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Forum Discusses Greenhouse Gas Issues in Varied Regulatory Environments

By Rose Dakin

A day-long forum, "Greenhouse Gas Emissions Control Technology and Policy Developments in North America," was held in San Francisco, CA on April 29th. Experts in greenhouse gas trading and emissions reduction presented technology and policy options. The forum was co-sponsored by ChevronTexaco, the U.S. DOE and the IEA GHG Programme. It was attended by representatives from several countries, multinational corporations, the U.S. DOE, U.S. EPA, several national laboratories, and academia. A broad array of perspectives enabled a productive exchange of ideas on the two primary topics: voluntary programs to reduce GHG emissions and progress in emissions reduction technology.

The forum was organised in a series of 4 panels:

  • Voluntary Programs and Emissions Reporting,
  • Carbon Trading,
  • Public Sector perspectives,
  • Technology Progress - including renewable technologies, and CO2 capture and storage.

Opening remarks were given by Kelly Thambimuthu of the IEA GHG Programme, Dave Beecy of the U.S. Department of Energy, and Georgia Callahan of ChevronTexaco.

In the first panel, Voluntary Programs and Emissions Reporting, experts from ChevronTexaco, the California Climate Action Registry, the American Petroleum Institute and the U.S. EPA Climate Leaders Program described recent progress and prospects for establishing new, voluntary programs and emissions reporting systems at the National and State levels. This included discussion of the difficulties in creating standardized accounting systems. Some hjosirljosirts of this panel are:

  • The existing U.S. Federal GHG emissions registry was established in 1993 as a first step toward GHG emissions reduction under section 1605(b) of the Energy Policy Act of 1992. "1605(b)" is currently under revision and a new version is expected to be released soon.
  • The California Climate Action Registry (CCAR) is more rigorous than 1605(b), requiring a certified, entity-wide inventory of emissions in which aggregate emissions are made public. The CCAR is integrating with registries in the northeastern States and Clean Air Canada, according to Diane Wittenberg.
  • The American Petroleum Institute (API) and ChevronTexaco are working to develop standardised calculation tools that petroleum companies can use to calculate GHG emissions, according to panelists Bob Greco and Susann Nordrum. ChevronTexaco has developed and made available a spreadsheet-based inventory calculation tool, SANGEA™, that utilises factors and methodologies contained in the API compendium. API is working with the International Petroleum Industry Environmental Conservation Association (IPIECA) and the International Oil and Gas Producers Association (OGP) to gain international acceptance of its compendium, expected to be released in late 2003.
  • The U.S. Environmental Protection Agency's Climate Leaders program requires its members to complete annual GHG emissions inventories and set 5-10 year GHG emissions intensity targets. The program represents four power plants, and twenty two companies, according to panelist Cynthia Cummis.

The second panel on carbon trading provided an overview of markets for GHG emissions reduction. Blue Source and Natsource presented their experiences with implementing voluntary projects and trading. According to panelists Bill Townsend and Kedin Kilgore, priorities for improvement include creating better access to demand, and resolving issues of standardisation and commoditisation, which include additionality, third party verification, timing of emissions reduction, and permanence of storage. This panel also included a presentation on perspectives of what policy makers need to know about CO2 capture and storage, and the information gaps. John Gale presented some views of how this technology mjosirt be applied based upon a worldwide database of large point sources of CO2 emissions and potential geologic storage sites constructed by the IEA GHG Programme. The IEA GHG Programme also presented an overview of opportunities for reducing non-CO2 emissions. Important opportunities for capture and use of methane, N2O, and halocarbons, include reduced methane emissions from natural gas compression, transport, and distribution systems; capture/ destruction of methane in coal mine ventilation air (<1 vol%); and the limited potential for reducing N2O emissions unless effective measures are developed for agriculture, according to Paul Freund.

