Biorefinery Meaning, Process, Products, and Comparison

A biorefinery is a system of facility that conserves biomass resources by converting them into a number of useful products. This article discusses biorefinery meaning, processes, products, integration, and comparison.


-Biorefinery Meaning: 9 Ways to Define a Biorefinery

-Biorefinery Process: An Outline of What Happens in a Biorefinery

-Biorefinery Products

-Integrated Biorefinery

-Biorefinery and Petroleum Refinery









Biorefinery Meaning: 9 Ways to Define a Biorefinery

A biorefinery is a facility in which organic material is optimized to produce various useful and non-harmful products.

An alternative biorefinery meaning can be given based on the link between the biorefinery concept and the concepts of sustainable development and sustainability;

Biorefinery is a system that is designed to make the process of organic waste management a sustainable one, by using organic materials to produce useful products [10].

The following biorefinery meaning or definition is based on the relevance of these systems to the ecosystem and environment;

A biorefinery is a system that mitigates environmental degradation and conserves ecologic resources by recycling organic materials and transforming them into a variety of usable products [16].

We can interpret the above definition to imply that biorefineries reduce the need for environmental remediation activities in environments where organic waste is produced, such as agricultural lands and biodegradable plastic industries [19].

Another way to outline the biorefinery meaning or definition is based on biomass conversion processes;

Biorefinery is a facility in which thermal, chemical, electrochemical and biochemical process of biomass conversion such as fermentation, anaerobic digestion, pyrolysis and electro-synthesis are used to transform organic matter to a series of useful products.

Some of the biomass conversion processes above are also relevant to the concept of waste-to-energy conversion. What this means is that we can provide an alternative biorefinery meaning or definition based on the conversion of waste to energy;

A biorefinery is a technological system that integrates waste management and waste-to-energy processes for the treatment of biogenic waste materials.

Renewable energy, bioenergy, and electricity are three concepts that can be used to outline the biorefinery meaning or definition, as follows;

A biorefinery is a facility that can produce renewable bioenergy from organic waste, which may be used for electricity generation and heating, among other purposes [23].

Another biorefinery meaning or definition, based on the production of biofuel, is given below;

A biorefinery is a system that applies conversion mechanisms to transform organic materials into biofuels like bio-ethanol, biodiesel, and biogas [4].

It is possible to outline the biorefinery meaning or definition based on industries where this technology is relevant;

Biorefinery is a technological system and concept that is used in crop processing, paper and pulp, bioplastic, and vegetable oil manufacturing industries, to convert organic matter to a variety of chemical and energy products [25].

Lastly, the biorefinery meaning and definition can be given in terms of similarity to a petroleum refinery;

A biorefinery is a sustainable alternative to a petroleum refinery; where the raw material is biomass, and the products are a number of fuels and industrial chemicals.

Biorefinery Facility (Credit: Manuelacarvajal 2010 .CC BY-SA 4.0.)
Biorefinery Facility (Credit: Manuelacarvajal 2010 .CC BY-SA 4.0.)


Biorefinery Process: An Outline of What Happens in a Biorefinery

What happens in a biorefinery is biomass conversion, which may be through chemical, biochemical, thermal, or electro-chemical mechanisms.

The biorefinery process consists of sorting, conversion, catalysis, refining and recycling. These are the 5 stages of the transformation process in biorefineries. They are discussed below;

1). Sorting as part of the Biorefinery Process

Waste sorting is a process in which waste is separated into different groups, elements of categories [7].

In organic waste sorting, the goal is to separate waste into organic and inorganic categories. It is part of the conventional recycling process.

Since biorefining is a form of recycling, sorting is also utilized. However, the need for sorting is less when waste is homogenous (that is; composed mostly of uniform or similar types of materials).

Sorting is most needed when waste is heterogeneous. This is the case for waste produced in municipalities (municipal solid organic waste, MSOW, MOW, or SOW), as well as waste from small farms and manufacturing industries. The treatment of these materials in a biorefinery becomes an option when alternative methods like composting and incineration are not desired or possible.

For municipal waste, the materials which comprise this type of waste includes metals, plastics, cardboard, paper, wood, garden waste, food waste or kitchen waste, and sewage. Sorting is needed to separate the organic materials like food waste, wood and garden waste; from the other categories, in order to send them to the biorefining facility.

Organic waste sorting affects the environment in terms of greenhouse emissions, energy efficiency and energy conservation [9]. The exact way in which it influences these factors may vary under different conditions. In general, sorting of organic waste for recycling reduces net greenhouse emissions from waste, increases energy efficiency and conserves energy in the recycling process.

