Does All Our Energy Come From the Sun?

A reader just asked me this: Doesn’t all our energy come from the sun?  Fossil fuels are old sunlight, and anything else we burn is new sunlight.  We have to burn this one way or the other, and that creates emissions.  Is there any way around this?

Fortunately, there are a number of factors that make what you’ve written above incorrect.

• There are flavors of renewable energy that come from the sun that don’t require burning anything, e.g., PV, concentrated solar power, wind, and hydro.

• Biomass is energy that comes from the sun, and yes, it needs to be “burned” in order to convert it to energy, but there are variations on the theme that create little or no emissions.  E.g., pyrolysis uses a lower temperature, a bit of pressure, and no added oxygen.

• Geothermal energy, i.e., the heat beneath the surface of the Earth, doesn’t involve the sun at all; there are four different reasons why that heat is there, the predominant of which is nuclear reactions.

• Speaking of nuclear, there are different varieties of converting a small amount of mass to large amounts of energy that do not use solar energy either.

As I explain here, when you mix the bullets above with all the economic and political issues, you get a very complicated but extremely important problem for humankind to solve—fairly soon.