On 25 September, the IPCC released a comprehensive report on CCS, (also known as geosequestration). The report is important given the commitment of the Australian government in Securing our Energy Future to pursue CCS as a greenhouse gas emissions reduction technology, and concerns that have been raised regarding this policy. The report begins by describing CCS, its characteristics, how it could contribute to mitigating climate change, the current status of the technology and the geographical relationship between the sources and storage opportunities for CO2 (hereafter carbon). The Report then addresses the following matters:
- What are the costs for CCS and what is the technical and economic potential?
Since neither Natural Gas Combined Cycle, Pulverized Coal nor Integrated Gasification Combined Cycle systems have been built at a a full scale with CCS, it is difficult to estimate the costs of these systems with confidence. Also the costs of any technology vary from country to country in absolute and relative terms. Costs could be reduced by research and technological development and by economies of scale.
- What are the local health, safety and environment risks of CCS?
In areas with low population density the risks of CCS are low. However, in high density areas there could be immediate dangers to human life and health if carbon was suddenly released from pipelines in a concentration of 7 - 10% by volume in air. So pipeline transport would require careful monitoring in terms of route selection, overpressure detection, leak detection and other design factors. The leakage of carbon from natural reservoirs carries substantial risks. While there is limited experience with CCS, closely related industrial experience and scientific knowledge could serve as a basis for appropriate risk management, including remediation. Leakage from storage sites in the ocean could increase acidity and cause the mortality of ocean organisms.
- Will physical leakage of stored carbon compromise CCS as a climate change mitigation option?
For well-selected, designed and managed geological storage sites, the vast majority of the carbon will be immobilised over time and could be retained for millions of years, and for hundreds of years in the ocean. With non-permanent storage options, the studies imply that CCS is only an acceptable measure if there is an upper limit on the amount of leakage allowed.
- What are the legal and regulation issues for implementing carbon storage?
The process and impacts of CCS may be managed under mining, oil and gas, pollution control, waste disposal, drinking water, treatment of high-pressure gases and subsurface property rights law.
- What are the implications of CCS for emissions inventories and accounting?
The IPCC guidelines on inventories and accounting do not yet provide specific methods for estimating emissions associated with CCS. These are expected to be provided in the 2006 guidelines.
- What are the gaps in knowledge?
The IPCC recognises that there are gaps in knowledge regarding CCS and the uncertainties will be reduced with increasing knowledge and experience.
Source: IPCC, 25 September 2005
