Direct Air Capture and its potential (1 of 3)

As I started writing this piece, I realized Direct Air Capture deserves space and thorough explanation, which is why I decided to divide this Article in three pieces, the first one where I explain what Carbon Removal and Direct Air Capture is, the Second One where I talk about the Challenges and advantages of it and the final one where I will address the next steps in the Direct Air Capture pathway. Let´s begin.

Why Carbon Removal?

I first got involved in Carbon Removal, when I read the Intergovernmental Panel on Climate Change special report on the impacts of global warming of 1.5 °C above pre-industrial levels and related global greenhouse gas emission pathways (IPCC Special Report), the report highlighted, among other things:

 “…Global warming of 1.5°C is projected to shift the ranges of many marine species to higher latitudes as well as increase the amount of damage to many ecosystems. It’s expected to drive the loss of coastal resources and reduce the productivity of fisheries and aquaculture (especially at low latitudes). The risks of climate-induced impacts are projected to be higher at 2°C than those at global warming of 1.5°C (high confidence). Coral reefs, for example, are projected to decline by a further 70–90% at 1.5°C (high confidence) with larger losses (>99%) at 2ºC (very high confidence). The risk of irreversible loss of many marine and coastal ecosystems increases with global warming, especially at 2°C or more (high confidence);P overty and disadvantage are expected to increase in some populations as global warming increases; limiting global warming to 1.5°C, compared with 2°C, could reduce the number of people both exposed to climate-related risks and susceptible to poverty by up to several hundred million by 2050 (medium confidence)”

This is triggered a question: why are we giving ourselves permission to continue to increase the temperature to 1.5°C, when the consequences are already so harsh?

Against this background, I started doing research for my master thesis, and since then I only find more and more reason to believe carbon dioxide removal (CDR) as one of the key tools for climate action, not only because it can help meet the temperature targets of the Paris Agreement, but also because it provides true sustainable development.

What is it?

Carbon dioxide removal is the process of removing carbon dioxide from the atmosphere and locking it away for decades, centuries, or millennia. While reducing greenhouse gas emissions is critically important, carbon removal is necessary to reach net-zero carbon emissions and slow, limit, or even reverse climate change. The IPCC estimates that up to 1,000 gigatons of carbon dioxide will need to be removed from the atmosphere by the end of the century. Some of the prominent methods for carbon removal include afforestation/reforestation, soil carbon sequestration, biochar, bioenergy with CCS or BECCS, enhanced mineralization, and direct air capture (DAC). Land-based carbon removal is currently one of the most available forms of carbon removal. However, there are concerns about how permanent these removals are.

Carbon removal is a complex and rapidly evolving field, with ongoing research and development focused on improving existing technologies and developing new approaches. One of the key challenges in the field is developing cost-effective and scalable solutions that can be implemented at a large scale. Many carbon removal technologies are still in the early stages of development and are not yet commercially viable.

Another challenge is ensuring that carbon removal is deployed in a responsible and sustainable way. For example, large-scale afforestation or reforestation projects can have negative impacts on biodiversity and local communities if they are not carefully planned and managed. Similarly, carbon removal technologies that rely on large amounts of energy or water may not be suitable for use in water-stressed or energy-poor regions.

Despite these challenges, there is growing recognition of the importance of carbon removal in meeting global climate goals. As many countries and organizations set ambitious targets for achieving net-zero emissions investing in carbon removal technologies becomes more and more relevant.

In addition, carbon removal can play a key role in addressing environmental justice and equity concerns. Low-income and marginalized communities often bear a disproportionate burden of climate impacts such as extreme weather events and air pollution. Carbon removal projects that are designed and implemented in collaboration with these communities can provide multiple benefits, including job creation, improved health outcomes, and increased resilience to climate change.

It is important to note that while CDR is an important tool for addressing climate change and it could potentially slow, limit, or even reverse climate change —it is not a substitute for cutting greenhouse gas emissions. CDR should not be seen as a silver bullet solution. The most effective way to address climate change is by reducing greenhouse gas emissions as quickly and aggressively as possible, through a combination of energy efficiency, renewable energy, electrification, and other measures. Carbon removal should be seen as a complementary strategy that can help to fill the gap between current emissions reduction efforts and the levels of emissions reductions needed to meet global climate goals.

Carbon Dioxide Removal and Negative Emissions Technologies.

