Carbon Capture and Storage (CCS), also known as geosequestration, is a process where CO2 is removed during an energy production process and securely stored in suitable high integrity naturally occurring underground geological formations.

The Intergovernmental Panel on Climate Change (IPCC) Special Report on Carbon Dioxide Capture and Storage, issued in October 2005, concluded that CCS had the potential to make a significant contribution (15% to 55% up to 2100) to the mitigation of carbon emissions.

The Intergovernmental Panel on Climate Change (IPCC) has been established by World Meteorological Organization (WMO), and the United Nations Environment Programme (UNEP) to assess scientific, technical and socio- economic information relevant for the understanding of climate change, its potential impacts and options for adaptation and mitigation.

Carbon Capture

Carbon capture is the process of removing CO2 from process streams before it is emitted to the atmosphere and making it suitable for long-term storage in a suitable location. Processes for removing CO2 have been used in the oil, gas and chemicals industries for many decades and are considered technically mature and cost effective. However the adaptation of these processes to capture large volumes of low pressure, dilute CO2 from, for example, power station flue gases, introduces new technological and cost challenges. This step represents about three quarters of the cost of CCS.

Three principal methods of CO2 Capture from power stations are being proposed, of which Monash Energy uses “pre-combustion capture”.
A large amount of research and development activity is being undertaken around the world to reduce the cost of CO2 Capture to make CCS more affordable.

CO2 Storage

The oil and natural gas which we use every day has been trapped in naturally occurring sedimentary geological formations (often called reservoirs) deep under the earth for millions of years. There are similar formations which contain almost pure CO2. Some of these CO2 reservoirs are found in Victoria and South Australia and are used to supply CO2 for various industrial uses.

A key feature of these reservoirs is that they have an effective low permeability cap (or seal) which has prevented the oil and gas escaping to the surface. This seal will usually consist of an impervious rock barrier ranging from 10s to 100s of metres thick. The initial stages of exploration for oil and gas consist of a search for the necessary sedimentary structures overlaid by an effective seal. The main technology in this early stage of oil and gas exploration (seismic imaging) is also useful in determining the likely suitability of sites for long-term CO2 storage.

However, before the existence of oil and gas can be confirmed or the suitability of a site for CO2 storage fully established it is necessary to drill into the deep structure to directly measure the properties of the various geological layers.

Two of the most promising types of sites for CO2 storage consist of either depleted oil and gas reservoirs or deep saline aquifers (whose water quality is unsuited for domestic, commercial or agricultural use due to the salt content). The advantages of the former include that the effectiveness of the seal has been well established and that the exploration and production activities have provided the data necessary to properly evaluate the storage operation. The main advantage of deep saline aquifers is that, globally, they represent the greatest potential for geological storage of CO2.

With assistance from the Federal Government, in 2005 Monash Energy completed a major study of the storage potential of the Gippsland Basin.