Gasification

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Gasification is a process that converts biomass- or fossil fuel-based carbonaceous materials into gases, including as the largest fractions: nitrogen (N2), carbon monoxide (CO), hydrogen (H2), and carbon dioxide (CO2). This is achieved by reacting the feedstock material at high temperatures (typically >700 °C), without combustion, via controlling the amount of oxygen and/or steam present in the reaction. The resulting gas mixture is called syngas (from synthesis gas) or producer gas and is itself a fuel due to the flammability of the H2 and CO of which the gas is largely composed. Power can be derived from the subsequent combustion of the resultant gas, and is considered to be a source of renewable energy if the gasified compounds were obtained from biomass feedstock. [1] [2] [3] [4]

Contents

An advantage of gasification is that syngas can be more efficient than direct combustion of the original feedstock material because it can be combusted at higher temperatures so that the thermodynamic upper limit to the efficiency defined by Carnot's rule is higher. Syngas may also be used as the hydrogen source in fuel cells, however the syngas produced by most gasification systems requires additional processing and reforming to remove the contaminants and other gases such as CO and CO2 to be suitable for low-temperature fuel cell use, but high-temperature solid oxide fuel cells are capable of directly accepting mixtures of H2, CO, CO2, steam, and methane. [5]

Syngas is most commonly burned directly in gas engines, used to produce methanol and hydrogen, or converted via the Fischer–Tropsch process into synthetic fuel. For some materials gasification can be an alternative to landfilling and incineration, resulting in lowered emissions of atmospheric pollutants such as methane and particulates. Some gasification processes aim at refining out corrosive ash elements such as chloride and potassium, allowing clean gas production from otherwise problematic feedstock material. Gasification of fossil fuels is currently widely used on industrial scales to generate electricity. Gasification can generate lower amounts of some pollutants as SOx and NOx than combustion. [6]

History

Adler Diplomat 3 with gas generator (1941) Adler Diplomat 3 GS mit Holzgasgenerator-hinten rechts.JPG
Adler Diplomat 3 with gas generator (1941)

Energy has been produced at industrial scale via gasification since the early 19th century. Initially coal and peat were gasified to produce town gas for lighting and cooking, with the first public street lighting installed in Pall Mall, London on January 28, 1807, spreading shortly to supply commercial gas lighting to most industrialized cities until the end of the 19th century [7] when it was replaced with electrical lighting. Gasification and syngas continued to be used in blast furnaces and more significantly in the production of synthetic chemicals where it has been in use since the 1920s. The thousands of sites left toxic residue. Some sites have been remediated, while others are still polluted. [8]

During both world wars, especially the World War II, the need for fuel produced by gasification reemerged due to the shortage of petroleum. [9] Wood gas generators, called Gasogene or Gazogène, were used to power motor vehicles in Europe. By 1945 there were trucks, buses and agricultural machines that were powered by gasification. It is estimated that there were close to 9,000,000 vehicles running on producer gas all over the world.

Another example, the Xe than (literally, "coal car" in Vietnamese) was a minibus that has been converted to run on coal instead of gasoline. This modification regained popularity in Vietnam during the subsidy period, when gasoline was in short supply. Xe than became much less common during the Đổi Mới period, when gasoline became widely accessible again.

Chemical reactions

In a gasifier, the carbonaceous material undergoes several different processes:

