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The High-Tech Solutions for Carbon Removal You Should Know About

Droughts, floods, and devastating forest fires, these are the climate disasters we have all seen on the news this year. Climate change impacts can no longer be ignored, and climate experts warn that this is just the beginning. Too much CO2 is already out in the atmosphere and while reducing emissions is crucial, so is removing CO2 from the atmosphere too in order to lower overall existing CO2 levels. Only by doing both will we be able to prevent a temperature rise of more than 1.5 degrees Celsius.

Natural systems, for example forests, absorb carbon from the air through photosynthesis but there are high-tech developments that do the same thing through chemicals and mechanics, called carbon dioxide removal (CDR) systems. These systems are gaining traction, showing some promising first results. One example of CDR is Direct Air Capture (DAC), which absorbs air from the atmosphere and separates the CO2, so it can be reused or stored underground. It is a straightforward idea: Filtering out what should not be in the air. Unfortunately, putting the idea into practice is not as straightforward, as the technology behind DAC is based on complex chemical reactions and mechanical systems.

While it is also critical to reduce emissions, our climate goals can only be met by removing the carbon that already exists in our atmosphere — Carbon180 [1]

Direct Air Capture

Humans have emitted way more carbon than could be safely sustained in the future, despite warnings to drastically lower emissions as soon as possible. As a result, to meet the UN Climate Goals we will not only have to reduce CO2 emissions but we will also have to remove a staggering 1,000 gigatons of CO2 by 2100 and pollute no extra [2]. So how do we achieve this goal? DAC can be part of the solution.

How it works

Example of Direct Air Capture Fans. Photo: Carbon Brief

During DAC, large fans draw air through a highly selective filter that collects CO2 molecules on its surface material. While there are many different methods to capture CO2 molecules, two ways stand out in particular and are used the most often today. The collector either works with CO2-grabbing chemicals that dissolve in water (liquid solvent), or CO2-grabbing chemicals that attach to solid material (solid sorbent). Apart from this difference in method, the facilities look the same and both rely on a chemical reaction with CO2.

In a follow on step, heat is needed to release the CO2 from either the solid or liquid chemicals. The process gasifies the captured CO2. There are two options to use the pure CO2, including temporary or permanent storage.

  1. Mix the captured CO2 with water and then pump it underground. Over the course of several years, it would then mineralise into stone [3]. This process is carbon-negative and thus a permanent solution.
  2. Reuse the CO2 in materials like plastic, fuel, and construction material. This is considered a temporary solution since reusing the gasified CO2 will not lower overall emissions, but rather reuse atmospheric CO2. Reusing the CO2 makes DAC possibly more attractive for companies because, in comparison to the underground storage alternative, money can be made from the captured CO2.

The “cleaned” air can be released into the atmosphere and the chemicals can be reused for another round of carbon capturing.

If you want to know more, here’s a short video explaining how DAC works.

[…] Carbon is more than just a pollutant — it is a fundamental part of the planet and our lives. With the carbon we draw from the air, we can power new industries, enrich our lands, and foster a prosperous world. — Carbon180 [1]

While this process may sound very easy and straightforward, it is in fact a really complex system and DAC technology does face an array of challenges.

Challenges of Direct Air Capture

Energy

Deeper and bigger collectors capture more CO2, but the bigger the collector, the more energy is needed for the process to work. DAC plants, therefore, need an optimized design to work with the maximum surface area possible and a relatively shallow collector depth.

The technology also relies on heat and therefore energy. The location of the plant should be chosen based on the availability of sufficient energy sources, for example, locations with geothermal heat, wind, or solar power. How green the DAC plant can operate heavily depends on the energy source that’s being used. DAC could potentially work on 100% renewable energy, while powering a DAC plant with coal would emit more CO2 than it captures. Some plants rely on natural gas as an energy source, and capture the CO2 emissions within the plant; so in this case no extra CO2 is released into the air.

Direct Air Capture technology today uses either a liquid or solid capture system. Solid sorbent systems require only 80–120 degrees C to separate the CO2 from the chemical material [4]. Hence, using lower-grade waste heat could be a cheap solution to achieve this temperature. Liquid solvent systems on the other hand must reach 900 degrees C, and are therefore much more energy-intense [4]. Liquid extraction systems only make sense if there are affordable and green energy systems nearby. Otherwise, it could easily cost as much as $1,000 per ton of CO2 just to capture the CO2, not including additional costs for processing.

Location

While DAC is generally location-independent, it’s difficult to find locations that provide ideal circumstances. Water accessibility, CO2 storage options, acceptable meteorological conditions, permitting issues and most importantly the energy source that fuels the carbon extraction determine the placement of a DAC site.

