A Different Perspective on “Solar Power”

One of the reasons I love mathematics is because it has the right answers, represented by the humble equals sign. No matter the problem, it equals something specific and provable, and I can solve it if I just think hard enough. I can find not only an answer, but the answer.

Alas, life doesn’t operate like mathematics (which is actually a good thing). Many questions that we confront, ranging from of utmost importance to trivial, have multiple answers, murky answers, and at times no answer at all. Uncertainty pervades our very existence.

So it is with a question I was pondering this morning: What percentage of electricity generated in the United States is solar powered? The answer depends on how you define “solar powered.”

Here’s the latest data I could find, from the U.S. Energy Information Administration. In 2015, we can see that solar energy generated 0.6% of our nation’s electricity. Presumably, this number includes electricity generated from photovoltaic panels and concentrated solar plants.

If we think of “solar powered” another way though, we get an answer of 79.9%. Let me show my work.

First, we should obviously include the 0.6% already mentioned. We can then add the 1.6% from biomass as well, since biomass is organic material that comes from plants performing photosynthesis, a solar powered energy conversion process.

Along that line of thinking, coal, natural gas and petroleum count as well. These fossil fuels are simply ancient organic materials. Much like biomass, the energy embedded in their chemical bonds originates from long-dead plants performing photosynthesis. That adds a whopping 67% to our running total.

By my logic, hydropower belongs in the mix as well. Hydropower is made possible by the movement of water through the hydrologic cycle (i.e. atmospheric condensation followed by rainfall followed by gravity pulling water into rivers followed by capturing the kinetic energy of those rivers at hydro plants). And how does water primarily end up in the atmosphere where it can turn into rain? Evaporation, another solar-powered process. That puts us up another 6%.

Finally, I’ll lobby for the inclusion of wind power as well. The science behind wind is rather complicated, but boiled down, wind comes from air’s tendency to move from high pressure areas to low pressure areas. So what causes some areas to have high pressure air and others low pressure? You guessed it – the sun, which heats different parts of the Earth unevenly, creating higher pressure in areas where the air is warmer. Tack on another 4.7%.

Added together, those numbers give us 79.9%. The types of energy that aren’t traced to the sun are basically just nuclear and geothermal.

So what’s the takeaway? Should we be celebrating that nearly 4 out of 5 electrons on our grid come from solar power, broadly defined?

Eh, not really. Far too many of those electrons come from ancient sunlight that shined on the Earth tens of millions of years ago (oil and gas) or even hundreds of millions of years ago (coal). Meanwhile, those other sources of solar power I mentioned are harnessing sunlight that shines on the Earth every day.

I’ll leave you with one more question. In general, would you rather use solar power that’s renewable daily or solar power that’s renewable over a period of millions of years? If you ask me, that question clearly has a right answer.