Pyrolysis of carbonaceous fuels Pyrolysis.svg
Pyrolysis of carbonaceous fuels
Gasification of char Gasification.gif
Gasification of char
  1. The dehydration or drying process occurs at around 100 °C. Typically the resulting steam is mixed into the gas flow and may be involved with subsequent chemical reactions, notably the water-gas reaction if the temperature is sufficiently high (see step #5).
  2. The pyrolysis (or devolatilization) process occurs at around 200–300 °C. Volatiles are released and char is produced, resulting in up to 70% weight loss for coal. The process is dependent on the properties of the carbonaceous material and determines the structure and composition of the char, which will then undergo gasification reactions.
  3. The combustion process occurs as the volatile products and some of the char react with oxygen to primarily form carbon dioxide and small amounts of carbon monoxide, which provides heat for the subsequent gasification reactions. Letting C represent a carbon-containing organic compound, the basic reaction here is C + O2 → CO2.
  4. The gasification process occurs as the char reacts with steam and carbon dioxide to produce carbon monoxide and hydrogen, via the reactions C + H2O → H2 + CO and C + CO2 → 2CO.
  5. In addition, the reversible gas phase water-gas shift reaction reaches equilibrium very fast at the temperatures in a gasifier. This balances the concentrations of carbon monoxide, steam, carbon dioxide and hydrogen: CO + H2O ⇌ CO2 + H2.

In essence, a limited amount of oxygen or air is introduced into the reactor to allow some of the organic material to be "burned" to produce carbon dioxide and energy, which drives a second reaction that converts further organic material to hydrogen and additional carbon dioxide. Further reactions occur when the formed carbon monoxide and residual water from the organic material react to form methane and excess carbon dioxide (4CO + 2H2O → CH4 + 3CO2). This third reaction occurs more abundantly in reactors that increase the residence time of the reactive gases and organic materials, as well as heat and pressure. Catalysts are used in more sophisticated reactors to improve reaction rates, thus moving the system closer to the reaction equilibrium for a fixed residence time.

Processes

Main gasifier types Gasifier types.svg
Main gasifier types

Several types of gasifiers are currently available for commercial use: counter-current fixed bed, co-current fixed bed, fluidized bed, entrained flow, plasma, and free radical. [1] [10] [11] [12]

Counter-current fixed bed ("up draft") gasifier

A fixed bed of carbonaceous fuel (e.g. coal or biomass) through which the "gasification agent" (steam, oxygen and/or air) flows in counter-current configuration. [13] The ash is either removed in the dry condition or as a slag. The slagging gasifiers have a lower ratio of steam to carbon, [14] achieving temperatures higher than the ash fusion temperature. The nature of the gasifier means that the fuel must have high mechanical strength and must ideally be non-caking so that it will form a permeable bed, although recent developments have reduced these restrictions to some extent.[ citation needed ] The throughput for this type of gasifier is relatively low. Thermal efficiency is high as the temperatures in the gas exit are relatively low. However, this means that tar and methane production is significant at typical operation temperatures, so product gas must be extensively cleaned before use. The tar can be recycled to the reactor.

In the gasification of fine, undensified biomass such as rice hulls, it is necessary to blow air into the reactor by means of a fan. This creates very high gasification temperature, as high as 1000 C. Above the gasification zone, a bed of fine and hot char is formed, and as the gas is blow forced through this bed, most complex hydrocarbons are broken down into simple components of hydrogen and carbon monoxide. [15]

Co-current fixed bed ("down draft") gasifier

Similar to the counter-current type, but the gasification agent gas flows in co-current configuration with the fuel (downwards, hence the name "down draft gasifier"). Heat needs to be added to the upper part of the bed, either by combusting small amounts of the fuel or from external heat sources. The produced gas leaves the gasifier at a high temperature, and most of this heat is often transferred to the gasification agent added in the top of the bed, resulting in an energy efficiency on level with the counter-current type. Since all tars must pass through a hot bed of char in this configuration, tar levels are much lower than the counter-current type.

