Chapter 01 · Climate & transitionEnergy & Transition
Clean energy
Definition
Energy generated from sources that emit no (or very low) climate-warming greenhouse gases during operation — typically solar, wind, hydro, geothermal, nuclear and, in some framings, sustainable bioenergy. The World Bank's IEA-based indicator defines clean energy as noncarbohydrate energy that does not produce CO₂ when generated; the term overlaps heavily with, but is not identical to, renewable energy.
References
Operational definition; clean vs renewable distinction; life-cycle caveat; comparative emissions intensities.
Statistical definition (noncarbohydrate energy producing no CO₂ when generated: hydro, nuclear, geothermal, solar, etc.).
Overview
What it means
"Clean" is doing quiet definitional work.
It is broader than "renewable" (nuclear is clean but not renewable) and narrower than "sustainable" (every clean source carries life-cycle impacts — embedded emissions in equipment, mining footprints, nuclear waste — so nothing is perfectly clean; life-cycle comparisons still show fossil generation roughly an order of magnitude more emissions-intensive: coal ~1,000 gCO₂/kWh vs wind ~10).
Because the boundary is contested, policy instruments define eligibility explicitly — clean energy standards and taxonomies specify which sources count, and whether gas with CCS or biomass qualifies.
How it is used
Policy targets and standards (clean energy standards, clean electricity tax credits) define eligible sources; corporate procurement claims (100% clean, 24/7 CFE) rely on the distinction; statistics track clean-energy shares of supply and investment.
Why it matters
"Clean energy" is the working category of energy-transition policy — and its contested edges (nuclear, biomass, CCS) are where transition politics actually happen.