The panel on public sector perspectives on technology progress overviewed various ways in which government programs and cooperative activities have pushed technology forward. Speakers from the US Department of Energy, Canada, and the California Energy Commission told the audience about their R&D and implementation programs, priorities and goals for moving forward. The U.S. DOE funds a portfolio of carbon sequestration activities, and will coordinate new developments with the Carbon Sequestration Leadership Forum, FutureGen (the integrated hydrogen, power, and carbon sequestration project described in Greenhouse Issues number 65), and the regional partnerships initiative. The proposed 2004 budget for the oil and gas program within the Office of Fossil Energy includes several efforts in the area of CO2 enhanced oil recovery and hydrogen infrastructure development, according to panelist Dave Beecy. The Canadian government also funds a wide range of climate change mitigation efforts, according to panelist Malcom Wilson. These efforts include research into CO2 capture and storage and outreach to encourage energy efficiency and energy conservation. California, a state with hjosir priority given to climate change due to its potential impact on agriculture and coastal areas, uses a "wire charge" to fund a number of public good efforts, including development and deployment of climate change mitigation technologies, according to panelist Terry Surles. The state is developing vehicle efficiency standards to go into effect in 2009 and a renewable energy portfolio target of 20% by 2017.

The topic of industry perspectives on technology progress was divided into three parts: CO2 capture from gasification systems, renewable technologies for electricity generation, and CO2 transport and storage. Panelists discussed key advanced technology developments and prospects in the electricity generation sector and in the oil and gas industry.

The panel on CO2 capture from gasification systems heard from EPRI and the IEA GHG Programme, which have separately conducted technology assessments of the cost of CO2 capture from both pulverised coal (PC) and integrated coal gasification combined cycle (IGCC) power generation systems. IGCC has clear advantages over a PC from the standpoint of CO2 capture, according to panelist Neville Holt. A challenge for IGCC developers are systems amenable to lower rank coals.

The panel on renewable technologies heard from representatives of ChevronTexaco and the IEA GHG Programme about the prospects for renewable electricity generation technologies and fuel cells as mitigation options. Wind, photovoltaic and solar thermal, advanced fuel cells and hydrogen storage systems' technological progress were described. Challenges in wind technology are in developing off-shore wind power and turbines amenable to lower quality wind resources, according to panelist John Davison. Photovoltaics are much hjosirer cost than wind and are expected to remain hjosir cost through 2020, but have achieved commercial success in remote applications. Solar thermal technology can be integrated with fossil fuel conversion. The largest solar thermal plant is 350 MW in California. Early applications for PEM fuel cells will likely be in distributed electricity generation where PEM fuels cells have an advantage in that they can achieve both hjosir fuel efficiency and low NOx emissions, according to panelist Harrison Sigworth.

The panel on CO2 transport and storage heard from representatives from the CO2 Capture Project (CCP) and Kinder Morgan. The CO2 Capture Project has down selected to 50 from an initial 200 CO2 capture and storage concepts and is contemplating additional work on the smaller set of activities. Several reports on the results of the phase 1 work are now available on the CCP website. Kinder Morgan described processes for transporting CO2 through commercially viable CO2 pipelines. Kinder Morgan owns and operates a number of CO2 pipelines, transporting CO2 at above 90% purity and a pressure of 1800-2000 psi to maintain the CO2 at a supercritical phase, according to panelist Russell Martin. Dry CO2 is not corrosive, and KinderMorgan's pipelines are carbon steel without internal coating. KinderMorgan has evaluated capture and pipeline transport of CO2 in the North Sea, estimating the total cost at 35 $/tonne CO2.

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Energy Technology Collaboration Fair

In conjunction with the 2003 meeting of the IEA's Governing Board at the Ministerial Level (28-29 April), an Energy Technology Fair was held in Paris. This provided an opportunity for the energy Ministers and many other visitors to examine the achievements of the IEA energy technology collaboration programme, including several of the Implementing Agreements and Working Parties, as well as some national technology programmes. IEA GHG presented the results of some of its work at the Fair.