Fluidized bed reactor

Visualisation of proposed fluidized bed gasification facility in Amsterdam designed to convert waste materials into biofuels Gasification facility "Advanced Methanol Amsterdam".jpg
Visualisation of proposed fluidized bed gasification facility in Amsterdam designed to convert waste materials into biofuels

The fuel is fluidized in oxygen and steam or air. The ash is removed dry or as heavy agglomerates that defluidize. The temperatures are relatively low in dry ash gasifiers, so the fuel must be highly reactive; low-grade coals are particularly suitable. The agglomerating gasifiers have slightly higher temperatures, and are suitable for higher rank coals. Fuel throughput is higher than for the fixed bed, but not as high as for the entrained flow gasifier. The conversion efficiency can be rather low due to elutriation of carbonaceous material. Recycle or subsequent combustion of solids can be used to increase conversion. Fluidized bed gasifiers are most useful for fuels that form highly corrosive ash that would damage the walls of slagging gasifiers. Biomass fuels generally contain high levels of corrosive ash.

Fluidized bed gasifiers uses inert bed material at a fluidized state which enhance the heat and biomass distribution inside a gasifier. At a fluidized state, the superficial fluid velocity is greater than the minimum fluidization velocity required to lift the bed material against the weight of the bed. Fluidized bed gasifiers are divided into Bubbling Fluidized Bed (BFB), Circulating Fluidized Bed (CFB) and Dual Fluidized Bed (DFB) gasifiers.

Entrained flow gasifier

A dry pulverized solid, an atomized liquid fuel or a fuel slurry is gasified with oxygen (much less frequent: air) in co-current flow. The gasification reactions take place in a dense cloud of very fine particles. Most coals are suitable for this type of gasifier because of the high operating temperatures and because the coal particles are well separated from one another.

The high temperatures and pressures also mean that a higher throughput can be achieved, however thermal efficiency is somewhat lower as the gas must be cooled before it can be cleaned with existing technology. The high temperatures also mean that tar and methane are not present in the product gas; however the oxygen requirement is higher than for the other types of gasifiers. All entrained flow gasifiers remove the major part of the ash as a slag as the operating temperature is well above the ash fusion temperature.

A smaller fraction of the ash is produced either as a very fine dry fly ash or as a black colored fly ash slurry. Some fuels, in particular certain types of biomasses, can form slag that is corrosive for ceramic inner walls that serve to protect the gasifier outer wall. However some entrained flow type of gasifiers do not possess a ceramic inner wall but have an inner water or steam cooled wall covered with partially solidified slag. These types of gasifiers do not suffer from corrosive slags.

Some fuels have ashes with very high ash fusion temperatures. In this case mostly limestone is mixed with the fuel prior to gasification. Addition of a little limestone will usually suffice for the lowering the fusion temperatures. The fuel particles must be much smaller than for other types of gasifiers. This means the fuel must be pulverized, which requires somewhat more energy than for the other types of gasifiers. By far the most energy consumption related to entrained flow gasification is not the milling of the fuel but the production of oxygen used for the gasification.

Plasma gasifier

In a plasma gasifier a high-voltage current is fed to a torch, creating a high-temperature arc. The inorganic residue is retrieved as a glass like substance.

Feedstock

There are a large number of different feedstock types for use in a gasifier, each with different characteristics, including size, shape, bulk density, moisture content, energy content, chemical composition, ash fusion characteristics, and homogeneity of all these properties. Coal and petroleum coke are used as primary feedstocks for many large gasification plants worldwide. Additionally, a variety of biomass and waste-derived feedstocks can be gasified, with wood pellets and chips, waste wood, plastics and aluminium, Municipal Solid Waste (MSW), Refuse-derived fuel (RDF), agricultural and industrial wastes, sewage sludge, switch grass, discarded seed corn, corn stover and other crop residues all being used. [1]

Chemrec has developed a process for gasification of black liquor. [17]

Waste disposal

HTCW reactor, one of several proposed waste gasification processes HTCW reactor.jpg
HTCW reactor, one of several proposed waste gasification processes

Waste gasification has several advantages over incineration:

A major challenge for waste gasification technologies is to reach an acceptable (positive) gross electric efficiency. The high efficiency of converting syngas to electric power is counteracted by significant power consumption in the waste preprocessing, the consumption of large amounts of pure oxygen (which is often used as gasification agent), and gas cleaning. Another challenge becoming apparent when implementing the processes in real life is to obtain long service intervals in the plants, so that it is not necessary to close down the plant every few months for cleaning the reactor.

