Gifts From Another Time

The light and heat from your campfire came from another time and place.

Green plants gathered carbon dioxide and water from the environment and utilized energy from the sun to create larger molecules like glucose. The sun’s energy was stored in the molecular bonds while oxygen was released as a byproduct.

Photosynthesis. Image from Wikipedia.

Long chains of D-glucose molecules formed cellulose, the structural component of trees and plants. Wood is 40–50% cellulose (cotton is 90%). When trees die, much of the energy they stored over decades or centuries remains in the cellulose. When we burn a log, it releases all that energy from the sun as heat and light.

Photo by Courtnie Tosana on Unsplash.

If we burn coal, the energy may be from hundreds or thousands of millennia ago. Intense pressure compressed the organic matter—plants and animals—changing the molecular structure of the biomass while preserving and concentrating the stored energy.

Our bodies carry out amazingly similar processes. They break glucose into carbon dioxide and water while releasing energy and heat. In fact, a calorie is a measure of heat. If you burn a doughnut in a calorimeter, it will tell you, in calories, how much energy was released.

Next time you eat s’mores around a campfire, thank the sun and plants for light, heat, and energy from far away and long ago.