Energy: Five Good Questions

“Almost every way we make electricity today, except for the emerging renewables and nuclear, puts out CO2. And so, what we’re going to have to do at a global scale, is create a new system. And so, we need energy miracles.” –Bill Gates

Energy is one of the most important topics facing our modern, industrialized civilization. What sources we get it from, what we use it for, and how we deal with the waste from its production are paramount to the future of our species on Earth.

Yet in many ways, energy is one of the most poorly understood quantities in all of physics. To help you better understand it, let’s take a look at five good questions about energy. Starting with…


1.) What is energy? Anyone who’s ever taught or taken a course in introductory physics has likely encountered this question. Most physicists, perhaps unfortunately, define energy as the ability to do work. And so you go and ask what work is, and you get the circular definition that it’s the transfer of energy from one source to another.

Maddening.

It’s not like wikipedia does any better, mind you. But just because we don’t have a good definition of it doesn’t mean we can’t quantify, test, and indirectly measure it.

Don’t feel bad; no less a physicist than Newton had no concept of energy. And yet unlike Newton, I bet that you know it when you see it. Some things we do know about energy are:

  • we know that all mass and matter contains it,
  • we know how to quantify it,
  • we know how much is stored electrically, chemically, thermally, sonically, etc.,
  • we know how to convert it from one form to another,
  • we know how to use it to accomplish things (i.e., to do work),
  • we think it can never be created nor destroyed,
  • and we can generate, calculate, and measure its various forms.

So let’s take on a more useful question than asking for a simple dictionary definition:

2.) What can we do with energy? Well, we already said, “work,” but that has a specific meaning to a physicist. If you “push” something, or otherwise apply a force to it, while it simultaneously moves in that direction, congratulations! That’s what work is!

Whether you’re lifting a weight up, pedaling a bicycle, driving a car, or spinning a turbine, work is being done. And that’s what energy can do.

More than that, of course, is that you don’t need to do it. Anything that lifts a weight, pedals a bike, drives a car, or spins a turbine can do work, and therefore, has energy. Atomic nuclei, molecular bonds, gravitation, relative motion of massive bodies and electromagnetism are all possible physical sources of energy, as nuclear power, fossil fuels, hydroelectric dams, wind power and solar power are respective examples of each.


3.) How much energy do we use? If you’re reading this, you’re probably in a location that has seemingly endless, cheap access to at least one of these forms of energy. Well, all total, humans use a lot of energy. In practice, it’s much easier to measure power, or the rate at which we use energy. So take that power and multiply it by a certain amount of time, and you’ll find out how much energy we use.

How much power do we use?

As of 2006, humans use 13 TeraWatts of power. That’s a mind-boggling number, mind you. 13,000,000,000,000 Watts of power, or about one Watt for every dollar of the United States’ GDP.

Except that’s power, not energy. If we want to turn that into energy, we use 13,000,000,000,000 Joules of energy every second. Over the course of a year, that’s 4 x 1020 Joules of energy. And we get most of it, as you can see, from oil, coal, and gas. We’re basically using all the energy we can make, and demand is only going up. It would take some type of major advance to meet our energy needs from a better, safer, cleaner source than these.

4.) What’s the “holy grail” of energy? Well, you have to be careful here. Some people dream about taking all the ambient thermal energy around us and using it to meet our energy needs.

This only works if there’s a difference in energy, heat, or temperature from one location to another. If you have the Earth, sitting pretty at 300 Kelvin, you can’t do anything with that energy on Earth, because there’s no way to make use of that energy, or to transfer it in a useful fashion.

What we’d love, of course, is a clean, non-polluting, abundant and easily controlled source of energy. The wind and the Sun are good options, but turning wind or sunlight/heat into usable energy are somewhat expensive and inefficient at this point. The “holy grail” of energy, as far as I’m concerned, is this.

Nuclear fusion. Unlike current nuclear power, where rare, heavy, radioactive elements are split apart via nuclear fission, releasing energy and also producing radioactive waste, nuclear fusion takes something light, common and inoffensive, like hydrogen, and produces something equally inoffensive, like helium. The Sun operates off of nuclear fusion, as do our most powerful nuclear bombs.

The key, of course, is controlling it, and getting a fusion reaction to occur in a way that released more usable energy than you had to input to make the elements fuse together in the first place. Which brings us to the final good question…

5.) What does the future hold for nuclear fusion? Well, we definitely don’t want to do it the same way the Sun does it. But we still want to start with our cheap, light, easy fuel and get that nuclear energy out of it. And we’ve got three ways we know of to make it happen, each one getting closer to the magical (metaphorically) breakeven point. What are they?

Inertial confinement fusion. Basically, it takes lasers in all directions, focused on a small hydrogen “pellet,” and forces the hydrogen nuclei together in one great push. (This is very similar to how a fusion bomb works, where a huge release of energy via a small fission bomb pushes the hydrogen together, causing a runaway fusion reaction.) This simple method can achieve nuclear fusion, but has not been able to release as much usable energy as is required to operate the lasers.

Magnetic confinement fusion. Instead of lasers, why not use magnetic confinement of a hot plasma instead? Invented in the 1950s in the Soviet Union, Tokamak reactors can achieve nuclear fusion as well. For the past 30 years or so, Tokamaks and inertial confinement teams have swapped the record for getting ever closer to the breakeven point, though there’s still a ways to go for both teams.

But recently, there’s been a low-budget newcomer to the scene.

Michael Laberge, an independent physicist, is actually giving these huge collaborations a run for their money in the fusion game. Using a sort-of hybrid design, called magnetized target fusion, a low-density fuel source is heated into a plasma and confined magnetically. However, hundreds of pistons surround this plasma, and once the plasma is in the desired state, the pistons all fire at once, compressing the plasma and — you guessed it — causing nuclear fusion!

This, too, is still a significant ways away from the breakeven point, but all three of these designs hold the promise of being a new, efficient, clean energy source, and we can control it. (You will notice cold fusion is not on this list. That’s because, by scientific standards, it is not yet verifiably successful.) So long as there’s hydrogen — the most abundant element in the Universe — there’s a chance for us to meet our energy needs through nuclear fusion.

And those are my takes on five good questions about energy!