CO
Technology Status Report Zero Emissions Technologies for Fossil Fuels IEA WPFF Zero Emission Technology Strategy Initiative Workshop on Technology Status & Perspectives
Technology Status Report (Draft)
January 14, 2001 Oslo, Norway Pamela Tomski [email protected]
Overview • Purpose of TSR • TSR Summary _ Introduction – CO2 Capture – CO2 Storage & Utilization – Conclusion – Country R&D Visions
Purpose of TSR • Outline basic information on zero emissions (ZE) technologies for fossil fuels • Provide members of the scientific, technology and policy communities with easily accessible information about ZE technologies • Convey concepts in relatively non-technical manner • Outline relative economics and issues (developmental timeframe) associated with ZE technologies • Present country R&D visions – ZE efforts underway internationally
Introduction • 80% of the world’s energy generated by fossil fuels
Introduction • World population will multiply, electricity demand will grow and fossil fuel consumption is likely to increase Trends in Global Population and Energy Consumption from Electricity
Introduction • Fossil fuels contribute to 3/4 of man-made CO2 emissions • Increasing emissions levels pose threat to planet’s natural systems, which can impact economic growth and well-being
Introduction • Abundant, affordable fossil fuels will be fuel of choice • Challenge: simultaneously attain energy security, economic growth and environmental protection • Critical need: advancements in ZE RD&D • “Technologies that capture CO2 or separate and prepare CO2 for sequestration (storage)” • Potential of substantial CO2 reductions in near-term; longterm use of fossil fuels with zero emissions • ZE Technology Strategy Initiative is a key IEA/WPFF activity
CO2 Capture • Post-Combustion CO2 Capture • O2 / CO2 Recycle Combustion • Pre-Combustion Capture • Novel Concepts • Capture from Electricity Generation • Industrial Capture and Use • Costs and Considerations
Post-Combustion CO2 Capture • CO2 can be separated and captured from flue gases after combustion • Best suited to large point sources of CO2: power stations, refineries and natural gas operations • Separation can be accomplished by: – absorption after contact with solvents – absorption on activated carbon or other materials – membrane separation – cryogenic separation
Post-Combustion CO2 Capture • Capture technology is not new -- 60 years experience in petroleum, natural gas, and chemical industries • Components exist but modifications for large-scale CO2 flue gas capture required • Potential as a retrofit option for existing systems • Primary method is amine-based absorption that is regenerated by heat -- recovery rates of 98%; product purity in excess of 99%
Post-Combustion CO2 Capture: Challenges • Flue gas CO2 concentrations are typically low: 2% to 12% of total gas volume and at low pressure • Process is energy intensive and equipment size is large • Acid gases in flue gas can degrade solvent performance
Post-Combustion CO2 Capture: Improvement Options • Advanced solvents are needed to reduce energy consumption • Novel chemistries could lead to smaller volumes and longer lifetimes • Better integration and optimization needed • Potential as a retrofit option for existing systems • Advanced membranes permeable only to CO2 for use at high temperatures or combination of amine and membrane process • Electrical Swing Adsorption (ESA) releases CO2 by an electric current without heating and is more energy efficient. While still in bench scale, shows promise
O2/CO2 Recycle Combustion
O2/CO2 Recycle Combustion • Oxygen (O2) is separated from air • Fuel is burnt in pure O2 resulting in flue gas with high CO2 concentration • Flue gas is eventually re-circulated to the combustor to moderate temperature • Boiler with flue gas recycle is based on existing technology • Concentrations of CO2 typically >90% (compared to 4-14% for air blown combustion). • CO2 can be reused or stored with little or no extra treatment
O2/CO2 Recycle Combustion: Challenges • Lack of nitrogen results in very high combustions temperatures; exhaust recycle or other option needed for cooling • Production of O2 for combustion is expensive (capital cost and energy consumption) • Gas turbine with flue gas recycle would require new turbine development
O2/CO2 Recycle Combustion: Improvement Options • Boilers/heaters with flue gas recycle could be retrofitted to most systems • Key is reducing O2 separation costs -- advances in O2 ion transport membranes and integration with combustor can reduce cost and improve efficiency • Water/steam injection to control combustion temperatures – hybrid steam/gas turbine cycles with up to 70% efficiency
Pre-Combustion Capture • Removes CO2 from fossil fuels before combustion • Carbon is separated from hydrogen (H2) either at the point of fuel extraction or during the refining process to produce H2 and CO2 • Technology well know for 50+ years in H2 production (natural gas is preferred feedstock) and is established worldwide but no large scale applications • Possible step toward greater use of H2 as fuel
