CO 2 Capture and Storage in Geological Formations ZERO EMISSIONS TECHNOLOGIES FOR FOSSIL FUELS

Transcription

1 WORKING PARTY ON FOSSIL FUELS INTERNATIONAL ENERGY AGENCY Capture and Storage in Geological Formations ZERO EMISSIONS TECHNOLOGIES FOR FOSSIL FUELS

2 INTERNATIONAL ENERGY AGENCY 9, rue de la Fédération, Paris Cedex 15, France The International Energy Agency (IEA) is an autonomous body which was established in November 1974 within the framework of the Organisation for Economic Co-operation and Development (OECD) to implement an international energy programme. It carries out a comprehensive programme of energy co-operation among twenty-six* of the OECD s thirty member countries. The basic aims of the IEA are: to maintain and improve systems for coping with oil supply disruptions; to promote rational energy policies in a global context through co-operative relations with nonmember countries, industry and international organisations; to operate a permanent information system on the international oil market; to improve the world s energy supply and demand structure by developing alternative energy sources and increasing the efficiency of energy use; to assist in the integration of environmental and energy policies. * IEA member countries: Australia, Austria, Belgium, Canada, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Japan, the Republic of Korea, Luxembourg, the Netherlands, New Zealand, Norway, Portugal, Spain, Sweden, Switzerland, Turkey, the United Kingdom, the United States. The European Commission also takes part in the work of the IEA. ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT Pursuant to Article 1 of the Convention signed in Paris on 14th December 1960, and which came into force on 30th September 1961, the Organisation for Economic Co-operation and Development (OECD) shall promote policies designed: to achieve the highest sustainable economic growth and employment and a rising standard of living in member countries, while maintaining financial stability, and thus to contribute to the development of the world economy; to contribute to sound economic expansion in member as well as non-member countries in the process of economic development; and to contribute to the expansion of world trade on a multilateral, non-discriminatory basis in accordance with international obligations. The original member countries of the OECD are Austria, Belgium, Canada, Denmark, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, Turkey, the United Kingdom and the United States. The following countries became members subsequently through accession at the dates indicated hereafter: Japan (28th April 1964), Finland (28th January 1969), Australia (7th June 1971), New Zealand (29th May 1973), Mexico (18th May 1994), the Czech Republic (21st December 1995), Hungary (7th May 1996), Poland (22nd November 1996), the Republic of Korea (12th December 1996) and Slovakia (28th September 2000). The Commission of the European Communities takes part in the work of the OECD (Article 13 of the OECD Convention). OECD/IEA, 2003 Applications for permission to reproduce or translate all or part of this publication should be made to: Head of Publications Service, OECD/IEA 2, rue André-Pascal, Paris Cedex 16, France or 9, rue de la Fédération, Paris Cedex 15, France.

3 CAPTURE AND STORAGE IN GEOLOGICAL FORMATIONS - 3 INTRODUCTION Climate change is a problem of global proportions. A number of anthropogenic gases are largely responsible for driving this process forward, the most significant contributor being carbon dioxide ( ) produced by the burning of fossil fuels. The latter provide a large proportion (>85%) of the world s commercial energy needs and will continue to do so for the foreseeable future (Figure 1). To ensure that substantial reductions in atmospheric levels can be made during the present century and beyond, technological solutions urgently require development and application in order to control the increasing amounts of being produced. The International Energy Agency 1 (IEA) is playing a major role in addressing this problem. Recognising the potential of capture and storage technologies, the IEA s Working Party on Fossil Fuels 2 (WPFF) launched its strategy for Zero Emissions Technologies (ZETs) in With this concept, almost all conventional pollutants produced by the burning of fossil fuels are eliminated and is captured and stored, thus precluding its emission into the atmosphere. The capture of from commercial and industrial operations, followed by its storage in geological formations, is viewed as an important strategy for achieving substantial reductions in emissions levels. Widespread deployment of capture and storage technologies will depend, however, on the widespread introduction of appropriate mandatory standards or mechanisms for pricing emissions. Figure 1 World Primary Energy Demand in a Business-as-Usual Scenario Source: IEA World Energy Outlook Further details on the IEA s activities can be obtained at: WPFF Chair: Barbara.McKee@hq.doe.gov

