Guest Op-Ed: Planting Trees: Thoughts On EROI

By Cal Abel - Reprinted from GridBrief

"A society grows great when old men plant trees whose shade they know they shall never sit in." – an American proverb

I have a lifelong love of watching nature. As a kid, I would run to watch The Nature of Things or Life on Earth on PBS, one of the three available TV channels. I would walk for hours hunting in the woods surrounding the family farm, observing everything mimicking the naturalists on TV. I ended up not shooting very many things. Instead, I learned by watching life in the woods change, grow, die, and be reborn. 

This experience impressed upon me that life feeds on life, ultimately feeding on the sun — nature wastes little of the precious energy that it collects. Also, wherever there is any stored energy, nature will always find a way of accessing it. 

Every living organism uses energy to structure its very being. In scientific terms, we describe a living organism as an open thermodynamic cycle that converts low entropy, high-value energy into something useful—growth and procreation—while rejecting high entropy low-value energy as waste heat. Life cannot exist without the flow of energy. 

This framework can even help describe ecosystems. But here, entropy takes on a different connotation, measuring the biodiversity/complexity of a particular biome. In a place like a rainforest with a significant amount of captured solar energy, the bio diversity/entropy is relatively high. In places where little solar energy is captured via photosynthesis, e.g. in deserts or the arctic, the biodiversity/entropy is relatively low. 

Entropy and Economics 

Ecologically, entropy measures the complexity of a biome and is an increasing function of the ability of the biome to capture and use sunlight. If, for some reason, the ability of the biome to capture solar radiation is reduced, the biome’s entropy lowers with it, as it can’t support as much life. Let’s consider the biomes’ ability to access solar energy as the biomes’ ability to do useful work, e.g., growth. We can make a direct analogy to how all life uses energy. 

We see a similar effect in economics. However, people have more ways of harnessing energy from their surroundings than directly relying upon the sun. It has only been recently that we have connected energy, more accurately exergy, as being economic value Abel (2022). Exergy is jargon for “useful work” and is the available energy that we have to do with what we want. This work can be either chemical or physical, but in nearly all cases, it ultimately comes down to physical work. Once produced, the useful work has to be immediately used. We use this work to make things (capital), to do things (action), and to get more energy. If the useful work is not used, it is lost — dissipated as waste heat to the environment. In economics, this is known as Walras’ Law, and in physics, it is called the first law of thermodynamics.  

Like all fundamental laws in the sciences, the first law is an equation;

E = T S − P M. (1) 

Each of the terms represents different things: 

1. E — the total activity of a society. 

2. T — how hard a society works, their economic temperature. 

3. S — the measure of how many different ways a society can be arranged for a given exergy input. Economists call this utility, while physicists call it entropy Abel (2022). We can think of this as our measure of freedom/liberty; the bigger the number, the more choices and, thus, more freedom we enjoy. 

4. P — the value of money. Basically, how much exergy a dollar can purchase.

5. M — the total amount of money in a society. 

The exergy input into a society/ecology is Q = T S. The work done by a society/ecology is W = P V . To give you some perspective on these quantities, in 2019, U.S. taxpayers consumed a Q of 317.28 gigajoules per person, had an entropy, S, of 12.11 person to the power of , a temperature, T, of 26.19 gigajoules, an average income, M, of 75 800 $/person, and a total activity, E, of 289.90 gigajoules per person and the dollar had a value, P, of 427 kilojoules/$. 

So let’s break down what this all means. A society’s wealth/action, E, is the exergetic input, Q, less the accumulated capital, W. The energy surplus that we enjoy defines our wealth in absolute terms. If we have a diminished exergy input or when we have to work too hard for our exergy, we are materially poorer. 

Exergy IS wealth. Exergy IS value. Exergy makes us free. 

But where does this available exergy come from? The answer to this is as simple as it is universal. Like all life, since life began, we take it from our environment. 

