Power stations, Engines, Air Conditioners Fuels Cells, Batteries and more

Innovative design can be spurred by scientific understanding of energy storage and transformation.

This diagram represents current scientific understanding of how energy may be stored and transformed.

A power station can theoretically convert 10,000 joules of thermal energy at 1200 degrees Kelvin into 7,500 joules of electrical energy and 2,500 joules of thermal energy at 300 degrees Kelvin.

It is also theoretically possible to decompose some chemical compound into its constituent elements with 10,000 joules of thermal energy at 1200 degrees Kelvin and produce 7,500 joules of electrical energy and 2,500 joules of thermal energy at 300 degrees Kelvin in a fuel cell that recombines those elements into the original chemical compound.

If it is cheaper and more reliable to construct a machine that operates at a temperature of just 900 degrees Kelvin instead of 1200 degrees Kelvin, then this machine could theoretically decompose the chemical compound into its constituent elements with 2,500 joules of electrical energy and 7,500 joules of thermal energy at 900 degrees Kelvin.

It is not necessary to view batteries as the only type of device that can store electrical energy:

At some later time the decomposed elements could be used to produce 7,500 joules of electrical energy and 2,500 joules of thermal energy at 300 degrees Kelvin in a fuel cell that recombines those elements into the original chemical compound.

The graph above is a representation of scientific knowledge from which these observations can be made.

Mathematics permits this simple geometric model to be created from three separate scientific models:

• Carnot's equation for efficiency of heat engines.
• Nernst's equation for electrochemical reactions.
• Gibbs-Helmholtz's equation for chemical reactions.