CO2CRC FACT SHEET 1

What is geosequestration? [view PDF]

The fossil fuels, coal, oil and natural gas currently supply around 85 per cent of the world’s energy needs.

The International Energy Agency predicts that fossil fuels will continue to be heavily used for many years to come.

The burning of fossil fuels is a major source of excess CO2, the most common greenhouse gas after water vapour, and the gas most likely to contribute to potential global warming.

The urgent need to reduce the atmospheric concentrations of CO2 requires a portfolio of solutions including energy efficiency; using less carbon-intensive fuels; enhancing natural carbon sinks (vegetation); and harnessing renewable energy from the wind, sun and tides. Geosequestration is an important part of this portfolio.
Geosequestration represents perhaps the only option for decreasing greenhouse gas emissions while using fossil fuels and retaining our existing energy-distribution infrastructure.

Geosequestration is the deep geological storage of carbon dioxide from major industrial sources such as: fossil fuel-fired power stations, oil and natural gas processing, cement manufacture, iron and steel manufacture and the petrochemical industry.

The CO2CRC research effort focuses developing efficient, economic and safe methods of capturing carbon dioxide and geologically storing or geosequestering it in the deep subsurface.

CO2CRC FACT SHEET 2

Capturing CO₂ [view PDF]

The capture of carbon dioxide (CO2) from a stationary source, such as a power plant, involves trapping, or capturing, the CO2 rather than allowing it to be released to the atmosphere.

The main sources potentially suitable for CO2 capture are: industrial processes; electricity generation; and, possibly in the future, hydrogen production.

Industrial processes that may lend themselves to CO2 capture now include natural-gas processing; ammonia production; and cement manufacture, but the total quantity of CO2 produced by these processes is limited. A far larger source of CO2, accounting for approximately half of all CO2 emissions in Australia, is fossil-fuelled electricity generation, whether that be from coal, oil or natural gas. While the basic building block technologies exist for capture from these sources, and such a plant could be built today, more research is required on these capture technologies to reduce the power cost increases to the community.

Technologies for capturing CO2 from electricity generation fall into three categories: post-combustion, pre-combustion and oxy-firing.

In post-combustion capture CO2 is separated from the flue gas after fuel is burnt from conventional power stations, either coal or natural gas.

During pre-combustion capture the fossil fuel is brought into contact with steam and oxygen, producing a synthetic gas (syngas), largely comprising carbon monoxide (CO), carbon dioxide and hydrogen (H2).

This syngas can then be combusted in power gas turbines to produce electricity – such plants exist today. However, for maximum CO2 removal an additional reaction (water gas shift) is used to convert the residual carbon monoxide to CO2 and additional hydrogen with water.

The CO2 is then removed from the syngas before combustion in the power turbines. This process can be applied to all fossil fuels, but in the case of coal, the solid fuel is gasified in either an oxygen or air-blown gasifier. Examples of these are Integrated Gasification Combined Cycle (IGCC) or Integrated Drying Gasification Combined Cycle (IDGCC) – an Australian-developed technology.

Oxy-firing combustion capture is where fuel is combusted in pure oxygen. The process produces about 75 per cent less flue gas than air-fueled combustion and the exhaust consists of between 80 and 90 per cent CO2. The remaining gas is water vapour, which simplifies the CO2 separation step. An air separation plant is required to produce pure oxygen for the process from air.

CO2 capture practised commercially for many years

While the capture of CO2 for geosequestration is a relatively new concept, CO2 capture for commercial markets has been practised in Australia and overseas for many years.

CO2 is captured from natural gas wells in South Australia, near Mt Gambier and in southern Victoria, near Port Campbell. The CO2 is then used for various commercial processes including carbonation of beverages and dry-ice production.

In the United States, CO2 capture at power plants using chemical absorption based on the monoethanolamine solvent has been practised since the late 1970s, with the captured CO2 being used for enhanced oil recovery as well as smaller scale CO2 beverage manufacture.

CO2 Capture and Geosequestration

Following capture, CO2 is usually transported from a source, such as a power station, to the geological storage site in a compressed form via a pipeline (though other forms of transportation such as road, rail or ship are feasible and may well be economic in certain situations).

CO2 is then injected deep underground into porous and permeable rocks within geological reservoirs between one and three kilometres beneath the surface. (See fact sheet 1, What is Geosequestration, and fact sheet 5, Storing CO2, for further information.)

CO2CRC FACT SHEET 3

CO₂ Capture Costs [view PDF]

Initial estimates indicate the current cost of capturing and storing carbon dioxide from a stationary industrial source today would range between $30 and $35 Megawatt hours (MWh) for pre-combustion applications using Integrated Gasification Combined Cycle (IGCC) and between $35 and $45/MWh for post combustion depending on whether black or brown coal is used and where the geological storage location is sited.