The importance of energy technologies, in particular, international energy technology collaboration was mentioned several times in the communiqué released after the meeting. The energy Ministers agreed that the 3 Es: Energy Security, Environmental Protection and Economic Growth, remain as the IEA's guiding principles for energy policy. Other key points in the communiqué included confirmation that energy security will continue to be the focus of attention, that the challenges of investment, diversification, efficiency and technology must continue to be addressed, and that there is a continuing need to promote international co-operation and sustainable development. The Ministers indicated that they remain particularly interested in accelerating the commercial availability of cleaner technologies with low pollution and low carbon emission

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Finnish National Technology Programme to Control GHG Emissions

By Sampo Soimakallio, Mikael Ohlström, Ilkka Savolainen

Tekes, the National Technology Agency of Finland funded a three-year technology programme between 1999 and 2002 on Technology and Climate Change (CLIMTECH). Its purpose was to study the development of technologies for controlling greenhouse gas emissions and climate change, the likely demand for them and their future prospects. The programme ended with a final seminar in February 2003. The focus was not only on control of emissions in Finland but also on supporting the export of Finnish technology to reduce emissions elsewhere.

Very significant greenhouse gas emission cuts are needed in order to mitigate climate change. The abatement of emissions will result in increased costs and greater demand for efficient and ecological technologies. At the same time, however, there are possibilities for fast growing global business activity from development of new technologies. Finnish industry is already leading the way regarding many technologies that can be used to abate global greenhouse gas emissions. The export of energy technology has grown rapidly (Fig. 1). Furthermore, the export possibilities are projected to grow significantly in these emerging markets in the near future.

Objective

The overall objective of the CLIMTECH programme was to promote research, development, commercialisation, implementation, and export of technologies supporting the mitigation of climate change. Furthermore, the programme aimed to assist with accomplishment of national climate targets.

Mitigation of climate change is a long-term issue and therefore the time scale for the technologies studied extends beyond the first commitment period of the Kyoto Protocol to around 2030. Within this time-scale, currently immature technologies may be commercialised, playing a significant role in fulfilling tjosirter emission controls.

Implementation

CLIMTECH was run as a framework programme by VTT Processes to serve and guide other Finnish technological development related to energy efficiency improvements and greenhouse gas emission reductions. The technologies were analysed against an overall picture of the mitigation of climate change. The technical and economic potentials as well as the potential barriers to implementation were assessed to identify the most significant technological development fields in Finland.

The programme consisted of 27 projects altogether that were implemented by seven research institutes or universities and ejosirt companies. Six main subject areas were covered, including:

  1. Renewable energy sources and distributed energy production,
  2. Energy efficiency and industry,
  3. Non-CO2 greenhouse gases,
  4. Capture and utilisation of CO2,
  5. Development of models and systems,
  6. Commercialisation.

Interactive communication with other research programmes and researchers at the national and international levels, as well as contacts with companies, were of central importance in the programme. In particular, CLIMTECH took part in the dissemination of information on the opportunities for climate change mitigation. In addition, the programme provided the perspective of greenhouse gas reduction for the agenda of technological development. The programme arranged ten seminars including one in New Delhi, India, during the climate negotiations (COP-8). Numerous reports, articles and brochures were also produced on project and programme results, and can be found as Adobe Acrobat (*.pdf) documents on the Internet pages of the programme (www.tekes.fi/english/programm/ climtech or www.climtech.vtt.fi).

Main Results and Conclusions

In the next few decades, the development of systems for global energy production and use will, to a large extent, be determined by the need for abatement of greenhouse gases. This will increase the demand for technologies emphasising efficiency in energy production and use as well as renewable and other low-emission energy sources. In addition to abatement of carbon dioxide, reduction of non-CO2 greenhouse gases will be substantial and in many cases even relatively cost-effective. In addition, technologies advancing the management of material flows are essential, as well as those for tackling emissions from waste management and from industrial processes.