A Brief History of Energy 

Life in the Paleozoic era was new. It needed more time to evolve sufficiently to be able to access the available energy that is stored in its physical structure. This resulted in an accumulation of energy in the upper portions of the earth’s crust: fossil fuels. As life evolved, it became better and better at recycling this stored energy, effectively ending the accumulation of fossil fuels at the beginning of the Cenozoic era, 66 million years ago. 

Life continued storing and recycling energy for another 63 million years with little change. Then, at the beginning of the quaternary period, 2.6 million years ago, a funny animal appeared that had figured out how to use energy stored in the living forests. As the story goes, a titan named Prometheus taught them how to use fire. Our early ancestors used this gift to cook the food they killed, profoundly impacting our evolution. Due to outsourcing much of the digestive process to the cooking fire, their bodies evolved over time: their intestines grew smaller, and their brains grew larger over the next 2.58 million years. 

The pace of change started to accelerate sometime near the beginning of the Holocene about 12 thousand years ago. We began to farm and domesticate animals. As Genesis refers to this, God gave us dominion over the world around us, marking the beginning of the Classical age. Until this point, all human work was done by our hands or carried by our bodies. One could say that the labor theory of value was correct before the Holocene; however, once we had domesticated animals, it was no longer valid. 

When we acquired beasts of burden, we started outsourcing our work to the animals. We grew feed as the fuel for their work. Before the Holocene, our Exergy Returned On exergy Invested, EROI, was about 3. The agricultural revolution nearly doubled our EROI to 5. 

Life drastically changed; we went from a society of hunter-gatherers to one of farmers capable of supporting civilization. Our population exploded as a result of the excess exergy. We were able to build massive structures which have stood the test of time. We accumulated knowledge and invented currency. 

Civilization slowly accumulated wealth over the next 11.8 ka. This process was not linear. The West almost lost 4 ka worth of culture and knowledge with the fall of Rome. But we recovered much of it during the Crusades around 1 ka ago. The restoration of our culture spurred our growth until we reached our limits by the 1700s. 

We had nearly deforested Europe. We were out of fuel. As Malthus noted, we were at the limits of our growth and would face starvation and population decline. What Malthus failed to appreciate was English ingenuity. Leave it to an Englishman to do the right thing when all other options have been exhausted. 

The English had been mining coal, ancient trees of the Carboniferous period, because they were out of living trees for fuel. They had a problem. The mines would flood with water, and characteristically of the Classical age, the miners would use animals to remove the water. Then in 1712, Thomas Newcomen began what would become known as the Industrial Revolution. His steam engine began the most extraordinary transformation in human history. 

In one fell swoop, human activity became decoupled from the living world. Newcomen unlocked our ability to access 470 Ma worth of stored energy. With this profound exergy surplus, our ability to accumulate capital skyrocketed. We went from the Classical age’s EROI of 5 to the Modern age’s EROI of 30. 

Our society transformed overnight. Progress until this point was characterized by millions of years in the Paleolithic age, thousands of years in the Classical age, to mere decades in the Modern age. Industrialization ended starvation globally, something that Malthus could not even consider. 

Clearly, energy is central in our lives, yet humanity’s energy transformation has yet to finish. On December 2nd, 1942, at 1525 CST, our “Italian Navigator,” Enrico Fermi, brought us to the “New World.” Humanity had entered the Atomic age. We became capable of harnessing the energy contained in atomic nuclei stored there by the supernova that formed our solar system billions of years ago. 

The quantity of energy released by nuclear fission is mind–boggling. Current reactors have an EROI of 75 , and the next–generation breeder reactors are around 800. If we consider our past, the consequences of the Atomic age will be profound as we now have access to enough energy to impact our evolution. EROI has played an essential role in human development, but why is this the case? 

The Role of EROI in Society 

Weißbach et al. (2013) claim that civilization needs a minimum EROI of 7 to maintain itself. But if we zoom out, this is clearly not the case. Humanity was supported at different levels of development at many different EROI levels. EROI has a deeper meaning. 

