The Carbon Negative Solutions That Remove CO2 From The Atmosphere

More companies than ever before are making commitments to be carbon neutral or even carbon negative. Earlier this year, Microsoft committed to going carbon negative by 2030. Swedish retail giant IKEA made the same promise along with a goal that all their products will be “100% circular”, meaning fully reusable or recyclable.

Both ‘climate positive’ and ‘carbon negative’ mean the same thing: removing CO₂ from the atmosphere in order to make a positive impact on climate change. While the term carbon negative is established in the U.S., climate positive is gaining ground in Europe.

Why we need carbon negative solutions

Achieving the challenging climate targets set out in the Paris Agreement requires more than just cutting emissions. For one thing, not all industries or sectors in society will be able to achieve net zero emissions by 2050. It is challenging to reduce emissions in agriculture and mobility to net zero and to offset other greenhouse gas emissions like methane and nitrous oxide. So, to keep the global temperature rise to no more than 1.5 degrees higher than pre-industrial levels, the IPCC has said we must proactively remove CO₂ from the atmosphere.

The IEA has consistently said that the global energy transition requires a portfolio of technologies and measures. Those for carbon removal can be grouped into three broad categories: nature-based ‘carbon sink’ solutions, the enhancement of natural processes, and new technologies. Within these categories individual approaches are interlinked in many ways and provide benefits beyond CO₂ removal.

Nature-based solutions

One of the simplest ways we can create carbon sinks is to stop cutting down trees and encourage reforestation and the seeding of forest in new areas. Simply put, trees absorb and store carbon but dead trees release it. Approximately 31% of the earth’s land surface is forested, but that is down from almost 46% in the pre-industrial era.

Norway has ploughed more than $1 billion into the Amazon Fund, a mechanism designed to reduce emissions from deforestation and forest degradation of the Amazon rainforest. Organizations like the Rainforest Foundation also deliver concrete results across central Africa and Asia/Oceania. There are concerns over the potential for wildfires to destroy that carbon store, so reforestation alone isn’t a silver bullet and the retention time and safeguarding are not straightforward.

Enhancing natural processes

The natural processes of our planet store carbon, but we can help the process along through proactive land management tools and techniques. Improved land management could store up to nine billion tonnes of CO₂ each year. Two such methods include the use of biochar and seaweed.

Managing waste is a major challenge for all cities. Organic waste from parks and gardens can be turned into biochar for use as soil, which minimizes waste while establishing a new carbon sink. Researchers from several Nordic countries have formed the Nordic Biochar Network to spread knowledge and experience about biochar.

Researchers have found that seaweed plays an important role in permanently moving CO₂ from the atmosphere into ocean sediments. While better managing seaweed-dense areas known to be carbon negative can help the climate crisis, increasing the amount of farmed seaweed could also help to solve the future food crisis. It is key though to keep track off the carbon, the retention time and where it ultimately ends up.

The concept of enhanced weathering also deserves wider consideration. Weathering erodes rocks over millions of years, washing them into the oceans and solidifies CO₂ in the process. Enhanced weathering is the process of pulverizing silicate rocks to bypass the slow weathering process and enjoy the benefits much faster. Enhanced weathering makes water more alkaline, helping to counter acidification, while the process can also improve crop yields and restore degraded soils.

This can also be done in industrial processes by mineralizing CO₂ using, for example, mafic minerals like Olivine or Basaltic rocks, but typically 3-10 kg of rock needs to be moved around for each kg of CO₂ saved.

The weathering processes are also quite slow as pointed out earlier and thus could become irrelevant for the 30-year timeframe for climate neutrality. Injecting CO₂ into young basaltic rock as undertaken at the CarbFix storage site in Iceland shows much faster reactions and fixation, albeit used to re-inject CO₂ and H₂S from geothermal heat extraction.

New carbon negative technologies

Finally, new technologies to remove CO₂ at source or from the atmosphere for storage elsewhere are in rapid development.

Carbon capture and storage (CCS) technologies can be used in conjunction with bioenergy, the burning of biomass for energy, to create a carbon negative solution. According to the IPCC this process alone has the potential to permanently store gigatonnes of CO₂ every year, although this is reliant on sustainable biomass availability and the full-scale implementation of CCS. Norway’s recent announcement of the Longship CCS project is a major step on the road to full-scale CCS implementation including CO₂ of biogenic origin from waste to energy plants.

Another technological solution that needs further development is the direct-air capture of CO₂. This technology uses chemicals to remove CO₂ from ambient air, which can be stored underground. If  used in the production of materials such as plastics it could be climate neutral, but if the ultimate disposal is in a waste to energy plant with CCS, it becomes carbon negative.

Further research and development is needed to bring down the cost and the amount of energy needed to power the necessary infrastructure for the technology to work at scale. Finally, an exciting new technology to indirectly remove CO₂ from the air via seawater is also under development, which could also help to slow the alarming acidification of the oceans which are increasing at an alarming rate.

The next steps

Of course, it is important to say that none of these carbon removal techniques and technologies are an alternative to cutting emissions nor an excuse for slowing down other measures. But they will inevitably play an important role in a portfolio of comprehensive solutions to the climate crisis.

As part of their recent commitment to going carbon negative, Microsoft pledged to invest $1 billion over the next four years into the technologies needed to achieve such a shift. “We understand that this is just a fraction of the investment needed, but our hope is that it spurs more governments and companies to invest in new ways as well,” said a company statement.

At present, such solutions experience market failure as they do not produce many other benefits besides removing CO₂ from the atmosphere, obviously a common good. In order to stimulate the market desire, it is important that Governments and the EU speed up the research and innovation efforts into such solutions.

There is no doubt that such solutions are needed, but it will take more than investment from technology companies to move the needle and develop these technologies to work at-scale.