4 4 - CAPTURE AND STORAGE IN GEOLOGICAL FORMATIONS As the IEA has commented: Numerous technology solutions offer substantial -reductions potential, including renewable energies, fossil-fuel use with capture and storage, nuclear fission, fusion energy, hydrogen, biofuels, fuel cells and efficient energy end use. No single technology can meet this challenge by itself. Different regions and countries will require different combinations of technologies to best serve their needs and best exploit their indigenous resources. The energy systems of tomorrow will rely on a mix of different advanced, clean, efficient technologies for energy supply and use. Energy Technology: Facing the Climate Challenge - paper prepared for the Meeting of the IEA Governing Board at Ministerial Level, April 2003 The fossil fuels currently supplying the majority of the world's energy needs will remain in abundant supply well into the 21st century. So no emissions reductions resulting from fossil fuel resource constraints will be seen in the foreseeable future. In fact, if no action is taken, emissions will continue to rise. This will remain the case, in spite of anticipated cost increases, as the cheapest oil and gas reserves are depleted and transport distances increase for obtaining new supplies. Global electricity demand is rising, particularly in the developing world, where population and economic growth are greater than in developed countries and where the rate of migration from rural to urban areas is significantly higher. Developing and developed countries alike can be expected to continue using their abundant coal reserves. Clearly, in the absence of action, levels can be expected to continue increasing (Figure 2). Figure 2 Energy-Related Emissions by Region in a Business-as-Usual Scenario Source: IEA World Energy Outlook 2002

5 CAPTURE AND STORAGE IN GEOLOGICAL FORMATIONS - 5 Continued fossil-fuel use in a emissions-constrained world will call for more efficient fossil-fuel combustion technology, capture and storage and switching among fossil fuels. Capture and storage is best suited to large point sources of, such as fossil fuel-fired power stations; these currently account for around one-third of all global emissions. In a future Hydrogen Economy, control of will be needed as well because hydrogen will be produced mainly from fossil fuels. There exist a number of capture techniques in use, or under development, some being at a more advanced stage than others. Such techniques can be grouped under the headings: pre-combustion; post-combustion; and oxyfuel technologies that involve closed cycle systems. The latter usually operate in oxygen-enriched atmospheres, flue gas is re-circulated and nitrogen is produced as a by-product of air separation. Some technologies, such as capture systems based on the use of amine scrubbers to remove, have already found limited commercial application. But considerable research and development work is required in order to further develop and optimise such techniques for most large-scale applications. Once captured, there are a number of potential options for the storage of, one of the most important being long-term storage in geological formations such as oil and gas reservoirs, unminable coal seams and saline aquifers. Storage Capacities of Geological Formations Potentially, huge quantities of could be stored in several types of formation (Figure 3). The most important of these and their estimated storage potential are: Sequestration option Oil and gas reservoirs Deep saline aquifers Coal seams Global capacity 100s Gt 100s-1000s Gt 10s-100s Gt Many uncertainties remain and capacity estimates vary significantly. But these formations have the potential to store all energy-related emissions for many years. During the period , the average amount of emitted would be ~27.5 Gigatonnes (Gt) per year. Based on current estimates, oil and gas reservoirs could accommodate such levels for >30 years, saline aquifers for ~ years, and coal seams for ~2-7 years (or longer if the target were to store only a certain fraction of the produced). In all cases, continuing efforts are being made to provide more accurate estimates of capacities. This will help target policy and technology development and may ease selection of a particular technology and site. Sources: Herzog, H. 1999; US Department of Energy, 1999; IEA GHG R&D Programme

