Greenhouse gas (GHG) emissions are categorised into three scopes by the Greenhouse Gas Protocol, a widely used international accounting tool that helps businesses and governments track, report, and manage greenhouse gas emissions.

Scope 1 GHG emissions come directly from sources that are owned or controlled by the company. For example, if a company operates factories that burn fuel, the emissions from these factories are considered Scope 1. This also includes emissions from company-owned vehicles and facilities. The company generally has full control over the factors that produce Scope 1 emissions. These are therefore the easiest emissions to reduce.

Scope 1 can be divided into five main categories:

Stationary combustion refers to the burning of fuels in fixed installations, such as power plants, industrial boilers, and heating systems, to produce energy.

Emissions from stationary combustion are calculated by measuring the amount of fuel burned and applying specific emission factors, which are values that estimate the amount of pollutants released per unit of fuel consumed. The primary greenhouse gases from these processes include carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O).

For example, consider a manufacturing plant that operates a large industrial boiler to generate steam for its processes. If the boiler burns natural gas, the resulting emissions depend on factors such as the type of fuel used, combustion efficiency, and operating conditions.

Mobile combustion emissions come from the burning of fuels in company-owned or controlled mobile sources, such as vehicles and fleets. This includes cars, trucks, buses, trains, airplanes, and ships operated by the reporting entity.

Emissions from mobile combustion are calculated by measuring the amount of fuel consumed and applying emission factors, which estimate the amount of pollutants released per unit of fuel used. The primary greenhouse gases from these processes include carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O).

For example, a logistics company operating a fleet of diesel trucks to transport goods will generate emissions based on factors such as the type of fuel used, vehicle efficiency, and driving conditions.

Fugitive emissions refer to the unintentional release of gases or vapors from pressurized equipment due to leaks or irregular discharges, often occurring in industrial activities. These emissions can arise during the production, processing, transmission, storage, and use of fuels and other chemicals. Common sources include equipment leaks, evaporative losses, and accidental releases.

Fugitive emissions often originate from valves, flanges, and other components that handle volatile organic compounds (VOCs). These emissions are primarily caused by leaks but can be minimized through regular maintenance and leak detection and repair (LDAR) programs. Implementing proactive inspection and maintenance schedules helps detect and repair leaks early, reducing emissions. Additionally, companies must stay informed about regulatory requirements and potential costs associated with fugitive emissions.

Process emissions are greenhouse gas emissions that result from chemical reactions required for manufacturing and industrial processes, rather than from fuel combustion. These emissions occur in various industries, including cement production, steel manufacturing, and chemical processing. They can be reduced through process optimization, alternative materials, or new technologies.

For example, in cement production, process emissions arise during the calcination of limestone, which releases carbon dioxide (CO₂) as a byproduct. The volume of emissions depends on factors such as the type of raw materials used and the efficiency of the production process.

Waste emissions are generated from waste management activities within a company’s operational control.

These emissions can come from incinerating waste, decomposing organic waste in landfills, and treating wastewater. To reduce emissions, companies should quantify emissions at each stage and explore solutions such as waste reduction, recycling, and alternative treatment methods.