Given the base-power generation costs from these different technologies this would result in overall increases in the cost of generation from a geosequestration-enabled power plant today of between $35-45/ MWh.*

Current research at CO2CRC, and other groups around the world, is aiming to reduce this cost increase to between $15 and $20/MWh.*

* The cost of power generation in Australian has traditionally been approximately $35/ MWh while domestic users have paid $120-150/MWh. It should be recognised that there are emerging factors that will put pressure on the base power cost, unrelated to the needs for low emission power. Issues such as global material and skills shortages and local factors such as water availability are beginning to manifest in higher base-power costs. These will eventually affect the cost of all forms of both conventional and low- or no-emission power in the future. Confidence in the cost of any new power facility will only be gained through the next round of demonstration and commercial power installations. In the case of carbon capture and storage the relative location of sources and sinks is also important.

CO2CRC FACT SHEET 4

CO2CRC Capture Research [view PDF]

CO2 capture represents up to 80 per cent of the cost of geosequestration. The CO2CRC Capture Program researches, develops and demonstrates technologies that can reduce capture costs by 75 to 80 per cent.

These reductions are being achieved by focusing on a number of themes including:

• selecting the best separation medium and/or process;
• designing for optimal heat integration within the power plant; and
• selecting equipment that is fit-for-purpose for this new CO2 removal application.

We have over 40 lead researchers, post doctoral fellows and doctoral students working at six universities around the country on a range of cost effective CO2 separation techniques, such as:

• gas separation and capture technologies for the full range of CO2-producing applications. (These include post-combustion, pre-combustion and oxyfuels power production and natural gas production);
• gas absorption processes;
• gas separation and gas absorption membranes;
• solid adsorption products and processes;
• cryogenic and hydrate gas separation processes; and
• other hybrid applications.

Over the past three years this work has resulted in innovative techniques to reduce costs and resulted in several world wide patents. An important aspect of commercialising technologies is to demonstrate them at ever increasing scale, thus moving from laboratory and desk based studies to plant based installations.
Consequently, the CO2CRC is involved in some major capture demonstration projects. They are:

• a world-first carbon dioxide CO2 capture technology project to trial technologies capable of making significant cost savings in the removal of CO2 from brown coal power generation. This is being conducted in association with the Victorian-based energy technology company HRL Developments. The project has received $2.06 million from the Victorian Government’s Energy Technology Innovation Strategy (ETIS) Brown Coal R&D Grants program; and
• a $5.6 million research project that focuses on the reduction of emissions from brown coal power stations. Loy Yang Power, International Power and CSIRO have joined CO2CRC to work on the Latrobe Valley Post Combustion Capture Project, which has also received $2.5 million from the ETIS program. This will allow development and demonstration of CO2 cost reduction at two power plants in the Latrobe Valley.
  Each of these projects (among other we are developing) will provide data and experience to reduce emissions and capture costs for any, and all, fossil fuel fired power stations and support our vision of a low emission future.
  

CO2CRC FACT SHEET 5

Storing CO₂ [view PDF]

The storage of carbon dioxide (CO2) secures the gas deep underground in a geological rock formation.

Geological reservoirs into which CO2 can be injected include depleted oil and natural gas fields; and deep saline formations.

Since the stored CO2 will be less dense than the water in and around the reservoir rocks, it needs to be geologically trapped to ensure that it does not reach the surface. The exact trapping mechanism depends on the geology.

In depleted oil and gas reservoirs geological traps contain the CO2. In some cases these are anticlines, or folds; in other cases fault traps.

In the case of deep saline formations, an impermeable caprock, above the formation is not needed as the CO2 is contained by the groundwater flow. This is known as hydrodynamic trapping.

Solubility and mineral trapping are two other important mechanisms. Solubility trapping involves the dissolution of CO2 into the saline water in the reservoir. Mineral trapping results from the CO2 reacting with minerals in the rocks to form stable carbonate minerals.

CO2CRC collaborates with leading research institutions and industry to investigate the storage potential of Australia’s sedimentary basins (See fact sheet 6, Geosequestration Storage Sites in Australia, for further information.)

Recent geosequestration research includes:

• a desktop study of SE Queensland storage sites;
• possible CO2 storage sites in China and SE Asia;
• a regional study on potential CO2 Geosequestration in the Collie Basin and the Perth Basin of Western Australia; and
• an assessment of the storage potential of the Latrobe Valley.

Current studies include:

• Storage assessment on the Gunnedah Basin, NSW;
• A storage assessment of the Sydney Basin, NSW;
• A regional geology study of the Galilee Basin, Qld; and
• CO2 enhanced oil recovery potential in Australia
• CO2 storage in coal systems.
  

CO2CRC FACT SHEET 6

CO2CRC Otway Project [view PDF]
Australia’s first demonstration of geosequestration

Global warming is a cause of great community concern both in Australia and overseas.

