What to do with all the carbon dioxide?

Symbol CO2 from clouds

Research Postgraduates Clara Heuberger and Clea Kolster, who recently attended the UNFCCC’s 23rd Conference of the Parties in Bonn, consider the significant potential of  carbon dioxide removal technologies, and the barriers they face. 

Research Postgraduates Clara Heuberger and Clea Kolster at COP23

A recent report published by the UN highlighted that, last year, the concentration of carbon dioxide in the atmosphere increased at record speed, hitting a level not seen for more than three million years. The report raised alarm amongst scientists, and prompted calls that drastic action was needed to meet climate targets set in the Paris Agreement.

Yet scientists have shown that the rate at which nations have pledged to reduce their greenhouse gas emissions is far from being enough to have half a chance of keeping global warming below a 1.5°C and even 2°C temperature rise.

Put simply, developing nations – and even European nations – remain heavily dependent on fossil fuels (e.g. Poland, India, China). Even if we could convert all electricity and heat production to renewable energy, like wind and solar, it would only cut about a quarter of all greenhouse gas emissions. Emissions from agriculture, land use, buildings and industries (like cement, iron and steel) remain very high – and reducing them remains a huge challenge. Similarly, while some progress is being made in the transport sector, with the electrification of light vehicles (e.g. Nissan Leaf, Chevrolet Bolt and Tesla cars), we are still far from a solution to reduce emissions from heavy-duty vehicles, shipping and aviation.

It has long been assumed that carbon capture and storage (CCS) will cover an important portion of the emissions that need to be reduced to avoid the risk of dangerous levels of climate change. But the technology has yet to be deployed on a scale large enough to do that. And the conversation has now shifted –  to avoid the risk of dangerous levels of climate change, the world will actually need to actively remove carbon dioxide from the atmosphere. This is where negative emissions technologies (NETs), which rely in large part on CCS (see box on NETs), come in.

Negative emissions technologies: What are the options?

Natural NETs refer to the increased uptake of carbon dioxide by land or ocean:

  • By improving agricultural practices, we can increase the amount of carbon stored in soil and biomass.
  • Forests act as carbon sinks. Today, they cover about 30% of total land and store the equivalent of 50 years’ worth of carbon dioxide emissions. Reforestation is vital to restock forests that have been depleted.
  • Afforestation is where trees are planted in areas that currently don’t have them, creating additional forests and thereby increasing the amount of carbon dioxide absorbed.

Technological NETs include:

  • Bioenergy with carbon capture and storage (BECCS) is the most advanced of the technological solutions for carbon dioxide removal. It involves the production of biomass (plant matter), using it as a fuel instead of (or with) coal or gas, and capturing the carbon dioxide emissions with CCS technology. CCS captures the carbon dioxide produced and buries it in carefully selected geological reservoirs.
  • Direct air capture filters the air to reduce the concentration of carbon dioxide, and will then store the carbon dioxide removed from the atmosphere using the same method as for CCS.
  • Carbon mineralization, the least developed of the NETs, is the conversion of carbon dioxide into a solid form. This is achieved by reacting the gas with minerals such as magnesium and calcium, to form materials like cement, which can be used in construction.
Graphic showing leading carbon removal solutions
Infographic supplied by Centre for Carbon Removal [http://www.centerforcarbonremoval.org]


Recent discussions on Carbon Capture and Storage (CCS)

Two years ago, the UK government announced the cancellation of their £1 billion CCS competition a week prior to COP21. Yet this year, the government has come back on board with a pledge from the Business, Energy and Industrial Strategy to allocate up to £20 million to carbon capture and utilisation (CCU) projects – and has emphasised the importance of CCS in the Clean Growth Plan. In the Netherlands, the Dutch Coalition Government recently announced its emissions reduction plan to 2030, which allocated a third of its emissions reduction to CCS in the industrial and waste sectors. Similarly, Sweden now has an extremely progressive law stating that the country should have “no net emissions” of carbon by 2045 (the fine print of this means that any emissions over an85% reduction from 1990 levels will have to be achieved by negative emissions technologies).

