Illustration by www.kjell-design.com

According to the Swedish Environmental Protection Agency industry in that country is responsible for 23 per cent of greenhouse gas emissions. If you add the generation of heat and electricity the proportion becomes 36 per cent. The transport sector is responsible for an even greater proportion, but industry and business have important parts to play in the struggle against climate change.

One of the most promising technical innovations developed to reduce the impact industry has on climate is CCS technology. CCS stands for carbon capture and storage, and simply means that carbon dioxide formed during various kinds of industrial processes is separated, captured and stored. In this way no carbon dioxide is released into the atmosphere and the impact industry has on climate is reduced.

Carbon capture

There are three main technologies for capturing carbon dioxide. In Oxy fuel technology fuel is burned with the aid of pure oxygen and recycled flue gases rather than air alone. This creates a nitrogen-free gas with water vapour and carbon dioxide as its main constituents. After combustion the gas is cooled causing the water to condense and allowing carbon dioxide to remain. However, the production of pure oxygen for combustion is energy-intensive, but research is under way to reduce the costs of this stage.

In pre-combustion capture technology carbon is removed from the fuel before the latter is burned. This is carried out by creating a gas that consists of carbon monoxide and water. This gas is converted in a so-called shift reactor to form carbon dioxide and hydrogen:

CO + H20 <-> CO2 + H2

The carbon dioxide is captured and transferred to storage while the hydrogen is burned in a gas turbine whose chief waste product is water vapour. However, technical advances will also be necessary here mainly concerning how to convert solid fuel into gas so that the technology becomes commercially viable.

The third technology is called post combustion capture, in which carbon dioxide is not captured until after the fuel is burned. By enabling the products of combustion to pass through a filter they are able to react with e.g. ammonia and bind the carbon dioxide through the formation of ammonium carbonate, which is then heated to form carbon dioxide, water vapour and ammonia. The carbon dioxide is transported to storage, while the ammonia is recycled. One disadvantage with this technology is that it is relatively energy intensive which reduces power station efficiency.

Other technologies, above all chemical-looping combustion, are also under development, but those described above are the three most common.

Pressurized carbon dioxide is held in place

Once the carbon dioxide has been captured it is transported, preferably via pipelines and shipping, to its place of storage. Various solutions for actual storage methods have been proposed; for example the carbon dioxide can be stored deep inside bedrock, or in the sea where pressure is so high that the gas is kept compressed. Other suggestions include pumping carbon dioxide into depleting oil wells where there is not only storage space but also the opportunity for the gas to aid the extraction of the last remaining oil.

It is estimated that CCS is able to reduce power station carbon dioxide emissions by around 80-90 per cent. However, such calculations are obviously subject to a great deal of uncertainty as technology does not yet exist in commercially viable forms. One Swedish company trying to change that is Vattenfall, which is at the leading edge of CCS development. The company inaugurated a pilot plant for the development of CCS technology at one of its German coal-fired stations, and it hopes to have a commercially viable solution by around 2015-2020.

The plant is connected to the Schwarze Pumpe power station and Vattenfall has invested around EUR 70 million in the project. Every day 240 tons of carbon dioxide are transported to an old gas field and stored.

Even though it is difficult to foresee precisely how big a part future technologies will play in the struggle against emissions, McKinsey & Co. states that CCS is a necessary technology for the reduction of industrial process emissions. The UN Intergovernmental Panel on Climate Change and climate economist Klas Eklund, author of Vårt klimat (“Our Climate”, 2009) are of the opinion that CCS has the potential to make a constructive contribution to the climate struggle. The International Energy Agency (IEA) also expects CCS will have a great impact on our ability to reduce emissions.

In many ways it would be desirable if we could produce all of our energy through renewables, but for the foreseeable future this is just a wish, rather than a realistic alternative. Nevertheless this will not prevent us from doing something about the climate issue, and CCS is one of the more exciting possibilities to pursue. It’s not the sole solution, but it is part of the answer.

Article first published February 2011