Environmental advocates have called gasification "incineration in disguise" and argue that the technology is still dangerous to air quality and public health. "Since 2003 numerous proposals for waste treatment facilities hoping to use... gasification technologies failed to receive final approval to operate when the claims of project proponents did not withstand public and governmental scrutiny of key claims," according to the Global Alliance for Incinerator Alternatives. [18] One facility which operated from 2009–2011 in Ottawa had 29 "emissions incidents" and 13 "spills" over those three years. It was also only able to operate roughly 25% of the time. [19]

Several waste gasification processes have been proposed, but few have yet been built and tested, and only a handful have been implemented as plants processing real waste, and most of the time in combination with fossil fuels. [20]

One plant (in Chiba, Japan, using the Thermoselect process [21] ) has been processing industrial waste with natural gas and purified oxygen since year 2000, but has not yet documented positive net energy production from the process.

In 2007 Ze-gen erected a waste gasification demonstration facility in New Bedford, Massachusetts. The facility was designed to demonstrate gasification of specific non-MSW waste streams using liquid metal gasification. [22] This facility came after widespread public opposition shelved plans for a similar plant in Attleboro, Massachusetts. [23] Today Ze-gen appears to be defunct, and the company website was taken down in 2014. [24]

Also in the US, in 2011 a plasma system delivered by PyroGenesis Canada Inc. was tested to gasify municipal solid waste, hazardous waste and biomedical waste at the Hurlburt Field Florida Special Operations Command Air Force base. The plant, which cost $7.4 million to construct, [25] was closed and sold at a government liquidation auction in May 2013. [26] [27] The opening bid was $25. The winning bid was sealed.

In December 2022, the Sierra BioFuels Plant opened in Reno, Nevada, converting landfill waste to synthetic crude oil. [28]

Current applications

Syngas can be used for heat production and for generation of mechanical and electrical power. Like other gaseous fuels, producer gas gives greater control over power levels when compared to solid fuels, leading to more efficient and cleaner operation.

Syngas can also be used for further processing to liquid fuels or chemicals.

Heat

Gasifiers offer a flexible option for thermal applications, as they can be retrofitted into existing gas fueled devices such as ovens, furnaces, boilers, etc., where syngas may replace fossil fuels. Heating values of syngas are generally around 4–10 MJ/m3.

Electricity

Currently Industrial-scale gasification is primarily used to produce electricity from fossil fuels such as coal, where the syngas is burned in a gas turbine. Gasification is also used industrially in the production of electricity, ammonia and liquid fuels (oil) using Integrated Gasification Combined Cycles (IGCC), with the possibility of producing methane and hydrogen for fuel cells. IGCC is also a more efficient method of CO2 capture as compared to conventional technologies. IGCC demonstration plants have been operating since the early 1970s and some of the plants constructed in the 1990s are now entering commercial service.

Combined heat and power

In small business and building applications, where the wood source is sustainable, 250–1000 kWe and new zero carbon biomass gasification plants have been installed in Europe that produce tar free syngas from wood and burn it in reciprocating engines connected to a generator with heat recovery. This type of plant is often referred to as a wood biomass CHP unit but is a plant with seven different processes: biomass processing, fuel delivery, gasification, gas cleaning, waste disposal, electricity generation and heat recovery. [29]

Transport fuel

Diesel engines can be operated on dual fuel mode using producer gas. Diesel substitution of over 80% at high loads and 70–80% under normal load variations can easily be achieved. [30] Spark ignition engines and solid oxide fuel cells can operate on 100% gasification gas. [31] [32] [33] Mechanical energy from the engines may be used for e.g. driving water pumps for irrigation or for coupling with an alternator for electrical power generation.

While small scale gasifiers have existed for well over 100 years, there have been few sources to obtain a ready-to-use machine. Small scale devices are typically DIY projects. However, currently in the United States, several companies offer gasifiers to operate small engines.