The aim of organic waste sorting is to select suitable feedstock for biorefining, biomass conversion, plastic and metal recycling, and other sustainable conservative practices that lead to the development of a circular economy.

A biorefinery system may be equipped to carry out automated sorting using a combination of mechanical engineering and artificial intelligence technology. This is usually needed when the feedstock is of very large quantity. In other scenarios, manual sorting is used to separate organic matter from other types of waste.

Some studies have described sorting as the process of separating toxic materials from the feedstock or processing stream in biorefineries. However, this is better described as refining, which is a different aspect of the biorefinery process.

Biorefinery Process: Waste Sorting (Credit: Kemberly Groue 2011)
Biorefinery Process: Waste Sorting (Credit: Kemberly Groue 2011)


2). Conversion as part of the Biorefinery Process

Biomass conversion is the most important stage of the biorefining process.

It can only occur after organic waste has been carefully separated or sorted, to be recycled as feedstock.

Proper sorting of organic feedstock helps to conserve energy as well as increase the efficiency of the process in terms time spent, energy consumed and effectiveness of conversion.

There are various biomass conversion methods and technologies. These may be used either individually or in combination.

The choice of conversion method or technology depends on the type and characteristics of organic feedstock, and the desired products or outcome of conversion.

For example, thermal methods like torrefaction are used when the feedstock is too complex or costly to be treated using chemical methods, and where products like solid residue for soil amendment are desired. On the other hand, biochemical methods like anaerobic digestion and hydrolysis are used when the feedstock can be effectively broken down and converted by microbes, and where fuels like biogas are desired.

During conversion, the major end-products of the biorefining process are formed.


3). Catalysis as part of the Biorefinery Process

Catalysis is the process by which an added substance influences and modifies a chemical reaction in a desired direction [21]. The added substance itself, called the catalyst; is usually not affected or consumed in the reaction process.

Catalysis is often an aspect of the biorefinery process (or biorefining process). It is included when there is need to alter and modify the reactions involved in converting biomass to a desired end product. In such cases, the conversion process is called ‘catalytic biomass conversion’ [13].

In order for catalytic biomass conversion to be effective. the organic feedstock involved in chemical reaction must be homogenous. This means that sorting must be done properly.

In many cases, catalytic conversion is needed to facilitate the breakdown of complex organic molecules. This may be through reaction processes like deoxygenation and hydrogenation.

Here, the role of the catalyst is to remove COx or H2O from organic molecules to enable them breakdown and transform into end products. Examples of catalysts used in the biorefinery process are formic acid, isopropanol and tetralin [12].

Catalysts may be used with different biomass conversion like anaerobic digestion, fermentation, and pyrolysis.


4). Refining as part of the Biorefinery Process

‘Refining’ is any process by which a substance is purified, to remove impurities and transform it to a more usable or useful product.

It may also be called post treatment of purification. Pretreatment is a form of purification to remove unwanted compounds and impurities before or during biomass conversion. An example of this is the removal of lignin from lignocellulosic organic matter to enable it breakdown effectively in hydrolysis conversion [27].

On the other hand, post-treatment or refining occurs after the organic feedstock has been converted and the products have been formed. Its role is simple to purify these products and make them more authentic, valuable and usable.

Various approaches may be used to refine biorefinery products, including chemical, physical and catalytic processes. Examples of biorefinery purification methods are gas stream scrubbing to remove greenhouse gases and toxins, adsorption, enzymatic purification, and distillation of liquid biofuel and other chemicals [18].

These methods lead to refined end-products after eliminating water, glyceride, and other impurities.


5). Recycling as part of the Biorefinery Process

Recycling is the final stage in the biorefinery process. It is important because the overall process of sorting, conversion, catalysis and refining, lead to the recycling of the original feedstock into other useful materials.

The role of biorefining technology in a sustainable and circular economy is that of recycling waste [11].

Aside organic waste of feedstock, other types of recycling occur in a biorefinery. For example, where biochemical conversion is being used, nutrients for microorganisms like algae can be recycled [1]. Other resources like water and bioenergy can also be recycled in biorefineries.


Biorefinery Products

Biorefinery products are the chemicals and energy resources produced when organic matter is transformed in a biorefinery, and they include; organic acids; biofuels like bioethanol, bio-methanol, biogas, syngas, and biodiesel; and residual materials like biochar and digestate.

