We’ve all seen the headlines and climate action plans shouting “net-zero by 2050,” right? It’s easy to assume that this means we’re aiming for a complete stop in the pollutants we emit. But here’s the catch: the “net” in “net-zero” means that we’re not aiming to drive production of carbon dioxide to zero — instead, it means striving to balance inputs and outputs so that we reach an equilibrium. This means that the CO2 being produced is digested by the environment at the exact same speed - preventing net increase in atmospheric CO2. Achieving net-zero doesn’t rely solely on cutting emissions, it also involves strategies known as carbon capture and carbon sequestration.

First, what’s the difference between carbon capture and carbon sequestration? Carbon capture involves directly capturing emissions from sources, like the smokestacks of power plants that release pollutants. Carbon sequestration, on the other hand, is a method to store the captured carbon dioxide for long-term purposes. .Carbon sequestration happens naturally in places like forests and oceans, which act as carbon sinks by absorbing CO2 through natural processes. We can use this concept to create our own sequestration methods. In short, carbon capture means collecting the gas, while carbon sequestration refers to storing it.

Carbon capture and sequestration is combined in the industry under the term ‘CCS’—carbon capture and storage. This process occurs in three stages: capture, transport, and storage. First, we capture the carbon dioxide that is mixed with other gases and concentrate it into pure CO2. Then, the carbon dioxide is chilled into a liquid and transported—by pipeline, ship, or vehicle—to a storage site. The storage, or sequestration, stage gets a bit more complicated, as you’ll read below.

One strategy for sequestration is deep ocean disposal, where a pipeline is used to inject carbon dioxide at least 2.7 km below the ocean’s surface. At this depth, the CO2 will sink and remain at the ocean floor, preventing it from resurfacing. Since carbon dioxide becomes acidic in water it can pose a risk to aquatic life.To address this issue, new technologies are being explored to ‘neutralize’ carbon dioxide before disposal. The CO2 can be reacted with water and a solid compound, such as calcium bicarbonate, to neutralize the acid before sending it down into the aquatic environment. The other sequestration strategies take place on land, where CO2 is injected into unmineable coal beds, empty salt mines, depleted oil or gas reserves, or deep aquifers (underground layers that store water).

These two categories — storage in water and  underground, covers most of the technology we see today with carbon sequestration. 

CCS technologies help us lock carbon dioxide away from our atmosphere where it’s contributing to warming - so we love it. While it clearly plays a crucial role in reducing emissions, it can’t be our only solution to reach net-zero. To effectively tackle climate change, we must address global consumption and prioritize investments in renewable energy.  Wind, solar, hydro, and geothermal power generate electricity without emitting carbon dioxide in the first place, making them essential to our net-zero goal. CCS technologies can sequester the carbon we have already emitted, but if we don’t stop these emissions even sequestration will reach it’s capacity. By expanding clean energy use and improving grid infrastructure, we can significantly lower emissions. In the meantime, CCS technologies provide a necessary backup, capturing and storing emissions from sectors that are struggling to decarbonize or places that still need time to transition to renewables. Together, these technologies form a complementary strategy that supports the transition to our net-zero target.

There are also some exciting new advancements in CCS. For instance, we can inject carbon dioxide into coal seams, forcing methane stored in the seams to rise to the surface, where it can be used as a natural gas for energy production. Scientists are also exploring the concept of carbon dioxide recycling! These innovations highlight the potential for new breakthroughs in our fight against climate change. By transforming waste into valuable resources alongside reducing emissions, we can make significant strides toward sustainability. As research continues, these technologies could play a crucial role in helping us achieve our global climate targets and build a more sustainable future!