Pre-Combustion Capture • Process divided into three sections: -
Hydrocarbons conversion – convert fuel into H2, CO and CO2 by steam reforming (adding steam), partial oxidation (add O2 or air) or in combination depending on feed stock
-
CO-conversion – CO is converted into H2 and CO2 by membrane water gas shift reaction
CO2 removal – remaining process gas is mainly H2 and CO2. Removal generally by absorption (used extensively in ammonia manufacture)
Pre-Combustion Capture: Improvement Options • IGCC is the least costly approach for de-carbonizing coal-based electric power; breakthrough may come with from use with IGCC Coal-fired IGCC with Pre-Combustion Capture of CO2
Pre-Combustion Capture: Improvement Options • More radical changes to power station design required but most of the technology is already well-proven • The fuel fed to the gas turbine is essentially H2. It is expected that H2 will be compatible with existing gas turbines with little modification, but technology has not been demonstrated • H2 could also be used to generate electricity in fuel cells or for transportation
Novel Concepts • Long-term concepts that possibly require significant technological breakthroughs and R&D. Also new methods that require further development or application to CO2 separation and capture – Chemical Looping – Hydrate Formation – Biological CO2 Fixation – Matiant Cycle – Direct Capture of CO2 from Air – Zero Emissions Anaerobic Hydrogen – Direct Solar Reduction of CO2
Chemical Looping • Metal oxide used to transfer O2 from combustion air to the fuel – CO2 obtained in separate stream without separation – Could be used in place of conventional combustion; integrated in a combined gas-turbine steam-power process Chemical looping combustion
Hydrate Formation • CO2 hydrates (ice-like material) may be formed from synthesis gas (mostly CO2 and H2) under partial pressures and nearfreezing temperatures • Transported as a slurry in chilled pipelines at lower pressures than supercritical CO2 • Technology is in early stages of development • Costs associated with flue gas compression remain high
Biological CO2 Fixation • CO2 from a power plant would be used to cultivate microalgae (optimized for high CO2 tolerance and high temperatures) in large open ponds. • Microalgae would be converted to fossil fuel substitutes or used in building materials • Long-term basic and applied R&D required • Market entry could be accelerated by integrating microalgae techniques with established wastewater systems • Potential CO2 utilization considered relatively small
The Matiant Cycle • Super-critical CO2 Rankine-like cycle on top of a regenerative CO2 Brayton cycle to gain efficiencies > 50 % – Compatible with currently available materials and can be used for cogeneration
• Provides liquid CO2, N2 and H2O as by-products • “Closed-loop” cycle with virtually zero emissions
Direct Capture of CO2 from Air • CO2 in the air could be removed from natural airflow by passing over absorber surfaces • Water could be pumped to the top of a convection tower to cool the air, causing a downdraft inside the tower. Air leaving at the bottom could drive wind turbines or flow over CO2 absorbers • The tower could generate electricity after pumping water to the top. Same airflow would carry CO2 through the tower for disposal • Still in conceptual stage
Zero Emissions Anaerobic Hydrogen • Transform coal with high-temperature chemical reaction to produce H2 and CO2 without combustion (H2 could be used to fuel a high-temperature solid oxide fuel cell for electricity) • CO2 is removed by reacting it with lime to form calcium carbonate (CaCO3). The CaCO3 is calcined at high temperatures releasing a concentrated steam of CO2. • CO2 would be reacted with a magnesium silicate to form magnesium carbonate for storage • Disposal volumes and costs could be high
Direct Solar Reduction of CO2 • Use high-temperature solar energy reduces CO2 to carbon monoxide that can be used to make chemicals and fuels (gasoline, methanol, diesel, etc.) • By-products include electricity and free O2 • Process recycles CO2 and closes the carbon fuel cycle • Prototype has been tested and meets design criteria • Full-scale prototype and demonstration needed
Capture from Electricity Generation • Power plants offer opportunity for high-impact CO2 reductions – Pulverized coal-fired cycles (PC) – Natural gas combined cycles (NGCC) – Integrated gasification combined cycle (IGCC) – Integrated gasification fuel cell (IGFC)
• Capture options influenced by CO2 concentrations and power plant type • Higher concentrations make capture less energy intensive, thus less expensive
Different Capture Technologies Applicable to Different Types of Power Plants