Price

Removing 1,000 gigatons of CO2 by 2100 would require 13,000 DAC plants; a capital investment at today’s rate, of almost $1.7 trillion.

Furthermore, current calculations for removing a ton of CO2 vary significantly. Arguably ambitious price rice tags are put between $100 and more than $1,100. However,high DAC prices are a problem today, but this may change in the future as prices for the technology will drop with further development and scale.

Opportunities for Direct Air Capture

PET bottles made from captured CO2. Photo: Mibelle Group

Captured CO2 can be used for the production of plastics, iron, steel, biofuels, natural gas processing, cement making and various other products.

Goodwill for removing CO2 does not pay the bills. Therefore, the fact that captured carbon can be manufactured and sold in new products helps make it an attractive business case. Luckily DAC receives increasing attention from governments, policymakers and investors which will further improve and drive the development of this technology [5].

Building more DAC sites will teach us more about the technology itself and also about how to bring the costs down. Companies like Climeworks, Carbon Engineering and Carbfix are all expanding and scaling their DAC technologies.

DAC sites are helpful but not the ultimate solution for the current climate crisis. Access to renewable energy to fuel DAC systems still poses a major challenge for the solution to scale. Yet, DAC has earned its place in the portfolio of CO2 solutions. DAC is location-independent, it is scalable and DAC sites provide job opportunities. As research progresses, we will be able to build DAC systems efficiently and sustainably in the future.

Other technologies

Next to DAC, there are of course other carbon capture techniques being tried and tested.

Carbon-rich bio-oils

Another approach for capturing CO2 from the atmosphere is the technology used by the company ‘Charm’. They collect agricultural residues after crop harvesting and turn the biomass into bio-oil that is rich in carbon. Charm works with pyrolysis, which is basically a process of heating organic material in the absence of oxygen [6]. The company pumps the bio-oil deep into the ground to permanently store away the carbon. Charm sells plans to offset CO2 emissions to households and companies.

Blockchain

You’ve probably heard about cryptocurrency by now, but there’s more than Bitcoin or Ethereum. The company NORI created a cryptocurrency that pays farmers for carbon capture and allows carbon removal activities to be measured and monetized easily.

With blockchain technology, the company created a marketplace to offset carbon. Farmers adopt sustainable farming practices, which can be quantified and verified. These carbon removals can then be purchased by everyone in the form of a cryptocurrency.

Machine learning and satellite data

Machine learning can support sustainable development. Offset projects have historically been not very transparent. Pachama has developed a new kind of carbon removal marketplace. Through machine learning they can check projects to ensure that carbon in old-growth trees stays protected. Using satellite data, they can monitor that new trees are planted and protected continuously. The result is more transparency in offseting carbon emissions for individuals and companies.

Summary

High-tech innovations can play a vital role in our carbon removal portfolio. While we still need to focus on technologies and systems to help us find ways to produce fewer emissions to fight climate change, we also need technologies like Direct Air Capture to help remove CO2 from the atmosphere and reach our climate goals by 2050. But technology alone won’t solve the current climate crisis. We also need regulation, subsidies and carbon taxes to build carbon-neutral and carbon-negative systems. To achieve this, a collective mindset in the same direction is needed across borders.

Advances in DAC technology have the potential to make removing CO2 from the atmosphere feasible, scalable and affordable. These technological advances give us hope, but their complexity can also leave us feeling unsure of where we fit into the process. On a smaller scale, tech can help us understand our own role in fighting climate change.The ecomove App helps you to measure your individual CO2 footprint and act to reduce it. Personal awareness and the ability to measure and quantify our own carbon emissions are the first steps you can take to start making effective decisions about living more sustainably. Start the change. Ignore no more. Identify, quantify and understand your personal transport emission using the ecomove app here.

Sources

[1] carbon180, 2021 | https://carbon180.org/

[2] Ober, 2021 | https://www.universityofcalifornia.edu/news/can-we-remove-carbon-dioxide-atmosphere

[3] iea, 2021 | https://www.iea.org/reports/direct-air-capture

[4] Lebling, McQueen, Pisciotta & Wilcox, 2021 | https://www.wri.org/insights/direct-air-capture-resource-considerations-and-costs-carbon-removal

[5] Ozkan, 2021 | https://link.springer.com/article/10.1557/s43581-021-00005-9

[6] Gossman Forensics, 2021 | https://gossmanforensics.com/pdf-library/pdf-analytical-methods/pyrolysis.pdf