Where does solar power go?

Here we explore the question regarding where energy from the sun, when converted by solar panels, or plants into a useable form of energy on this planet ends up.

# The Solar Powered Train

Solar powered Hungarian train - wikitrend.org

Here we explore a thought experiment about a solar powered train. The train charges itself at the train yard using solar energy and charges up it's batteries. It then converts this stored energy to drive it's engine and powers to the next station at 100 km/h - financialexpress.com

After applying it's breaks it comes to a stop, with flat batteries and has to wait for ore solar energy to charge up the batteries before it can start again.

# What happens to the energy?

The energy from the sun, originally created by nuclear fusion, is radiated to earth in sunlight. Sunlight delivers about 340 watts for every square meter of the surface of the earth.

About half (51%) of this reaches the earths surface, and about half of it ends up being transferred eventually to the atmosphere, with just over a third immediately reflected due to the earths albedo - see Global Solar Budget.

This compares favourably to the Power Consumption of many domestic appliances. So the >170 watts of energy reaching the surface could power a couple of laptops and a a printer, or a TV and a radio. The question is where does this energy end up after we have made productive use of it?

# The energy is used up!

A common thought is that the energy from the sun, is converted into various forms of energy until it is "used up" or "used" to move the train from one place to another.

This is just plain wrong.

# It ends as heat

While there are many forms of energy, the most important systemic thing to keep in mind is that in the end most useful energy ends up as the degraded energy we know as low level heat.

In the case of the solar train, the energy is transformed as follows: - created from matter via nuclear fusion - radiated to earth as sunlight - chemical energy in the trains batteries - kinetic energy of the train - dissipated heat energy (degraded energy)

That is the radiant (or electromagnetic radiation) that is embodied in the sunlight hitting the surface of the earth is converted eventually to the kinetic energy of the train. When this train is brought to a stop through friction, all this energy is converted into heat - perhaps some sound and radiation energy, but this in turn eventually ends up as heat.