#5B: Energy Underdogs (Biomass, Tidal, and Geothermal)
Welcome, welcome, welcome.
If you’re joining us for the first time, this is a little series about ‘energy underdogs’. In other words, energy technologies that haven’t really broken into the mass market, for one reason or another, and different types of energy that people don’t really think of. You might wanna check out our last episode which was on biomass burning! We had some interesting conversations about whether or not it was actually worth it.
If you’re returning, you already have a hint of what we’re going to discuss. That’s right, it’s right there in the tidal (see what I did there?). Tidal energy. What is it? How does it work? Is it sustainable? Why is it an underdog? To find out, keep on reading. Enjoy!
So, a lot of people have probably heard of hydroelectric power. It’s pretty cool, right? If you haven’t heard of it, you should check it out. It’s pretty much a giant dam, with water pouring through it, that produces electricity. Sweet, right?
Well, although most people have heard of hydroelectric energy, most haven’t heard of its close-but-also-distant cousin: tidal power. What’s tidal power. Well, quite simply, it’s hydroelectric energy, but in the ocean instead of in a river.
HOLD UP! Before energy fanatics (like myself) attack me in the comments section, I need to point something out. This is the most common version of tidal energy. We won’t be looking at the others today. Since I’ve never done an article on hydropower, I figured it would be good to kill two birds with one stone.
Okay, so, when it comes to tidal energy or any water-based energy, the question comes down to: how can we convert water into energy? It’s pretty simple, but the solution is even cooler!
If you’ve taken a physics class (or even a chemistry class), you’ll probably have heard of the law of conservation of energy. You know, that thing that says that energy can only be transferred, not created or destroyed? Well turns out, that’s more than just a buzz-phrase, but it also applies to energy.
So, based on that, we need to consider our types of energy and see which one we want to convert.
Kinetic energy? Maybe, but initially, the water isn’t moving very much.
Elastic energy? I don’t really see any strings or elastic bands anywhere.
Thermal energy? I mean, I guess you could try that, but it might be a bit dangerous.
Potential energy? Hmm, that could be interesting.
After all, water is affected by the force of gravity (if not it would be floating around). And, some of it is definitely above sea level, right? I mean, you do stack ‘sheets’ of water onto each other to make an ocean…
Sounds close enough. Time for challenge two: how do we turn potential energy into electricity? It’s not like you can just throw the end of your charger into the ocean and get power, right? Alright, so let’s try something else. How about turning the potential energy into another form first?
Okay, well, in like 99% of energy conservation problems you’ll see in your physics class, it’s always about turning some kind of potential energy into kinetic energy. So, let’s do that.
How, exactly? Well, an easy way to do it is to get the water moving. In hydroelectric power, this is done by storing all the water behind a dam, and then, all of sudden, letting it crash down, which inevitably causes A LOT of movement. And that’s what we want, right?
Well, in tidal energy, we actually don’t need to go that far….the Moon just does all of it for us! What do I mean by that? Well, the Moon is actually what causes tides in the oceans (by which I mean its gravitational pull). So, since there are tides, we already know that the water is going to be moving in and out several times a day. Sure, it might not be as fast as hydroelectric power, but it still works.
So, alright, now we’ve just got kinetic energy in the form of tide shifts. What’s next? Well, quite simply, we get to revisit our old turbine buddy! I already explained how a turbine actually works in my last episode which you should check out if you haven’t already. If you’re too busy to read another article right now, I’ll repaste what I wrote last time below (it’s exactly the same process). If you read the last article, just scroll right past this section.
So, since we have some kinetic energy in the form of water, we can push all of that through a turbine. The turbine spins, turning the kinetic energy into rotational motion, and then turning that rotational motion into electricity.
Why does this matter? Well, since this circuit is actually placed in a constant magnetic field, what ends up happening is that electricity (specifically an alternating current) can be produced in this way. It’s given in accordance with Faraday’s law of induction, as shown here.
So, if you’re confused by this, that’s completely understandable. It’s pure physics. Watch the video linked above if you need to learn it, or if you just want a refresher. Anyway, Faraday’s law above essentially states that the electromotive force ε (which is kind of like the voltage, but still different) is equivalent to the rate of change of magnetic flux. Of course, flux is represented by the symbol.
For physics gearheads out there, you’ll know that flux can be represented by the following equation.
Since the circuit in question is spinning around due to the steam-powered turbine, that means that there is a rate of change in flux over time. At certain points, when the circuit is perpendicular to the magnetic field, the flux will be maximized, and when it’s parallel, there will be no flux.
If you’d like to get a better understanding of how this actually works click here to be taken straight to a PhET simulation that deals with understanding Faraday’s’ law of induction. After all, that is the process used to make this stuff work!
This, in turn, is able to create an electromotive force, and therefore create electricity. Isn’t that cool?
In the same way as biomass burning, tidal energy uses turbines to produce electricity as alternating current. It’s a pretty neat process, actually!
Now, we come to the point where we need to ask ourselves the big questions. Is tidal energy a good thing? Is it renewable and sustainable? Should we be implementing it over other forms of electricity, like photovoltaics, or wind turbines?
Yes, yes, probably not. Why? Well, tidal energy is definitely a good thing. Powered solely by the movement of tides, it can really provide electricity through a very weird, yet familiar process. And that’s always a good thing. Also, since it doesn’t depend on any natural resources at all (except to build the actual turbines), it’s a very renewable source of energy as well (perhaps even more so than hydroelectric energy).
Some might argue that it hurts fish populations, but that’s only a minor concern since there are very few fish near coastal areas. Overall, it’s a really good, sustainable piece of energy production technology, and we should definitely look further into it.
But is it really, worth it? Probably not. The reason I say this, though, doesn’t actually have anything to do with the engineering aspect of tidal power or the efficiency and effectiveness of these systems. Rather it has to do with money.
Money? Yes, money. Tidal energy is extremely expensive, especially compared to other forms of sustainable energy (like solar cells). It costs a lot to set it up, and we shouldn’t ignore the economic aspects when considering the potency of a technology. Also, it can only be implemented in coastal areas, whereas solar energy, wind turbines, and even biomass burning, can be placed pretty much anywhere.
And, even worse, asking a government to start funding tidal energy would mean that they would need to sacrifice miles of coastline–which could otherwise be allocated to fishing, or even tourism–to build a big, engineering structure. It’s important not to forget these interdisciplinary aspects when talking about tidal energy. They are the reason why it’s not widely implemented, and the reason why I, personally, think it shouldn’t be.
Note: Since we’ve only discussed one form of tidal power, this analysis only applies to that form and that form alone. Other forms of tidal energy could be cheaper, less obtrusive, and more efficient. However, that won’t be discussed today.
Hope you enjoyed the second episode of this journey into the ‘energy underdogs’! I’ve got one more episode lined up, and it’s probably the most unknown of all three! Can you guess what it is? Hint, it has to do with the ground. Join me next time for that exploration (also, it doesn’t have to do with turbines, if you were getting bored of that)!
