"And then there was light!"

This is how many creation myths begin, and the origins of thermochemistry are certainly no different. Thermodynamics is the branch of chemistry that deals with phase transitions (think; water to steam), energy changes (Think; wood before and after combustion), and equilibrium reactions that occur in chemical reactions. We can determine the first time humans took thermochemistry to their liking from the discovery and subsequent long cultivation of fire. In this series of four articles, we will take you into the world of thermochemistry and how it has influenced our lives in the past and will continue to shape our future.  

Cellcius' thermal battery technology uses thermochemical concepts. Energy storage and transformation is one of the greatest challenges of today and tomorrow.  

How far does thermochemistry go back?

The fuel used in prehistoric times was dried wood. This wood burned at a fine temperature for the purposes that would be invented in the next million or so years. For not only did the day become longer thanks to this first artificial light source, the manufacture of tools became possible. Fire helped with hunting. With the burning down of pieces of forest, it created open fertile places where game migrated for food. It also offered protection from those same wild animals and provided the pleasant warmth that humans so craved.

The leaves and pieces of wood that were used would today be called "biomass." This fuel was ideal because it was controllable AND divisible. After all, you could simply throw more or less wood on the fire. If it had to go out quickly, a jug of water was also immediately at hand. If the wood was dried properly, only a minimal amount of smoke was released. For the hunter-gatherers, smoke was not yet a huge problem, but for the farmers who followed them, containing it was certainly of great importance when the fires moved from outdoors to indoors.

Archaeological traces

Ice age traces show that fire was a cherished and widely used means of salvation. But how do we know that a campfire burned thousands of years ago? Often, of course, we find nothing at all; the ashes have been blown off, the earth has been tilled, or there has been a forest fire so that there is no longer a distinction between the forest fire and a fire started by humans.

Nevertheless, we can find out if a campfire was repeatedly lit in the same place. Research shows that two types of traces can be found that give indication of a fire lit and maintained by humans. The first is an oxidation layer about 15 cm deep in the soil. A spontaneous fire leaves only a 1-2 cm layer of oxidation. The second trace is the change in the magnetic properties of the soil. This change is not present in remains of spontaneous forest fires.

The combination of oxidation and magnetization marks created a characteristic "bowl-shaped" spot left behind on a fire pit. This is how the oldest known fire site was eventually discovered. This spot is located at Koobi Fora in Kenya and is 1.6 million years old. Part of this heavily oxidized soil consists of remains of a fire that was kept burning for at least four to five days. In addition, thousands of stone artifacts and bones have been found which contain no traces of burning. Therefore, the theory is that the fire pit was not used for roasting meat, but served as a source of heat and light and provided protection from predators. Homo ergaster is most likely the early human species that kept this fire burning.

Foundations of civilization

Fire was a familiar phenomenon; forests burn and thunderstorms strike, however, what was so special about the "discovery" of fire was the discovery of using and controlling fuels. Being able to "store" energy for later by gathering wood now and lighting it when needed is what gave humans their "kick start. This "taming" of fire caused a huge leap in man's quality of life. Fires allowed people to bake bread, roast meat, bake clay, build houses, and so on. This first step of thermochemistry laid the foundation for every civilization that would develop in the centuries to come.

The second step of thermochemistry deals with peat, coal and coke. In the second edition of this series on thermochemistry coming soon, we would like to tell you more about it.

By: Denise Veldhuis - Marketing & Communications at Cellcius and Chemical Engineering & Chemistry student