Combustion — Science definition

The chemical reaction of burning a fuel with oxygen, releasing the fuel's stored chemical energy as heat and light and producing carbon dioxide and other emissions.

Where it is taught

In use

Combustion emissions include CO₂ and may include particles, nitrogen oxides, and sulfur compounds depending on fuel and controls.

Nonrenewable Energy & Fossil Fuels

Questions using combustion

Problem 1

Trace upstream and downstream effects instead of using one labelTrace upstream and downstream effects instead of using one labelExtractionLeaks / land / waterProcessing /transportEnergy / lossesCombustion /serviceCO₂ / pollutantsLife-cycle boundary includes more than the smokestack.Different pollutants require their own quantities and impact models.
Original pathway inventory; no current plant emission factor or universal fuel ranking is asserted.
Interpret the supplied visual. Why can a lower combustion CO₂ factor be insufficient for a full climate ranking?
Answer and explanation

Upstream methane, conversion efficiency and other life-cycle emissions can change the result under the stated horizon/boundary.

A fuel life cycle includes extraction, processing, transport, conversion and residual management. Direct CO₂, methane leakage, particulates, sulfur compounds and land/water effects are different pathways that need separate evidence. “Cleaner” is incomplete without naming the pollutant, service and boundary. A climate comparison using CO₂-equivalent values also needs a stated time horizon and conversion method; it is not simply a count of molecules emitted.

Upstream methane, conversion efficiency and other life-cycle emissions can change the result under the stated horizon/boundary.

Response criteria

  • Interpret labels, structures, axes, units and directions correctly.
  • Explain the physical or environmental relationship or mechanism.
  • Respect stated assumptions and distinguish observation from inference.

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