With the constantly increasing energy demands with the increase of population and urbanization, conventional energy resources like coal, petroleum, natural gas, etc., are on the brink of extinction as you can see in the proportional usage of all energy types. But mostly, we are using conventional energy sources that are non-replenishable. It draws the attention of researchers. Search for renewable energy sources starts from there. Then we choose renewable energy sources for our energy requirements like wind, water, solar energy, biomass, etc.
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Source: Researchgate World energy consumptionBiomass is considered one of the most suitable and eco-friendly options for renewable energy sources. Using many thermo-chemical processes like combustion, gasification, liquefaction, hydrogenation, and pyrolysis, biomass conversion begins into various energy-yielding end products. Pyrolysis and types of the pyrolysis process are like a way to convert some of our waste to energy. If you are interested, you can also see our Waste V/s Byproduct blog. To know about biomass in detail, connect with biomass experts here.
Pyrolysis is still in the developing stage. But it receives special attention due to its quality to transform biomass directly into solid, liquid, and gaseous end products. In this blog, I'll inform you about the types of pyrolysis processes. But, before that, I'll also give you a rundown about pyrolysis. So, buckle up, and let's get started.
What Does Pyrolysis Mean?Pyrolysis is a thermal decomposition process at high temperatures in an inert atmosphere. It is considered the first step in gasification or combustion. It is different from combustion and hydrolysis as it does not involve the addition of reagents like oxygen or water.
Pyrolysis of organic materials forms volatile products and leaves char behind. Char is a solid carbon-rich residue. In this process, biomass transforms into solid (char), condensable liquid (tar), and non-condensing gases. This technique efficiently utilizes particular importance for agriculture countries with vastly available biomass by-products.
How Pyrolysis is Done
Pyrolysis of woodPyrolysis is generally the heating of matter above its decomposition point in the absence of oxygen. This leads to the breakage of chemical bonds and the form of small molecules. But it can combine and form residues of larger molecular mass. Pyrolysis temperature ranges from medium (300'800°C) to high temperatures (800'°C). A series of reactions take place in biomass degradation by a gradual increase in temperature.
Up to 100 degrees in the water, waxes, fat, and sugar heat-sensitive substances like proteins and vitamins degrade. At temperatures between 100-500 degrees, common organic compounds like lignin, cellulose, and most sugar decompose. A non-volatile carbon-rich residue is formed, which is black and brown in color. At 200-400 degrees, if oxygen is involved, an exothermic reaction starts remaining nitrogen, sulphur, and chlorine. Arsenic, etc., are volatile in oxides. Combustion leaves the solid, powdery residue of oxidized inorganic materials. Now that you know the process of pyrolysis, you must be thinking about where it is being used. The next heading will answer your questions.Where Pyrolysis is Used
Were is Pyrolysis UsedFind top machinery, plants, tools, resources, companies, and consultancy for comprehensive pyrolysis solutions.
Know more Post requirementPyrolysis is used in many processes. Let me list out some:
Through this process, many types of carbon are produced that are used as fuels, structural materials, reagents, etc. Charcoal and coke are less smoky fuels. Activated carbon is used as an absorbent of chemicals. Biochar is a residue of complete pyrolysis. Biochar is used for retaining soil quality and increasing the fertility and quality of the soil.
Carbon fibers are carbon filaments that are very strong and give strong yarns and textiles. Thomas Edison used the pyrolysis carbon filament of bamboo splinters to make the bulb. Pyrolysis carbon coating has many applications, like artificial heart valves.
Pyrolysis is the base method for fuel-making from biomass. Some examples are synthetic diesel, syngas, bio-oil, and some low-quality oils.
Pyrolysis is a non-polluting industrial process to produce hydrogen from methane. It is a high-volume yield, low-cost process.
Ethylene is produced by pyrolysis. Resulting ethylene being used to make many other polymers like PVC, Ethylene glycol (anti-freezing agent), polystyrene, and polyethylene.
Semiconductors of many volatile organometallic compounds are made through pyrolysis. Some examples of semiconductors are silane, Gallium arsenide, trimethylgallium, and arsenide.
Pyrolysis for waste managementPlastic waste and municipal waste are treated by pyrolysis. Waste reduction is the main advantage. Get plastic treatment consultation from plastic waste experts on our platform.
Thermal cleaning is the pyrolysis process to remove the organic substance from parts, components, and products. Molten salt baths, fluidized bed systems, and burn-off ovens vacuum ovens are several types of thermal cleaning.