Capture from Industrial Sources • CO2 is separated during natural gas production to meet commercial fuel specs • CO2 could be captured from H2 production applications in the chemical process and petroleum refinery industries
Capture Costs and Consideration • A variety of technologies are available or in different stages of development • Major barrier - significant costs of separation and capture • The key cost drivers: – heat rate – energy requirement – capital costs
• Cost estimates for power plant/carbon capture options must account for full fuel cycle -- typically about 70% of total
Capture Costs and Consideration • Capture method depends on CO2 concentrations • Increasing CO2 concentrations reduces energy requirement and costs: – O2/ CO2 recycle; pre-combustion gasification/CO-shift and IGCC options
• Capture techniques will evolve to match developmental pace of newer and more efficient plants (IGCC) • Technological improvements in existing technology and optimization of the system needed (system-level analyses) • Improved solvents and system components can reduce capital and energy costs
CO2 Storage and Utilization Options for Carbon Storage •
Geologic Formations
•
Terrestrial Ecosystems
•
Oceans
•
Advanced Concepts
Costs and Considerations
Geologic Formations • Vast potential and considered option that can most rapidly achieve CO2 reduction
Oil and Gas Reservoirs & Enhanced Oil Recovery • EOR -- process that injects CO2 into depleted oil reservoirs to recover oil that would otherwise have been left behind Enhanced Oil Recovery
Oil and Gas Reservoirs & Enhanced Oil Recovery •
Mature technology – about 70 oil fields worldwide use CO2 injection for EOR; industry can build on this experience
•
Most CO2 comes from gas fields and transported by pipeline. To supply low cost CO2 for EOR, source should be near oil field
•
Revenues from recovered product can offset costs CO2
•
Injection into depleted oil and gas reservoirs
•
Advantages: – immediately available; – well known geology – quasi-impermeable rock layer or “seal” above the storage repository
•
Uncertainty regarding gas residency times, leakage and the sensitivity of reservoirs to different gas pressures
Deep Unminable Coal Beds & Enhanced Coalbed Methane Recovery • Coalbed methane (CBM) -- naturally occurring gas found in coal seams that consists mainly of methane • Vast resource that lie in deep seams around the world unlikely to be mined in the near future • In enhanced coalbed methane recovery (ECMB), CO2 is injected into coalbeds for methane extraction and carbon storage • At lease two volumes of CO2 are sequestered for each volume of methane produced • Not commercially established – pilot application with good results underway since 1996
Deep Unminable Coal Beds & Enhanced Coalbed Methane Recovery
ECBM Well Configuration and Surface Facilities for CO2 Injection
Deep Unminable Coal Beds & Enhanced Coalbed Methane Recovery • Methane absorbed on the coal desorbs, diffuses, then flows with the water to the production well where a CO2 injection well is drilled • Greatest cost associated with drilling, which are variable and depend on time, location and economy of scale • Revenue from ECBM can offset the costs of CO2 collection and transport • Untapped methane will become more valuable as technology makes it easier to upgrade methane to pipeline quality natural gas
Deep Saline Aquifers • Deep saline aquifers (depths > 800 meters) are second-largest, naturally-occurring potential CO2 storage medium • Widely distributed below both the continents and the ocean floor • Permeable beds -- generally contain carbonate/sandstone formations • Pore structure allows gases/liquids to flow through the bed; CO2 will dissolve and reacts with minerals to form carbonates that permanently sequester CO2 • Most existing large point sources within access of injection point • Injection techniques similar to EOR; many aspects of EOR apply -- substantial baseline of information and experience exists
Deep Saline Aquifers • Norway’ Statoil pioneered carbon sequestration in the North Sea with world’s first commercial CO2 capture and storage project • Since 1996 about 1 million tons/year of CO2 from the Sleipner West gas field has been injected into an undersea aquifer • Efforts to measure sequestration, understand leakage rates and ecological impacts underway
Deep Saline Aquifers
Terrestrial Ecosystems • Vegetation, plants, trees and soils, etc. considered natural or biological “sinks” • Goal is to increase levels of CO2 that are removed from the atmosphere and stored. Increases can be achieved through: – conservation practices – enhanced plant growth, – conversion of marginal lands to compatible land use systems – restoration of degraded lands
Terrestrial Ecosystems • Multiple benefits include: – increased CO2 uptake from the atmosphere – improved soil fertility and quality – enhanced water-use efficiency and storage – larger crop and biomass yields – reduced risk of erosion – rehabilitation of degraded lands