Renewable energy and fuels

Gasification plant, Gussing, Austria (2001-2015) Holzvergaser Gussing.jpg
Gasification plant, Güssing, Austria (2001–2015)

In principle, gasification can proceed from just about any organic material, including biomass and plastic waste. The resulting syngas can be combusted. Alternatively, if the syngas is clean enough, it may be used for power production in gas engines, gas turbines or even fuel cells, or converted efficiently to dimethyl ether (DME) by methanol dehydration, methane via the Sabatier reaction, or diesel-like synthetic fuel via the Fischer–Tropsch process. In many gasification processes most of the inorganic components of the input material, such as metals and minerals, are retained in the ash. In some gasification processes (slagging gasification) this ash has the form of a glassy solid with low leaching properties, but the net power production in slagging gasification is low (sometimes negative) and costs are higher.

Regardless of the final fuel form, gasification itself and subsequent processing neither directly emits nor traps greenhouse gases such as carbon dioxide. Power consumption in the gasification and syngas conversion processes may be significant though, and may indirectly cause CO2 emissions; in slagging and plasma gasification, the electricity consumption may even exceed any power production from the syngas.

Combustion of syngas or derived fuels emits exactly the same amount of carbon dioxide as would have been emitted from direct combustion of the initial fuel. Biomass gasification and combustion could play a significant role in a renewable energy economy, because biomass production removes the same amount of CO2 from the atmosphere as is emitted from gasification and combustion. While other biofuel technologies such as biogas and biodiesel are carbon neutral, gasification in principle may run on a wider variety of input materials and can be used to produce a wider variety of output fuels.

There are at present a few industrial scale biomass gasification plants. Since 2008 in Svenljunga, Sweden, a biomass gasification plant generates up to 14 MWth, supplying industries and citizens of Svenljunga with process steam and district heating, respectively. The gasifier uses biomass fuels such as CCA or creosote impregnated waste wood and other kinds of recycled wood to produces syngas that is combusted on site. [34] [35]

Examples of demonstration projects include:

See also

Related Research Articles

Syngas, or synthesis gas, is a mixture of hydrogen and carbon monoxide, in various ratios. The gas often contains some carbon dioxide and methane. It is principally used for producing ammonia or methanol. Syngas is combustible and can be used as a fuel. Historically, it has been used as a replacement for gasoline, when gasoline supply has been limited; for example, wood gas was used to power cars in Europe during WWII.

<span class="mw-page-title-main">Pyrolysis</span> Thermal decomposition of materials

Pyrolysis is the process of thermal decomposition of materials at elevated temperatures, often in an inert atmosphere without access to oxygen.

<span class="mw-page-title-main">Fluidized bed combustion</span> Technology used to burn solid fuels

Fluidized bed combustion (FBC) is a combustion technology used to burn solid fuels.

The Fischer–Tropsch process (FT) is a collection of chemical reactions that converts a mixture of carbon monoxide and hydrogen, known as syngas, into liquid hydrocarbons. These reactions occur in the presence of metal catalysts, typically at temperatures of 150–300 °C (302–572 °F) and pressures of one to several tens of atmospheres. The Fischer–Tropsch process is an important reaction in both coal liquefaction and gas to liquids technology for producing liquid hydrocarbons.

In industrial chemistry, coal gasification is the process of producing syngas—a mixture consisting primarily of carbon monoxide (CO), hydrogen, carbon dioxide, methane, and water vapour —from coal and water, air and/or oxygen.

Coal liquefaction is a process of converting coal into liquid hydrocarbons: liquid fuels and petrochemicals. This process is often known as "Coal to X" or "Carbon to X", where X can be many different hydrocarbon-based products. However, the most common process chain is "Coal to Liquid Fuels" (CTL).