There are many more examples of pyrolysis. Let's learn about the type of pyrolysis processes.
Types of Pyrolysis Processes Types of Pyrolysis ProcessesFind Expert
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Connect NowDepending upon the process, parameters, and conditions, there are several types of pyrolysis processes. Appropriate reactors are chosen for different pyrolysis processes depending on their process.
Term fast pyrolysis refers to the gradual rapid heating of biomass for a temperature range of 800' °C. Rate of heating ranges between 10'200 °C for a short life span between 1-10 sec. Fast Pyrolysis is done for liquid products as it yields more liquid. The product distribution range is 60'75% biofuel liquid products, 15'20% solid biochars, and 10'20% noncondensable gaseous products.
Different reactors are used on the basis of desired products, conditions, and biomass. Some of the most popular reactors for fast Pyrolysis are:
Fast pyrolysis is used in many areas. Some examples of fast pyrolysis are mentioned below.
The most recent renewable energy source is biomass. Biomass is easily available. It can transform into a quantum of energy-yielding products. It is a safe alternative for the conservation of conventional energy sources.
Types of pyrolysis processes: Fast pyrolysis of biomassFast pyrolysis of wood is now quite famous for coke production as coke is considered one of the clean fuels.
Plant biomass has biopolymers like cellulose, xylans, and lignin. On fast pyrolysis of lignin, a bio-oil having methoxyphenyl, phenolic aldehydes/ketones, low-molecular-weight phenols, and light oxygenates forms. This bio-oil is a good fuel.
Pyrolysis of plastics is done to convert them into energy and bio-oil. Pyrolysis of plastic waste is performed at 300'900°C, which produces a liquid oil.
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Get Connected TodayIt is a conventional type of pyrolysis. It involves a long residing time and a slow heating rate. In slow pyrolysis, biomass is pyrolyzed for about 400'500 °C temperature, with a heating rate of 0.1'1 °C/s. The approximate time for slow pyrolysis ranges between 5-30 mins.
Slow pyrolysis leads to the production of solid carbonaceous char. Liquid and gaseous products are formed but in low quantities.
Terms and conditions are applied depending on the various factors in order to use suitable reactors. Some widely known reactors for slow pyrolysis are:
Auger-type reactors are used for both fast and slow pyrolysis.
Slow pyrolysis is used in many fields to make solid biofuel. I'm mentioning some of the examples below:-
Slow pyrolysis of biomass mainly targets biochar (up to '60 wt%), together with 25-30 wt% of bio-oil and the balance as gas. Slow pyrolysis leads to a good amount of charcoal production. With controlled temperature and nitrogen ratio, results can be altered. With increasing temperature, solid, liquid, gas fuels, and oils are formed, respectively.
Types of pyrolysis processes: Slow pyrolysis of woodDifference Between Fast and Slow Pyrolysis
Qualities
Fast pyrolysis
Slow pyrolysis
Residence time
Short upto few seconds to a minute
Long upto few minutes to hours
Heating rate
High
Low
Decomposition rate
Rapid decomposition
Slow decomposition
Particle size
Small particles
Relative big particles
Temperature
Higher
Lower
Product
Liquid
Solid
Typical reactors
Rotary kiln, fluidized
Fixed bed reactors
It is called very fast pyrolysis. Its reaction time is several seconds. It involves very high temperature and a very high heating rate, i.e.,> °C/s. It affords a very high yield of bio-oil with very low water content. This bio-oil conversion efficiency is approx 70%.
Due to sudden high temperatures, special reactors are made. Biomass residence time in these reactors is less. The most commonly used reactors for flash pyrolysis are:
Some newly made specialized reactors are also available in markets.
Generally, flash pyrolysis forms 60% biochar and 40% bio-oil and syngas. Bio-oil is the preferred product of this process. Bio-oils are extracted through several means. Some examples are:
With cellulosic biomass and wood, the organic oil yield is as high as 65'70%. The resultant liquid is acidic, stable, and easy to pour. As its production cost from wood is competitive but it is a conventional full or present time.
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Connect TodayFlash pyrolysis is of following types:
Due to the vacuum, condensable products are removed from the hot reaction. That prevents further cracking and re-condensation reactions.