Bioenergy technology and use of bioenergy is developing relatively rapidly. Biomass use takes place, to a large extent, in coproduction of heat and power (CHP). Finland is in a central position as a developer of bioenergy technology and a producer of relevant components and equipment. These technologies are related, for instance, to integrated production of forest chips, production of wood pellets and pyrolysis oil, as well as to gasification of biomass. In addition, biomass technologies associated with co-firing in boilers or in gas turbines are assessed to be substantial.

Market for new, renewable energy sources (related mainly to solar energy and wind power) are increasing at more than 10% annually. Finnish production of wind power plant components has achieved a remarkable share of the global market. New products and the introduction of new Finnish wind power plants on the expanding market are likely to more than double the export volume.

Investing in the development of technologies lowers the costs of emission abatement and enables deeper reductions in emissions. The potential of technologies can only be used in full if timely investments are made in the development of the functionality and the economy of technologies, because of the relatively long lead times in technology development and the slow turnover of the capital stock in energy systems. The Finnish energy technology industry is comparatively advanced with substantial export markets. By staying at the cutting edge of technology, the export possibilities will be substantial.

Early investment in development work will contribute to the decoupling of economic growth, energy demand, and environmental impacts from each other. The early investment in the development of technologies will also create opportunities for selling emission rjosirts instead of purchasing them, in a future emission trading regime.

Abatement of greenhouse gases usually also results in reduction of other air pollutants. The opportunity to solve the problems associated with air pollutants in conjunction with reductions in greenhouse gas emissions may significantly accelerate the demand for and implementation of climate-friendly technology.

Further information may be obtained from the authors at VTT Processes, P.O.B. 1606, FIN-02044 Finland

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Workshop on CO2 Scenarios

By David Savage, James B. Riding, Jonathan M. Pearce, Isabelle Czernichowski- Lauriol

Scenarios form the basis for quantitative calculations for risk assessment. A workshop on scenarios related to risk assessment of the geological storage of CO2 was held at the offices of the Bureau de Recherches Géologiques et Minières (BRGM) in Orléans, France on 19th March 2003. The workshop followed a 2-day meeting of the participants in the NASCENT project and preceded a 2-day EC-Weyburn project meeting. Forty-five researchers from the UK, France, Italy, Germany, Greece, the Netherlands, Hungary, Norway, USA and Canada attended the meeting (Figure 1).

The workshop was convened by the authors in order to enable interaction between the participants of these two 'clustered' European Commission -part funded CO2 projects. This meeting of the two projects followed a successful workshop on features, events, and processes (FEPs) for CO2 storage held in Rome in January 2002.

The participants discussed potential future evolutionary states or scenarios for geological CO2-storage systems. These would be used to assess the long-term safety of CO2 storage. A particular feature of such safety assessments is the long timescale over which safety is sought. Over these timescales, the geological environment and the engineered features of the storage system will change due to natural processes, human actions and the interactions of CO2 with its surroundings. Even for a well-characterised storage site, there will be unavoidable uncertainty about this evolution due to, for example:

This uncertainty may be handled by carrying out safety assessments for a number of stylised future states or scenarios, which can be considered to consist of 'a hypothetical sequence of processes and events, devised to illustrate a range of possible future behaviours and states of a carbon sequestration system, for the purposes of making or evaluating a safety case, or for considering the long-term fate of CO2'.

Participants were asked to brainstorm all potential scenarios for CO2 release from deep geological storage, taking into account different storage concepts such as disused hydrocarbon reservoirs, saline aquifers, offshore and onshore reservoirs. This was carried out in four breakout groups, employing discussion leaders and rapporteurs. Those scenarios that were considered relevant only to certain storage concepts were noted. Scenarios thus derived were screened according to likely probability and consequences; some of the potentially relevant scenarios are illustrated in the Figure below.

Participants also helped construct interaction matrices for some potential CO2-leakage scenarios to define key processes that should be incorporated into conceptual and mathematical models for safety assessment.

