Of Thermodynamics, and Sealing Wax, and Other Fancy Stuff

Power plant cooling towers venting waste heat

The gauntlet has been thrown down. The US needs to cut their carbon dioxide emissions by 50% by 2030, starting with a baseline of 2005. In order to accomplish this, real changes in the US economy must occur, along with some sacrifice by US citizens. And, the entrenched interests in continuing the status quo (energy companies, Republicans, utility providers) must be convinced of the necessity of this extreme action. Pretty difficult to do especially since the Republicans have made it their brand to not only dismiss the need for change, but they have proudly waved the banner of climate change hoax / no science to refute the claims of climate scientists. They have waved these banners for generations, and their influence will not go away, especially at the state and local levels.

First, it is necessary to present some simplified discussions of thermodynamics. This is the branch of physics which describes the limits nature imposes upon humanity. The first item needing description is black body radiation. Simply put, it means a body will emit radiation which puts it at equilibrium with the incoming radiation. Any disruption that affects the radiation balance will affect the equilibrium temperature. In our case, radiation from the earth is dispersed into the coldness of space. One is most aware of this phenomena on cold clear nights, but still above the freezing point of water, where frost forms on surfaces that are exposed to the vastness of space. Like, your car windshield which requires scraping when there’s no frost anywhere else.

The increase in carbon dioxide concentration (CO2) in the atmosphere affects this radiation balance. Put simply, CO2 absorbs some of the radiation that is escaping to space, and re-radiates it in all directions. The fraction that is radiated back to earth is radiation that increases the total amount of radiation earth normally receives. It increases the equilibrium temperature of earth, which is global warming. Since CO2 happens to absorb radiation in a range normal atmospheric components do not absorb, this means that CO2 exerts an outsized influence even though it is a minimal component of the atmosphere. Those who say that a small amount of this gas cannot affect the temperature of the globe are ignorant of basic physics and mathematics.

There is a second aspect of thermodynamics that comes into play with fossil fuels. That is the limitation in the amount of useful work that can be extracted from a high-energy fluid. All large-scale power plants depend upon a heat source (burning fossil fuels, nuclear fission, burning biomaterials) to heat and vaporize water to form steam. It is the steam that turns the turbines and results in the generation of electricity. Well, thermodynamics imposes a limit of about 50% peak efficiency for this type of power plant. You’ll have to trust me on this figure, since understanding and calculating the Carnot system efficiency is a staple of college engineering and science courses. There’s only so much explanation you can put into a blog post.

This says that whenever you have a concentrated source of energy being converted to another type of energy (combustion of fuel to electricity), you only get about 50% of the useful energy as an output. The rest is wasted as heat. Any time you convert one type of energy to another, there are losses involved. So why are folks so convinced that renewable energy sources are so necessary? One reason is that the conversion losses from solar and wind energy are much less than from a standard power plant. In the case of solar electricity, there is also much more potential for locating the power generation at the point of consumption. This reduces transmission losses.

The problems with renewable energy production? It’s variable. In the case of solar, it is guaranteed to not produce at least half of the time due to earth’s rotation. In the case of wind, it is at the mercy of the wind. Therefore, you need to either supplement renewables with a concentrated source of production, or you need efficient means of energy storage. While progress in energy storage is impressive, it is still expensive to use either battery storage or capacitors to bridge the gap between availability of renewable energy and consumption of that energy. The second problem with renewables is that you are depending upon a diffuse source of energy. The sun only shines so hard, and even wind turbines can’t compare to the energy density of a classical fossil fuel source.

The other problem with renewables is that they allow the consumer to bypass the utilities and the fossil fuel companies for some of the energy demand. While the prospect of going off the grid is extolled as an ideal, it is not practical for most people. We still need an energy infrastructure to cover those times when energy is required to supplement locally produced electrons. It is expensive to maintain and improve this grid, and what we’ve seen, especially with Texas, is that the grid can fail catastrophically if it is not maintained. So as much as we might want to be rid of giant monopolies governing our energy supplies, we need to construct a future system where they play a role, or else their looming obsolescence will cause them to resist any needed changes.

In my state of West Virginia, we’ve been in denial about the future of coal ever since I moved here in 1986. Coal was the exclusive source of electricity in this state for decades. Only with the increase in natural gas availability due to fracking did anyone in this state seriously doubt the moral goodness of coal, and of those who mined it. So we have suffered as local communities were shattered by the blasting needed to support mountain top removal. This form of mining only employed a small fraction of the workforce needed for an underground mine, but when it is all you know, you put up with a lot. We now have many acres of once pristine woodland and hillside covered in scrub grasses, devoid of topsoil, and unable to sustain much life. Such places would be ideal for solar farms, and slowly this state seems to be growing aware of this possibility.

West Virginia has suffered population loss for decades, ever since the coal mines first became mechanized. What better way to offer hope to the youth who now succumb to opioids than to provide jobs in solar energy? Education to enable people to learn the basics of electrical installations would raise the general education levels in this state. We must resist the siren song of reversing coal’s decline, and embrace the trend towards renewable energy that is the wave of the future. No matter what the Republicans say.