Carbon Capture
Carbon capture separates CO₂ from an industrial exhaust stream or from ambient air so it can be stored or used. Carbon capture and storage (CCS) sends it underground; carbon capture, utilization and storage (CCUS) uses part of it in products such as concrete or fuels.
Point-source capture treats the flue gas of a cement kiln, steel plant, refinery, or power station, where CO₂ concentrations are high enough to make separation practical. Direct air capture pulls CO₂ out of ambient air at about 420 parts per million, which takes far more energy per tonne and costs several times more.
Capture matters most for industries that cannot decarbonize by switching fuel. Cement releases CO₂ from the chemistry of turning limestone into clinker, not only from the heat, so capture is one of the few routes to a low-carbon product.
In an inventory, captured CO₂ only reduces reported emissions if it is permanently stored, and the energy used to run the capture equipment counts as an emission of its own. Utilization complicates the accounting further: CO₂ turned into a fuel is released again when that fuel is burned, so it is not a removal. Companies buying low-carbon materials made with capture should ask for the storage evidence, since the claim usually reaches them through Scope 3 purchased goods.
Frequently asked questions
What is carbon capture? +
Carbon capture separates CO₂ from an industrial exhaust stream or from ambient air so it can be stored underground or used in products. Storage-only projects are called CCS; those that also use the CO₂ are called CCUS.
What is the difference between point-source capture and direct air capture? +
Point-source capture treats concentrated flue gas at a plant, which is cheaper per tonne. Direct air capture removes CO₂ from ambient air at about 420 parts per million, which takes much more energy and costs more.
Does carbon capture reduce reported emissions? +
Only when the CO₂ is permanently stored, and the energy used by the capture equipment must be counted as an emission. CO₂ used to make fuels is released again on combustion, so it is not a removal.
Related terms
Carbon Sequestration
Carbon sequestration is the long-term storage of carbon dioxide so that it stays out of the atmosphere. It happens biologically, in trees and soils, and geologically, by injecting captured CO₂ into deep rock formations.
Carbon Sink
A carbon sink is any reservoir that absorbs more carbon than it releases. Oceans, forests, and soils are the main natural sinks, and together they remove a little over half of the CO₂ that human activity emits each year.
Scope 3 Emissions
Scope 3 emissions are all indirect greenhouse gas emissions that occur in an organization's value chain — both upstream (suppliers, purchased goods, business travel, employee commuting) and downstream (product use, end-of-life treatment, investments). Scope 3 typically represents 70–90% of a company's total carbon footprint.
Product Carbon Footprint (PCF)
A product carbon footprint (PCF) quantifies the total greenhouse gas emissions associated with a product throughout its lifecycle — from raw material extraction (cradle) through manufacturing, distribution, use, and end-of-life disposal (grave). It is expressed in units of CO₂e per functional unit of the product.
Net Zero
Net zero means reducing greenhouse gas emissions as close to zero as possible, with any remaining residual emissions balanced by an equivalent amount of carbon removal from the atmosphere. The SBTi Corporate Net-Zero Standard requires at least 90–95% absolute emission reductions before carbon removals can be used.