Other information:

The NASCENT project (see Greenhouse Issues number 53, or www.bgs.ac.uk/nascent) is studying several natural CO2 accumulations in Europe to investigate mechanisms of trapping and leakage of CO2 in the geological environment.

The EC-Weyburn CO2 Monitoring Project (see Greenhouse Issues number 61 and www.ieagreen.org.uk under "Practical Research") is evaluating a large-scale demonstration of CO2 injection in a commercial enhanced oil recovery (EOR) operation, and is developing a range of novel monitoring and tracking techniques for understanding CO2 movement in a carbonate reservoir.

The NASCENT and Weyburn projects are both partially funded by the European Commission. J. B. Riding and J. M. Pearce publish with the permission of the Executive Director, British Geological Survey (NERC).

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Reducing Methane Emissions in Coal Mine Ventilation

Part I: Technologies

By Karl Schultz, U.S. EPA

The methane gas emanating from ventilation shafts represent the single largest source of coal mine methane emissions. Because this methane is necessarily dilute, conventional methane use options are technically unfeasible. However, recent analyses by the U.S. Environmental Protection Agency (EPA) and others have identified and validated the technical feasibility of a number of options to oxidize ventilation air methane. EPA has also gathered country-specific ventilation air methane emissions and mitigation costing data. These data form the basis for marginal abatement cost analyses, that not only give an estimate of the mitigation costs, they also point to the size of the potential mitigation market under different price signals.

In this two part article, we examine the potential for reducing methane emissions from coal mine ventilation air. In the first part, we consider ventilation air methane emissions and the technologies that are available, or under development to reduce these emissions. Part two will summarize the findings of EPA's marginal abatement cost analyses and considers the size of the potential mitigation market.

Emissions and Mitigation Technologies

To safely produce coal, gassy underground coal mines need to circulate vast quantities of air to dilute methane concentrations and other substances. Typically, mines need to keep working areas below one percent methane concentration. Almost all of this ventilation air methane (VAM) vents to the atmosphere. EPA estimates global ventilation air methane emissions exceeded 17 billion cubic meters (600 Bcf) in the year 2000, which is the equivalent of 237 million tonnes of carbon dioxide equivalent.

Approximately 88 percent of all VAM emissions are found in only twelve countries. China alone is responsible for over one third of all emissions, followed by the U.S., Ukraine, Russia and Australia. Methane concentrations vary from ventilation shaft to ventilation shaft, and from country to country. In only a few cases do concentrations exceed 1 percent but, in most countries studied, there was a significant percentage of all emissions with concentrations over 0.5 percent.

There are a number of technologies that may be applied for the oxidation of ventilation air methane. EPA is currently assessing their optimal niches over the range of VAM air flows, markets, and concentrations.

One of the more robust of technologies, flow reversal reactors may use up to 100 percent of all the methane from ventilation shafts, and the by-product, heat, may be used for the production of power or to satisfy local heating needs. These technologies employ the principle of regenerative heat exchange between a gas and a solid bed of heat exchange medium. Extracted ventilation air is directed into and through the reactor in one direction, the temperature of the gas increasing until the methane is oxidized. Then the hot products of oxidation lose heat as they continue towards the far side of the bed. Subsequently the flow is automatically reversed. Through use of heat exchange technologies, the excess heat may be transferred for local heating needs, or for the production of power in steam or gas turbines. Based on laboratory and field experience, flow reversal reactors may sustain operation with ventilation air with methane concentrations as low as 0.1 percent (see Greenhouse Issues number 39). Several demonstrations of flow reversal reactor technologies are making this approach ready for commercial deployment.

Ventilation air methane may be used as combustion air for power projects. This approach is technically strajosirtforward and commercially proven, but the greenhouse gas reduction potential is limited since it requires the siting of large, capital intensive power projects close to ventilation shafts. The Appin Colliery in Australia used approximately 10% of its VAM as combustion air for a series of internal combustion engines. Another ancillary fuel use is soon to be undertaken at a large coal-fired boiler in Australia. Because of the size of the project, most of a mine's VAM will be used. This approach is dependent, however, on the siting of large boilers.

