A load of hot air that costs the earth

From Richard Branson to the New York Times, everyone is toasting Climeworks, a start-up from the ETH. By 2025, the company aims to use its air filtration system to clean up one percent of the world’s CO2 emissions caused by fossil fuels. Its founders have an entrepreneurial approach – but their business model is based on a risky bet, at the taxpayers’ expense.

Climeworks has triggered more international hype than any other Swiss start-up. The promise made by this ETH spin-off is bang on trend: according to a statement made by its two founders, Christoph Gebald and Jan Wurzbacher, the company has developed “the world’s first commercial carbon removal technology” that enables carbon dioxide (CO2) to be filtered out of the surrounding air. The New York Times’s Sunday magazine recently published a long ode to Climeworks, entitled “The Tiny Swiss Company That Thinks It Can Help Stop Climate Change”.

The start-up was also the subject of favourable press in the Financial Times a few days ago. In addition to all this, it is one of the finalists in the Virgin Earth Challenge. Richard Branson put this $25 million prize up for grabs in 2007 for the best technology to remove CO2 from the atmosphere on a massive scale, but it has never been won. Climeworks has been mentioned 387 times in the Swiss press since it was set up in 2009. The Wochenzeitung newspaper was among the first to cheer on the start-up. (Conversely, the left-wing publication withdrew its support for Climeworks when it became apparent that the filtered CO2 was also being sold to Coca-Cola, who uses it to produce fizzy drinks.)

In 2017, Climeworks opened a demonstration plant in Hinwil near Zurich, which has now become a mecca for journalists interested in all things green. The system uses waste heat from the Kezo waste incinerator to extract CO2 from the surrounding air. It then sends it to a nearby greenhouse where the gas helps tomatoes and cucumbers grow. According to its inventors, it collects 900 tons of CO2 a year.

The hype surrounding Climeworks has overshadowed the fact that a different company (using Swiss technology) has been recycling around 400,000 tons of CO2 per year globally since 2014. The company? The Messer Group, the world’s fifth largest producer of industrial gases. Unlike Climeworks, Messer’s technology does not rely on using the surrounding air. Instead, it filters CO2 out of the gases emitted by industrial plants, such as production plants or waste incineration plants.

In terms of cost-effectiveness, Messer’s process is greatly superior to Climeworks’ technology. The table compares the average Messer unit to Climeworks’ model in Hinwil. Using Climeworks’ system, it currently costs around 600 Swiss francs to filter out a ton of CO2. For Messer, the price is less than 100 Swiss francs. This major difference in cost-effectiveness is primarily due to the fact that the concentration of CO2 in waste gases is more than 300 times greater than the figure for normal air. As a result, it is much easier to extract large quantities using Messer’s method. The most powerful Climeworks machine currently only exists on paper, but could hypothetically handle a maximum of 1,800 tons of CO2 per year. While this is twice as much as Hinwil deals with, Messer’s machines can get up to 96,000 tons, according to their brochure.

The weaker concentration of CO2 also goes hand-in-hand with another disadvantage. Climeworks’ machines need about twice as much electrical energy to suck in the air and spit it back out, free from CO2, compared to Messer’s systems. This can have a considerable impact on the CO2 balance, depending on the source of the electricity. If it was generated in a coal-fired power plant, it would emit two-thirds of the CO2 captured by the Climeworks machine it powers. (In addition to the electrical energy needed to move the air, about five times more thermal energy is needed for physical processes in the filter itself.)

“A deadly sin, in terms of technology”

The idea of “direct air capture”, which Climeworks specialises in, is controversial in the fields of science and technology. When the topic first reared its head in 2011 or thereabouts, Marco Mazzotti from the Institute of Process Engineering at ETH Zurich issued a warning in the NZZ newspaper, stating that the process was very expensive. According to him, we would be better off investing the money in filtering waste gases. Howard Herzog of the Massachusetts Institute of Technology also thinks that it is “ridiculous” to suck CO2 from the surrounding air. There are “so many other ways that are much cheaper”, he thinks. By way of comparison, creating additional woodland areas to absorb one ton of CO2 would cost between five and fifty US dollars. An engineer who asked to remain anonymous even describes trying to capture a gas at its lowest concentration as a “deadly sin, in terms of technology”.

He also points out that the scientific foundations for the absorption of CO2 had been laid a good century or so ago. The technology in question has long been used in submarines and manned space flights to filter the air and remove the CO2 exhaled by the crew. At Climeworks, “only the sorbent used can be considered special or new”. This “sorbent” is a cellulose filter which traps CO2 molecules, like a sponge. The material was developed by Climeworks in collaboration with the Swiss Federal Laboratories for Materials Science and Technology (Eidgenössische Materialprüfungs- und Forschungsanstalt, or Empa).