Terrestrial Ecosystems: Challenges • Fundamental molecular to landscape understanding of interactions between carbon, microbes and water required in order to maximize potential of storage sites • Need to accurately measure and verify carbon inventories -development of measurement and monitoring technologies essential
Oceans • Oceans represent the largest potential storage medium for CO2 sequestration. The two major strategies under consideration: – deep injection – iron fertilization
Injection • CO2 from large point sources is transported to injection sites by tanker or sub-sea pipelines • CO2 behaves differently according to state and discharge depth • As CO2 dissolves, density increases; CO2 sinks as dense plume • Model simulations indicate retention times > 1000 years at depths of 3000 meters • Injections below 3700 meters, liquid CO2 sinks to sea floor and forms a stable CO2 “lake” • Further research is needed to understand environmental impacts and ecosystem structure and function
Oceans
Iron Fertilization • Ocean phytoplankton grows by photosynthesis and is consumed by larger plant life and, in turn, eaten by larger marine animals • Remaining organic matter sinks to ocean floor as sediment; remineralized to CO2 by bacteria • This naturally occurring process is called the “biological pump” • Natural process can be enhanced with iron (acts as a fertilizer) • Iron stimulates phytoplankton growth resulting in CO2 in ocean floor • Research needed to simulate impacts over a wide range of temporal and spatial scales
Carbon Storage: Advanced Concepts • Storage concepts that fall outside of tradition storage categories • Potential to increase storage capacities or considered innovative storage option -
Advanced biological and chemical processes
-
Mined salt domes
-
Carbonate minerals
Direct Utilization
• Does not seem to offer large-scale opportunities for mitigation, can play a role • CO2 currently used by industry is not normally derived from flue gases, rather from natural fields • Additional infrastructure would be needed for delivery • EOR, ECBM largest potential users • Natural gas and chemical industries potential producers • Considerable industry expertise with capture • Possible economic drivers for use
Storage Costs and Considerations • Studies conducted by the IEA and others indicate the following storage potential worldwide:
Capture Costs and Considerations • Costs of sequestering CO2 vary according to disposal volumes, distance to and the nature of sequestration option • Although sequestration costs vary, the majority of options are judged to cost between $5 and $15/ton CO2 • As a rule of thumb, disposal costs account for 30% to 40% of the total cost • Cost data typically model-based projects or project specific • Differing storage/utilization options make capacity comparisons difficult
Capture Costs and Considerations •
Depleted oil and gas reservoirs most promising land storage option in the near term, especially if EOR is an option
•
ECMB recovery also emerging near-term option
•
In absence of EOR/ECMB, carbon tax may provide motivation (Norway)
•
Many environmental uncertainties remain - additional investigation prior to full-scale implementation required
•
Further research needed to understand long-term chemical and physical impacts on reservoir rocks and fluids
•
Methodology to assess long-term integrity and ecological impacts needed
•
Improved ability to measure and verify carbon storage essential
•
Viability of ocean storage may hinge on social/public considerations
Conclusion • A portfolio of carbon management strategies are needed • ZE technologies must be a key component of any GHG mitigation strategy • A diverse and expanding array of technical processes under development internationally • In the near-term, potential to reduce CO2 emissions and in the long -term, achieve production of fossil fuels with virtually zero emissions • Capture costs are high and important technical problems remain unsolved • Little R&D has been devoted and many avenues that might reduce costs remain unexplored
Conclusion • Evolutionary improvements in existing CO2 capture systems; revolutionary new capture/sequestration concepts necessary • Multiple approaches are warranted; significant breakthroughs expected • Without mechanism to attribute price for emissions avoidance, CO2 capture and storage opportunities not economically viable • Industry is not likely to deploy technologies without explicit government action based on a public policy mandate • Funding for R&D, field testing, modeling and monitoring needs to be enriched • International collaborative RD&D that includes partnerships with industry, government and academia, is needed
Country R&D Visions • Australia • Canada • Japan • The Netherlands • Norway • United Kingdom • United States • Others to be included
Contact For comments, questions or to provide additional input, please contact: Pamela Tomski Consultant IEA/WPFF 1130 17th Street, NW Suite 312 Washington, DC 20036 Tel: (202) 861-2841 Fax: (202) 861-2840 E-mail: [email protected]