<span class="mw-page-title-main">Synthetic fuel</span> Fuel from carbon monoxide and hydrogen

Synthetic fuel or synfuel is a liquid fuel, or sometimes gaseous fuel, obtained from syngas, a mixture of carbon monoxide and hydrogen, in which the syngas was derived from gasification of solid feedstocks such as coal or biomass or by reforming of natural gas.

<span class="mw-page-title-main">Coal pollution mitigation</span>

Coal pollution mitigation is a series of systems and technologies that seek to mitigate health and environmental impact of burning coal for energy. Burning coal releases harmful substances that contribute to air pollution, acid rain, and greenhouse gas emissions. Mitigation includes precombustion approaches, such as cleaning coal, and post combustion approaches, include flue-gas desulfurization, selective catalytic reduction, electrostatic precipitators, and fly ash reduction. These measures aim to reduce coal's impact on human health and the environment.

Water gas is a kind of fuel gas, a mixture of carbon monoxide and hydrogen. It is produced by "alternately hot blowing a fuel layer [coke] with air and gasifying it with steam". The caloric yield of the fuel produced by this method is about 10% of the yield from a modern syngas plant. The coke needed to produce water gas also costs significantly more than the precursors for syngas, making water gas technology an even less attractive business proposition.

An integrated gasification combined cycle (IGCC) is a technology using a high pressure gasifier to turn coal and other carbon based fuels into pressurized gas—synthesis gas (syngas). It can then remove impurities from the syngas prior to the electricity generation cycle. Some of these pollutants, such as sulfur, can be turned into re-usable byproducts through the Claus process. This results in lower emissions of sulfur dioxide, particulates, mercury, and in some cases carbon dioxide. With additional process equipment, a water-gas shift reaction can increase gasification efficiency and reduce carbon monoxide emissions by converting it to carbon dioxide. The resulting carbon dioxide from the shift reaction can be separated, compressed, and stored through sequestration. Excess heat from the primary combustion and syngas fired generation is then passed to a steam cycle, similar to a combined cycle gas turbine. This process results in improved thermodynamic efficiency, compared to conventional pulverized coal combustion.

<span class="mw-page-title-main">Waste-to-energy</span> Process of generating energy from the primary treatment of waste

Waste-to-energy (WtE) or energy-from-waste (EfW) refers to a series of processes designed to convert waste materials into usable forms of energy, typically electricity or heat. As a form of energy recovery, WtE plays a crucial role in both waste management and sustainable energy production by reducing the volume of waste in landfills and providing an alternative energy source.

Plasma gasification is an extreme thermal process using plasma which converts organic matter into a syngas which is primarily made up of hydrogen and carbon monoxide. A plasma torch powered by an electric arc is used to ionize gas and catalyze organic matter into syngas, with slag remaining as a byproduct. It is used commercially as a form of waste treatment, and has been tested for the gasification of refuse-derived fuel, biomass, industrial waste, hazardous waste, and solid hydrocarbons, such as coal, oil sands, petcoke and oil shale.

<span class="mw-page-title-main">Thermal oxidizer</span>

A thermal oxidizer is a process unit for air pollution control in many chemical plants that decomposes hazardous gases at a high temperature and releases them into the atmosphere.

Second-generation biofuels, also known as advanced biofuels, are fuels that can be manufactured from various types of non-food biomass. Biomass in this context means plant materials and animal waste used especially as a source of fuel.

<span class="mw-page-title-main">Chemical looping combustion</span>

Chemical looping combustion (CLC) is a technological process typically employing a dual fluidized bed system. CLC operated with an interconnected moving bed with a fluidized bed system, has also been employed as a technology process. In CLC, a metal oxide is employed as a bed material providing the oxygen for combustion in the fuel reactor. The reduced metal is then transferred to the second bed and re-oxidized before being reintroduced back to the fuel reactor completing the loop. Fig 1 shows a simplified diagram of the CLC process. Fig 2 shows an example of a dual fluidized bed circulating reactor system and a moving bed-fluidized bed circulating reactor system.

