Work Types
Heating¶
Combustion and other heat-induced transformation of materials.
Low Temperature Heating¶
This process involves raising the temperature of an environment, object, or substance to a moderate level, typically not exceeding 100°C. It is commonly applied in both residential and commercial settings for comfort, as well as in various industrial processes where high temperatures are not required.
Combustion¶
This is a chemical reaction where a fuel combines with an oxidant, usually oxygen, to release energy in the form of heat and light. This reaction is characterized by the production of flame or fire and results in high temperatures and the emission of gases such as carbon dioxide and water vapour. Combustion is fundamental to power generation, heating, and the operation of internal combustion engines.
Incineration¶
Incineration involves burning organic materials and waste at high temperatures, generally between 850°C and 1,200°C. This process is used to significantly reduce the mass and volume of waste, transforming it into ash, flue gas, and heat. The heat generated can be harnessed to produce electricity.
Gasification¶
In gasification, organic materials or biomass are heated in a controlled environment with a limited supply of oxygen or other oxidants, typically at temperatures above 700°C. This process converts the material into a mixture known as syngas, which consists of carbon monoxide, hydrogen, and carbon dioxide. Syngas can be utilised directly as a fuel or as an intermediate in the production of other chemicals.
Plasma torch gasification¶
This process involves the gasification of organic materials using a plasma torch, which generates extreme temperatures typically ranging from 2,000°C to 14,000°C. The high energy density of the plasma torch allows for the complete breakdown of materials into their basic molecular components, producing a clean and energy-rich syngas.
Pyrolysis¶
Pyrolysis is the controlled heating of organic materials in an environment completely devoid of oxidants, usually occurring at temperatures above 430°C. This process thermally decomposes organic material, resulting in the production of various byproducts, including char, oil, and syngas, without combustion.
Carbonisation¶
Carbonisation is an intense form of pyrolysis, conducted at temperatures between 500°C and 1,000°C. This process primarily focuses on the conversion of organic substances into carbon or charcoal, typically used in fuel production, metallurgical processes, and as a filtration method.
Torrefaction¶
Torrefaction is a mild form of pyrolysis occurring at temperatures ranging from 200°C to 320°C. This process is used to partially decompose biomass into a more energy-dense form, improving its properties as a fuel. The resultant material has lower moisture content and greater thermal stability, making it easier to grind and combust.
Smouldering¶
Smouldering is a slow, flameless form of combustion that occurs at lower temperatures than typical combustion. It involves the gradual oxidation of solid fuel, such as wood or coal, producing heat, smoke, and minimal flame. This process is often characterised by a persistent, low-temperature burn that can continue for extended periods, making it a common hazard in fire safety due to its ability to remain undetected.
Steam reformation¶
Steam reformation, also known as steam methane reforming, is a process used to produce syngas (a mixture of hydrogen and carbon monoxide) by reacting hydrocarbons with steam. Typically involving methane as the primary hydrocarbon, this endothermic reaction occurs at high temperatures (around 700°C to 1,000°C) and under pressure, catalysed by nickel. It is a key industrial route for producing hydrogen gas and synthesising other chemicals.
Energy Processes¶
Photovoltaic¶
This process converts sunlight directly into electricity using photovoltaic cells, which are semiconductor devices that generate a voltage and electric current when exposed to light. Photovoltaic systems are widely used in solar panels for residential, commercial, and industrial applications to provide a sustainable and renewable source of energy.
Wind¶
Wind energy harnesses the power of the wind to generate electricity. This is achieved through wind turbines, which convert the kinetic energy of wind into mechanical power. A generator then converts this mechanical power into electricity. Wind farms can be located on land or offshore and are among the leading sources of renewable energy worldwide.
Geothermal¶
Geothermal energy is derived from the natural heat stored within the Earth. This process involves extracting heat from beneath the Earth’s surface to generate electricity or to provide direct heating. Techniques include deep-earth drilling to tap steam or hot water reservoirs, which drive turbines connected to electricity generators.
Hydro¶
Hydroelectric energy, or hydro energy, involves the generation of electricity through the movement of water. Typically, water from a dam or river flows through a turbine, triggering it to spin and activate a generator to produce electricity.
