Question by Bobby: How does geothermal energy not contradict the second law of thermodynamics?
If entropy increases because of increasing amounts of heat, how does geothermal energy, which basically gets energy out of the heat in the earth, not contradict the second law of thermodynamics?
Best answer:
Answer by MarcThyme
The Second Law of Thermodynamics applies to a CLOSED system (like, for example, the Universe); the planet Earth is NOT a “closed system”, it is both receiving energy from and losing energy to the Universe around it….
Silly goose!
What do you think? Answer below!
One Response
The vast majority of the heat in Earth’s interior—up to 90 percent—is fueled by the decaying of radioactive isotopes like Potassium 40, Uranium 238, 235, and Thorium 232 contained within the mantle. These isotopes radiate heat as they shed excess energy and move toward stability. “The amount of heat caused by this radiation is almost the same as the total heat measured emanating from the Earth.”
Radioactivity is present not only in the mantle, but in the rocks of Earth’s crust. For example, Marone explains, a 1-kilogram block of granite on the surface emanates a tiny but measurable amount of heat (about as much as a .000000001 watt light bulb) through radioactive decay.
That may not seem like much. But considering the vastness of the mantle, it adds up, Marone says.
Sometime billions of years in the future, he predicts, the core and mantle could cool and solidify enough to meet the crust. If that happens, Earth will become a cold, dead planet like the moon.