A plethora of insane energy policy proposals are touted by clueless politicians, including the apparent Democrat candidate for US President.  So all talking heads need reminding of some basics of immutable energy physics.  This post is in service of restoring understanding of fundamentals that cannot be waved away.

The Key to Energy IQ

This brief video provides a key concept in order to think rationally about calls to change society’s energy platform.  Below is a transcript from the closed captions along with some of the video images and others added.

We know what the future of American energy will look like. Solar panels, drawing limitless energy from the sun. Wind turbines harnessing the bounty of nature to power our homes and businesses.  A nation effortlessly meeting all of its energy needs with minimal impact on the environment. We have the motivation, we have the technology. There’s only one problem: the physics.

The history of America is, in many ways, the history of energy. The steam power that revolutionized travel and the shipping of goods. The coal that fueled the railroads and the industrial revolution. The petroleum that helped birth the age of the automobile. And now, if we only have the will, a new era of renewable energy.

Except … it’s a little more complicated than that. It’s not really a matter of will, at least not primarily. There are powerful scientific and economic constraints on where we get our power from. An energy source has to be reliable; you have to know that the lights will go on when you flip the switch. An energy source needs to be affordable–because when energy is expensive…everything else gets more expensive too. And, if you want something to be society’s dominant energy source, it needs to be scalable, able to provide enough power for a whole nation.

Those are all incredibly important considerations, which is one of the reasons it’s so weird that one of the most important concepts we have for judging them … is a thing that most people have never heard of. Ladies and gentlemen, welcome to the exciting world of…power density.

Look, no one said scientists were gonna be great at branding. Put simply, power density is just how much stuff it takes to get your energy; how much land or other physical resources. And we measure it by how many watts you can get per square meter, or liter, or kilogram – which, if you’re like us…probably means nothing to you.

So let’s put this in tangible terms. Just about the worst energy source America has by the standards of power density are biofuels, things like corn-based ethanol. Biofuels only provide less than 3% of America’s energy needs–and yet, because of the amount of corn that has to be grown to produce it … they require more land than every other energy source in the country combined. Lots of resources going in, not much energy coming out–which means they’re never going to be able to be a serious fuel source.

Now, that’s an extreme example, but once you start to see the world in these terms, you start to realize why our choice of energy sources isn’t arbitrary. Coal, for example, is still America’s second largest source of electricity, despite the fact that it’s the dirtiest and most carbon-intensive way to produce it. Why do we still use so much of it? Well, because it’s significantly more affordable…in part because it’s way less resource-intensive.

An energy source like offshore wind, for example, is so dependent on materials like copper and zinc that it would require six times as many mineral resources to produce the same amount of power as coal. And by the way, getting all those minerals out of the ground…itself requires lots and lots of energy.

Now, the good news is that America has actually been cutting way down on its use of coal in recent years, thanks largely to technological breakthroughs that brought us cheap natural gas as a replacement. And because natural gas emits way less carbon than coal, that reduced our carbon emissions from electricity generation by more than 30%.

In fact, the government reports that switching over to natural gas did more than twice as much to cut carbon emissions as renewables did in recent years. Why did natural gas progress so much faster than renewables? It wasn’t an accident.

Energy is a little like money: You’ve gotta spend it to make it. To get usable natural gas, for example, you’ve first gotta drill a well, process and transport the gas, build a power plant, and generate the electricity. But the question is how much energy are you getting back for your investment? With natural gas, you get about 30 times as much power out of the system as you put into creating it.  By contrast, with something like solar power, you only get about 3 1/2 times as much power back.

Hard to fuel an entire country that way. And everywhere you look, you see similarly eye-popping numbers. To replace the energy produced by just one oil well in the Permian Basin of Texas–and there are thousands of those–you’d need to build 10 windmills, each about 330 feet high. To meet just 10% of the country’s electricity needs, you’d have to build a wind farm the size of the state of New Hampshire. To get the same amount of power produced by one typical nuclear reactor, you’d need over three million solar panels, none of which means, by the way, that we shouldn’t be using renewables as a part of our energy future.

But it does mean that the dream of using only renewables is going to remain a dream,
at least given the constraints of current technology. We simply don’t know how
to do it while still providing the amount of energy that everyday life requires.

No energy source is ever going to painlessly solve all our problems. It’s always a compromise – which is why it’s so important for us to focus on the best outcomes that are achievable, because otherwise, New Hampshire’s gonna look like this.

Addendum from Michael J. Kelly

Energy return on investment (EROI)

The debate over decarbonization has focussed on technical feasibility and economics. There is one emerging measure that comes closely back to the engineering and the thermodynamics of energy production. The energy return on (energy) investment is a measure of the useful energy produced by a particular power plant divided by the energy needed to build, operate, maintain, and decommission the plant. This is a concept that owes its origin to animal ecology: a cheetah must get more energy from consuming his prey than expended on catching it, otherwise it will die. If the animal is to breed and nurture the next generation then the ratio of energy obtained from energy expended has to be higher, depending on the details of energy expenditure on these other activities. Weißbach et al. have analysed the EROI for a number of forms of energy production and their principal conclusion is that nuclear, hydro-, and gas- and coal-fired power stations have an EROI that is much greater than wind, solar photovoltaic (PV), concentrated solar power in a desert or cultivated biomass: see Fig. 2.

In human terms, with an EROI of 1, we can mine fuel and look at it—we have no energy left over. To get a society that can feed itself and provide a basic educational system we need an EROI of our base-load fuel to be in excess of 5, and for a society with international travel and high culture we need EROI greater than 10. The new renewable energies do not reach this last level when the extra energy costs of overcoming intermittency are added in. In energy terms the current generation of renewable energy technologies alone will not enable a civilized modern society to continue!

On Energy Transitions

Postscript