Biorefinery feedstock include food waste, sewage, agricultural waste and organic industrial waste. These are the materials from which biorefinery products are derived.


1). Organic Acids as Biorefinery Products

Organic acids are often formed as byproducts during the breakdown and conversion of biomass [22]. These acids include lactic and acrylic acids, among others.

Organic acids are often isolated, either for use, or due to their toxicity toward microbes that are being used in the conversion process [26].


2). Biofuels and Bio-based Chemicals as Biorefinery Products

Biofuels and biobased chemicals are major products of biorefineries.

Respectively, these products are relevant in renewable energy production and industrial manufacturing.

Bio-ethanol is the most important and common biofuel produced in biorefineries, and accounts for up to 94% of the global production volume of biofuels [24].

Biobased chemicals may be produced in the form of biosurfactants, biopigments and biopolymers [17]. Their uses range from neutraceuticals to energy and agricultural fertilizer applications [15].


3). Residual Materials as Biorefinery Products

‘Residual materials’ here refers to the residue from biorefining processes and include biochar (from pyrolytic conversion) and digestate (from anaerobic digestion).

These materials are useful especially in soil conservation for agricultural purposes [20] [14]. They can also be utilized for algae cultivation, which is useful in bioremediation and other biochemical processes [3].


Integrated Biorefinery

An integrated biorefinery is a refinery that makes use of multiple biomass conversion methods and produces multiple types of bio-based products.

The bio-based methods and products in an integrated biorefinery may occur either simultaneously or non-simultaneously.  

Integrated biorefineries can also be defined based on their performance; as a type of biorefinery that converts organic materials into valuable products under optimal and conservative energy efficiency and material recycling.

In an integrated biorefinery, energy efficiency and energy conservation are two important criteria used to evaluate performance. When these criteria are optimized, it implies that the operation of the integrated biorefinery is effective, efficient and sustainable.

Integrated biorefineries are also evaluated based on their ability to produce a wide variety of end-products like biochemicals, bioenergy and biofuel [6].


Biorefinery and Petroleum Refinery

A biorefinery and a petroleum refinery are similar in that they are both used to process and refine raw materials to yield useful products for energy, agriculture and industrial manufacturing.

There are some ways in which these two types of refineries are different from each other. Differences between a biorefinery and a petroleum refinery include raw materials or feedstock used; and products formed [5].

The two types of refineries are also different in terms of the methods and processes used.

Raw materials used in petroleum refineries are crude oil and natural gas. In biorefineries, the raw materials are various forms of organic matter like food waste, agricultural residue, sewage and industrial organic waste.

Methods and processes used in petroleum refineries are fractional distillation, reforming, cracking, treatment, desulfurization (an aspect of treatment) and recovery. On the other hand, processes used in biorefineries include sorting, thermal treatment, anaerobic digestion, hydrolysis, and post-treatment or purification.

Products of petroleum refineries are; diesel, gasoline, methane (major component of natural gas), ethane, propane, butane, hydrogen, and asphalt [2]. On the other hand, products of biorefineries include biogas, bio-ethanol, syngas, bio-methanol, biodiesel, digestate and biochar.


The following table summarizes the comparison between biorefineries and petroleum refineries;


Comparison Criteria Biorefinery Petroleum Refinery
Raw Materials or Feedstock Organic materials Petroleum, Natural Gas
Methods Biochemical, Chemical, Thermal, Electrochemical Thermal, Physical, Chemical
Methodological Processes Pyrolysis, Anaerobic Digestion, Hydrolysis, Torrefaction, Gasification Distillation, Treatment, Recovery, Cracking, Reforming
Products Biogas, Bio-ethanol, Bio-Methanol, Digestate, Biyochar Gasoline, Diesel, Natural Gas, Asphalt, Bitumen
Technical Complexity Relatively Low Relatively High




A biorefinery is a system that converts biomass to biofuel, bio-based chemicals and bioenergy through thermal, chemical and biochemical processes.

The biorefinery meaning can be outlined based on methods, processes, sustainability, energy efficiency, renewable energy, environmental impact, and comparison to petrochemical refineries.


The biorefinery process is made up of;

  1. Sorting
  2. Conversion
  3. Catalysis
  4. Refining
  5. Recycling


Biorefinery products are;

  1. Organic Acids
  2. Biofuels
  3. Bio-based Chemicals
  4. Residual Materials


Biorefineries are similar to petroleum or petrochemical refineries. The differences between them occur in terms of raw materials, methods and processes of conversion, end products, and technical complexity.



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