6 6 - CAPTURE AND STORAGE IN GEOLOGICAL FORMATIONS Figure 3 Sequestration Options Source: IEA Greenhouse Gas R&D Programme EXISTING EXPERIENCE WITH CAPTURE AND HANDLING capture systems Although many capture and storage techniques have not yet been fully developed and optimised, a body of hands-on experience exists, in some areas, that is increasing steadily as further investigative activities are undertaken in each respective technological sector. In some cases, investigations and development have only begun recently, whereas in other cases, industrial-scale activities like scrubber-based capture technologies have been in operation for many years. The experience gained so far in these areas is described below. Some types of capture technology (based on both chemical and physical absorption) are well established and have been used for a number of industrial applications for several decades. The majority of chemical-based methods involve wet scrubbing systems that utilise amine solutions to remove from exhaust gases produced by the particular process. Typically, prior to the removal stage, the flue gas is cooled, then treated to reduce the levels of particulates and other impurities present. It is then passed into an absorption tower, where it is brought into contact with the absorption solution. In chemical absorption (preferred for low-moderate partial pressures) an amine solvent selectively absorbs the by reacting with it chemically to form a loosely bound compound. The -rich absorbent is then pumped into a desorber (stripper tower) where the pressure is reduced and/or the temperature increased to ~120 o C in order to release the. As the released is compressed, the regenerated absorbent is recycled to the stripper in a fully continuous process. Amine scrubbers have been applied in coal-, oil- and gas-fired power generation stations, in chemical production plants, in fertiliser production units and in natural gas processing

7 CAPTURE AND STORAGE IN GEOLOGICAL FORMATIONS - 7 transportation storage and utilisation operations. In most cases, the systems used are similar in concept and configuration and usually employ a regenerable amine such as monoethanolamine (MEA) as the working solvent. Such systems can recover up to 98% of the present and produce a stream of up to 99% purity. Depending on the individual situation, reported capture costs range between US$35/tonne and US$100/tonne of. On-going developments are making progress towards reducing these costs. Physical absorption can also be used for a variety of applications and is considered the preferred technique for applications such as integrated gasification combined cycles (IGCC) that operate at higher pressures. Physical solvents commonly used in commercial processes include methanol (Rectisol process), dimethylether of polyethylene glycol (Selexol process) and propylene carbonate (Fluor solvent process). Following the capture stage, can be compressed to form a supercritial or dense fluid, which is generally then transported by high-pressure pipeline. The costs of transportation depend largely on the distance between the point of dispatch and the final destination, as well as the availability of existing infrastructure. Studies suggest that costs are approximately US$1/tonne to US$3/tonne per 100 km. In the United States more particularly, there is already an existing network of pipelines that predominantly carry to oil fields for enhanced oil recovery (EOR) operations, some of which have been working for upwards of 20 years. Globally, there are some km of pipelines in use, with a capacity of 44.7 Mt/y. The majority are in North America and comprise a combination of both main and lateral lines. The longest individual pipeline covers 808 km and has been in use since It carries 19.3 Mt of each year. Most transported by pipeline is obtained from naturally occurring sources. But a recent important addition has been a pipeline connecting the Great Plains lignite gasification plant in North Dakota, United States, with the Weyburn oil field in Canada. A 205- mile cross-border pipeline carries 2.7 million Nm 3 /day of (~5000 tonnes), which is used for EOR operations. Overall, there thus exists considerable and growing commercial experience with the movement of via pipelines. Potentially, there are a number of important options applicable for the long-term storage of. These include primarily storage in oil and gas reservoirs, coal seams, deep saline formations and the oceans. The latter will not be discussed here because of current strong environmental concerns. In some cases, storage can also involve a benefitadded factor. The degree of maturity of the technologies associated with each option varies. In some cases, such as storage in both depleted and operational oil fields, practical solutions already exist and are being applied. Some issues relating to handling and transportation are common to most types of storage option, although other requirements may be specific to the particular technology. Practical experience has thus been gained in a number of areas encompassing the injection of into various types of geological formation, including oil reservoirs and deep saline aquifers (see below). There are also a number of commercial activities in operation where is being utilised in other ways, notably for food processing applications, production of mineral products and fertilisers, and for artificially enhancing algae and plant growth.

8 8 - CAPTURE AND STORAGE IN GEOLOGICAL FORMATIONS WORK IN PROGRESS ON STORAGE Deep saline aquifers Figure 4 In recent years, significant advances have resulted from work in hand, for instance from that of the IEA Greenhouse Gas R&D Programme. Further information on the following and many other -related projects can be obtained from the Programme s interactive website 3. A brief outline of major RD&D activities follows. These are underground, water-filled strata (aquifers) that are distributed widely below many major land masses and the oceans. They are generally to be found in carbonate or sandstone formations and contain large amounts of saline water. can be injected into such reservoirs using techniques similar to those applied to enhanced oil recovery schemes. A number of RD&D projects are investigating the use of aquifers. Issues being examined include cost minimisation, risk assessment, reservoir geology and characteristics, along with detailed surveying in specific regions. Important projects are being undertaken in North America, China, Japan and parts of Europe. A major demonstration project in Europe is underway in the Norwegian Sleipner West gas field in the North Sea 4 (Figure 4). Here, the technical and economic viability of the process is being confirmed by the injection of ~1 Mt/y of into an undersea aquifer known as the Utsira formation. It is the first commercial-scale storage in an aquifer. The facility incorporates separation and injection equipment. The Sleipner Demonstration Project Source: Statoil 3 At: 2 sequestration.info/ 4 Information on the Sleipner project can be found at: Contact: Tore A. Torp at: tat@statoil.com.