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4. Catalytic Biomass Pyrolysis
From the literature, it can be depictured that liquid obtained from different pyrolysis processes cannot be used directly as biofuel. Due to high oxygen and water content, it needs upgrading. Catalytic biomass pyrolysis is performed to improve the quality of bio-oil.
This procedure involves the use of catalysts to improve the quality of bio-oil. Pre upgradation techniques like condensation and re-evaporation are not needed for this oil. So it can be used as transportation oil or altered its quality to meet several demands.
Various catalysts are used in this process. The use of a catalyst depends upon the product, procedure, and biomass used. Mainly zeolites and basic materials are used as catalysts.
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Buyer Listings Seller Listings ConclusionIt is necessary to find ways that can change biomass into useful energy sources. We have to think primarily about liquid fuel because diesel and petroleum are on the verge of extinction. Thermochemical processes are one of the best alternatives as they are eco-friendly and suitable for achieving desirable requirements. Pyrolysis receives major attention because it produces the best quality product.
It can be depicted by the literature and my blog that slow pyrolysis yields good-quality char. Fast and flash-yield liquid oil to use as fuel. Catalytic biomass pyrolysis is an option to improve the quality of products. It can also be applied to gaseous products to improve their quantity and quality. Researchers also mention that it is a good alternative for waste to energy. Energy from biomass can be very beneficial for developing countries like India. For more detailed information regarding pyrolysis processes, connect with pyrolysis consultants on our platform.
Summary
Article Name
Types of Pyrolysis Processes: To Conserve Renewable Resources
Description
Thermolysis processes as pyrolysis are worthwhile to meet growing energy demands. Here you will know about the types of pyrolysis processes.
Author
Andleep Zahra
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mywastesolution.com
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The figure below shows a graphic of the four methods of thermochemical conversion of biomass, with pyrolysis highlighted. We just went over combustion and gasification, and we'll cover direct liquefaction later on in the semester.
Thermochemical routes for the conversion of biomass
Credit: Dr. Hilal Ezgi Toraman © Penn State, licensed under CC BY-NC-SA 4.0
There are differences in each of the thermal processes. For combustion, the material is in an oxygen-rich atmosphere, at a very high operating temperature, with heat as the targeted output. Gasification takes place in an oxygen-lean atmosphere, with a high operating temperature and gaseous products being the main target (syngas production in most cases). Direct liquefaction (particularly hydrothermal processing) occurs in a non-oxidative atmosphere, where biomass is fed into a unit as an aqueous slurry at lower temperatures, and bio-crude in liquid form is the product.
So, what is pyrolysis? There are several definitions depending on the source, but essentially it is a thermochemical process, conducted at 400-600°C in the absence of oxygen. The process produces gases, bio-oil, and a char, and as noted in Lesson 4, is one of the first steps in gasification or combustion. The composition of the primary products made will depend on the temperature, pressure, and heating rate of the process.
There are advantages, both economical and environmental, to doing pyrolysis. They are:
Pyrolysis was initially utilized to produce charcoal. In indigenous cultures in South America, the material was ignited and then covered with soil to reduce the oxygen available to the material ' it left a high carbon material that could stabilize and enrich the soil to add nutrients ([Discussion of applications of pyrolysis], (n.d.), Retrieved from MagnumGroup.org). It has also been used as a lighter and less volatile source of heat for cooking (i.e., 'charcoal' grills) in countries where electricity is not widely available and people use fuel such as this to cook with or heat their homes (Schobert, H.H., Energy, and Society: An Introduction, , Taylor & Francis: New York). Not only is there a solid product, such as charcoal, but liquid products can also be produced depending on the starting material and conditions used. Historically, methanol was produced from the pyrolysis of wood.
This process for pyrolysis can also be called torrefaction. Torrefaction is typically done at relatively low pyrolysis temperatures (200-300°C) in the absence of oxygen. The feed material is heated up slowly, at less than 50°C/min, and is done over a period of hours to days ' this way the volatiles are released and carbon maintain a rigid structure. In the first stage, water, which is a component that can inhibit the calorific value of a fuel, is lost. This is followed by a loss of CO, CO2, H2, and CH4, in low quantities. By doing this, approximately 70% of the mass is retained with 90% of the energy content. The solid material is hydrophobic (with little attraction to water) and can be stored for a long period of time.
There are three types of pyrolysis: 1) conventional/slow pyrolysis, 2) fast pyrolysis, and 3) ultra-fast/flash pyrolysis. The table and figure below summarize how each method differs in temperature, residence time, heating rate, and products made.
