The environmental and economic sustainability of carbon capture and storage.

For carbon capture and storage (CCS) to be a truly effective option in our efforts to mitigate climate change, it must be sustainable. That means that CCS must deliver consistent environmental and social benefits which exceed its costs of capital, energy and operation; it must be protective of the environment and human health over the long term; and it must be suitable for deployment on a significant scale. CCS is one of the more expensive and technically challenging carbon emissions abatement options available, and CCS must first and foremost be considered in the context of the other things that can be done to reduce emissions, as a part of an overall optimally efficient, sustainable and economic mitigation plan. This elevates the analysis beyond a simple comparison of the cost per tonne of CO(2) abated--there are inherent tradeoffs with a range of other factors (such as water, NOx, SOx, biodiversity, energy, and human health and safety, among others) which must also be considered if we are to achieve truly sustainable mitigation. The full life-cycle cost of CCS must be considered in the context of the overall social, environmental and economic benefits which it creates, and the costs associated with environmental and social risks it presents. Such analysis reveals that all CCS is not created equal. There is a wide range of technological options available which can be used in a variety of industries and applications-indeed CCS is not applicable to every industry. Stationary fossil-fuel powered energy and large scale petroleum industry operations are two examples of industries which could benefit from CCS. Capturing and geo-sequestering CO(2) entrained in natural gas can be economic and sustainable at relatively low carbon prices, and in many jurisdictions makes financial sense for operators to deploy now, if suitable secure disposal reservoirs are available close by. Retrofitting existing coal-fired power plants, however, is more expensive and technically challenging, and the economic sustainability of post-combustion capture retrofit needs to be compared on a portfolio basis to the relative overall net benefit of CCS on new-build plants, where energy efficiency can be optimised as a first step, and locations can be selected with sequestration sites in mind. Examples from the natural gas processing, liquefied natural gas (LNG), and coal-fired power generation sectors, illustrate that there is currently a wide range of financial costs for CCS, depending on how and where it is applied, but equally, environmental and social benefits of emissions reduction can be considerable. Some CCS applications are far more economic and sustainable than others. CCS must be considered in the context of the other things that a business can do to eliminate emissions, such as far-reaching efforts to improve energy efficiency.