How do lifecycle greenhouse gas emissions differ between renewable energy sources and fossil fuels?

• A. Lifecycle emissions are determined solely by fuel combustion.
• B. Renewables typically have much lower lifecycle emissions than fossil fuels.
• C. Renewables have higher lifecycle emissions.
• D. Lifecycle emissions are the same for renewables and fossil fuels.

Answer: (B)

Lifecycle greenhouse gas emissions account for all emissions across an energy system’s life: making the components, transporting and constructing them, operating and maintaining the facility, and finally decommissioning and disposing of materials. For renewables, most emissions come from producing materials and building the infrastructure; once installed, there’s little to no fuel combustion during operation, so ongoing emissions are minimal. In contrast, fossil-fuel systems release CO2 and methane at multiple stages—extraction, processing, transport, and especially burning fuel to generate electricity—leading to much higher total emissions over the system’s lifetime. That combination makes renewables typically much lower in lifecycle emissions than fossil fuels. The other statements treat emissions as if they hinge only on burning fuel, or as if renewables aren’t cleaner over their entire life, which isn’t accurate.