As mentioned earlier, slow pyrolysis is typically used to modify the solid material, minimizing the oil produced. Fast pyrolysis and ultra-fast (flash) pyrolysis maximizes the gases and oil produced.
Fast pyrolysis is a rapid thermal decomposition of carbonaceous materials in the absence of oxygen at moderate to high heating rates. It is the most common of the methods, both in research and in practical use. The major product is bio-oil. Pyrolysis is an endothermic process. Along with the information listed in the table, the feedstock must be dry; of smaller particles (< 3 mm); and typically done at atmospheric temperature with rapid quenching of the products. The yields of the products are: liquid condensates ' 30-60%; gases (CO, H2, CH4, CO2, and light hydrocarbons) ' 15-35%; and char ' 10-15%.
Ultra-fast, or flash pyrolysis is an extremely rapid thermal decomposition pyrolysis, with a high heating rate. The main products are gases and bio-oil. Heating rates can vary from 100-10,000° C/s and residence times are short in duration. The yields of the products are: liquid condensate ~10-20%; gases ' 60-80%; and char ' 10-15%.
Classification of pyrolysis methods with differences in temperature, residence time, heating rate, and major products. Method TemperatureCredit: Boyt, R., (November ), Wood Pyrolysis. Retrieved from Bioenergylists.org
Click for a text description of the figure.
Effect on product distribution of different pyrolysis conditions. All values are visual approximations based on the image Heating rate Time Temperature (ºC) Char Liquid Gas Slow (<103 W/m2) s ~500ºC 25% 35% 40% Medium (>104 W/m2) 100s ~500ºC 17% 58% 35% Fast (>105 W/m2) 1s ~500ºC 15% 65% 20% Flash (>106 W/m2) 0.01s ~500ºC 10% 70% 20% Slow (<103 W/m2) s ~ºC 40% 35% 25% Medium (>104 W/m2) 100s ~ºC 20% 37% 43% Fast (>105 W/m2) 1s ~ºC 15% 20% 65% Flash (>106 W/m2) 0.01s ~ºC 0% 15% 95%Credit: (Created based on Xavier DEGLISE, Emeritus Professor at University Henri Poincaré, France. BEEMS Module C2, Brian He.)
Figure summarizing different pyrolysis conditions and the effect on product distribution.
Crude bio-oils are different from petroleum crude oils. Both can be dark and tarry with an odor, but crude bio-oils are not miscible with petro-oils. Bio-oils have high water content (20-30%); their density is heavier than water (1.10-1.25 g/mL); their heating value is ~- Btu/lb (13-18 MJ/kg). Bio-oils have high oxygen content (35-50%), which causes high acidity (pH as low as ~2). Bio-oils are also viscous (20- cp @ 40°C) and have high solid residues (up to 40%). These oils are also oxidatively unstable, so the oils can polymerize, agglomerate, or have oxidative reactions occurring in situ which lead to increased viscosity and volatility. The values in the table below compare the properties of bio-oil to petroleum-based heavy fuel oil.
Typical properties of wood pyrolysis bio-oil and heavy fuel oil. Physical Property Bio-oil Heavy fuel oil Moisture Content 15-30 0.1 pH 2.5 -- Specific gravity 1.2 0.94 Elemental composition (wt%) - - C 54-58 85 H 5.5-7.0 11 O 35-40 1.0 N 0-0.2 0.3 Ash 0-0.2 0.1 HHV, MJ/kg 16-19 40 Viscosity (cp, @50°C) 40-100 180 Solids (wt %) 0.2-1 1 Distillation residue (wt%) Up to 50 1Credit: Czemik, S. and Bridgewater, A.V., . Overview of Applications of Biomass Fast Pyrolysis, Energy Fuels 18, 590-598.
Several components are necessary for any pyrolysis unit, outside of the pyrolyzer itself. The units and how they are connected are shown in the figure below.
General components of a process for pyrolysis.
Credit: Dr. Caroline B. Clifford © Penn State, licensed under CC BY-NC-SA 4.0
The goal of the process is to produce bio-oil from the pyrolyzer. The bio-oil that's generated has potential as a transportation fuel after upgrading and fractionation. Some can be used for making specialty chemicals as well, especially ring-structure compounds that could be used for adhesives. The gases that are produced contain combustible components, so the gases are used to generate heat. A biochar is produced as well. Biochar can be used as a soil amendment that improves the quality of the soil, sequesters carbon, or can even be used as a carbon material as a catalyst support or activated carbon. There will also be a mineral-based material called ash once it's been processed. Typically, the ash must be contained.
