Energy Returned On Energy Invested, or EROI, is quite the mind boggling concept, isn’t it?

In this week’s lesson, I learned that:

Energy return on investment (EROI) is the ratio of the energy delivered by a process to the energy used directly and indirectly in that process.
Source: Encyclopedia of Earth

The main take aways I gathered from learning about EROI are:

  • It takes energy to get energy.
  • You get 20 times more energy out of gas than was put in.
  • The higher the EROI, the more energy you get out for every unit of energy put in.
  • EROI does not take into account factors to obtaining energy, it only measures energy use.
  • There is 100 times less energy today than was available just 90 years ago!

For me, there was a lot to unpack emotionally when learning about EROI. I’d never previously realized the full extent of expended energy in order to obtain it. At some point in my life, I’d understood that gas was used to get more gas to the gas station I frequented. I recall being in high school, when seeing giant tankers refilling the reserves at my favored station late at night ignited this thought. I knew the tanker needed gas to get to the gas station. At the time, my only thought was how silly it was that there was now less gas available to use since the tanker had to utilize who knows how many gallons to get to that particular station. So the concept of using energy to obtain energy wasn’t completely new to me.

However, the fact that we have so much less available energy today compared to 90 years ago deflated me quite a bit, and even changed how pertinent I view the sustainability of the planet. This lesson specifically states “A very interesting finding in the Hall, Lambert, and Balogh article is that oil discovery in the U.S. has decreased from 1000:1 in 1919 to only 5:1 in the 2010s, meaning we get 100 times less energy now than 90 years ago!” In the grand scheme of things, 100 years is a small blip of time. That much energy used in such a minuscule span of time blew my mind away. It helped me understand that living within our ecological budget is more dire than I previously thought. Until now, I’ve been of the mindset that we have time to correct, reverse, and/or slowdown our use of the earth’s resources enough to exist within the available biocapacity.

The fact is, though, we’re already hitting tipping points. We’re seeing ecosystems change, and the earth is responding in the only ways it can. Humans are not changing their consumption habits or inventing technology soon enough to prevent use of unsustainable resources and/or live within nature’s sustainable yield of replenishable resources. For me, this woke me up from my “we have time” attitude, to a more “we must address this now” stance.