline aquifers – These are underground layers of rock filled with salty water. They’re found deep beneath the Earth’s surface and can hold large amounts of CO2 safely.

The CO2 is injected into these sites and kept at high pressure to prevent it from escaping. Over time, the carbon dioxide becomes trapped in the rock layers, just like oil or gas was in the past, making sure it stays secure. The Intergovernmental Panel on Climate Change (IPCC) has commented that the right geological storage site could trap carbon dioxide for millions of years and keep 99% of the injected CO2 for over 1,000 years.

The benefits of carbon capture

Carbon capture and storage offers multiple benefits, especially when it comes to fighting climate change and reducing carbon emissions.

Here’s a closer look at the positive sides of CCS:

1. Helps reduce harmful CO2 emissions

One of CCS's biggest advantages is its ability to significantly reduce CO2 emissions from industries that produce a lot of carbon, like power plants, cement factories, and steel mills.

By capturing and storing this CO2, CCS helps prevent it from entering the atmosphere and contributing to global warming.

2. Supports industries while reducing their carbon footprint

Industries like power generation and manufacturing are essential to our daily lives, but they also produce large amounts of CO2. Instead of shutting down these high-emission industries, CCS allows them to reduce their carbon footprint while continuing to meet the demand for goods and services.

3. Provides a way to meet net-zero targets

The UK government has set ambitious net-zero goals to reduce its greenhouse gas emissions to virtually zero by 2050.

CCS is a key technology in achieving these goals, particularly in industries that are difficult to decarbonise, like heavy manufacturing and chemical production.

By capturing and storing excess CO2, CCS helps the UK move closer to reaching net zero without drastically changing these industries.

Read more about net zero here.

4. Can create new jobs and support the green economy

The development and implementation of CCS technology could create a range of new jobs, from engineers to technicians to researchers. As new storage sites are developed and the technology becomes more widespread, it could also support the growth of a green economy, helping to shift industries towards sustainable practices.

The disadvantages of carbon capture

While carbon capture and storage (CCS) has many benefits, it’s not without its challenges. Here are some of the potential downsides to consider:

1. High costs

One of the biggest hurdles for carbon capture and storage is the cost. The technology itself, including building capture plants, transportation pipelines, and storage sites, which also require careful monitoring to keep them safe, can be very expensive.

Not only does the initial setup require significant investment, but maintaining storage sites over long periods of time adds to the cost. As a result, it can be financially challenging, especially for smaller companies or industries.

2. Energy-intensive process

Capturing and compressing CO2 is extremely energy-intensive, requiring a substantial amount of energy itself. In some cases, the energy needed for the CCS process can come from fossil fuels, cancelling out some environmental benefits. In fact, capturing and compressing CO2 boosts the fuel consumption of a coal-powered electricity plant by 25–40%.

Because of this, it’s essential to make sure that carbon capture and storage systems are powered by renewable energy to truly reduce carbon emissions in the long run.

3. Long-term storage uncertainty

Although CCS is designed to store CO2 safely underground, there are still some questions about its long-term stability. Over time, there’s a risk of leaks or fractures in the rock formations, which could cause the CO2 to escape back into the atmosphere. While unlikely, these leaks could be caused by human activities like mining or natural disasters like earthquakes.

4. Limited availability of suitable storage sites

Not all locations are suitable for carbon dioxide storage, which limits the areas where it can help. For example, depleted oil and gas fields and saline aquifers need the right geological conditions, and there’s only so much space available. This can reduce the scale of carbon capture in some regions, meaning it may not be a viable solution everywhere.

5. It doesn’t address the root cause

Carbon capture and storage help reduce emissions, but they don’t directly address the root cause of the problem: the burning of fossil fuels.

While it’s an important tool in the fight against climate change, CCS shouldn’t be seen as a substitute for shifting to renewable energy sources, such as wind, solar, and hydroelectric power.

A balanced approach that combines CCS with renewable energy solutions is essential for tackling climate change in the long run.

Do your part in achieving net zero with UW

Understanding how CCS fits into the bigger picture is essential as we all work towards a more sustainable future. Alongside shifting to renewable energy sources, we can also make changes in our daily lives to reduce our energy consumption.

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