The next units to be considered are separation units. Char is solid, so it is typically separated using a cyclone or baghouse. It can be used as a catalyst for further decomposition into gases because the mineral inherent in the char as well as the carbon can catalyze the gasification reactions. The liquids and gases must also be separated. Usually, the liquids and gases must be cooled in order to separate the condensable liquids from the non-condensable gases. The liquids are then fractionated and will most likely be treated further to improve the stability of the liquids. At times, the liquid portion may plug due to heavier components. The non-condensable gases need to be cleaned of any trace amounts of liquids and can be reused if needed.
The next consideration is the heat sources for the unit. Hot flue gas is used to dry the feed. As the flue gas contains combustible gases, they can be partially combusted to provide heat. Any char that is left over is burned as a major supply of heat. And, biomass can be partially burned as another major source of heat.
Another important process to consider is the means of heat transfer. Much of it is indirect, through metal walls and tube and shell units. Direct heat transfer has to do with char and biomass burning. In the fluidized bed unit, the carrier (most often sand) brings in the heat, as the carrier is heated externally and recycled to provide heat to the pyrolyzer.
So, what types of pyrolyzers are used? The more common types are fluidized-bed pyrolyzers. The figures below show schematics of two different types. The advantages of using fluid beds are uniform temperature and good heat transfer; high bio-oil yield of up to 75%; a medium level of complexity in construction and operation; and ease of scaling up. The disadvantages of fluid beds are the requirement for small particle sizes; a large quantity of inert gases; and high operating costs. The circulating fluid bed pyrolyzer, (CFB), shown below, has similar advantages, although medium-sized particle sizes for feed are used. Disadvantages include a large quantity of heat carriers (i.e., sand); more complex operation, and high operating costs.
Click for a text description of the fluid bed.
Schematic of a fluid bed with electrostatic precipitator. The carrier gas enters the fluid bed that has an intake feed. The gas then goes through a cyclone and the char and ash are removed as a product or taken to the char burner. The gas then passes through the quencher and the heavier fraction is removed as bio-oil, it then passes to the condenser where the lighter fraction is condensed as bio-oil and the non-condensable are taken to the boiler or the burner. Any gases created at the burner are used as carrier gas.
Credit: BEEMS
Fluid-bed with electrostatic precipitator.
Click for a text description.
Schematic of a fluid-bed with circulating heat carrier (circulating fluid-bed (CFB) pyrolyzers. The carrier gas enters the bottom of the fluid bed through a pyrolyzer. The fluid bed also has an intake feed halfway up. The gas then goes through a cyclone and the char and heat carriers are removed and taken to a burner. The heat carriers (sand) are returned to the fluid bed/pyrolyzer. The ash is removed and flue gas is taken to the heating unit. The gases that come out of the cyclone then pass through the quencher and the heavier fraction is removed as bio-oil, it is then passed to the condenser where the lighter fraction is condensed as bio-oil, and the non-condensable is taken to the boiler or the burner. Any gases created at the burner are used as carrier gas.
Credit: BEEMS
Fluidized bed with circulating heat carrier (circulating fluid-bed (CFB) pyrolyzers).
Two other types of pyrolyzers are the Rotating Cone and the Auger pyrolyzers. The rotating cone creates a swirling movement of particles through a g-force. This type of pyrolyzer is compact, has a relatively simple construction and operation, and has a low heat carrier/sand requirement. However, it has a limited capacity, requires feed to be fine particles, and is difficult to scale up. Auger pyrolyzers are also compact, simple in construction, and easy to operate; they function at a lower process temperature as well (400 °C). The disadvantages of Auger pyrolyzers include long residence times, lower bio-oil yields, high char yield, and limits in scaling up due to heat transfer limits.
Click for a text description of the rotating cone pyrolyzer.
Schematic of a rotating cone pyrolyzer. The cone has feed at the bottom and heat is applied to the outside walls of the cone. A motor spins the cone and the gas/condensables come out the top as does the char/ash.
Credit: BEEMS
Rotating cone pyrolyzer.
Click for a text description of the Auger pyrolyzer.
Schematic of an Auger pyrolyzer. The diagram looks like a cylinder with a corkscrew inside. A motor is attached to the rotating corkscrew. The walls of the cylinder are heated and at one end there is a feed. On the other end, there are outtake ports for condensables to come out the tops and char/ash to come out the bottom.
