Saturday, July 1, 2017

The Swiss company hoping to capture 1% of global CO2 emissions by 2025 | Carbon Brief

On the roof of a waste incinerator outside Zurich, the Swiss firm Climeworks has built the world’s first commercial plant to suck CO2 directly from the air.

Climeworks says that its direct air capture (DAC) process – a form of negative emissions often considered too expensive to be taken seriously – costs $600 per tonne of CO2 today. This is partly covered by selling the CO2 to a nearby fruit and vegetable grower for use in its greenhouse.

Climeworks hopes to get this down to $100/tCO2 by 2025 or 2030. It aims to be capturing 1% of global CO2 emissions each year by 2025.
Negative emissions might be necessary to meet the goals of Paris, where an overspend against the carbon budget is paid back by pulling CO2 from the air.

Some estimates suggest as much as five billion tonnes of CO2 (GtCO2) would have to be removed from the atmosphere, and then locked away underground, each year by 2050. (Last year, Carbon Brief produced a series of articles on the need for negative emissions, the options available and whether they are feasible – or merely a distraction that encourages complacency).

Direct air capture (DAC) is one of those options, with DAC machines often described as “sucking CO2 from the air” or “artificial trees”. It has a number of attractive features, including a limited land footprint, the ability to site units near to CO2 storage sites and a clarity around how much CO2 it sequesters, in contrast to negative emissions that use biomass.
Academic estimates for the cost of CO2 capture, transport and storage, along with regeneration of chemicals used in the process, range from $400 to $1,000 per tonne of CO2.
According to a 2016 Nature paper, DAC would require a theoretical minimum of 0.5 gigajoules (GJ) of energy to remove and store each tonne of CO2. Or, perhaps, as much as 12GJ/tCO2 once inefficiencies and other stages of the process are taken into account.

On this basis, the paper says that capturing 12 billion tonnes of CO2 equivalent (GtCO2e) per year (around a third of annual global emissions) would require 156 exajoules (EJ) of energy. This is more than a quarter of total annual global energy demand for all uses, of around 550EJ.

The paper says the costs and energy requirements would be “prohibitive” and that research and development is required to bring them down.
10 Climeworks Plant Greenhouse Background Copyright Climeworks Photo by Julia Dunlop.jpg
In the past two years, Climeworks has grown rapidly, reaching 45 employees today. Its $20m in financing includes $5m in Swiss government grants and $15m from private equity.
The market price in Switzerland, for small amounts of CO2, is $200-250/t...

Driving the Climeworks process uses 2.5 megawatt hours (MWh) of heat, at around 100C, for each tonne of CO2, along with 0.5MWh of power. This energy requirement is roughly equivalent to the 12GJ/tCO2 estimates set out above, though the firm hopes to shave 40% off this figure, bringing it down to around 7GJ/tCO2. Gebald says an increase in energy resources – he points to wind and solar – would be needed to scale up direct capture.

Carbon Brief

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