9 CAPTURE AND STORAGE IN GEOLOGICAL FORMATIONS - 9 Enhanced coalbed methane recovery (ECBM) projects Enhanced gas recovery (EGR) Enhanced oil recovery (EOR) Deep unminable coal beds represent a large potential geological storage medium for, with value-added benefit. The production of methane, naturally present in coals, can be enhanced by injecting into the seam. This displaces the methane present, which is then drained and used as a valuable fuel source. There are some 20 major R&D projects investigating ECBM technology, located in North America, Europe and Asia. Although not yet proven, it has been suggested that may have the potential to displace gas from natural gas fields, maintaining or boosting output. EGR issues are being investigated as component parts of several major initiatives. These are looking at development and application of enhanced modeling and monitoring techniques, reductions in operational costs, site characterisation and mapping, as well as capacity estimation. On-going projects include GEO-SEQ 5 (Geological Storage of Carbon Dioxide), CCP 6 (Carbon Capture Project) and GESTCO 7 (Assessing European Potential for Geological Storage of from Fossil Fuel Combustion). With EOR, is injected into operational oil reservoirs in order to increase the mobility of the oil (Figure 5). As well as boosting or maintaining oil output, much of the injected remains trapped in the reservoir. Based on some current estimates, it is suggested that, globally, ~130 Gt of could be stored in this manner. The costs associated with injection of the can be offset by the increased revenue generated from the additional oil produced. While most of the currently used for EOR operations is sourced from naturally occurring reserves, efforts are continuing to develop viable, cost-effective techniques for utilising from sources such as fossil fuel combustion plants and other major point sources. There are around 80 EOR sites currently in use around the world, all operated by major oil companies; the majority are in North America. Others are planned or already operating in the United Arab Emirates, China and parts of Europe. By the late 1990s, global EOR production averaged ~ m 3 /day of oil for these projects. Apart from such commercial activities, there are also a number of R&D programmes examining issues that include the development of novel monitoring and tracking techniques, the development of enhanced modeling capabilities to investigate the long-term fate of injected, and progressing techniques to assess reservoir characteristics and capacities. Risk assessment studies are also being undertaken. EOR is considered to be a strong candidate for near-term storage of because, apart from the economic advantages accrued through the generation of additional oil sales, such reservoirs are examples of natural stratigraphic traps with stable caprock formations that have contained oil for very long periods. In many cases, the geological structure and physical properties of reservoirs have been comprehensively characterised and modeled, allowing for accurate prediction of oil displacement and trapping behaviour. Widespread expertise and experience exist already for these types of industrial-scale operation Project website: Contact: Sally Benson at: SMBenson@lbl.gov Information on project is available from: www. captureproject.com/index.htm Contact N P Christensen, GESTCO project manager at: NPC@GEUS.dk

10 10 - CAPTURE AND STORAGE IN GEOLOGICAL FORMATIONS Figure 5 Schematic Diagram of EOR Operations Source: IEA GHG R&D Programme ISSUES TO BE ADDRESSED/KEY QUESTIONS A growing number of R&D organisations, government bodies, process developers, universities and energy producers are becoming actively involved in projects examining different aspects of capture and storage in geological formations. Many projects comprise international, multi-partner, collaborative ventures; organisations and major programmes are reviewed more fully in another brochure in the present series. A range of technological solutions allowing to be stored in various ways have been or are being developed and applied. As with any such developments, however, there remain issues to be resolved fully. Some of these concern practicalities, while others focus on issues of environmental safety associated with storage. In order for such techniques to be deemed acceptable by national governments, regulators and the public at large, work needs to be carried out to confirm that there are no inherent dangers that could result from either gradual or sudden release of from a particular store. Confirmation that leakage is minimal is also required from an economic standpoint, as there are clearly financial implications associated with injection into the particular formation. If these technologies are to be fully accepted, it will therefore be necessary to develop suitable storage protocols and procedures that can be proven effective and verifiably safe.

