How does Climeworks' direct air capture technology work?
Climeworks direct air capture machines consist of modular CO₂ collectors, which selectively capture carbon dioxide in a two-step process. First, air is drawn into the collector with a fan. Carbon dioxide is captured on the surface of a highly selective filter material that sits inside the collectors (“adsorption”). Second, after the filter material is full with carbon dioxide, the collector is closed. We increase the temperature to between 80 and 100 °C, which releases the carbon dioxide at a purity of over 99% (“desorption”). The gas is then cooled to 45 °C and collected. Each CO₂ collector can capture approx. 50 tons of carbon dioxide per year. You can find more info here.
Why do we need direct air capture?
Multiple climate studies published recently (IPCC Special Report, EASAC, NAS) clearly state that in order to achieve climate targets, not only do we need to do everything we can to reduce emissions; we also need to actively remove carbon dioxide from the atmosphere. Leading studies indicate that by mid-century around 10 billion tons of carbon dioxide will need to be removed from the atmosphere every year. Direct air capture is one way of doing so. In order to scale direct air capture up to these levels, we need to start today.
Why don't we just plant trees?
We love trees and believe many more should be planted. We need more trees and we need direct air capture. Sadly, for decades, humans have cut down trees rather than plant them. Hence, based on the learnings history, betting on afforestation (i.e. planting more trees) as the only solution to remove carbon dioxide from the atmosphere is a risky approach. If done well, afforestation comes with a number of important benefits such as reduced soil erosion and increased biodiversity. Disadvantages of afforestation are that lots of water and surface area is required, and the precise amount of carbon dioxide sequestered is difficult to measure. Direct air capture is a complementary approach to planting trees.
Why not capture CO₂ from point sources, e.g. directly from a smokestack, where the CO₂ concentration is much higher?
Capturing carbon dioxide from point source is one approach to emissions reduction: it prevents new emissions from entering into the atmosphere. It is, however, no longer a question of “either/or”. In order to achieve climate targets, we need both emissions reduction and carbon dioxide removal from the atmosphere.
By capturing carbon dioxide directly from air, not from point sources (or “flue gas”), Climeworks focuses on the latter, namely carbon dioxide removal. Only with direct air capture can you remove carbon dioxide that is already in the air. Further advantages of direct air capture over point source capture is that direct air capture machines can be built anywhere, eliminating the need for transport. With air being an infinite resource, direct air capture can moreover secure long-term carbon dioxide supply.
In the near future, many point sources will be phased out and will likely not be sufficient in the future to cover the world’s entire carbon dioxide demand, e.g. for renewable fuels or materials.
How much energy is required to run Climeworks' direct air capture process?
We need energy to power our CO₂ collectors. On the one hand, we need heat. Importantly, our machines use low-temperature heat at < 100 °C as their main energy source. Further, we need some electricity. The electrical energy is mainly required to ventilate air through the filter material via fans and the heat is required to heat up the sorbent material for regeneration.
As energy sources, we solely use renewable energy, energy-from-waste, or other waste heat. Typical energy consumption figures expected for scaled-up machines are approx. 2'000 kWh heat and approx. 650 kWh electricity per ton of carbon dioxide that is captured.
Do Climeworks' direct air capture machines operate better at higher levels of CO₂ in the air?
The global and local variations in the CO₂ content of the atmosphere are actually relatively small, since the diffusion and mixing of carbon dioxide in the atmosphere happens very fast. Climeworks direct air capture machines can thus be built nearly anywhere and run efficiently. However, local climate and weather conditions, as well as altitude have a certain effect on the performance characteristics. Further, in highly polluted areas, our filter material is likely to clog quicker due to other pollutants.
Is the air really free from carbon dioxide when it leaves the Climeworks CO₂ collector?
The concentration of air coming out of the collectors is substantially lower than the approx. 400 ppm at the inlet but typically never zero. A benefit of direct air capture is that air is a “free” resource and thus not all carbon dioxide needs to be captured from the incoming gas stream straight away. This allows us to design a more efficient capture process.
What can the CO₂ produced by direct air capture be used for?