If we go back and think about equation 1, something interesting happens. Let’s consider the exergy input into the society, Q = T/S. Our temperature, T, represents how hard we work for the exergy we get. Thus, EROI becomes the maximum limitation on our social entropy. Said another way, to maintain our standard of living in the U.S., we need energy sources with an EROI of at least 12.1 If we are also trying to increase the available capital, we need a higher EROI. 

Thus, the environmentalists are correct in their claims on the limitations of growth. The limits are absolute. But these limits are far, far above our imagination. Here’s why: entropy is the logarithm of the multiplicity of the system. If we look at Paleolithic humans, there were at most 20 different ways of existence. In the Classical age, this increased to about 150, allowing a level of complexity that Paleolithic man could not even imagine. For Modern humans, this increased to 10 to the 13th power, representing more ways of being human than there are people in the world. For the Atomic age, it is an unimaginable 10 to the 350th power ways of realizing society, more than the number of atoms in the universe! 

So, what is it that environmentalists fear? Fossil fuels have nearly decoupled human existence from our living world. We have ended world hunger. We have drastically reduced the number of deaths due to environmental disasters, having in the developed world virtually eliminated all environmental deaths. Our forests in North America and Europe have begun to regrow. According to the World Bank, arable farmland in the U.S. peaked in 1986 and has been declining, yet we produce more food than ever for what is now 8 billion people. 

The greening of the northern hemisphere has halted because of some unfortunate policy decisions regarding our energy sources and failure to understand the importance of decoupling human existence from the environment. In the American South, we are cutting down our forests to make pellets that we ship to Europe to be used as “renewable” fuel. In the Midwest, we grow corn to make ethanol for our cars with an EROI < 1. None of these have an EROI that can sustain current levels of social complexity. 

We are covering vast swaths of our countryside with wind turbines and solar panels that don’t have an EROI that would sustain a Classical society. Forcing technologies that artificially limit human flourishing to the detriment of the environment isn’t even short– sighted; it is nihilistic. 

Instead, let's take an alternative constructive approach. Let's allow nature to recover from our arduous demands by using an independent source of power that is  "too cheap to meter." Let's rekindle the optimism of the early Atomic age and see what amazing things we can achieve together.

Some have already started. South Korea is building 1,000 MW sized nuclear reactors in 4 years. These reactors cost 3 billion USD. Others are trying. In Georgia, my home state, we are now over 14-years building Vogtle 3 and 4, with an estimated cost of 10 billion USD for each unit. Clearly, policy matters.

Are the Korean reactors less safe than their American counterparts? That is an emphatic “No!” In the West, we are, for some reason, punishing ourselves for unlocking the power to save the planet. We must stop this neo-Luddism of intentionally destroying the one thing that will simultaneously help the planet and transform humanity.

This December 2nd, let’s pause and take the time to consider the potential of the nearly limitless power of the atom on this 80th anniversary of the dawn of the Atomic age.

Cal Abel is a nuclear engineer who served 10 years onboard submarines. After leaving the Navy, his first task was to develop the technology that allows repowering coal plants with nuclear reactors. He is now working on using atomic heat to transform coals into liquid fuels. You can find him playing in the Alabama dirt, digging up coal, and making synfuels. Also, you can watch his dissertation being built in Wyoming repowering a retired coal plant.

References 

Abel, C., 2022. The quantum foundations of utility and value. Phil. Trans. R. Soc. A, Forthcoming URL: https://papers.ssrn.com/sol3/ papers.cfm?abstract_id=4228762. Submitted for peer review. 

Pearse, R., 2017. A society grows great. Online. URL: https://www.roger pearse.com/weblog/2017/08/26/a-society-grows-great when-old-men-plant-trees-in-whose-shade-they-know-they-shall-never-sit-an-ancient-greek-proverb/. Last accessed 24 Nov 2022. 

Weißbach, R., Ruprecht, G., Huke, A., Czerski, K., Gottlieb, S., Hussein, A., 2013. Energy intensities, erois (energy returned on invested), and energy payback times of electricity generating power plants. Energy doi: 10.1016/j.energy.2013.01.029. 

Credit to Emmett Penney, @GridBrief, @nukebarbarian
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