Hydromethanation, [hahy-droh- meth-uh-ney-shuhn] is the process by which methane is produced through the combination of steam, carbonaceous solids and a catalyst in a fluidized bed reactor. The process, developed over the past 60 years by multiple research groups, enables the highly efficient conversion of coal, petroleum coke and biomass into clean, pipeline quality methane.

<span class="mw-page-title-main">Ze-gen</span> Converting waste into synthesis gas since 2004

Ze-gen, Inc. was a renewable energy company developing advanced gasification technology to convert waste into synthesis gas. Founded in 2004, Ze-gen was a venture-backed company based in Boston, Massachusetts.

Syngas to gasoline plus (STG+) is a thermochemical process to convert natural gas, other gaseous hydrocarbons or gasified biomass into drop-in fuels, such as gasoline, diesel fuel or jet fuel, and organic solvents.

Lower-temperature fuel cell types such as the proton exchange membrane fuel cell, phosphoric acid fuel cell, and alkaline fuel cell require pure hydrogen as fuel, typically produced from external reforming of natural gas. However, fuels cells operating at high temperature such as the solid oxide fuel cell (SOFC) are not poisoned by carbon monoxide and carbon dioxide, and in fact can accept hydrogen, carbon monoxide, carbon dioxide, steam, and methane mixtures as fuel directly, because of their internal shift and reforming capabilities. This opens up the possibility of efficient fuel cell-based power cycles consuming solid fuels such as coal and biomass, the gasification of which results in syngas containing mostly hydrogen, carbon monoxide and methane which can be cleaned and fed directly to the SOFCs without the added cost and complexity of methane reforming, water gas shifting and hydrogen separation operations which would otherwise be needed to isolate pure hydrogen as fuel. A power cycle based on gasification of solid fuel and SOFCs is called an Integrated Gasification Fuel Cell (IGFC) cycle; the IGFC power plant is analogous to an integrated gasification combined cycle power plant, but with the gas turbine power generation unit replaced with a fuel cell power generation unit. By taking advantage of intrinsically high energy efficiency of SOFCs and process integration, exceptionally high power plant efficiencies are possible. Furthermore, SOFCs in the IGFC cycle can be operated so as to isolate a carbon dioxide-rich anodic exhaust stream, allowing efficient carbon capture to address greenhouse gas emissions concerns of coal-based power generation.

Chemical looping reforming (CLR) and gasification (CLG) are the operations that involve the use of gaseous carbonaceous feedstock and solid carbonaceous feedstock, respectively, in their conversion to syngas in the chemical looping scheme. The typical gaseous carbonaceous feedstocks used are natural gas and reducing tail gas, while the typical solid carbonaceous feedstocks used are coal and biomass. The feedstocks are partially oxidized to generate syngas using metal oxide oxygen carriers as the oxidant. The reduced metal oxide is then oxidized in the regeneration step using air. The syngas is an important intermediate for generation of such diverse products as electricity, chemicals, hydrogen, and liquid fuels.

References

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  37. ↑ Youcefi, Fouad (3 April 2018). "Investerade nästan två miljarder i Gobigas – nu läggs projektet ner". SVT Nyheter. Archived from the original on 2018-04-26. Retrieved 2018-04-25.
  38. ↑ "RENET – The path to energy autonomy". Archived from the original on 2007-08-20. Retrieved 2007-08-13.
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  40. ↑ "The FICFB-gasification system". www.ficfb.at. Archived from the original on 2018-03-30. Retrieved 2018-12-06.
  41. ↑ "Technology – GRE". gussingcleanenergy.com. Archived from the original on 2018-06-13. Retrieved 2018-06-13.
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  43. ↑ Abrahamson, Håkan. "Biobränsleanläggning läggs ner". Ny Teknik. Archived from the original on 2018-03-08. Retrieved 2018-03-07.
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  45. ↑ "HTW Gasification Technology by GIDARA Energy".
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