Today I’d like to address one concept that I read about in Richard Heinberg’s The End of Growth, Energy Return on Energy Investment or EROEI. The concept is an attempt to quantify the efficiency of a given energy source, and in the hands of Heinberg and other degrowthers it is a way to “prove” that we are running out of usable energy.

EROEI is a simple and intuitive concept, taking the amount of energy produced by a given source and dividing by the amount of energy it costs to set up and use that source. Oil is a prime example. In the beginning of the 20th century oil extract was easy since it just seeped out of the ground in many places. Drilling a small oil well won’t cost you that much, hell you can probably do it with manpower alone. In that case the oil gushing forth will easily give you a good energy return.

In the 21st century however, things have become harder. Oil wells require powerful machines to drill (which costs energy), and the amount and quality of the oi you get out is often lower. Add to that the fact that modern wells require huge amounts of metal and plastics, all of which cost energy to produce and even more energy to transport to their location, then add the energy it took to find the oil wells in the first place using complex geographical surveys and seismographic data, and taken together some people claim that the EROEI for a modern oil well is already less than 1, meaning that more energy is being put in than the energy we get out.

And oil isn’t the only fuel source heading towards and EROEI of less than 1. Modern mining techniques for coal require bigger and bigger machines, natural gas requires more and more expansive facilities, even solar panels require minerals that are more and more difficult to acquire. It seems everything but hydro power and (perhaps) nuclear power are becoming harder and harder to produce, sending energy returns down further and further.

This phenomenon, where the EROEI for our energy sources is less than 1, is supposed to presage an acute energy crisis and the economic cataclysm that degrowth advocates have been warning us about. If we’re getting out less energy than we’re putting in, then we’re really not even gaining, aren’t we? The problem is, I’m struggling to see how EROEI is even a meaningful way to look at this.

First let me note that not all energy is created equal. Energy in certain forms is more usable to us than in others. A hydroelectric dam holds water which (due to its being elevated above its natural resting place) acts as a store of potential energy. The release of that water drives a turbine to produce electricity. But you can’t fly a plane using water power nor keep it plugged in during flight. Jet fuel is another source of potential energy, and it has a number of advantages versus elevated water. Jet fuel is very easy to use and transport, you can fill a tank with it and move it to wherever your plane is, then fill the plane’s tanks from there.

If the only two energy sources in the world were jet fuel and hydroelectric power, we would still find it beneficial to somehow produce jet fuel using hydroelectric power even though that would necessity an EROEI of less than one. Because although this conversion would have less total energy, the energy would be in a more useful form. People would happily extract oil using hydroelectric power, then run refineries using hydroelectric power, because jet fuel has so much utility. This utility means that (supply being equal), jet fuel would command a higher price than hydroelectric power per unit of energy. And so the economic advantages would make the EROEI disadvantages meaningless.

This is the fatal flaw of EROEI in my mind. The fact that some forms of energy are more useful than others means we can’t directly compare energy out and energy in. The energy that is used to run a modern oil well comes to it from the grid, which is usually powered by coal, solar, wind, or nuclear, none of which can be used to fuel a plane. Converting these forms of energy into oil is an economic gain even if it is an energy loss. Furthermore EROEI estimates are generally overly complex and try to account for every joule of energy used in extraction, even when those calculations don’t really make sense. Let me give you an example:

A neolithic farmer has to plow his own fields, sow his own seeds, reap his own corns. Not only that, but the sun’s rays must shine upon his fields enough to let them grow. Billions of kilocalories of energy are hitting his plants every second, and most of then are lost during the plants’ growth process because photosynthesis is actually not all that efficient to begin with. The plant will have used billions of kilocalories of energy, and from them the farmer gets a few thousands of kilocalories of energy. Most of the energy is lost.

This is the kind of counting EROEI tries to do, applied to farming. When you count up every joule of energy that went into the farmer’s food, you find his food will necessarily provide him with an EROEI of less than one thanks to the first law of thermodynamics. But this isn’t a problem because Earth isn’t a closed system, nor are our oil wells. We are blasted by sunlight every minute, our core produces energy from decaying nucleotides, our tides are driven in part by the moon’s gravity, there is so much energy hitting us that we could fuel the entire world for a thousand years and never run out. The problem is that there are some scenarios where that energy isn’t useful. You can’t fly a plane with solar or geothermal or gravitational energy, but you can power an oil well. So we happily use the energies we have lots of (including our use of solar power to grow useful plants and animals!) and use that energy to help us extract the energies with greater utility.

I think EROEI failed from the very beginning for this very reason. It ignores economic realities and the massive amount of energy that surrounds us, and instead argues from the first law of thermodynamics. Yes in any closed system energy eventually runs out, but it isn’t even clear that our universe is a closed system, and the earth definitely is not, so we need to face up to economic reality on this.