Air-captured carbon dioxide has two broad use cases: it can either be re-used as a raw material or permanently and safely stored (carbon dioxide removal). Carbon dioxide is used as a raw material for several applications, such as for the carbonation of drinks or the production of renewable synthetic fuels. Such fuels will be crucial for transforming the mobility sector and making it carbon neutral, because they can immediately substitute conventional fuels without any retrofitting required for existing vehicles. If the carbon dioxide is stored, it is permanently removed from the air, which lowers its level in our atmosphere and counteracts climate change.
Your machines capture carbon dioxide. But how much carbon dioxide is caused by the production, commissioning and recycling of your machines?
We have performed multiple Life Cycle Analyses (LCAs) on our technology with independent partners.
According to them, the grey emissions for the construction, operation and deconstruction of a Climeworks machine are less than 10% of the captured carbon dioxide with the use of waste heat and renewable electricity. Our goal is to reduce this to 4%.
How many direct air capture machines have you sold?
Climeworks currently has 15 machines in operation across Europe. Some are sold to customers and some belong to and are operated by Climeworks. We operate the machines and sell the carbon dioxide, or in the case of Iceland, our carbon dioxide removal service, to our customers.
Is it safe to remove carbon dioxide from the atmosphere and turn it into stone?
The pioneering process of turning carbon dioxide into stone is safe. It happens through a combination of carbon dioxide capture from the air and rapid underground mineralization - a natural process whereby the carbon dioxide reacts with the basaltic rock to become solid calcite matter (another form of rock) within a few years. No weather conditions or fire can harm it or cause an outbreak of carbon dioxide: in this calcite form the greenhouse gas is removed from the atmosphere permanently and safely. The basaltic conditions at existing geothermal power plants in Iceland make it one of the best places to start the permanent storage of carbon dioxide. There are, however, more places that can have ideal conditions. For example, the Icelandic Rift System with a capacity of 50 million tons of carbon dioxide per year (source here). On a global scale studies have estimated an overall capacity of 30 trillion tons of carbon dioxide (source here). Other suitable locations can be found in North America, the Middle East or China.
You can learn more about an exemplary mineralization process that turns carbon dioxide into stone on the CarbFix website.
How does Climeworks remove the CO₂ I have subscribed for and how long does it take?
To remove CO₂ in your name, Climeworks does two things:
1) Build and install CO₂ capture plants at sequestration sites
2) Operate the CO₂ capture plants and hand over the CO₂ to our storage and monitoring partners (in Iceland this is Carbfix), who proceed with underground storage of the CO₂.
Building and installing a plant typically takes 1-2 years, the foreseen operational time of a plant is currently 10 years (and will presumably be even longer for future plants). Subject to the utilization and operation schedule of our plants, for CO₂ removal currently being subscribed for, our CO₂ removal service and the safe and permanent storage underground are completed within 5 years or earlier following the subscription date.
For comparison, this is at least 2 times faster than for typical other CO₂ removal approaches (for example, if trees are planted, it will typically take at least 10 years [source] until the CO₂ is removed from the air, for natural mineralization processes (enhanced weathering), it might take at least an order of magnitude longer [source] to complete CO₂ removal).
What is the difference between Climeworks' carbon dioxide removal service and traditional carbon offsetting?
Traditional carbon offsets are typically a trade of pollution rights. If done in a transparent way, this trade will at best result in a short-term emissions reduction but never lead to the zero and negative emissions that we need to keep global heating in check. What Climeworks does is fundamentally different. Rather than trading avoided emissions, we physically remove carbon dioxide emissions that are difficult to otherwise avoid.
Climeworks' carbon dioxide removal is further fully measurable, as every ton of carbon dioxide removed from the air and stored underground can be precisely measured using standard industry measurement equipment.
Do I get some sort of certificate?
On the carbon dioxide removal confirmation you will receive by the end of each year we state the amount of carbon dioxide that has been ordered for removal in your name. No one else can put a claim to that amount. We can exactly measure how much carbon dioxide our collectors capture from air, so we know exactly how much carbon dioxide has been removed in your name.
How can I edit or cancel my subscription?
You can edit or cancel your subscription any time. Log in to the customer portal with your e-mail address. A one-time password will be sent to your inbox. Log in with that password. Now you can see an overview of your subscriptions.
Cancellation: Click on the subscription you would like to cancel. Below you find the options to edit and to cancel your subscription.
Editing: Press edit and you will have an overview of your subscription. Press "Update subscription" to edit.