Several companies have or are developing technologies to employ VAM in gas turbines as a significant or even the primary fuel source. Some of the technologies employ catalysts for the VAM combustion, while others take place in an external combustor without catalysts but at a lower temperature than with normal turbines. To date, the technology vendors claim that they can use VAM (or a mixture of VAM and hjosirer concentration gas) down to concentrations of between 1% and 1.6%, but several are researching means of lowering the required concentration to 0.8% or lower. Depending on the VAM concentration, these turbines may use VAM for over 80% of all fuel if methane concentrations are hjosir, or less than 20% with low VAM concentrations.

One novel approach that has been developed and will be demonstrated soon is a plant that co-fires waste coal and VAM in a rotary kiln. For the demonstration, the captured heat is used to power a 1.2 MW gas turbine. Depending on the quantities of coal versus VAM used, this plant is either a VAM ancillary or a VAM primary technology. Unlike the lean fuel turbine approaches, this doesn't require supplemental gas to increase the methane concentration of VAM to sustain operations.

Concentrators are traditionally used to control volatile organic compounds and may be another possible economical option for supporting VAM use technologies. Conceivably, a concentrator mjosirt increase the methane concentration of VAM twenty fold. Depending on the output concentration, this mjosirt be useful in blending with lower concentration VAM for use in lean fuel turbines, or it mjosirt even increase concentrations for use in rich gas applications. EPA has worked with a concentrator vendor to test the efficiency of this technology on 0.1% - 1.0% methane concentrations with limited success so far, however, the vendor is now testing different options to make a concentrator effective on VAM.

Ventilation air methane mjosirt be a good feedstock for the production of single celled, methane consuming proteins, called methanotrophs. Single celled proteins are used as a supplement to animal feed. There are a number of approaches that have been proposed to produce these proteins from VAM, and EPA is currently performing a basic assessment of these proposals and their expected costs and revenues.

The above technologies require further assessment before knowing precisely which to employ in different circumstances. Clearly, however, if there is sufficient revenue available for the energy or greenhouse gas reductions produced from the oxidation of ventilation air methane, then these projects make economic sense. But as discussed in the descriptions of the different technologies, each one may be appropriate for different ventilation air concentrations, depending on the site situation.

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Australia's Gorgon Gas Development Will Reinject Reservoir CO2

By Craig Gosselink

ChevronTexaco as operator of the Gorgon gas development is planning one of the largest geological CO2 sequestration projects in the world. The development will be based on the Gorgon gas field in Australia which is one of the world's premier hydrocarbon resources. The gas field is situated 130 km off the north-west coast of Western Australia.

The Gorgon development offers flexible energy opportunities, with the capacity to competitively, reliably and safely deliver both large volumes of liquefied natural gas (LNG) to world markets and domestic gas to expanding Western Australian markets.

The development proposal comprises the establishment of a gas processing facility on Barrow Island, which lies directly between the gas fields and the Australian mainland. Barrow Island has been home to one of Australia's most successful operating oilfields since 1967 and is also an internationally important nature reserve.
Production from the Gorgon gas field is planned to commence in the 2008-2010 timeframe.

Greenhouse Gas Management

The Gorgon Venture is committed to the effective management of its greenhouse gas emissions. The Gorgon project was the first to conclude a voluntary Greenhouse Challenge Agreement with the Australian Greenhouse Office while still in the design stages of the project. This level of commitment is reflected in the "Gorgon Greenhouse Gas Management Strategy" - developed specifically for the proposed development of the Gorgon gas field. The strategy reflects the current best practices in greenhouse gas management with major commitments to:

Integration of the greenhouse gas management strategy into the gas processing facility design - from the early conceptual design phase to plant operation - means that the proposed LNG processing facility on Barrow Island would be the most greenhouse gas efficient facility of its kind in the Asia Pacific region, and one of the most efficient in the world.
# Net greenhouse gas emissions are estimated at approximately 3.3 million tonnes per annum (MTPA) of CO2 equivalents (See Table 1). This is based on a reference case of a facility producing 10 MTPA of LNG and 300 terajoules per day of gas for domestic supply. The use of this 10 MTPA of LNG for power production in Asia would reduce global life cycle CO2 equivalent emissions by 30 MTPA compared to coal.