So far, Climeworks’ machines are being manufactured by hand in Switzerland. However, over the next decade, the company plans to cut costs to around $100 – $200 per ton of CO2 captured, primarily hoping to achieve this by automating its production processes. But even if this ploy succeeds, the price for removing one ton of CO2 would still be much higher than the cost for Messer’s approach of filtering waste gases.

The much-praised Climeworks plant in Hinwil apparently cost between 3 and 4 million Swiss francs – and was only able to be built thanks to generous taxpayer funding. The Swiss Federal Office for Energy (Bundesamt für Energie, BfE) contributed 1.22 million Swiss francs to the project. (Between 2012 and 2015, the BfE had already provided the company with subsidies to the tune of just under 500,000 francs.) Climeworks shipped a machine half the size of Hinwil’s to Italy. As part of “Horizon 2020”, the State Secretariat for Education, Research and Innovation provided more than one million Swiss francs in funding for it.

According to Climeworks, the company has so far received around CHF 50 million in capital and grants. It now has sixty employees, and the two founders hold the majority stake in the firm. Zurich Cantonal Bank, which is government-owned by the Canton of Zurich, is one of the largest outside investors, while the investment company Hesta, owned by the Bechtler brothers, and the technology group Cadfem International also have stakes in the company. Last year, Climeworks managed to increase its capital by CHF 30 million.

Can Climeworks pull this business model off? So far, investors are far from seeing jaw-dropping returns. The company says that its current production capacity is for one hundred units per year, but in total, there are only nine Climeworks machines in operation, eight of which are for research purposes and one, in Hinwil, for commercial use. Weltwoche confronted Climeworks with its doubts about the company’s technological and commercial effectiveness, but did not receive a response.

However, the company does an outstanding job of selling grand visions. It wants to be nothing less than “the Apple of renewable energy”, as co-founder Christoph Gebald put it two years ago, when speaking to the Finanz und Wirtschaft newspaper. In order to reach this goal, it is drawing in investors and the public with prodigious plans for the future. By 2025, Climeworks’ machines are expected to capture one percent of global CO2 emissions originating from fossil sources. In figures, this means that 411,111 systems like the one in Hinwil are to filter out 370 million tons of CO2 from the air, every year. At today’s prices, these machines would cost well over 1000 billion Swiss francs, more than the annual economic output of Switzerland. They would consume 185 terawatt hours of electrical energy: this is two and a half times Switzerland’s annual electricity consumption and five times Germany’s solar power production. This is not exactly an inconsiderable outlay for capturing just a tiny fraction of the CO2 emitted by the use of fossil fuels.

Competing with Bill Gates

The fact of the matter is that the company has barely been able to sell a single machine without state funding, even ten years after it was founded. Most recently, it has turned to private individuals who want to voluntarily offset their CO2 emissions, such as those caused by air travel, for example. Even for this purpose, Climeworks is also exorbitantly expensive, for the same reasons given in the previous paragraphs. According to the Wochenzeitung newspaper, the company doesn’t see this as an issue: “We work on the basis that there is a premium segment in matters of sustainability, too.”

Climeworks’ idea might still be able to take flight if it receives an internationally coordinated state subsidy on a massive scale. For example, if the EU’s emissions trading price for CO2 were to increase tenfold, to around 25 euros per ton, then Climeworks’ machines might well suddenly be in business. In interviews, Climeworks’ founders demand higher levies on CO2 emissions, and the company is zealous in its attendance of UN climate conferences. On its Facebook page, the ETH start-up proclaims its support for climate activist Greta Thunberg.

Despite its gigantic bet on state funding, Climeworks is not alone in its approach. The Canadian start-up Carbon Engineering, with shareholders including several oil companies and Microsoft’s founder Bill Gates, is gearing up to produce fuel using CO2 that has been filtered from the air. The company raised $60 million in fresh funding last year. If Climeworks really wants to win the jackpot in the face of ever-advancing climate regulation, it has to pick up the pace. On the other hand, even Apple was not built in a day.


Climeworks vs. Messer

The two CO2 filtration machines, side by side



Climeworks DAC-18

Messer Asco 1000 kg/h

Procurement costs,

in millions of Swiss francs




Annual capacity,

in tons of CO2




Thermal energy required per ton of CO2 captured, in megawatt hours




Electrical energy required per ton of CO2 captured, in megawatt hours




Price per ton of CO2 captured, in Swiss francs



< 100


There is a considerable difference in terms of cost-effectiveness.




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