Carbon capture and storage
This might rule out deep ocean storage as an option. It should also be noted that at the conditions of the deeper oceans, (about 400 bar or 40 MPa, 280 K) water–CO2(l) mixing is very low (where carbonate formation/acidification is the rate limiting step), but the formation of water-CO2 hydrates is favorable. The water vapour is condensed, leaving pure carbon dioxide which can be sequestered.This proposed plant would be able to generate approximately 914 megawatts of electricity, an amount equal to half of Seattle s total power requirements. This system is converting carbon from smokestacks into baking soda.
While CO2 is drastically reduced (though never completely captured), emissions of air pollutants increase significantly, generally due to the energy penalty of capture. that could be used to store 500 years worth of U.S.
For new supercritical pulverized coal (PC) plants using current technology, the extra energy requirements range from 24-40%, while for natural gas combined cycle (NGCC) plants the range is 11-22% and for coal-based gasification combined cycle (IGCC) systems it is 14-25% . In addition, there are several pilot programs in various stages to test the long-term storage of CO2 in non-oil producing geologic formations.
The solid metal particles are circulated to another fluidized bed where they react with air, producing heat and regenerating metal oxide particles that are recirculated to the fluidized bed combustor. The first commercial example is Weyburn in 2000; integrated pilot-scale CCS power plant was to begin operating in September 2008 in the eastern German power plant Schwarze Pumpe run by utility Vattenfall, in the hope of answering questions about technological feasibility and economic efficiency. CCS applied to a modern conventional power plant could reduce CO2 emissions to the atmosphere by approximately 80-90% compared to a plant without CCS.) Capturing and compressing CO2 requires much energy and would increase the fuel needs of a coal-fired plant with CCS by 25%-40%. Storage of the CO2 is envisaged either in deep geological formations, in deep ocean masses, or in the form of mineral carbonates.
Sleipner The Weyburn-Midale CO2 Project is currently the world s largest carbon capture and storage project. The fourth site is In Salah, which like Sleipner and Snøhvit is a natural gas reservoir located in In Salah, Algeria. However, some recent credible estimates indicate that a carbon price of US$60 per US-ton is required to make capture and storage competitive, corresponding to an increase in electricity prices of about US 6c per kWh (based on typical coal fired power plant emissions of 2.13 pounds CO2 per kWh).
It is funded jointly by government and industry. However, when storage is combined with enhanced oil recovery to extract extra oil from an oil field, the storage could yield net benefits of US$10–16 per tonne of CO2 injected (based on 2003 oil prices).
Greenpeace claim that CCS could lead to a doubling of plant costs. Most notabl In this process, CO2 is exothermically reacted with abundantly available metal oxides which produces stable carbonates.
The required temperature can be achieved by using a chamber containing a mirror to focus sunlight on the gas. By combining sequestration and biomass feedstocks, the ICF project will achieve dramatic reductions in the lifecycle carbon footprint of the fuels they produce.
There are a number of projects investigating this possibility. GreenFuel Technologies Corp.
However, current research shows that several trapping mechanisms immobilize the CO2 underground, reducing the risk of leakage. For well-selected, designed and managed geological storage sites, the IPCC estimates that CO2 could be trapped for millions of years, and the sites are likely to retain over 99% of the injected CO2 over 1,000 years. In 2009 it was reported that scientists had mapped 6,000 square miles of rock formations in the U.S. programs designed to research, develop and deploy CCS technologies on a broad scale.
Available geological information shows absence of major tectonic events after the deposition of the Utsira formation Phase I of the Weyburn Project in Weyburn, Saskatchewan, Canada has determined that the likelihood of stored CO2 release is less than one percent in 5,000 years. A potentially useful way of dealing with industrial sources of CO2 is to convert it into hydrocarbons where it can be stored or reused as fuel or to make plastics. to capture CO2 from the air.
This would likely negate some of the effect of the carbon capture when the oil was burnt as fuel. Furthermore, because CO2 pipelines for enhanced oil recovery are already in use today, policy decisions affecting CO2 pipelines take on an urgency that is unrecognized by many.
