Hydrothermal energy is a fairly simple concept. We can divide the word ‘hydrothermal’ into its two parts to better understand it:
Hydro – Water
Thermal – Having to do with heat
In other words hydrothermal energy is the energy that is stored in heat form in water.
Water is a remarkable substance because it has a huge capacity to store heat. It’s like an energy sponge. It takes more heat energy to heat water up and a great deal longer for it to cool down than most other substances on the planet.
Have you ever wondered why coastal areas are warmer in the winter and cooler in the summer than areas just a little further inland? It is because of this heat property of water. Like a sponge, the ocean absorbs much of the heat from the sun in the summer, keeping the overall temperature from rising very quickly at the coast. Inland the earth doesn’t absorb as much of the heat energy, heating up quickly. In the winter, like a solar energy sponge being slowly wrung out, all the energy that the water absorbed during the summer is slowly released, keeping the temperature at the coast warmer. Inland there is no such reservoir of heat energy, so the temperature drops much more quickly.
The amount of energy that is absorbed from the sun into our lakes and oceans each year is many times more than we would ever need to sustain our way of life. The challenge is harnessing that reservoir of energy and converting it to electricity. In future posts we’ll discuss the keys to using this solar energy stored in water, some of the attempts to do so, and where we are going now.