Hydropower vs. Geothermal – Which Renewable Energy Is Best?
Hydroelectric is the use of moving water to turn turbines that generate electricity, usually through the building of dams or pump stations on rivers.
And hydroelectricity is the king of renewable energy, making up 70% of the renewable energy produced around the world. And for good reason.
They’re kind-of the perfect energy source. It’s stable, base-load energy that’s flexible. If you need more electricity, just release more water into the turbines.
They’re cheap to run and maintain once they’re built and they’re 95% efficient at generating energy, compared to 33% for coal and 15% for solar.
And of course they create no pollutants, consume no fuel, and the water never stops flowing.
The Three Gorges Dam in China is actually the largest energy plant of any kind in the world and generates just under a hundred terawatt hours per year all by itself.
So, hydro is kinda perfect. The problem is, it’s location-specific.
If you don’t live by a large river, you’re not going to be able to use it. Luckily, most cities were built near rivers, but not all rivers are large and powerful enough to make enough difference to justify the cost of building them.
Which is also a problem. While they produce free energy for decades and even centuries after they’re built, hydroelectric dams are huge engineering projects that cost tons of money up front.
(By the way, the whole ‘expensive at first but then free for decades’ thing is a common theme amongst renewable energies)
They also create reservoirs and lakes that flood a lot of land whose landowners may not want to give up.
There are some concerns about the disruption of fish habitats, but… that’s not at the top if my list of concerns.
So each hydroelectric plant is a birds nest of legal and construction challenges to overcome but even so, the number of hydropower plants are expected to double by 2050.
Another base load energy source is geothermal energy.
Geothermal uses the heat from natural geologic hotspots to turn turbines that generate electricity.
Iceland and the Philippines are major producers of geothermal power, which can be used in huge commercial plants to power entire cities or just pump the heat directly into homes for heating.
It’s a consistent flow of energy so it never runs out, but the efficiency isn’t great. Only an average of 12% efficiency.
Which really just means it will take longer for the investment to build it to pay off because once it’s turned on, it’s just free energy basically. And the efficiency is getting better, with newer plants getting over 20%.
Even in Iceland, which is covered in hotspots and has a very progressive attitude toward clean energy, it only accounts for 30% of their energy production.
So it’s not likely to become a major source of energy worldwide
And as if all that wasn’t enough of a bummer, it also turns out that geothermal can produce greenhouse gasses.
Geologic hotspots churn up all kinds of stuff from inside the Earth, stuff like sulfur dioxide and silica emissions, and heavy metals like mercury, arsenic and boron.
These can get in the reservoirs and eventually the water supply.
Oh, and by the way, one of the methods they use to open up geothermal wells is hydraulic fracking. Yeah. That hydraulic fracking.
Let’s drill down and inject extremely high pressure water and other chemicals… Right over a volcano.
What could go wrong?
Earthquakes. That’s what.
Just like fracking for natural gas has caused earthquakes in Oklahoma…
Earthquakes. In Oklahoma.
A geothermal well that was drilled in Switzerland set off an earthquake that measured a 3.4 on the Richter scale.
Geothermal… Why do you hurt me so?
I used to think geothermal was really cool. Used to.
So am I wrong about this? Do you have experience using geothermal, or working in hydro plants? Are my numbers garbage? Let me know in the comments
The next video in this series will focus on biomass energy and harnessing the motion of the ocean to make power.