co2 control methods. co2 emissions vrs efficiency

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CO2 Control Methods

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Page 1: CO2 Control Methods. CO2 Emissions vrs Efficiency

CO2 Control Methods

Page 2: CO2 Control Methods. CO2 Emissions vrs Efficiency

CO2 Emissions vrs Efficiency

Page 3: CO2 Control Methods. CO2 Emissions vrs Efficiency

Overview: CO2 Reuse, Capture and Storage

Page 4: CO2 Control Methods. CO2 Emissions vrs Efficiency

CO2 Control Methods

Pre-combustion capturePost-combustion captureOxy-fuel Combustion

Page 5: CO2 Control Methods. CO2 Emissions vrs Efficiency

Pre-combustion Capture

• The oil, gas and chemical industries have been separating CO2 from gas streams for decades to meet the required downstream product requirements

• The term pre-combustion capture recently used in the context of gasification based power plants,

• Those plants are designed to convert the gas produced from gasification ( ‘syngas’) to hydrogen and CO2 and to remove the CO2 from the syngas stream prior to the combustion of the hydrogen rich gas in the gas turbine.

Page 6: CO2 Control Methods. CO2 Emissions vrs Efficiency

Pre-combustion Capture Technology

• The ultimate capture of the CO2 is accomplished under pressure by an acid gas removal process of absorption in a solvent followed by regenrative stripping of the rich solvent to relase the CO2 which with supsequent compression can be sent to sequestration or supplied for enhanced oil recovery.

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Pre-combustion Capture Technology

Global CCS Institute

Page 8: CO2 Control Methods. CO2 Emissions vrs Efficiency

Post Combustion CapturePost-combustion capture (PCC) refers to the separation of CO2 from flue gas derived from combusting fossil fuels in air.The combustion results (for coal) in a flue gas mixture consisting of N2, CO2, H2O, O2, and a host of compounds such as SOx, NOx, and heavy metals amongst others. Some of these are removed using existing technologies such as selective catalytic reduction (SCR), electrostatic precipitation (ESP), and flue-gas desulphurization (FGD). A PCC process then aims to selectively separate CO2 from the remaining gas mixture.

After capture, CO2 can be compressed and stored underground, used in some other processes such as enhanced oil recovery (EOR), or used in some other capacity that does not result in its emission into the atmosphere.

Page 9: CO2 Control Methods. CO2 Emissions vrs Efficiency

A Typical PCC Process

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Specific CO2 Control Methods

• Absorption (Lithium Hydroxide, Molecular Sieves, Solid Phase Amines, Silver Oxide)

• Adsorption• Mineralization• Biological Methods

Page 11: CO2 Control Methods. CO2 Emissions vrs Efficiency

PCC AbsorptionThe most common example of a PCC absorption process is 30 wt% aqueous monoethanolamine (MEA) which has been used commercially capturing up to 1000 tonne/day of CO2. Current estimates of capture with MEA followed by compression for underground storage increases the cost of electricity by 60-90%. These relatively high values result from the relatively large quantity of energy needed to regenerate the solvent. Therefore, much of the current research in absorption-based PCC is focus on development of new solvents that reduce the regeneration energy.Some early-stage research is also being conducted in more novel chemistries involving ionic liquids, phase separation solvents, and siloxane oligomers.

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Page 13: CO2 Control Methods. CO2 Emissions vrs Efficiency

Adsorption Adsorption refers to uptake of CO2 molecules onto the surface another material

– for example, adhering CO2 molecules onto the surfaces of a solid sorbent such as 13X zeolites.

A claimed advantage of adsorption is that the regeneration energy should be lower relative to solvents since the heat capacity of the solid sorbent is lower than aqueous solvents. However, such claims based on singular rationale are often insufficient, and a careful analysis requires consideration of multiple effects such as heat capacity, working capacity, and heats of reaction. These analyses are not straightforward, do not often point to one clear technology choice over another, and is the subject of early-stage research to help guide development of new capture materials.

Potential disadvantages for adsorbents include particle attrition, handling of large volumes of sorbent and thermal management of large-scale adsorber vessels.