Tidal¶
Tidal energy is a form of hydropower that converts the energy obtained from tides into electricity. This process generally uses large underwater turbines that are driven by the shifting tides. The movement of these tides due to the gravitational pull of the moon and sun generates kinetic energy, which is then converted into electrical power.
Electromagnetism¶
In the context of energy processes, this often refers to the generation of electricity through electromagnetic induction. When a conductor moves through a magnetic field, an electromotive force is generated across the conductor, creating an electrical current. This principle is fundamental in the operation of electrical generators, where mechanical energy (from wind, water, steam, etc.) is converted into electrical energy.
Industrial processes¶
Extraction¶
This process involves the removal of raw materials from the earth. It is a fundamental industrial activity used to gather natural resources such as minerals, metals, fossil fuels, and aggregates. Extraction methods can vary widely, including mining, drilling, and quarrying, depending on the resource and its location.
Construction¶
Construction refers to the process of assembling infrastructure or buildings from raw materials. This involves various stages including planning, design, financing, and execution, where materials such as steel, concrete, and wood are manipulated and assembled to create physical structures like houses, office buildings, and bridges.
Assembly¶
In industrial contexts, assembly is typically a robotic or automated process where pre-manufactured parts are put together to form a more complex product. This can involve the use of robotic arms and automated machinery to join components through techniques like welding, screwing, and adhesive bonding, commonly seen in manufacturing sectors such as automotive and electronics.
Blending¶
Blending is the process of combining two or more distinct materials to produce a homogenous mixture. This is commonly used in various industries such as chemicals, pharmaceuticals, food, and beverage. The process ensures that the final product has consistent properties and quality, achieved by thorough mixing of the constituent materials.
Chemical reactions¶
Setting¶
Setting often refers to the process of a material becoming solid or hardening from a more fluid state, usually through a chemical reaction, such as the setting of cement or concrete. This involves the hydration of cement compounds which react with water and other components to form a hard, stone-like material that is durable and strong.
Electrolysis¶
This is a chemical process that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commonly used for the decomposition of substances, such as the electrolytic reduction of alumina into aluminium and oxygen in the Hall-Héroult process, or the splitting of water into oxygen and hydrogen gas. The process involves passing an electric current through an electrolyte, causing ions to move towards the electrodes, where reduction and oxidation reactions occur.
Calcination¶
This is a thermal treatment process in which a solid chemical compound or material is subjected to high temperatures in an environment typically containing controlled amounts of air or oxygen. It is used primarily to remove volatile substances, induce thermal decomposition, or cause phase transitions. A common example is the calcination of limestone (calcium carbonate) to produce lime (calcium oxide) and carbon dioxide gas.
Coking¶
Coking is a thermal process that heats coal in the absence of air to remove volatile components. The result is coke, a porous, carbon-rich material that is primarily used as a fuel and as a reducing agent in smelting iron ore in a blast furnace. The process also generates byproducts like coal tar, ammonia, and benzene, among others.
Flash smelting¶
This process involves the rapid smelting of sulfide ores by suspending finely ground particles in a high-temperature airstream, which causes them to react and oxidise quickly. It is primarily used in the extraction of copper, nickel, and other base metals. Flash smelting is highly efficient in terms of energy consumption and reduces the emission of sulfur dioxide gases compared to other smelting methods.
Biological processes¶
Anaerobic digestion¶
This is a biological process in which microorganisms break down organic material in the absence of oxygen, typically within a closed system. The process produces biogas, primarily composed of methane and carbon dioxide, which can be used as a renewable energy source. Anaerobic digestion is commonly employed in waste management systems to treat sewage sludge, agricultural waste, and organic industrial waste, helping reduce the emission of landfill gases and producing digestate that can be used as fertiliser.
Aerobic digestion¶
Aerobic digestion occurs when organic materials are decomposed by bacteria using oxygen. This process is used extensively in wastewater treatment plants to reduce the volume of waste sludge and make it less odorous and easier to handle. The aerobic process requires aeration to maintain oxygen levels, and it stabilises the organic matter, resulting in a reduction of pathogens and the production of carbon dioxide and water as byproducts.