The theoretically required energy for air capture is only slightly more than for capture from point sources. However similar (approximate) price increases would likely be expected in coal dependent countries such as Australia, because the capture technology and chemistry, transport and injection costs from such power plants would not, in an overall sense, vary significantly from country to country. The reasons that CCS is expected to cause such power price increases are several.
The initial pilot will sequester 1,000 tonnes per day in 2010, while the commercial phase could see 10,000 tonnes per day as soon as 2015. Another Canadian initiative called the Integrated CO2 Network (ICO2N) is a proposed system for the capture, transport and storage of carbon dioxide (CO2). Various physical (e.g., highly impermeable caprock) and geochemical trapping mechanisms would prevent the CO2 from escaping to the surface. CO2 is sometimes injected into declining oil fields to increase oil recovery.
This has the potential to be used as a negative carbon emission technique, and is by some regarded as geoengineering. Capturing CO2 might be applied to large point sources, such as large fossil fuel or biomass energy facilities, industries with major CO2 emissions, natural gas processing, synthetic fuel plants and fossil fuel-based hydrogen production plants. Generally, environmental effects from use of CCS arise during power production, CO2 capture, transport and storage.
In 2008, there were approximately 5,800 km of CO2 pipelines in the United States, used to transport CO2 to oil production fields where the CO2 is injected in older fields to extract oil. However, it is more conventional to use the term carbon capture and storage to describe non-biological processes of capturing carbon dioxide from combustion at the source. Although CO2 has been injected into geological formations for various purposes, the long term storage of CO2 is a relatively new concept.
Although the injection pipe is usually protected with Non-return valves (to prevent release on a power outtage), there is still a risk that the pipe itself could tear and leak due to the pressure. Plants equipped with flue gas desulfurization (FGD) systems for SO2 control require proportionally greater amounts of limestone and systems equipped with SCR systems for NOX require proportionally greater amounts of ammonia. IPCC has provided estimates of air emissions from various CCS plant designs (see table below).
Carbon dioxide capture and storage is more commonly proposed on plants burning coal in oxygen extracted from the air, which means the CO2 is highly concentrated and no scrubbing process is necessary. According to the Wallula Energy Resource Center in Washington state, by gasifying the coal, it is possible to capture approximately 65% of carbon dioxide embedded in coal and sequester them into the solid form. After capture, the CO2 would have to be transported to suitable storage sites. These include the National Energy Technology Laboratory’s (NETL) Carbon Sequestration Program, regional carbon sequestration partnerships and the Carbon Sequestration Leadership Forum (CSLF). The United Kingdom Government has launched a tender process for a CCS demonstration project.
The technology is expected to use between 10 and 40% of the energy produced by a power station. A second concern regards the permanence of storage schemes. Also, as part of the CO2 reacts with the water to form carbonic acid, H2CO3, the acidity of the ocean water increases.
ICO2N members represent a group of industry participants providing a framework for carbon capture and storage development in Canada. Based in Wallula, Washington, Wallula Energy Resource Center is proposing a coal plant that incorporates the use of technology and carbon sequestration in order to create electricity in a clean and environmentally friendly manner. The mini pilot plant is run by an Alstom-built oxy-fuel boiler and is also equipped with a flue gas cleaning facility to remove fly ash and sulphur dioxide.
Costs for deep ocean disposal of liquid CO2 are estimated at US$40−80/ton The bicarbonate approach would reduce the pH effects and enhance the retention of CO2 in the ocean, but this would also increase the costs and other environmental effects. An additional method of long term ocean based sequestration is to gather crop residue such as corn stalks or excess hay into large weighted bales of biomass and deposit it in the alluvial fan areas of the deep ocean basin. It is claimed that safe and permanent storage of CO2 cannot be guaranteed and that even very low leakage rates could undermine any climate mitigation effect. Finally there is the issue of cost.
Issues relating to storage are discussed in those sections. Additional energy is required for CO2 capture, and this means that substantially more fuel has to be used, depending on the plant type. It can also be used to describe the scrubbing of CO2 from ambient air as a geoengineering technique. The term carbon dioxide capture and storage has also been used to describe biological techniques such as biochar burial, which use trees, plankton, etc.
The project is expected to come online in mid-2013. This option is attractive because the geology of hydrocarbon reservoirs are generally well understood and storage costs may be partly offset by the sale of additional oil that is recovered.