Technology Status Report (Draft)
January 14, 2001 Oslo, Norway Pamela Tomski [email protected]
Overview • Purpose of TSR • TSR Summary _ Introduction – CO2 Capture – CO2 Storage & Utilization – Conclusion – Country R&D Visions
Purpose of TSR • Outline basic information on zero emissions (ZE) technologies for fossil fuels • Provide members of the scientific, technology and policy communities with easily accessible information about ZE technologies • Convey concepts in relatively non-technical manner • Outline relative economics and issues (developmental timeframe) associated with ZE technologies • Present country R&D visions – ZE efforts underway internationally
Introduction • 80% of the world’s energy generated by fossil fuels
Introduction • World population will multiply, electricity demand will grow and fossil fuel consumption is likely to increase Trends in Global Population and Energy Consumption from Electricity
Introduction • Fossil fuels contribute to 3/4 of man-made CO2 emissions • Increasing emissions levels pose threat to planet’s natural systems, which can impact economic growth and well-being
Introduction • Abundant, affordable fossil fuels will be fuel of choice • Challenge: simultaneously attain energy security, economic growth and environmental protection • Critical need: advancements in ZE RD&D • “Technologies that capture CO2 or separate and prepare CO2 for sequestration (storage)” • Potential of substantial CO2 reductions in near-term; longterm use of fossil fuels with zero emissions • ZE Technology Strategy Initiative is a key IEA/WPFF activity
CO2 Capture • Post-Combustion CO2 Capture • O2 / CO2 Recycle Combustion • Pre-Combustion Capture • Novel Concepts • Capture from Electricity Generation • Industrial Capture and Use • Costs and Considerations
Post-Combustion CO2 Capture • CO2 can be separated and captured from flue gases after combustion • Best suited to large point sources of CO2: power stations, refineries and natural gas operations • Separation can be accomplished by: – absorption after contact with solvents – absorption on activated carbon or other materials – membrane separation – cryogenic separation
Post-Combustion CO2 Capture • Capture technology is not new -- 60 years experience in petroleum, natural gas, and chemical industries • Components exist but modifications for large-scale CO2 flue gas capture required • Potential as a retrofit option for existing systems • Primary method is amine-based absorption that is regenerated by heat -- recovery rates of 98%; product purity in excess of 99%
Post-Combustion CO2 Capture: Challenges • Flue gas CO2 concentrations are typically low: 2% to 12% of total gas volume and at low pressure • Process is energy intensive and equipment size is large • Acid gases in flue gas can degrade solvent performance
Post-Combustion CO2 Capture: Improvement Options • Advanced solvents are needed to reduce energy consumption • Novel chemistries could lead to smaller volumes and longer lifetimes • Better integration and optimization needed • Potential as a retrofit option for existing systems • Advanced membranes permeable only to CO2 for use at high temperatures or combination of amine and membrane process • Electrical Swing Adsorption (ESA) releases CO2 by an electric current without heating and is more energy efficient. While still in bench scale, shows promise
O2/CO2 Recycle Combustion
O2/CO2 Recycle Combustion • Oxygen (O2) is separated from air • Fuel is burnt in pure O2 resulting in flue gas with high CO2 concentration • Flue gas is eventually re-circulated to the combustor to moderate temperature • Boiler with flue gas recycle is based on existing technology • Concentrations of CO2 typically >90% (compared to 4-14% for air blown combustion). • CO2 can be reused or stored with little or no extra treatment
O2/CO2 Recycle Combustion: Challenges • Lack of nitrogen results in very high combustions temperatures; exhaust recycle or other option needed for cooling • Production of O2 for combustion is expensive (capital cost and energy consumption) • Gas turbine with flue gas recycle would require new turbine development
O2/CO2 Recycle Combustion: Improvement Options • Boilers/heaters with flue gas recycle could be retrofitted to most systems • Key is reducing O2 separation costs -- advances in O2 ion transport membranes and integration with combustor can reduce cost and improve efficiency • Water/steam injection to control combustion temperatures – hybrid steam/gas turbine cycles with up to 70% efficiency
Pre-Combustion Capture • Removes CO2 from fossil fuels before combustion • Carbon is separated from hydrogen (H2) either at the point of fuel extraction or during the refining process to produce H2 and CO2 • Technology well know for 50+ years in H2 production (natural gas is preferred feedstock) and is established worldwide but no large scale applications • Possible step toward greater use of H2 as fuel