CO2CRC has developed a leading-edge research project that is demonstrating technologies that can make deep cuts into our CO2 emissions and help prevent potential climate change.

During the project, which is situated in south-western Victoria, researchers are producing naturally occurring CO2 and methane from a gas well (Buttress).

The gases are compressed then piped to a depleted natural-gas field (Naylor). Here, the CO2 and a small amount of methane is being safely injected and stored at least two kilometres below the Earth’s surface.

At a later stage of the project a small gas plant may be built to separate the CO2 and methane before the CO2 is injected.

Purified CO2 will be transported and injected into the existing reservoir.

Scientists would then have two sets of important data: the pure CO2 and CO2 containing a small amount of methane, from which they could forecast the behaviour of CO2 in an underground storage site.

CO2CRC will monitor the CO2 in the air, groundwater, soil and subsurface for the life of the project.

CO2CRC has kept the community and stakeholders regularly informed about the progress of the project though meetings, newsletters, email and our website.

CO2CRC FACT SHEET 7

CO2CRC Otway Project Monitoring Program [view PDF]

Showing the community, government regulators and industry that the geosequestration project is running according to plan is a high priority for CO2CRC.

In order to do this we have put in place a monitoring program that involves the regular testing of the soil, groundwater, air and subsurface for changes in the carbon dioxide (CO2) content. These monitoring activities are outlined below.

Monitoring the Soil

Soil gas sampling aims to evaluate the gases associated with natural gas deposits including naturally occurring CO2, hydrocarbons, such as methane; and oxygen and nitrogen.
During the survey, researchers will evaluate naturally occurring CO2, methane, oxygen and nitrogen, which are the usual gases found near CO2 sources. This work will provide CO2CRC with a baseline against which researchers can compare the soil tests that will be undertaken throughout the CO2CRC Otway Project and identify any changes to the soil gas chemistry that may take place.

There could be a number of reasons for changes to the soil gas levels. The baseline surveys undertaken by CO2CRC would enable us to identify the reason for those changes. Nirranda has a variable geology that includes limestone, sand dune, swamp/lake and river sedimentary deposits. Each geological variation results in the production of different soil and soil gas chemistry, which in turn affects the biology and productivity of the area.

Soil gases will also differ depending on climatic conditions for example warmer conditions lead to enhanced biological production and in time increased concentrations of CO2 in the soil. The application of fertiliser to a paddock will have a similar effect. The survey will also detect any gases from deeper natural gas sources including natural hydrocarbons and CO2.

The baseline soil sampling will cover the immediate area where the CO2 will be injected and areas where CO2 has naturally accumulated in the past and is currently stored. The soil gas surveys will continue throughout the life of the project.

Monitoring the Water

As part of the monitoring program, CO2CRC researchers will sample and analyse the groundwater in wells, both public and private in and around the pilot project area, throughout the life of the project.

The groundwater tests have the same objective to that of the soil gas surveys: to identify the baseline or current levels of CO2 in the water and monitor those levels for the life of the project.

As with the soil gas surveys, CO2CRC will investigate the cause of any changes to the composition of the groundwater. Reasons for such changes include seasonal variation, climate, drought or high rainfall, landuse and geology.

CO2CRC will provide the results of the tests to landowners. They are being carried out in cooperation with the Warrnambool office of Southern Rural Water.

Monitoring the Air

CO2CRC has set up atmospheric or air monitoring program that, like the soil gas surveys and the groundwater sampling, will record baseline or current levels of CO2 in the air.
The monitoring is planned to start well before operations begin and will continue through the life of the project. It will take place at the CO2 source well (Buttress) and storage reservoir site at the Naylor-1 well.

Funded by the Australian Government, the atmospheric monitoring program is one of the most advanced of its kind in the world.

As with the other monitoring activities, CO2CRC will investigate the cause of any changes to the composition of the air. The atmospheric CO2 levels will be used to confirm monitoring that will take place below the surface, scheduled to begin later in the project.

Monitoring the Storage Site

Deep subsurface monitoring of the storage reservoir complements air, soil and groundwater monitoring.

It is through physical and chemical subsurface monitoring that researchers will obtain an accurate picture of the CO2 and be able to can confirm that the storage site is secure and not leaking.

CO2CRC has two wells accessing the storage reservoir. One well for injecting the CO2 (CRC1) and another (Naylor 1) is dedicated to monitoring the physical and chemical makeup of the reservoir. The chemical (also known as geochemical) make-up of the water in the monitoring well (Naylor 1) will tell researchers when the CO2 arrives in this depleted natural gas well.

The other subsurface monitoring technique used at the storage site is geophysical. It primarily consists of seismic surveys. This technique uses a vibrating, truck-mounted weight and sensors that produce a three-dimensional picture of the CO2 and the rocks that contain it in the subsurface.

