#5A: Energy Underdogs (Biomass, Tidal & Geothermal)
Welcome back!
So, when most people think of sustainable energy, they probably imagine solar panels, wind farms, or maybe even nuclear power plants. Some might also think of those giant hydroelectric dams. And that’s true, all of those can be considered a form of sustainable energy (though nuclear energy is debatable).
However, putting these aside, could you think of any other forms of renewable/sustainable energy? No? Well, there are plenty of others, which is what this article is all about. I dub them the ‘energy underdogs’ because although they’re really useful, and have high potential, they’re not nearly as flashy as others, and so most people tend to ignore them. But they’re just as important. So, let’s see what we can find out.
First, up let’s take a second to talk about biofuels (also known as biomass burning).
So, when most people think of biofuels, they probably imagine some chemists, working in a lab, trying to come up with a new recipe for car fuel that’s produced almost entirely from biotic matter (in other words, living things). While that’s true in certain cases, biomass burning can be explained in a much simpler, four-step process.
The initial step is the power-up. And, it just so happens that it’s the simplest step to understand. If you’ve ever taken a basic biology class, you’ll know that each plant cell has this weird thing floating around it.
It’s called a chloroplast, and it’s an organelle, which is actually responsible for making stuff green. So, you might be wondering, what does a chloroplast actually do? Well, quite simply, it turns sunlight into energy. If you’d like a more scientific explanation, you can consider this chemical equation below.
So, to break it down, on the left-hand side, we have the carbon dioxide that’s in the air, along with some water, which the plant takes in through its roots. By using the energy from the sun, the plant is able to produce glucose (which is basically just sugar), as well as oxygen for all of us to breathe.
Now, why does any of this matter? Well, it’s because biomass burning can pretty much be thought about as a natural process of solar energy. Instead of solar panels, though, it uses plants. You see after the tree continues producing all of this glucose, we can find ways to turn that into energy. The way biomass burning does it is, as the name suggests, by literally burning the plants, which brings us to the next step of our process: burning.
What? Isn’t that bad? Well, kind of, but we’ll come back to that later on in this article. So, what ends up happening when you burn a biomass plant is that the glucose which was formed over dozens of years can now be brought out into the real world. In chemistry, we call that an exothermic combustion reaction. That simply means that it’s releasing energy, by burning. For glucose, the combustion reaction looks something like this.
Essentially, glucose is burned in oxygen, to form H2O and CO2. Since it’s a burning process, both of these are produced in the gas state. But wait, isn’t CO2 bad for the environment? Yes, but….I’ll get back to that later.
So, the next step of the process is called the turbine. So, when plants are burned, steam is produced, as we saw in the equation above. What does this mean for electricity production? Well, quite simply, that steam can help spin a turbine (since it’s moving).
What does that do? Now, I’m going to spare you the entire explanation of the physical processes that run a turbine (but here’s a cool video about it if you’re interested). However, the main idea is that spinning a turbine ends up spinning a weird-looking square circuit, like the one below.
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? It’s solar energy, but instead of having to deal with designing, constructing and building solar cells, you instead just burn a bunch of plants, which have already collected energy from the sun over several decades. It’s great, new and revolutionary!
Now, before we move onto the next ‘energy underdog’, we need to consider something that we left out. Is this stuff actually good for the environment? I mean, it does end up producing carbon dioxide through the combustion process, and isn’t that really bad for the environment?
This is the key turning point of what we’re talking about here. We need to understand the difference between renewable energy and sustainable energy. Is biomass burning renewable? Of course it is!
When you burn biomass, most people might think it leads to depletion of forests and what not. But, of course, you can always grow plants, so long as there is the sun, and so long as there is water. Because these resources can be replenished in a relatively short amount of time, that means it is renewable. It doesn’t involve wasting the fossil fuels that are in limited supply, buried deep into the earth.
Okay, so, if it’s renewable, is it also sustainable? No, no, definitely not. Biomass burning, despite being a renewable resource is not sustainable at all. When you burn biomass, it ends up creating carbon dioxide, which is a horrible greenhouse gas. When it’s released into the atmosphere, it can absorb infrared radiation. That then is released back towards Earth. In other words, carbon dioxide is one of the main gases that’s causing climate change and global warming! (see the others below)
So, is biomass burning better than fossil fuels? Yes, definitely. It’s renewable, which means we won’t run out of it anytime soon. On the other hand, fossil fuels are quickly being depleted. Although it does produce carbon dioxide, fossil fuels do this too, as well as produce a whole slew of other dangerous greenhouse gases.
What’s the conclusion then? Is biomass burning worth doing? Let’s put it this way: if all other renewable energy sources (most of which are sustainable), were to break down and no longer work, then biomass burning would be our best option. It’s preferable over fossil fuels in terms of environmental destruction, and at least it can be renewed.
Thank you for reading the first part of my exploration into the energy underdogs! I hope you all enjoyed. Don’t worry, next time, we’ll be exploring a type of energy which is not only renewable but also sustainable. Next episode will also be focused on physics (less chemistry), but we’ll also be considering the economic incentives surrounding it, and wondering why it’s still an ‘underdog’. But until then…see ya!