The main advantage of saline aquifers is their large potential storage volume and their common occurrence. It is also claimed by opponents to CCS that money spent on CCS will divert investments away from other solutions to climate change. Although the processes involved in CCS have been demonstrated in other industrial applications, no commercial scale projects which integrate these processes exist, the costs therefore are somewhat uncertain.
Geological formations are currently considered the most promising sequestration sites. This process occurs naturally over many years and is responsible for much of the surface limestone.
The reaction rate can be made faster, for example by reacting at higher temperatures and/or pressures, or by pre-treatment of the minerals, although this method can require additional energy. (ch.7, p. 321, p. 330) The following table lists principal metal oxides of Earth s Crust.
These methods are currently used for transporting CO2 for other applications. According to the Congressional Research Service, There are important unanswered questions about pipeline network requirements, economic regulation, utility cost recovery, regulatory classification of CO2 itself, and pipeline safety. Global Research Technologies demonstrated a pre-prototype in 2007.
Carbon dioxide-rich gas is extracted from a reservoir via a well, compressed and piped 2.25 km to a new well. Hence, the use of CCS entails a reduction in air quality. .
CO2 could be trapped for millions of years, and although some leakage occurs upwards through the soil, well selected stores are likely to retain over 99% of the injected CO2 over 1000 years. This is done by pipeline, which is generally the cheapest form of transport.
Based on this fact the idea of a methanol economy was born. At the department of Industrial Chemistry and Engineering of Materials at the University of Messina, Italy there is a project to develop a system which works like a fuel-cell in reverse, whereby a catalyst is used that enables sunlight to split water into hydrogen ions and oxygen gas. The project will use post-combustion technology on coal fired power generation at 300-400 MW or equivalent.
In other instances, especially with air capture, a scrubbing process would be needed. Broadly, three different types of technologies exist: post-combustion, pre-combustion, and oxyfuel combustion. There are several advantages and disadvantages when compared to conventional post combustion carbon dioxide capture. An alternate method, which is under development, is chemical looping combustion (CLC). To keep the cost of storage acceptable the geophysical exploration may be limited, resulting in larger uncertainty about the aquifer structure.
Federal classification of CO2 as both a commodity (by the Bureau of Land Management) and as a pollutant (by the Environmental Protection Agency) could potentially create an immediate conflict which may need to be addressed not only for the sake of future CCS implementation, but also to ensure consistency of future CCS with CO2 pipeline operations today. Various forms have been conceived for permanent storage of CO2. James May, the British TV presenter, visited a demonstration plant in a recent programme in his Big Ideas series. As of 2007, four industrial-scale storage projects are in operation.
In addition to individual carbon capture and sequestration projects, there are a number of U.S. Saline aquifers have been used for storage of chemical waste in a few cases.
The project aims to be operational by 2014 . Doosan Babcock will modify a Test Rig at Renfrew in Scotland to accommodate Oxyfuel firing on pulverised coal with recycled flue gas and demonstrate the operation of a full scale 40 MW burner for use in coal-fired boilers. To further investigate the safety of CO2 sequestration, we can look into Norway s Sleipner gas field, as it is the oldest plant that stores CO2 on an industrial scale.
These forms include gaseous storage in various deep geological formations (including saline formations and exhausted gas fields), liquid storage in the ocean, and solid storage by reaction of CO2 with metal oxides to produce stable carbonates. Also known as geo-sequestration, this method involves injecting carbon dioxide, generally in supercritical form, directly into underground geological formations. In the case of deep ocean storage, there is a risk of greatly increasing the problem of ocean acidification, a problem that also stems from the excess of carbon dioxide already in the atmosphere and oceans.
Several concepts have been proposed: The environmental effects of oceanic storage are generally negative, but poorly understood. The project is expected to begin operation in 2013. The Basin Electric Power Cooperative in North Dakota captures half of it s CO2.
But air away from the point source also contains oxygen, and so capturing air, scrubbing the CO2 from the air, and then storing the CO2 could slow down the oxygen cycle in the biosphere. Concentrated CO2 from the combustion of coal in oxygen is relatively pure, and could be directly processed. This would double the typical US industrial electricity price (now at around 6c per kWh) and increase the typical retail residential electricity price by about 50% (assuming 100% of power is from coal, which may not necessarily be the case, as this varies from state to state).
