**2.5.3 Coal beds**

For the storage of CO2 in coal beds to be feasible, this process must be associated with the production of methane from the bed. The injection of CO2 enhances the production of methane, hence the name enhanced coal bed methane recovery (ECBM). The process is being studied by, among others, the Swiss Federal Institute of Technology (ETH) and other research organizations funded by European Commission and US Department of Energy (US DOE). These studies aim to obtain the necessary knowledge to apply the technology in large scale.

Carbon Capture and Storage – Technologies and Risk Management 251

Risk is the product of the probability of a negative event's occurrence and the magnitude of the consequences. Risk management is a tool used to make decisions to help manage adverse events. For proper assessment of risks, it is necessary to identify all the possible causes of risk and their consequences. This can be done by preparing a chart showing the

Normally in industrial undertakings, the causes of events with large adverse effects are treated by managing the technology, that is, by specifying the equipment and materials, preparing rules and procedures, training programs, etc. The effort to reduce risk is concentrated in diminishing the probability of the occurrence of the causes that can trigger a series of events that lead to catastrophe and to assess the consequences. These consequences are analyzed by using the data on the area surrounding the project, its population and natural resources. Therefore, contingency plans are drawn up for mitigation of the catastrophic events if they

The risks of CCS projects are hybrid in nature, meaning they are a combination of technological and natural risks, because the possibility of leaks and other problems does not depend on the technology alone. The size of the reservoir, demographic changes, seismic behavior of the region, micro-climate and many other factors can modify the characteristics of the process and thus its complexity. Hence, there is less control over the causes that can lead to a catastrophic event, and it is important to monitor and identify anomalies in the process that can require taking action to control the emergency, by application of

The magnitude and complexity of the events involved in CCS projects prevent the application of traditional risk management based on administrative procedures and operational controls. Unlike an industrial plant, the CCS process is part of a natural formation that is responsible for its final function. The activities of the people in the surrounding area and the possibility of seismic events that trigger natural geophysical and geochemical changes in the reservoir are just some of the aspects that must be considered to

series of risk-posing events that can lead to a catastrophe, as shown in Figure 14.

**3. Risk assessments** 

Fig. 14. Series of Risks

occur. However, the focus is on the causes.

contingency plans prepared in advance.

A pilot ECBM project financed by the US DOE was developed in the San Juan Basin in New México, with the use of 4 CO2 injection wells and 16 methane production wells, besides an observation well. The methane production started in July 1989 and the CO2 injection began in April 1995 and continued until August 2001, when the operations were suspended to study the results. Figure 13 shows the results of the variations in methane output as a result of the injection of CO2 (Reeves & Clarkson, 2003).

Source: US DOE.
