CO₂ Capture and Storage

10. Conclusion: the future of CO₂ capture and storage

• 10.1 What knowledge gaps remain?
• 10.2 How much could CO₂ capture and storage contribute to climate change mitigation?

10.1 What knowledge gaps remain?

CO₂ capture and storage is technologically feasible and could play a significant role in reducing greenhouse gas emissions over the course of this century. Although parts of the technology are tried and tested, increased knowledge, experience, and reduced uncertainty about specific aspects of CO₂ capture and storage would be important to enable its large scale deployment.

First, the technology needs to mature further. While the individual components of CO₂ capture and storage are well developed, they still need to be integrated into full scale projects in the electricity sector. Such projects would demonstrate whether the technology works when fully scaled up, thus increasing knowledge and experience. More studies are needed to analyse and reduce the costs and estimate the potential capacity of suitable geological storage sites. Regarding other forms of storage, pilot scale experiments on mineral carbonation are needed to reduce costs and net energy requirements. In addition, studies concerning the ecological impact of CO₂ in the deep ocean are required.

The adequate legal and regulatory environment also needs to be further developed. This must include agreed methods for estimating and reporting the amount of CO₂ avoided by CO₂ capture and storage as well as the amounts that may leak over the longer term. Long-term liabilities of geological storage and potential legal constraints on storage in the marine environment need to be taken into account.

Other issues to be resolved include the potential for transfer and diffusion of CO₂ capture and storage technologies, opportunities for developing countries to exploit them, application of these technologies to biomass sources of CO₂, and the potential interaction between investment in CO₂ capture and storage and other mitigation options. More...

10.2 How much could CO₂ capture and storage contribute to climate change mitigation?

If knowledge gaps are filled and various conditions are met, CO₂ capture and storage systems could be deployed on a large scale within a few decades as long as an explicit policy is put into place to substantially limit greenhouse gas emissions to the atmosphere.

A particularly critical issue remains that of incentives. If a “carbon price” is established for each unit of greenhouse gas emissions, this could create incentives to invest in processes which emit less greenhouse gases. CO₂ capture and storage systems are only likely to be widely adopted for power generation – the sector with by far the greatest potential – when the price of emitting a tonne of CO₂ exceeds 25–30 US$ (in 2002 dollars) over the lifetime of the project. A price on emitting CO₂ can only result from policy decisions for limiting CO₂ emissions. CO₂ capture and storage systems would be competitive with other large-scale mitigation options such as nuclear power and renewable energy technologies.

As part of a portfolio of actions to mitigate climate change, CO₂ capture and storage could reduce the cost of stabilizing the concentration of greenhouse gases in the atmosphere by 30% or more. Most scenarios for achieving such stabilisation at least cost estimate that the amount of CO₂ that could potentially be stored underground and in oceans during this century ranges between 220 and 2 200 GtCO₂. To achieve this potential, several hundreds or thousands of CO₂ capture and storage systems would be required worldwide over the next century, each capturing some 1 to 5 MtCO₂ per year. Such systems would need to be built in significant numbers in the first half of the century with the majority of them being built in the second half.

In the absence of measures for limiting CO₂ emissions, there would only be small, niche opportunities for carbon capture and storage technologies to deploy with a maximum potential of about 360 MtCO₂ per year. Such opportunities alone are unlikely to contribute significantly to the mitigation of climate change unless extended to the power sector.

Concerning long term leakage from storage, there must be an upper limit to the amount of leakage that can take place if CO₂ capture and storage is to be acceptable as a climate change mitigation measure. A fraction retained on the order of 90–99% for 100 years or 60–95% for 500 years could still make such impermanent storage valuable for the mitigation of climate change.

The consensus of the literature shows that CO₂ capture and storage could be an important component of the broad portfolio of policies and technologies that will be needed if climate change is to be successfully addressed at least cost. More...