Pre-Combustion Capture • Process divided into three sections: -
Hydrocarbons conversion – convert fuel into H2, CO and CO2 by steam reforming (adding steam), partial oxidation (add O2 or air) or in combination depending on feed stock
-
CO-conversion – CO is converted into H2 and CO2 by membrane water gas shift reaction
CO2 removal – remaining process gas is mainly H2 and CO2. Removal generally by absorption (used extensively in ammonia manufacture)
Pre-Combustion Capture: Improvement Options • IGCC is the least costly approach for de-carbonizing coal-based electric power; breakthrough may come with from use with IGCC Coal-fired IGCC with Pre-Combustion Capture of CO2
Pre-Combustion Capture: Improvement Options • More radical changes to power station design required but most of the technology is already well-proven • The fuel fed to the gas turbine is essentially H2. It is expected that H2 will be compatible with existing gas turbines with little modification, but technology has not been demonstrated • H2 could also be used to generate electricity in fuel cells or for transportation
Novel Concepts • Long-term concepts that possibly require significant technological breakthroughs and R&D. Also new methods that require further development or application to CO2 separation and capture – Chemical Looping – Hydrate Formation – Biological CO2 Fixation – Matiant Cycle – Direct Capture of CO2 from Air – Zero Emissions Anaerobic Hydrogen – Direct Solar Reduction of CO2
Chemical Looping • Metal oxide used to transfer O2 from combustion air to the fuel – CO2 obtained in separate stream without separation – Could be used in place of conventional combustion; integrated in a combined gas-turbine steam-power process Chemical looping combustion
Hydrate Formation • CO2 hydrates (ice-like material) may be formed from synthesis gas (mostly CO2 and H2) under partial pressures and nearfreezing temperatures • Transported as a slurry in chilled pipelines at lower pressures than supercritical CO2 • Technology is in early stages of development • Costs associated with flue gas compression remain high
Biological CO2 Fixation • CO2 from a power plant would be used to cultivate microalgae (optimized for high CO2 tolerance and high temperatures) in large open ponds. • Microalgae would be converted to fossil fuel substitutes or used in building materials • Long-term basic and applied R&D required • Market entry could be accelerated by integrating microalgae techniques with established wastewater systems • Potential CO2 utilization considered relatively small
The Matiant Cycle • Super-critical CO2 Rankine-like cycle on top of a regenerative CO2 Brayton cycle to gain efficiencies > 50 % – Compatible with currently available materials and can be used for cogeneration
• Provides liquid CO2, N2 and H2O as by-products • “Closed-loop” cycle with virtually zero emissions
Direct Capture of CO2 from Air • CO2 in the air could be removed from natural airflow by passing over absorber surfaces • Water could be pumped to the top of a convection tower to cool the air, causing a downdraft inside the tower. Air leaving at the bottom could drive wind turbines or flow over CO2 absorbers • The tower could generate electricity after pumping water to the top. Same airflow would carry CO2 through the tower for disposal • Still in conceptual stage
Zero Emissions Anaerobic Hydrogen • Transform coal with high-temperature chemical reaction to produce H2 and CO2 without combustion (H2 could be used to fuel a high-temperature solid oxide fuel cell for electricity) • CO2 is removed by reacting it with lime to form calcium carbonate (CaCO3). The CaCO3 is calcined at high temperatures releasing a concentrated steam of CO2. • CO2 would be reacted with a magnesium silicate to form magnesium carbonate for storage • Disposal volumes and costs could be high
Direct Solar Reduction of CO2 • Use high-temperature solar energy reduces CO2 to carbon monoxide that can be used to make chemicals and fuels (gasoline, methanol, diesel, etc.) • By-products include electricity and free O2 • Process recycles CO2 and closes the carbon fuel cycle • Prototype has been tested and meets design criteria • Full-scale prototype and demonstration needed
Capture from Electricity Generation • Power plants offer opportunity for high-impact CO2 reductions – Pulverized coal-fired cycles (PC) – Natural gas combined cycles (NGCC) – Integrated gasification combined cycle (IGCC) – Integrated gasification fuel cell (IGFC)
• Capture options influenced by CO2 concentrations and power plant type • Higher concentrations make capture less energy intensive, thus less expensive
Different Capture Technologies Applicable to Different Types of Power Plants
Capture from Industrial Sources • CO2 is separated during natural gas production to meet commercial fuel specs • CO2 could be captured from H2 production applications in the chemical process and petroleum refinery industries
