A plain-language clean-energy glossary

Clean energy is full of jargon. Here are the terms that come up most, in plain language.

The essentials

Renewable energy — power from sources that naturally replenish: sun, wind, water, geothermal heat.
Clean / low-carbon energy — power that emits little or no carbon at generation. Includes renewables and nuclear.
Firm power — electricity available on demand, around the clock, regardless of weather (e.g., nuclear, hydro, geothermal).
Intermittency / variability — the up-and-down output of sources like solar and wind that depend on the weather.
Baseload — the steady minimum level of demand a grid must always meet.
Capacity factor — how much a plant actually produces versus its maximum if it ran flat-out all the time.
Grid — the network of generation, wires, and controls that delivers electricity from producers to users.
Electrolyzer — a device that splits water into hydrogen and oxygen using electricity (how green hydrogen is made).
Fuel cell — a device that combines hydrogen and oxygen to make electricity, emitting only water and heat.
Energy carrier — something that stores and moves energy (like hydrogen or electricity) but isn't a primary source.
kW vs. kWh — a kilowatt (kW) is a rate of power; a kilowatt-hour (kWh) is an amount of energy. Power is the speed; energy is the distance.
Decarbonization — cutting carbon emissions out of an activity, often by electrifying it and cleaning the electricity.

One mental model. Sources make energy; carriers move and store it; the grid delivers it; firm power and storage keep it reliable. Most clean-energy debates are really about how to keep that whole chain clean and dependable.

About the author — George Howell Ward is a long-time clean-energy advocate and early adopter, not a licensed engineer, energy professional, or scientist. He holds a B.S. in Civil Engineering from the University of California, Berkeley, and writes here as an enthusiast and technologist. He attended the National Fuel Cell Research Center seminar at the University of California, Irvine more than a decade ago (mentioned descriptively; not an endorsement by the Center). These guides are educational, draw on legitimate science only, and avoid debunked claims. He is also involved with a nuclear-power-adjacent venture focused on integrating agentic AI into clean-power workflows — an informal, non-fee involvement in his own venture, described here only in general terms.

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