The Swedish company Vattenfall AB invested some 70 million Euros in the two year project which began operation September 9, 2008. Sponsors of the project include the UK Department for Business Enterprise and Regulatory Reform (BERR) and a group of industrial sponsors and university partners comprising Scottish and Southern Energy (Prime Sponsor), E.ON UK PLC, Drax Power Limited, ScottishPower, EDF Energy, Dong Energy Generation, Air Products Plc (Sponsors), and Imperial College and University of Nottingham (University Partners). The German industrial area of Schwarze Pumpe, about 4 km south of the city of Spremberg, is home to the world s first CCS coal plant.
There is no project anywhere in the world storing CO2 stripped from the products of combustion of coal burnt for electricity generation at coal fired power stations although work currently being carried out by the New South Wales government and private industry intends to have a working pilot plant in operation by 2013. One limitation of CCS is its energy penalty. The power plant, which is rated at 30-megawatts, is a pilot project to serve as a prototype for future full-scale power plants. German utility RWE operates a pilot-scale CO2 scrubber at the lignite-fired Niederaußem power station built in cooperation with BASF (supplier of detergent) and Linde (engineering). The Federal Resources and Energy Minister Martin Ferguson opened the first geosequestration project in the southern hemisphere in April 2008.
The major disadvantage of saline aquifers is that relatively little is known about them, compared to oil fields. The Fischer-Tropsch process can then be used to convert the CO into hydrocarbons.
Dropping these residues in alluvial fans would cause the residues to be quickly buried in silt on the sea floor, sequestering the biomass for very long time spans. The additional costs come from the devices that use the natural air flow. Removing CO2 from the atmosphere is a form of geoengineering by greenhouse gas remediation.
The process would increase the fuel requirement of a plant with CCS by about 25% for a coal-fired plant and about 15% for a gas-fired plant. The cost of CCS depends on the cost of capture and storage which vary according to the method used. If sufficient biomass is used, the plant should have the capability to go life cycle carbon negative (meaning that effectively, for each gallon of their fuel that is used, carbon is pulled out of the air, and put into the ground.) Baard Energy, in their Ohio River Clean Fuels project, are developing a 53,000 BPD Coal and Biomass to Liquids project, which has announced plans to market the plant’s CO2 for Enhanced Oil Recovery. Rentech is developing a 29,600 barrel per day coal and biomass to liquids plant in Natchez Mississippi which will market the plant’s CO2 for enhanced oil recovery.
carbon dioxide emissions. Another proposed form of carbon storage is in the oceans. Currently, biofuels represent the other potentially carbon-neutral jet fuel available. Carbon dioxide scrubbing variants exist based on potassium carbonate A proven process to produce a hydrocarbon is to make methanol.
Techniques of this type have received widespread media coverage as they offer the promise of a comprehensive solution to global warming if they can be coupled with effective carbon sequestration technologies. It is more usual to see such techniques proposed for air capture, than for flue gas treatment. The injection of CO2 to produce oil is generally called Enhanced Oil Recovery or EOR.
Disadvantages of old oil fields are their geographic distribution and their limited capacity, as well as that the subsequent burning of the additional oil so recovered will offset much or all of the reduction in CO2 emissions. Unminable coal seams can be used to store CO2 because CO2 adsorbs to the surface of coal. Chemical looping uses a metal oxide as a solid oxygen carrier.
However, as the table above shows, the benefits do not outweigh the extra costs of capture. Comparisons of CCS with other energy sources can be found in wind energy, solar energy, and Economics of new nuclear power plants. The theoretical merit of CCS systems is the reduction of CO2 emissions by up to 90%, depending on plant type. Methanol is rather easily synthesised from CO2 and H2 (See Green Methanol Synthesis).
If discussions with these proponents are not successful, Government will evaluate its options and may proceed to discussions with other proponents. A major Canadian initiative called the Alberta Saline Aquifer Project (ASAP) is a consortium of 38 industry participants that are developing a pilot site for commercial scale carbon capture and storage in a saline aquifer. The ions cross a membrane where they react with the CO2 to create hydrocarbons. If CO2 is heated to 2400°C, it splits into carbon monoxide and oxygen.