Capture Costs and Consideration • A variety of technologies are available or in different stages of development • Major barrier - significant costs of separation and capture • The key cost drivers: – heat rate – energy requirement – capital costs
• Cost estimates for power plant/carbon capture options must account for full fuel cycle -- typically about 70% of total
Capture Costs and Consideration • Capture method depends on CO2 concentrations • Increasing CO2 concentrations reduces energy requirement and costs: – O2/ CO2 recycle; pre-combustion gasification/CO-shift and IGCC options
• Capture techniques will evolve to match developmental pace of newer and more efficient plants (IGCC) • Technological improvements in existing technology and optimization of the system needed (system-level analyses) • Improved solvents and system components can reduce capital and energy costs
CO2 Storage and Utilization Options for Carbon Storage •
Geologic Formations
•
Terrestrial Ecosystems
•
Oceans
•
Advanced Concepts
Costs and Considerations
Geologic Formations • Vast potential and considered option that can most rapidly achieve CO2 reduction
Oil and Gas Reservoirs & Enhanced Oil Recovery • EOR -- process that injects CO2 into depleted oil reservoirs to recover oil that would otherwise have been left behind Enhanced Oil Recovery
Oil and Gas Reservoirs & Enhanced Oil Recovery •
Mature technology – about 70 oil fields worldwide use CO2 injection for EOR; industry can build on this experience
•
Most CO2 comes from gas fields and transported by pipeline. To supply low cost CO2 for EOR, source should be near oil field
•
Revenues from recovered product can offset costs CO2
•
Injection into depleted oil and gas reservoirs
•
Advantages: – immediately available; – well known geology – quasi-impermeable rock layer or “seal” above the storage repository
•
Uncertainty regarding gas residency times, leakage and the sensitivity of reservoirs to different gas pressures
Deep Unminable Coal Beds & Enhanced Coalbed Methane Recovery • Coalbed methane (CBM) -- naturally occurring gas found in coal seams that consists mainly of methane • Vast resource that lie in deep seams around the world unlikely to be mined in the near future • In enhanced coalbed methane recovery (ECMB), CO2 is injected into coalbeds for methane extraction and carbon storage • At lease two volumes of CO2 are sequestered for each volume of methane produced • Not commercially established – pilot application with good results underway since 1996
Deep Unminable Coal Beds & Enhanced Coalbed Methane Recovery
ECBM Well Configuration and Surface Facilities for CO2 Injection
Deep Unminable Coal Beds & Enhanced Coalbed Methane Recovery • Methane absorbed on the coal desorbs, diffuses, then flows with the water to the production well where a CO2 injection well is drilled • Greatest cost associated with drilling, which are variable and depend on time, location and economy of scale • Revenue from ECBM can offset the costs of CO2 collection and transport • Untapped methane will become more valuable as technology makes it easier to upgrade methane to pipeline quality natural gas
Deep Saline Aquifers • Deep saline aquifers (depths > 800 meters) are second-largest, naturally-occurring potential CO2 storage medium • Widely distributed below both the continents and the ocean floor • Permeable beds -- generally contain carbonate/sandstone formations • Pore structure allows gases/liquids to flow through the bed; CO2 will dissolve and reacts with minerals to form carbonates that permanently sequester CO2 • Most existing large point sources within access of injection point • Injection techniques similar to EOR; many aspects of EOR apply -- substantial baseline of information and experience exists
Deep Saline Aquifers • Norway’ Statoil pioneered carbon sequestration in the North Sea with world’s first commercial CO2 capture and storage project • Since 1996 about 1 million tons/year of CO2 from the Sleipner West gas field has been injected into an undersea aquifer • Efforts to measure sequestration, understand leakage rates and ecological impacts underway
Deep Saline Aquifers
Terrestrial Ecosystems • Vegetation, plants, trees and soils, etc. considered natural or biological “sinks” • Goal is to increase levels of CO2 that are removed from the atmosphere and stored. Increases can be achieved through: – conservation practices – enhanced plant growth, – conversion of marginal lands to compatible land use systems – restoration of degraded lands
Terrestrial Ecosystems • Multiple benefits include: – increased CO2 uptake from the atmosphere – improved soil fertility and quality – enhanced water-use efficiency and storage – larger crop and biomass yields – reduced risk of erosion – rehabilitation of degraded lands
