Carbon intensity is defined as what?

• A. The price of carbon credits.
• B. The total annual CO2 emissions of the plant.
• C. The share of energy used from renewable sources.
• D. CO2 emissions per unit of output; reductions come from energy efficiency, switching to cleaner energy, and process improvements.

Answer: (D)

Carbon intensity is the amount of CO2 emitted per unit of output. It measures how carbon-heavy a unit of production is, rather than the total footprint of the plant. The correct description fits because it highlights emissions relative to what is produced, capturing improvements in efficiency and energy choices. Reductions come from making energy use more efficient, switching to cleaner energy sources, and refining processes to emit less CO2 for each unit produced.

Think of it this way: if a plant makes 100 units and emits 50 CO2, the intensity is 0.5 CO2 per unit. If efficiency or cleaner energy cut emissions to 30 for the same 100 units, intensity becomes 0.3. If output climbs to 200 units with the same 50 CO2, intensity drops to 0.25. Total emissions can rise or fall independently of intensity, which is why the per-unit measure is the key idea here.