Credit: BEEMS
Auger pyrolyzer.
As noted earlier, bio-oil has issues and must be upgraded, which means essentially processed to remove the problems. These problems include high acid content (which is corrosive), high water content, and high instability both oxidatively and thermally (which can cause unwanted solids formation).
The oils must be treated physically and chemically. Physical treatments include the removal of char via filtration and emulsification of hydrocarbons for stability. Bio-oils are also fractionated, but not before chemical treatments are done. The chemical treatments include esterification (a reaction with alcohol to form esters ' this will be covered in detail when discussing biodiesel production); catalytic de-oxygenation/hydrogenation to remove oxygen and double bonds; thermal cracking for more volatile components; physical extraction; and syngas production/gasification.
Catalytic de-oxygenation/hydrogenation takes place. A catalyst is used along with hydrogen gas; specialty catalysts are used, such as sulfides and oxides of nickel, cobalt, and molybdenum. Hydrogenation is commonly used in petroleum refining for the removal of sulfur and nitrogen from crude oil and to hydrogenate the products where double bonds may have formed in processing. Catalytic processes are separate processes and use specific equipment to perform the upgrading. One problem can be that there may be components of bio-oil that may be toxic to catalysts.
Esterification reacts to the corrosive acids in bio-oils with alcohol to form esters. An ester is shown below. A discussion of the esterification reaction will be discussed in the biodiesel lesson.
A general chemical formula of an ester compound, where R and R' can be any type of hydrocarbon. The R group is attached to the C=O and is the acidic part of the molecule, while the R' group is attached to the O and is the alcoholic part of the molecule.
Credit: Ester-general: from Wikimedia Commons
Bio-oil can also be thermally cracked and/or made into syngas through gasification. Please refer to Lesson 2 for the thermal cracking discussion and Lesson 4 for the gasification discussion. One other process that can be utilized is physical extraction, although extraction takes place due to the affinity of some of the compounds to a particular fluid. One example is the extraction of phenols. Phenols can be extracted using a sodium solution such as sodium hydroxide in water; the phenolic compounds are attracted to the sodium solution, while the less oxygenated compounds will stay in the organic solution. Again, this will be discussed in more detail in later lessons. The figure below shows a schematic of a typical processing unit to upgrade bio-oil.
Click for a text description of a typical processing unit.
Schematic of a typical processing unit to upgrade bio-oil. Crude bio-oil and auxiliary chemicals ender the pre-reactor which does things such as de-acidify or esterify. From the pre-reactor, the crude bio-oil goes to the separator. The aqueous fraction is removed and goes to the solubles recovery unit. The organic fraction goes to the reactor where hydrogen gas is pumped in to do hydrogenation and deoxygenation. The gases are removed to a hydrogen scrubber which cleans and separates the gases. The hydrogen gas is recycled. The bio-oil then goes to a distillation column. The heavy fraction is a fuel oil candidate and could be cracked for lighter components. The medium fraction can become kerosene or a diesel candidate. The lightest fraction can become a gasoline candidate.
Credit: BEEMS
Schematic of a typical processing unit to upgrade bio-oil.
Current methods of generating biofuels are primarily from starch or grain, and starch hydrolysis is fairly straightforward. However, because the starch feedstocks are typically food-based, the goal is to develop technologies to produce ethanol from cellulose; cellulose is obtained from lignocellulosic biomass sources and must be pretreated before breaking down into ethanol. Below is a schematic of the differences in processing for starch (current) and cellulose (emerging). Before we go any further, we will have a short tutorial on the various components of lignocellulosic biomass.
Click for a text description of the schematic.
Schematic of processing differences for cellulose and starch. For starch or grain, it goes through starch hydrolysis and then the fermentation of glucose to recover the final product. The final products are food products, animal feed, ethanol, and chemicals.
For cellulose (lignocellulosic biomass) it must go through a pretreatment before entering cellulose hydrolysis and then the fermentation of carbon 5 and 6 sugars to recover the final products. The final products are food products, animal feed, ethanol, and chemicals. Any lignin residue goes through thermochemical conversion to become heat and power, and fuels and chemicals: pyrolysis oil and synthesis gas.
Credit: Source: The National Renewable Energy Laboratory (NREL)
Schematic of processing differences for cellulose and starch.
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