It aims to store up to 100,000 tonnes of carbon dioxide extracted from a gas well. Obviously, fuel use and environmental problems arising from mining and extraction of coal or gas increase accordingly.
Even though life appears to be rather sparse in the deep ocean basins, energy and chemical effects in these deep basins could have far reaching implications. Leakage of CO2 back into the atmosphere may be a problem in saline aquifer storage.
There the gas is injected into a depleted natural gas reservoir approximately two kilometres below the surface. This plant does not propose to capture CO2 from coal fired power generation. Leakage through the injection pipe is a greater risk.
The Wallula Energy Resource Center plans to use Integrated Gasification Combined Cycle (IGCC) to gasify the coal therefore capturing 65% of the coals CO2 and sequestering the CO2 into basalt formations underground. According to Sandia these chambers could provide enough fuel to power 100% of domestic vehicles using 5800 km², but unlike biofuels this would not take fertile land away from crops but would be land that is not being used for anything else.
These are discussed below. COA conveyor belt system or ships could also be used. Mineral storage is not regarded as having any risks of leakage.
The sale of the methane can be used to offset a portion of the cost of the CO2 storage. Unlike storage in oil fields or coal beds no side product will offset the storage cost.
Geological storage in saline formations or depleted oil or gas fields typically cost US$0.50–8.00 per tonne of CO2 injected, plus an additional US$0.10–0.30 for monitoring costs. A variant of chemical looping is calcium looping, which uses the alternate carbonation and then calcination of a CaO based carrier as a means of capturing CO2. A few engineering proposals have been made for the more difficult task of capturing CO2 directly from the air, but work in this area is still in its infancy.
(a kind of solid water cage that surrounds the CO2). Air capture is also possible.
A general problem is that long term predictions about submarine or underground storage security are very difficult and uncertain and CO2 might leak from the storage into the atmosphere. When applied on plants which use biomass, the process is known as bio-energy with carbon capture and storage. There are a couple of rival teams developing such chambers, at Solarec and at Sandia National Laboratories, both based in New Mexico.
Metal oxide particles react with a solid, liquid or gaseous fuel in a fluidized bed combustor, producing solid metal particles and a mixture of carbon dioxide and water vapour. Oil fields, gas fields, saline formations, unminable coal seams, and saline-filled basalt formations have been suggested as storage sites.
On January 29, 2008, however, the Department of Energy announced it was recasting the FutureGen project and on June 24 2008, DoE published a funding opportunity announcement seeking proposals for an IGCC project, with integrated CCS, of at least 250MW. Examples of carbon sequestration at an existing US coal plant can be found at utility company Luminant s pilot version at its Big Brown Steam Electric Station in Fairfield, Texas. The IPCC recommends that limits be set to the amount of leakage that can take place.
Firstly, the increased energy requirements of capturing and compressing CO2 significantly raises the operating costs of CCS-equipped power plants. However, this project was later cancelled. In the United States, four different synthetic fuel projects are moving forward which have publicly announced plans to incorporate carbon capture and storage. American Clean Coal Fuels, in their Illinois Clean Fuels project, is developing a 30,000 Barrel Per Day Biomass and Coal to Liquids project in Oakland Illinois, which will market the CO2 created at the plant for Enhanced Oil Recovery applications.
On June 30, 2009, Government announced three projects it will pursue letters of intent with and work to have the letters signed in the fall. Large concentrations of CO2 kills ocean organisms, but another problem is that dissolved CO2 would eventually equilibrate with the atmosphere, so the storage would not be permanent.
In its 2007 Carbon Sequestration Atlas, the National Energy Technology Laboratory (NETL) reported that North America has enough storage capacity at its current rate of production for more than 900 years worth of carbon dioxide. Approximately 30 to 50 million metric tonnes of CO2 are injected annually in the United States into declining oil fields.
Skyonic plans to circumvent storage problems of liquid CO2 by storing baking soda in mines, landfills, or simply to be sold as industrial or food grade baking soda. However, the technical feasibility depends on the permeability of the coal bed.
According to an environmental assessment of the gas field which was conducted after ten years of operation, the author affirmed that geosequestration of CO2 was the most definite form of permanent geological storage of CO2. The resulting environmental effects on benthic life forms of the bathypelagic, abyssopelagic and hadopelagic zones are poorly understood.
