An Introduction to Carbon Capture

When the wind blows from east to west in the Gobi Desert singing can heard as the grains of sand vibrate together with a layer of silica to make a deep hum. The desert – a vast expanse in northern China and southern Mongolia – is known for its breath-taking dunes, mountains, and rare animals, such as snow leopards and Bactrian camels. 1,580 metres above sea level, spanning across 1,295 million square metres on land, the Gobi Desert is also home to the Gansu Wind Farm: the largest wind farm in existence. “With a planned capacity of 20GW, it’s the world’s largest wind farm in the world” (Nesfircroft). The project, worth a reported 17.5 billion USD, “will be home to 7,000 turbines and will produce enough energy to power a small country” (Nesfircroft). Thanks to the increased introduction of renewable energies, CO2 emissions have been massively reduced over recent years, but the existing carbon content in the atmosphere is too high to avoid catastrophic climate change. The latest IPCC report warns that limiting global warming to 1.5 degrees by 2100 will require “large-scale deployment of carbon dioxide removal measures” – beyond the increase of renewable energy (BBC). 

Carbon capture is the process of capturing carbon dioxide before it enters the atmosphere. This can be done through a variety of methods; Carbon Engineering’s system uses a fan to drag air (containing 0.04% CO2) across a filter soaked in a potassium hydroxide solution. The filter then absorbs CO2 from the fanned air, which then flows to a second chamber where the liquid is mixed with calcium hydroxide (builder’s lime). The calcium hydroxide, lime, then adopts the dissolved CO2, releasing flakes of limestone. Once sieved off, the flakes are heated in a third chamber until they decompose, releasing pure carbon dioxide, which is captured and stored. At each stage of this process the chemicals employed for the process are recycled back into the process, thus creating a closed reaction that repeats endlessly without the need for waste materials (BBC). 

aware_ presents 3 leading carbon capture companies on a mission to save the planet: 

carbon capture

Carbfix Turning Carbon Capture into Stone 

Carbfix is one the leading companies in carbon capture, operating as a single company since 2020 from Iceland. Revolutionary in its field, their pilot project enabled the process of turning carbon capture into stone within a matter of years, a process that was previously thought to take centuries (MindsetCo).

Once the carbon is captured at the source of the emitter, it is dissolved in water where it interacts “with reactive rock formations, such as basalts – highly reactive rocks – to form stable minerals providing a permanent and safe carbon sink” (Carbfix). The CO2 dissolved in water is then injected into the ground, where it creates reactive rock formations of basalt. In essence, the process developed by Carbix imitates and accelerates the natural process of storing carbon in rocks. Favourable rocks, water, and a source of carbon dioxide are required to successfully transform the carbon capture into stone.

Climeworks Carbon Capture Directly from the Air 

Climeworks captures carbon directly from passing winds. Their highly technical system successfully captures carbon in a two-step process. Firstly, using a fan the air is drawn into the collector. Captured upon a “highly selective” filter material the carbon dioxide is then captured on the surface. After this, the captured carbon dioxide is locked in a heated to a temperature between 80 and 100 degrees, which leads to a “high-purity, high-concentration carbon dioxide” (Climeworks).

This carbon capture is then recycled, used a raw material or removed from the air through safe storage. In addition to their unique modular design that can be stacked to build machines of any size, their direct capture machines are powered solely by renewable energy.  

“The grey emissions of our machines are below 10%, which means that out of 100 tons of carbon dioxide that are captured from the air, at least 90 tons are permanently removed and only up to 10 tons are re-emitted.” 


Net Power Carbon Capture to Create Clean Energy 

The clean energy company Net Power has developed a four-step process to use carbon capture to generate advanced clean energy. Through burning natural gas with pure oxygen, the resulting captured CO2 is recycled “through the combustor, turbine, heat exchanger, and compressor, creating lower-cost power with zero emissions” (Net Power).

The first step is the process of burning natural gas with pure oxygen (instead of air). Pure oxygen leads to less fuel consumption and the flame temperature can be increased, leading to higher levels of efficiency. The resulting carbon capture is subsequently led to a heat exchanger, water is then removed and “pumped back into high-pressure”. After this, the high-pressure CO2 is reheated and recycled. Finally, the surplus CO2 from step 2 is captured and prevented from entering the atmosphere.

“The resulting CO2 is recycled through the combustor, turbine, heat exchanger, and compressor, creating lower-cost power with zero emissions. 

Captured CO2 is pipeline ready and can either be cheaply sequestered or sold to industries such as the medical, agricultural, and industrial sectors.” 

– Net Power

– By Kim N. Fischer

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