Enteric fermentation¶
Enteric fermentation is a digestive process that occurs in the stomachs of ruminant animals like cows, sheep, and goats. In this process, microbes decompose and ferment the plant-based food consumed by the animals, producing methane as a byproduct. This methane is released into the atmosphere primarily through belching. Enteric fermentation is a significant source of methane emissions, a potent greenhouse gas, contributing to global warming.
Photosynthesis¶
Photosynthesis is a fundamental process carried out by plants, algae, and certain bacteria, whereby sunlight is used to convert carbon dioxide and water into glucose and oxygen. This process is crucial for life on Earth as it provides the primary energy source for nearly all ecosystems and also contributes to the atmospheric oxygen essential for aerobic life forms. In addition to its role in natural ecosystems, understanding and harnessing photosynthesis is crucial for agriculture and can be integral to innovative technologies aimed at carbon capture and biofuel production.
Methanogenesis¶
This is a form of anaerobic respiration carried out by a group of microorganisms known as methanogens. Methanogenesis occurs in environments devoid of oxygen, such as deep marine sediments, wetlands, and the digestive tracts of ruminants. During this process, methanogens convert carbon dioxide, acetate, and other non-oxygen molecules into methane, a potent greenhouse gas. Methanogenesis is crucial in natural carbon cycling and is exploited in biogas production technologies.
Microbial peat oxidation¶
This process involves the aerobic decomposition of organic matter in peatlands by microorganisms. When peat, which is formed from the gradual accumulation of decayed vegetation, is exposed to air, microbes begin to oxidise the carbon stored in the peat, releasing carbon dioxide into the atmosphere. Microbial peat oxidation is a significant source of carbon emissions, particularly when peatlands are drained for agriculture or other land uses.
Peat fires¶
Peat fires occur when layers of peat, a type of soil made up of decomposed plant material, ignite and burn, often smouldering for extended periods. These fires can be sparked naturally by lightning or through human activities such as land clearing and agricultural practices. Peat fires are challenging to extinguish and can release large amounts of carbon dioxide and other pollutants, contributing to air quality issues and climate change.
Biomechanics¶
Biomechanics involves the conversion of chemical energy within cells into mechanical energy that powers physical actions in biological organisms. This process underpins the mechanical functions of muscles, bones, and joints, enabling movements such as walking, lifting, or running. By harnessing cellular energy, biomechanics facilitates the efficient execution of complex motions and activities, playing a crucial role in both everyday movements and high-performance athletic endeavors. This mechanism is essential for maintaining mobility and function across various species and environments.
Waste processes¶
Composting¶
Composting is the aerobic decomposition of organic solid waste, such as food scraps, yard waste, and other biodegradable materials. This process relies on microorganisms, such as bacteria and fungi, and occasionally earthworms, to break down organic matter into humus—a nutrient-rich material. Composting helps reduce landfill waste, lowers greenhouse gas emissions, and produces a valuable amendment for improving soil health and fertility.
Recycling¶
Recycling involves the process of collecting waste materials and transforming them into new products. This can include sorting, cleaning, and reprocessing materials such as plastics, metals, glass, and paper to prevent the waste of potentially useful materials, reduce the consumption of fresh raw materials, reduce energy usage, and decrease air and water pollution by reducing the need for conventional waste disposal.
Wastewater treatment¶
Wastewater treatment is the process of removing contaminants from wastewater, including household sewage and industrial runoff. The treatment involves physical, chemical, and biological processes to remove physical, chemical, and biological contaminants. The goal is to produce an environmentally safe fluid waste stream and a solid waste suitable for disposal or reuse, often as farm fertiliser.
Fugitive emissions¶
Fugitive emissions refer to the release of gases or vapours from pressurised equipment due to leaks and other irregular releases. These emissions can include gases that escape from pipeline systems, tanks, and other facilities where they are not intended to be released. Fugitive emissions are a significant source of environmental pollution and contribute to air quality degradation and climate change.