Autotrophs use energy from sunlight to make their own food, and some use chemical energy from inorganic substances.

Quick Scoop

Most autotrophs, like plants and algae, capture light energy from the sun and use it in photosynthesis to turn carbon dioxide and water into glucose (a sugar) and oxygen.

A smaller group of autotrophs, such as certain bacteria near deep‑sea vents, use chemical energy from reactions with inorganic molecules like hydrogen sulfide instead; this process is called chemosynthesis.

So, when someone asks “what is the energy autotrophs use to make their own food?” the simple school‑level answer is:

They use sunlight (light energy), and in special cases some use chemical energy from inorganic compounds.

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