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Biological Removal

Biological removal of CO2 from an exhaust stream is possible by passing the stack emissions through an algae or bacterial solution in sunlight. Removal rates of 80% for CO2 and 86% for NOX have been reported, resulting in the production of 130,000 litres/ha/yr of biodiesel (Greenfuels 2004) with residues utilized as animal feed. Other unconventional biological approaches to CCS or fuel production have been reported (Greenshift, 2005; Patrinos, 2006). Another possibility is the capture of CO2 from air. Studies claim costs less than 75 US$/tCO2 and energy requirements of a minimum of 30% using a recovery cycle with Ca(OH)2 as a sorbent. However, no experimental data on the complete process are yet available to demonstrate the concept, its energy use and engineering costs.

Page 15: CO2 Control Methods. CO2 Emissions vrs Efficiency

Membrane technology in carbon dioxide removal

Page 16: CO2 Control Methods. CO2 Emissions vrs Efficiency

Membrane technology in carbon dioxide removal

• Membranes can separate CO2 from flue gas by selectively permeating it through the membrane material. If CO2 has a higher permeability (permeability, defined as the product of solubility and diffusivity, in the membrane relative to other species in the flue gas, then CO2 will selectively permeate the membrane. In some cases, chemical agents that selectively react with CO2 are also added to the membrane to increase the membrane’s selectivity for CO2.

• CO2 transports a membrane only if its partial pressure is higher on one side of the membrane relative to the other side. This partial pressure gradient can be obtained by pressurizing the flue gas on one side of the membrane, applying a vacuum on the other side of the membrane, or both.

Page 17: CO2 Control Methods. CO2 Emissions vrs Efficiency

Mineralization

• The mineral carbonation (MC), a process of converting CO2 into stable minerals (mineralization)

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Current Status

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Oxy-fuel Combustion • Pure O2 instead of air is used in combustion. • CO2 in emission is easier to capture• Because a high concentration of nitrogen in

the flue gas can make CO2 capture unattractive

• The use of pure oxygen in the combustion process instead of air eliminates the presence of nitrogen in the flue gas, but combustion with pure oxygen results in very high temperatures

Page 20: CO2 Control Methods. CO2 Emissions vrs Efficiency

Oxy-fuel Combustion

Oxygen at greater than 95% purity and recycled flue gas are used for fuel combustion, producing a gas that is mainly CO2 and water

Page 21: CO2 Control Methods. CO2 Emissions vrs Efficiency

• Captured CO2 can be transfered through pipelines after pressurizing with comprressor

• Another alternative would be to liquidfy CO2 under appropriate T and P, and then transfer with tankers. This method would be more costly though.

Transfer

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Phase Diagram for CO2

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CARBON STORAGE and SEQUESTERATION

• Geological Storage– Oil-Natural Gas Areas– Deep Saline Formations

• Ocean Storage• Mineral Carbonation (Industrial fixation CO2

into inorganic carbonates)

Page 24: CO2 Control Methods. CO2 Emissions vrs Efficiency

GEOLOGICAL STORAGE

Page 25: CO2 Control Methods. CO2 Emissions vrs Efficiency

STORAGE

• Injection of CO2 in suitable geological reservoirs could lead to permanent storage of CO2. Geological storage is the most mature of the storage methods, with a number of commercial projects in operation.

• Ocean storage, however, is in the research phase and will not retain CO2 permanently as the CO2 will re-equilibrate with the atmosphere over the course of several centuries. Industrial fixation through the formation of mineral carbonates requires a large amount of energy and costs are high. Significant technological breakthroughs will be needed before deployment can be considered.

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CO2 Storage• Storage of CO2 can be achieved in deep saline formations, oil and gas reservoirs and deep unminable

coal seams using injection and monitoring techniques similar to those utilized by the oil and gas industry. Of the different types of potential storage formations, storage in coal formations is the least developed. If injected into suitable saline formations or into oil and gas fields at depths below 800 m, various physical and geochemical trapping mechanisms prevent the CO2 from migrating to the surface. Projects in all kinds of reservoirs are planned.

