A by-product or byproduct is a secondary product derived from a production process,

manufacturing Manufacturing is the creation or production of goods with the help of equipment, labor, machines, tools, and chemical or biological processing or formulation. It is the essence of secondary sector of the economy. The term may refer to a r ...

process or

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

; it is not the primary product or service being produced. A by-product can be useful and marketable or it can be considered waste: for example,

bran Bran, also known as miller's bran, is the hard outer layers of Cereal, cereal grain. It consists of the combined aleurone and pericarp. Corn (maize) bran also includes the pedicel (tip cap). Along with cereal germ, germ, it is an integral pa ...

, which is a byproduct of the milling of

wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...

into refined

flour Flour is a powder made by grinding raw grains, roots, beans, nuts, or seeds. Flours are used to make many different foods. Cereal flour, particularly wheat flour, is the main ingredient of bread, which is a staple food for many culture ...

, is sometimes

compost Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical and biological properties. It is commonly prepared by decomposing plant, food waste, recycling organic materials and manure. The resulting m ...

ed or burned for disposal, but in other cases, it can be used as a nutritious ingredient in

human food Humans eat various food substances for enjoyment and nutritional support. It is usually of plant, animal, or fungal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals. Omnivorous humans are hi ...

animal feed Animal feed is food given to domestic animals, especially livestock, in the course of animal husbandry. There are two basic types: fodder and forage. Used alone, the word ''feed'' more often refers to fodder. Animal feed is an important input to ...

Gasoline Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic co ...

was once a byproduct of

oil refining An oil refinery or petroleum refinery is an industrial process plant where petroleum (crude oil) is transformed and refined into useful products such as gasoline (petrol), diesel fuel, asphalt base, fuel oils, heating oil, kerosene, liquefie ...

that later became a desirable

commodity In economics, a commodity is an economic good, usually a resource, that has full or substantial fungibility: that is, the market treats instances of the good as equivalent or nearly so with no regard to who produced them. The price of a comm ...

motor fuel An engine or motor is a machine designed to convert one or more forms of energy into mechanical energy. Available energy sources include potential energy (e.g. energy of the Earth's gravitational field as exploited in hydroelectric power gen ...

. The plastic used in

plastic shopping bag Plastic shopping bags, carrier bags, or plastic grocery bags are a type of plastic bag used as shopping bags and made from various kinds of plastic. In use by consumers worldwide since the 1960s, these bags are sometimes called single-use bags, r ...

s also started as a by-product of oil refining.

In economics

In the context of production, a by-product is the "output from a

joint production process In Economics, joint product is a product that results jointly with other products from processing a common input; this common process is also called joint production.Wouters, Mark; Selto, Frank H.; Hilton, Ronald W.; Maher, Michael W. (2012): ''Cos ...

that is minor in quantity and/or

net realizable value Net realizable value (NRV) is a measure of a fixed or current asset's worth when held in inventory, in the field of accounting. NRV is part of the Generally Accepted Accounting Principles (GAAP) and International Financial Reporting Standards (IFRS ...

(NRV) when compared with the

main products A main product is a joint output that generates a significant portion of the net realizable value (NRV) within a joint production process. The classification of a product resulting from a joint production process as either a main product or a by-p ...

". Because they are deemed to have no influence on reported financial results, by-products do not receive allocations of

joint cost A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...

s. By-products also, by convention, are not inventoried, but the NRV from by-products is typically recognized as "other income", or as a reduction of

ing costs when the by-product is produced. The

International Energy Agency The International Energy Agency (IEA) is a Paris-based autonomous intergovernmental organisation, established in 1974, that provides policy recommendations, analysis and data on the entire global energy sector, with a recent focus on curbing carb ...

(IEA) defines ''by-product'' in the context of

life-cycle assessment Life cycle assessment or LCA (also known as life cycle analysis) is a methodology for assessing environmental impacts associated with all the stages of the Product lifecycle, life cycle of a commercial product, Process lifecycle, process, or ...

by defining four different product types: "main products, co-products (which involve similar revenues to the main product), by-products (which result in smaller revenues), and

waste products Waste (or wastes) are unwanted or unusable materials. Waste is any substance discarded after primary use, or is worthless, defective and of no use. A by-product, by contrast is a joint product of relatively minor economic value. A waste produ ...

(which provide little or no revenue)."

In chemistry

While some chemists treat "by-product" and "side-product" as synonyms in the above sense of a generic secondary (untargeted) product, others find it useful to distinguish between the two. When the two terms are distinguished, "by-product" is used to refer to a product that is not desired but inevitably results from molecular fragments of starting materials and/or

reagents In chemistry, a reagent ( ) or analytical reagent is a substance or compound added to a system to cause a chemical reaction, or test if one occurs. The terms ''reactant'' and ''reagent'' are often used interchangeably, but reactant specifies a ...

that are not incorporated into the ''desired product'', as a consequence of

conservation of mass In physics and chemistry, the law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as the system's mass can ...

; in contrast, "side-product" is used to refer to a product that is formed from a competitive process that could, in principle, be suppressed by an optimization of reaction conditions.

References

{{Authority control Recycling Product> P1 : + C ->[] P2 P1 is th ...

In economics

In chemistry

See also

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