Seismic activities are expected to occur in 2008, 2009 and 2010.

CO2CRC FACT SHEET 8

Geosequestration Sites in Australia [view PDF]

An Australia-wide study of sedimentary basins conducted by CO2CRC and previously the Australian Petroleum CRC over the past nine years has assessed 100 sites for the suitability for the safe, long-term storage of CO2.

The majority of these sites were found to be potentially suitable. Ideally, these areas have rocks such as permeable sandstone that are overlain by a seal of non-permeable rocks.
CO2CRC is undertaking a more detailed look at these and other sites to determine the most suitable areas for geosequestration.

Areas being evaluated are:

• Storage assessment on the Gunnedah Basin, NSW;
• A storage assessment of the Sydney Basin, NSW;
• A regional geology study of the Galilee Basin, Qld; and
• the Otway Basin in Victoria, which is the site of Australia’s first geosequestration project, the CO2CRC Otway Project. (See fact sheet No 4, CO2CRC Otway Project, for further information.)

Geosequestration sites must have simple geology. This means they should have no active faults and permeable and porous rock, such as sandstone, to absorb the CO2. The sandstone must be overlain by a mudstone or caprock that will trap the CO2 in the deep subsurface. (See fact sheet No 1, What is Geosequestration, for further information.)

CO2CRC FACT SHEET 9

Offshore Geological and Ocean Storage of CO₂ [view PDF]

Offshore geological and ocean storage of CO2 both involve capturing the gas from a stationary emissions source such as a power plant or other industrial facility and then transporting the highly compressed CO2 offshore via a sub-sea pipeline or ocean tanker.

There is, however, a major difference between offshore geological sequestration and ocean sequestration in the way in which the CO2 is stored.
Offshore geological storage involves the CO2 being injected into a geological formation deep beneath the seabed where it will be stored for thousands of years, isolated from the ocean water.

In the case of ocean storage, the CO2 is injected directly into the water column either at mid-depth (1500 to 3000 metres), where it dissolves in the ocean waters, or at greater depths (below 3000 metres), where it forms a deep CO2 lake.

Offshore geological storage has been successfully demonstrated at Statoil’s Sleipner field in the North Sea (about 250 km off the coast of Norway) since 1996. At Sleipner, CO2 is separated from produced natural gas and stored in a deep saline formation about 1000 metres beneath the seabed.

No ocean sequestration demonstration projects as yet exist.

CO2CRC FACT SHEET 10

The Lake Nyos Gas Burst [view PDF]

In August 1986 at Lake Nyos, in Cameroon, West Africa, a volcanic crater lake released a large volume of CO2. This was not a volcanic eruption, but a gas burst.
Being denser than air, the CO2 failed to disperse and flowed down into nearby populated valleys resulting in the deaths of about 1700 people.

What happened at Lake Nyos?

Cameroon is situated on the Cameroon Volcanic Line, an area of volcanic activity that makes it susceptible to the release of volcanic CO2.

After degassing from the hot magma, the CO2 gas is trapped underground or escapes to the surface. In the case of Lake Nyos, the CO2 slowly moved into natural pathways feeding into the lake and directly into the lake. CO2 is soluble in water and so dissolved into Lake Nyos.

The lake is very deep and contained a very large volume of stratified or layered water. When these layers become unstable through seasonal turnover, the CO2 is circulated to upper layers where it is released from the water in non-catastrophic events.

However, Lake Nyos existed in long-term physical and chemical equilibrium resulting in stratified lake waters with very high CO2 concentrations. Either the addition of simply too much CO2 (the water was supersaturated in CO2) or external mechanical forces (underwater land slip or earthquake) caused the equilibrium of the lake to be disturbed.
This disturbance caused the stratified lake layers to mix and the CO2-rich waters were suddenly exposed to lower pressures and became unstable. This sudden destabilisation caused large amounts of the CO2 to be released out of the lake as gas burst.

This event is not the only sudden release of CO2 from a lake that has been documented. Lake Monoun, Cameroon, only 100km away from Lake Nyos erupted in 1984, releasing a large volume of gas, this time, into largely unpopulated areas.

Does Lake Nyos Suggest that Geosequestration is Unsafe?

The answer is no. In Australia a site selected for CO2 geosequestration would lack any of the readily identifiable natural pathways or the volcanic activity that is present in Cameroon.
The potential storage sites currently being explored by CO2CRC have:

• simple geology to avoid movement and leakage of CO2;
• the capacity to store the CO2 deep beneath the Earth’s surface (at least 800m);
• the right sort of permeable rocks to absorb the CO2; and
• the necessary rocks to trap or seal in the CO2.

Our research to date strongly suggests that in many of Australia’s sedimentary basins CO2 emissions could be safely stored in the subsurface for thousands of years and longer.

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