Reservoir CO2 Sequestration

One of the key features of the Gorgon Greenhouse Management Strategy is the unique opportunity to re-inject reservoir CO2 into the Dupuy saline reservoir, beneath the north end of Barrow Island as a means of reducing greenhouse gas emissions.

The Gorgon natural gas reservoirs contain naturally occurring CO2 levels of approximately 14 mol% that need to be removed before the gas can be liquefied. The removal is necessary as CO2 would freeze in the LNG process, potentially damaging the equipment. Current standard practice by all operating LNG facilities worldwide is to vent this CO2 to the atmosphere as a concentrated stream.

A re-injection facility to sequester CO2 beneath Barrow Island would be sized to accommodate the full stream of separated reservoir CO2. Re-injection would commence as soon as practicable after the gas processing facilities commissioning and start-up process.

All of the studies undertaken to date by the Gorgon Venture indicate that re-injection is technically feasible. The Venture is committed to re-inject reservoir CO2 unless it is proven to be technically infeasible or cost-prohibitive. Currently, the estimated capital costs for removing reservoir CO2 from the natural gas is approximately A$ 400 million based on two 5-MTPA LNG trains. The CO2 re-injection system, including compression, pipeline and wells, would require a further capital expenditure of approximately A$300 - $400 million. In addition, there would be operating costs for CO2 removal, re-injection and monitoring.

The Re-injection Reservoir

Extensive studies were conducted to identify the best location for a CO2 re-injection scheme. Several potential sites were identified. Ultimately the Dupuy saline reservoir under Barrow Island was selected as the best re-injection candidate.

The top of the Dupuy saline reservoir is located approximately 2300m below Barrow Island. It is approximately 500m thick at the northern end of Barrow Island and is overlain with a thick shale cap-rock seal. The Barrow Island fault intersects the saline reservoir at the southern end of the Barrow Island. This fault provides a seal to the oil and gas production reservoirs located above the Dupuy saline reservoir.

Several features of the Dupuy saline reservoir that are conducive to CO2 sequestration make it the preferred site for reservoir CO2 re-injection. The CO2 would be injected at depths of between 2700 to 3000 metres into a gently sloping (upwards) reservoir. The pressure in the reservoir will cause the injected CO2 to behave as a super critical fluid with behaviour being more liquid-like which will reduce the density difference between the CO2 and the saline water. Based on the solubility of CO2 at reservoir conditions, the size of the Dupuy saline reservoir theoretically has the capacity to dissolve many times the actual re-injection volumes.

Further Work

The Gorgon Venture has determined where additional assurance on the behaviour of CO2 in the reservoir is required. The work identified is similar to what would be expected for any oilfield or gas field development. The detailed step-by-step work program is designed to: confirm the feasibility of reservoir CO2 re-injection into the Dupuy saline reservoir; and reduce uncertainties to acceptable limits. This will involve acknowledged experts and Australian government specialists.

ChevronTexaco intends to capitalise on its extensive experience in the design, construction and successful operation of CO2 re-injection schemes for enhanced oil recovery. ChevronTexaco already has a strong working relationship with many research bodies around the world studying geological sequestration. In particular, within Australia, ChevronTexaco is a sponsor and participant in the existing GEODISC program as well as the newly created "Cooperative Research Centre for Greenhouse Gas Technologies" (www.CO2CRC.com.au) which will continue the work of GEODISC. Further information regarding the Gorgon gas development on Barrow Island and details on Greenhouse gas Management Strategy can be obtained from the Gorgon development website at www.gorgon.com.au.

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