Terrestrial Ecosystems: Challenges • Fundamental molecular to landscape understanding of interactions between carbon, microbes and water required in order to maximize potential of storage sites • Need to accurately measure and verify carbon inventories -development of measurement and monitoring technologies essential
Oceans • Oceans represent the largest potential storage medium for CO2 sequestration. The two major strategies under consideration: – deep injection – iron fertilization
Injection • CO2 from large point sources is transported to injection sites by tanker or sub-sea pipelines • CO2 behaves differently according to state and discharge depth • As CO2 dissolves, density increases; CO2 sinks as dense plume • Model simulations indicate retention times > 1000 years at depths of 3000 meters • Injections below 3700 meters, liquid CO2 sinks to sea floor and forms a stable CO2 “lake” • Further research is needed to understand environmental impacts and ecosystem structure and function
Oceans
Iron Fertilization • Ocean phytoplankton grows by photosynthesis and is consumed by larger plant life and, in turn, eaten by larger marine animals • Remaining organic matter sinks to ocean floor as sediment; remineralized to CO2 by bacteria • This naturally occurring process is called the “biological pump” • Natural process can be enhanced with iron (acts as a fertilizer) • Iron stimulates phytoplankton growth resulting in CO2 in ocean floor • Research needed to simulate impacts over a wide range of temporal and spatial scales
Carbon Storage: Advanced Concepts • Storage concepts that fall outside of tradition storage categories • Potential to increase storage capacities or considered innovative storage option -
Advanced biological and chemical processes
-
Mined salt domes
-
Carbonate minerals
Direct Utilization
• Does not seem to offer large-scale opportunities for mitigation, can play a role • CO2 currently used by industry is not normally derived from flue gases, rather from natural fields • Additional infrastructure would be needed for delivery • EOR, ECBM largest potential users • Natural gas and chemical industries potential producers • Considerable industry expertise with capture • Possible economic drivers for use
Storage Costs and Considerations • Studies conducted by the IEA and others indicate the following storage potential worldwide:
Capture Costs and Considerations • Costs of sequestering CO2 vary according to disposal volumes, distance to and the nature of sequestration option • Although sequestration costs vary, the majority of options are judged to cost between $5 and $15/ton CO2 • As a rule of thumb, disposal costs account for 30% to 40% of the total cost • Cost data typically model-based projects or project specific • Differing storage/utilization options make capacity comparisons difficult
Capture Costs and Considerations •
Depleted oil and gas reservoirs most promising land storage option in the near term, especially if EOR is an option
•
ECMB recovery also emerging near-term option
•
In absence of EOR/ECMB, carbon tax may provide motivation (Norway)
•
Many environmental uncertainties remain - additional investigation prior to full-scale implementation required
•
Further research needed to understand long-term chemical and physical impacts on reservoir rocks and fluids
•
Methodology to assess long-term integrity and ecological impacts needed
•
Improved ability to measure and verify carbon storage essential
•
Viability of ocean storage may hinge on social/public considerations
Conclusion • A portfolio of carbon management strategies are needed • ZE technologies must be a key component of any GHG mitigation strategy • A diverse and expanding array of technical processes under development internationally • In the near-term, potential to reduce CO2 emissions and in the long -term, achieve production of fossil fuels with virtually zero emissions • Capture costs are high and important technical problems remain unsolved • Little R&D has been devoted and many avenues that might reduce costs remain unexplored
Conclusion • Evolutionary improvements in existing CO2 capture systems; revolutionary new capture/sequestration concepts necessary • Multiple approaches are warranted; significant breakthroughs expected • Without mechanism to attribute price for emissions avoidance, CO2 capture and storage opportunities not economically viable • Industry is not likely to deploy technologies without explicit government action based on a public policy mandate • Funding for R&D, field testing, modeling and monitoring needs to be enriched • International collaborative RD&D that includes partnerships with industry, government and academia, is needed
Country R&D Visions • Australia • Canada • Japan • The Netherlands • Norway • United Kingdom • United States • Others to be included
Contact For comments, questions or to provide additional input, please contact: Pamela Tomski Consultant IEA/WPFF 1130 17th Street, NW Suite 312 Washington, DC 20036 Tel: (202) 861-2841 Fax: (202) 861-2840 E-mail: [email protected]