• Storage capacity in oil and gas fields, saline formations and coal beds is uncertain. The IPCC (IPCC, 2005) reported 675 to 900 GtCO2 for the relatively well-characterized gas and oil fields, more than 1000 GtCO2 (possibly up to an order of magnitude higher) for saline formations, and up to 200 GtCO2 for coal beds. Bradshaw et al. (2006) highlighted the incomparability of localized storage-capacity data that use different assumptions and methodologies. They also criticized any top-down estimate of storage capacity not based on a detailed site characterization and a clear methodology, and emphasized the value of conservative estimates. In the literature, however, specific estimates were based on top-down data and varied beyond the range cited in the IPCC (2005). For instance, a potential of >4000 GtCO2 was reported for saline formations in North America alone (Dooley et al., 2005) and between 560 and 1170 GtCO2 for injection in oil and gas fields (Plouchart et al., 2006). Agreement on a common methodology for storage capacity estimates on the country- and region-level is needed to give a more reliable estimate of storage capacities.

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• Before the option of ocean injection can be deployed, significant research is needed into its potential biological impacts to clarify the nature and scope of environmental consequences, especially in the longer term (IPCC, 2005). Concerns surrounding geological storage include the risk of seismic activity causing a rapid release of CO2 and the impact of old and poorly sealed well bores on the storage integrity of depleted oil and gas fields. Risks in CO2 transportation include rupture or leaking of pipelines, possibly leading to the accumulation of a dangerous level of CO2 in the air. Dry CO2 is not corrosive to pipelines even if it contains contaminants, but it becomes corrosive when moisture is present. Any moisture therefore needs to be removed to prevent corrosion and avoid the high cost of constructing pipes made from corrosion-resistant material. Transport of CO2 by ship is feasible under specific conditions, but is currently carried out only on a small scale due to limited demand (IPCC, 2005).

• Clarification of the nature and scope of long-term environmental consequences of ocean storage requires further research (IPCC, 2005). Concerns around geological storage include rapid release of CO2 as a consequence of seismic activity and the impact of old and poorly sealed well bores on the storage integrity of depleted oil and gas fields Risks are estimated to be comparable to those of similar operations (IPCC, 2005). For CO2 pipelines, accident numbers reported are very low, although there are risks of rupture or leaking leading to local accumulation of CO2 in the air to dangerous levels (IPCC, 2005).

CO2 Storage

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OCEAN STORAGE

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OCEAN STORAGE• Atmosferde CO2 konsantraysonunun artmasını ve küresel

ısınmayı önlemek için dip denizlerin çok geniş hacimleri dikkati çekmektedir (12 trilyon ton CO2).

• Okyanuslarda CO2 depolaması 1000 m den fazla derinliklerde yapılıyor(345-3627 m).

• Yüzeye yakın yapılmamasının en önemli nedeni ani gaz boşalımından kaçınılmasıdır ve ayrıca derin denizlerdeki dip sedimentlerde (absorpsiyon) tutunması.

• Derin denizlerde depolanma sadece zaman kazanmaktır(to buy time).300 Yıl

• 10000 yıl depolama ömrü.• Atmosferle denizler arasında CO2 dengesi

Page 30: CO2 Control Methods. CO2 Emissions vrs Efficiency

POTANSİYEL ETKİLERİ

• Fiziksel ve kimyasal etkileri olacaktır.• En önemlisi denizin pH sını düşürecek.• CO2 konsantrasyonunu arttıracaktır.• Düşük pH ve yüksek CO2 konsantrasyonu canlılar ve

ekosisteme ciddi etkileri olacaktır.• Denizlerde depolanacak olan CO2 içinde bir kırılma

noktası mevcut (denizler ısınırsa).• Afrikada bir köyde onlarca kişi köydeki bir göle kayaların düşmesi sonucu çıkan CO2 den ölmüştür.

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POTENTIAL EFFECTS

• On August 21, 1986, possibly as the result of a landslide, Lake Nyos suddenly emitted a large cloud of CO2, which suffocated 1,700 people and 3,500 livestock in nearby towns and villages.

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POTENTIAL EFFECTS

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Mıneral Carbonation and Industrial Use

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Current Maturity of CCS

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Leakage of Stored CO2 (IPCC, 2005)

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Gaps in Knowledge