11 CAPTURE AND STORAGE IN GEOLOGICAL FORMATIONS - 11 What needs to be done in order to increase governmental, regulatory and public confidence and acceptance regarding the integrity and safety of storage in geological formations? Initially, suitable tools and working methodologies need to be developed to allow comprehensive analysis of the risks associated with long-term storage of in a range of such formations. This includes development of criteria characterising optimal conditions and characteristics of a range of geological options, including oil and gas reservoirs, deep saline aquifers and deep unminable coal seams. Comprehensive monitoring studies need to be carried out to follow the fate of the injected into a particular formation. This will help confirm that it remains safely stored within the formation over the required timescale. These investigations may require the development and demonstration of innovative monitoring and tracking technologies. While some techniques already exist, others require further development. Several large-scale projects presently underway are actively developing further selected monitoring techniques. This type of work will rely heavily on the use of improved computer simulation models for examining and modeling the characteristics of reservoir structures and predicting the behaviour of in different storage media. Data from such modeling and monitoring studies will help reduce associated risks and ease selection of the best geological sites for storage. Several major projects are currently examining these issues, based on enhanced oil recovery, unmineable coal seams and deep saline aquifers. Important progress is already being made by a number of such projects, helping to confirm geological storage as a viable and environmentally sound disposal option. Many of these projects are being pursued through collaborative programmes involving academia, governmental organisations, R&D organisations, and commercial and industrial enterprises. These range from small-scale laboratory-based exercises, through pilot-scale studies, to large-scale demonstration programmes. Some projects are at early stages of development, whereas others are further advanced and already generating useful information. Most contain components that are addressing issues of reliability and safety aimed at: producing improved working methodologies and information for assessing behaviour and storage capacity and safety of oil, gas, brine and coal bed formations; improving the capability and reliability of computer simulation models for predicting the performance of sequestration in such formations; developing and optimising a range of novel monitoring and tracking techniques for understanding movement in different types of reservoir; undertaking field demonstration experiments to better understand, predict and monitor the migration and ultimate fate of injected in different storage options; producing guidelines for maximising safe geological storage, for measuring and verifying stored volumes, and for assessing and mitigating storage risks. Overall, these RD&D programmes are endeavouring to enhance understanding of global storage options, maximise storage potential, develop monitoring and verification strategies, and assess risks associated with this form of storage.

12 12 - CAPTURE AND STORAGE IN GEOLOGICAL FORMATIONS CONCLUDING REMARKS At present, the possibilities of capture and storage are not appreciated widely outside the scientific community. Their potential should be brought to the attention of a wider audience, including planners and policy makers. In the future, continuing use of fossil fuels will be crucial to the further development of many national economies, so use of these fuels will remain at significant levels. capture and storage options have the potential to play an important role in countering the effects of global climate change resulting from such industrial activity. A considerable body of practical expertise already exists on some aspects of capture, handling and storage, whereas on others, experience is much more limited. A number of capture techniques already exist, although these were not designed for application at large point sources such as power stations. Considerable RD&D is therefore required in order to develop technological solutions offering greater efficiency and lower cost. If significant uptake of capture and storage technologies is to be achieved, strong, concerted international consensus and action is needed to drive the research and development effort forward. But no single technology will meet all the requirements. In order to secure meaningful reductions, a portfolio of technological solutions needs to be developed and implemented. Zero Emissions Technologies (ZETs) for fossil fuels have a key role to play here. The IEA Working Party on Fossil Fuels (WPFF) is promoting these activities through its initiative on ZETs for Fossil Fuels. This complements the on-going work of the IEA Greenhouse Gas R&D Programme and other Implementing Agreements dealing with fossil fuels. The collective objective of these initiatives is to move forward the RD&D necessary for achieving the goal of near-zero emissions from fossil fuels. Successful implementation of this strategy will impact positively on global energy security, economic growth and environmental sustainability.