In order to measure accidental carbon releases more accurately and decrease the risk of fatalities through this type of leakage, the implementation of CO2 alert meters around the project perimeter has been proposed. In 1986 a large leakage of naturally sequestered carbon dioxide rose from Lake Nyos in Cameroon and asphyxiated 1,700 people. The demonstration plant is near Nirranda South in South Western Victoria.
Much more work is needed here to define the extent of the potential problems. The time it takes water in the deeper oceans to circulate to the surface has been estimated to be in the order of 1600 years, varying upon currents and other changing conditions. The CO2 will be separated from the natural gas and re-injected into the subsurface at a rate of about 1.2 million tonnes per year. In July 2008, the Government of Alberta announced a $2 billion investment in three to five large-scale carbon capture and storage projects.
Carbon capture and storage (CCS) is a means of mitigating the contribution of fossil fuel emissions to global warming, based on capturing carbon dioxide (CO2) from large point sources such as fossil fuel power plants, and store it away from atmosphere by different means. Alluvial fans exist in all of the world s oceans and seas where river deltas fall off the edge of the continental shelf such as the Mississippi alluvial fan in the gulf of Mexico and the Nile alluvial fan in the Mediterranean Sea. Carbon sequestration by reacting naturally occurring Mg and Ca containing minerals with CO2 to form carbonates has many unique advantages.
In the process of absorption the coal releases previously absorbed methane, and the methane can be recovered (enhanced coal bed methane recovery). In addition there are added investment or capital costs.
IGCC, coupled with sequestration, will enable WERC to fully comply with the CO2 emission performance standards recently adopted by Washington State. In October 2007, the Bureau of Economic Geology at The University of Texas at Austin received a 10-year, $38 million subcontract to conduct the first intensively monitored, long-term project in the United States studying the feasibility of injecting a large volume of CO2 for underground storage per year, for up to 1.5 years, into brine up to 10,000 feet (3,000 m) below the land surface near the Cranfield oil field about 15 miles (25 km) east of Natchez, Mississippi. A small incident of this type of CO2 leakage was the Berkel and Rodenrijs incident in December 2008, where a modest release of greenhouse gas emissions resulted in the deaths of a small group of ducks.
For well-selected, designed and managed geological storage sites, IPCC estimates that risks are comparable to those associated with current hydrocarbon activity. is piloting and implementing algae based carbon capture, circumventing storage issues by then converting algae into fuel or feed. In November 2008, the DOE awarded a $66.9 million, eight-year grant to a research partnership headed by Montana State University to demonstrate that underground geologic formations “can store huge volumes of carbon dioxide economically, safely and permanently.” Researchers under the Big Sky Regional Carbon Sequestration Project plan to inject up to one million tons of CO2 into sandstone beneath southwestern Wyoming. In the Netherlands, a 68 MW oxyfuel plant ( Zero Emission Power Plant ) was being planned to be operational in 2009.
Experimental equipment will measure the ability of the subsurface to accept and retain CO2. Currently, the United States government has approved the construction of what is touted as the world s first CCS power plant, FutureGen. However, burning the resultant methane would produce CO2, which would negate some of the benefit of sequestering the original CO2. Saline formations contain highly mineralized brines, and have so far been considered of no benefit to humans.
The first phase of the project is expected in 2011. DKRW is developing a 15,000-20,000 Barrel Per Day coal to liquids plant in Medicine Bow Wyoming, which will market it plant’s CO2 for enhanced oil recovery. (35°19′S 149°08′E / 35.31°S 149.14°E / -35.31; 149.14) The plant is owned by the Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC).
While the carbon had been sequestered naturally, some point to the event as evidence for the potentially catastrophic effects of sequestering carbon. For ocean storage, the retention of CO2 would depend on the depth; IPCC estimates 30–85% would be retained after 500 years for depths 1000–3000 m. The IPCC estimates that a power plant equipped with CCS using mineral storage will need 60-180% more energy than a power plant without CCS.
Theoretically up to 22% of this mineral mass is able to form carbonates. A major concern with CCS is whether leakage of stored CO2 will compromise CCS as a climate change mitigation option.