There was a lot of positive discussion around CCS and NETs at COP23, the UNFCCC’s 23rd Conference of the Parties hosted in Bonn. At an event hosted by the IEA Greenhouse Gas R&D Program, which focused on the developments of CCS to help small island states, Professor David Alexander from the University of Trinidad and Tobago emphasised the potential of CCS to decarbonise the heavily fossil-fuel reliant Caribbean island nation. Similarly, in another discussion at COP, a delegate from Bahrain signalled that oil and gas rich Middle Eastern countries are also very engaged about the role CCS will play in their decarbonisation policies. For such countries, where the economy depends on the consumption of fossil fuels, CCS can play a vital role in helping them transition away from high carbon emissions and move towards greener economies.

What’s stopping it from taking off?

These solutions, like all things, come at a cost – and at present, there are few public or private entities willing to pay for it. Informal discussions at COP23 implied that EU policy makers are not ready to take this step. One EU representative put it simply as “NETs are not on the map for EU energy policy”. But the reality is that, without strong incentives – whether in the form of subsidies or a carbon tax, the deployment and the cost of CCS is unlikely to go down. And, if the costs of CCS fail to decrease, then bioenergy with carbon capture and storage (BECCS) will also remain prohibitively expensive – even though studies have shown that it is most cost efficient to invest in such technologies earlier rather than later.

In Bonn, Oliver Geden, Associate fellow at the University of Oxford’s Institute for Science, Innovation and Society, highlighted that “politicians are relying, to a large extent, on negative emissions”. Yet, even when they can recognize their importance, policymakers and various international organisations seem to have a hard time stomaching NETs and CCS. Scepticism abounds when it comes to carbon dioxide removal because of the high technological costs. Pushback on CCS also comes from the ardent 100% renewable advocates, who see CCS as a means to perpetuate the use of fossil fuels. In fact, the German pavilion hosted an event about catalysing the shift from low carbon to negative carbon in Europe, during which Jochen Flasbarth, the state secretary of Germany’s Federal Ministry for the Environment, suggested that pushing for NETs and CCS would “divert the focus away from reducing positive emissions first”.

Disillusioned by technical concerns

Meanwhile, there are a number of widespread concerns and misconceptions around CCS, most notably on carbon dioxide storage. Many think that storing carbon dioxide in deep geological reservoirs is analogous to landfill storage or nuclear waste storage – something that will have to be dealt with in the future, like any other type of waste. However, the reservoirs where carbon dioxide is stored are known to have stored gases for thousands of years without any significant leakages. In fact if carbon dioxide is stored in a reservoirs filled with brine, the gas will eventually dissolve in the brine and become a part of the surrounding formation. In a discussion at the UK pavilion, Dr Carol Turley, one of the pioneers of ocean acidification research, confirmed that even if there were a local leak of carbon dioxide from a geological reservoir into the ocean, the effects are minute, local and temporary – contrary to the effect the atmospheric concentration of carbon dioxide has on ocean acidification.

What next?

There is real a lack of alignment amongst different technology advocates as to what the solution should be for reducing carbon dioxide emissions. For example, renewable energy representatives hosted a 100% renewable energy event at COP23, with wind, solar, geothermal, and hydropower representatives. This polarised both CCS advocates and nuclear energy groups, and omitted key supporting solutions like battery storage.

It will undoubtedly be a combination of technologies that gets the world to net-zero emissions at some point this century. Organizations like the Centre for Carbon Removal play an important role in honing together these different actors, raising awareness on the topic and initiating collaboration in the field. But, for CCS and NETs technologies to become viable ways to reduce emissions, they also need to be backed with consistent, active political and economic support. Only then, will we find a way to deal with all the carbon dioxide.

One thought on “What to do with all the carbon dioxide?

  1. Carbon capture does require a lot of energy and resources, merely to discard it as waste. Conversion of CO2 into useful products does require energy but with some return. Time for Grantham to host a grown-up debate on fission energy , especially as Gen 4 reactors and recycling of fissionable materials are near-term possibilities with cost and resource savings. John Edwards

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