Carbon dioxide removal (CDR) and negative emissions technologies (NETs) are often used interchangeably, but there is a subtle difference between them. CDR is a broader concept that includes all methods of removing carbon dioxide from the atmosphere, including natural processes such as afforestation, soil carbon sequestration, and ocean fertilization, as well as technological approaches like direct air capture (DAC) and carbon capture and storage (CCS).

NETs, on the other hand, specifically refer to methods that remove more carbon dioxide from the atmosphere than they emit during their production and operation. These methods are considered "negative" because they result in a net reduction in atmospheric carbon dioxide levels. In other words, NETs are CDR methods that have a carbon-negative impact.

NETs include a range of approaches, such as afforestation, soil carbon sequestration, bioenergy with carbon capture and storage (BECCS), and DAC with carbon storage (DACS). BECCS, for example, involves growing crops, processing them into bioenergy, capturing the carbon dioxide released during the process, and storing it underground. DACS, on the other hand, involves capturing carbon dioxide directly from the air, and then storing it underground.

While CDR methods have the potential to remove carbon dioxide from the atmosphere, not all of them result in negative emissions. For example, afforestation may absorb carbon dioxide, but if the trees are later burned or decay, the carbon dioxide is released back into the atmosphere. Therefore, NETs are considered a critical tool for achieving climate goals, as they have the potential to actively remove carbon dioxide from the atmosphere and contribute to the fight against climate change.

CDR techniques complement carbon capture and storage methods that primarily focus on reducing CO2 emissions from point sources such as fossil fuel power plants.

It is important to point out that CDR should not be confused with carbon capture use or storage (CCUS). A distinction should be made for clarity purposes: CDR captures carbon dioxide from the atmosphere, while carbon capture and storage (CCS) captures carbon dioxide from point sources(such as a coalfired power plants) and then sequesters that carbon dioxide underground. Processes that capture carbon dioxide and use it to create new products that can be commercialized are known as carbon capture and use (CCU), CCUS refers to both storage and use processes. Given that CDR and CCUS processes involve capturing carbon dioxide and (in some cases) even the same infrastructure, these two processes may be confused. For example, applying CCS on fossil-fueled power plant would not qualify as CDR, as it does not actually removes CO2, but rather it prevents CO2 from being emitted into the atmosphere. These distinctions are in fact very important as cannot actually decrease current atmospheric carbon dioxide concentration levels, as can CDR. CDR removes carbon dioxide from the atmosphere and stores it for long periods of time, while CCUS can only reduce or prevent the amount of carbon dioxide from entering the atmosphere.

CCS deals with capturing CO2 directly from a fossil carbon flow, before ever emitted, CCS does not address CO2 stock already in the atmosphere. So regardless of the scale of implementation of CCS, CO2 needs to be removed from the atmosphere.

Direct Air Capture

Direct air capture is an approach to carbon removal in which mechanical systems capture carbon dioxide (CO2) directly from the atmosphere and compress it to be injected into geological storage or used to make long-lasting products, such as cement. Other uses of direct air capture technology, such as using captured CO2 in greenhouses or to manufacture synthetic fuels, are a form of carbon capture and use or “carbon recycling” because the CO2 returns to the atmosphere quickly after the products are consumed.

The current implementation of DAC is to manufacture alternative fuels or even feedstock for other industries (i.e. ClimeWorks Direct Air Capture plant in Switzerland uses captured CO2 to feed nearby green houses). For purposes of being considered CDR, storage must always be part of the equation and it can happen either in plants, soils, oceans, geological or in long lived products.

Direct Air Capture and CO2 storage is not an innovative idea, its basically the process of the plants. DAC is the technological replication of a natural process, (as it is considered CDR) storage must (or should) always be part of DAC. The purpose is to reduce carbon dioxide concentrations in the atmosphere however, the extent to which DAC actually delivers CO2 reductions in the atmosphere depends on the details of the implementation, specifically in whether the CO2 is actually stored or recycled.

The key of DAC should be to remove carbon from the atmosphere, so the correct way to assess a DAC project is in terms of “net” CO2 removal, which is the amount of CO2 removed minus any corresponding emissions resulting from the whole cost of removal or as a consequence of removal. Therefore the importance of examining the removal process from a full lifecycle perspective is key to foster DAC projects.

In my next post I will address the challenges and advantages of DAC. Stay tuned.