Month: August, 2017

Renewable Energy Series: Solar Vs Wind

Legendary oilman T. Boone Pickens called the US the Saudi Arabia of wind and when you see maps like this, you understand why.

As the Earth spins toward the west, it slides underneath the air in the atmosphere, giving it from our perspective a generally eastward direction.

That easterly wind sweeps over the rocky mountains and then rushes back down across the Great Plains, creating one of the largest wind corridors in the world.

And in the last 10 years, investments in commercial wind energy have boomed across the United States. Economies of scale have started to kick in, causing the price of wind turbines to drop.

They also cost little to maintain and operate and help create energy independence for smaller communities and provide a revenue source for local ranchers who lease out the land to the energy companies.

And they’re more space-efficient. On the ground they take up very little space and those ranchers can still use the land below them for agriculture.

Plus it’s a large growth sector for jobs and currently employs over 100,000 people, expected to rise up to 600,000 in the next 30 years.

And there’s a reason I saved saved solar for last. Because there’s something different about solar from all other forms of energy, clean or dirty.

Photovoltaic solar panels, or PV panels, have no moving parts.

Every other energy source creates electricity by using heat or steam or water or wind to turn a turbine. Solar literally just collects the energy coming out of the sun and repurposes it.

When asked if he was interested in fusion power as a source of energy, Elon Musk famously said that we already have a massive fusion reactor in the sky just feeding us energy every day. All we have to do is collect it.

Now there are some negatives to solar power, let’s just get that out of the way…

First the obvious one, there’s no sun at night, so solar power is intermittent. But intermittent more like tidal energy than wind energy because we know the sun will be coming up every day.

And even in cloudy weather, it is producing something.

They take up a lot of land, unlike wind farms mentioned earlier, if you have a solar farm, you can’t use that for other things.

But, you can also use existing infrastructure like buildings and transport corridors.

The big hangups come in the construction of the solar panels because there are some hazardous materials used that need to be properly disposed of at the end of the panel’s life span.

And some PV panels require rare Elements like those found in cadmium telluride (CdTe) or copper iridium gallium selenide (CIGS), which is all the more reason to recycle the panels properly.

Luckily, 96% of a solar panel can be recycled. Unfortunately, the recycling infrastructure for solar panels is pretty small, but expected to grow tremendously in the next 30 years.

But the one that gets the solar haters the most worked up is that producing solar panels does generate greenhouse gasses. Specifically nitrogen trifluoride and sulfur hexafluoride. And yes, that sucks.

But the argument that we should stick with something like coal because PV panels create greenhouse gasses is frankly absurd.

Because with the solar panels, it’s a one-shot deal and then you’re getting clean, free energy for the next 20 or 30 years, while coal is constantly pumping out greenhouse gasses that whole time.

This debate was laid to rest by Wilfried Van Sark of Utrecht University in the Netherlands. In a paper for the trade Nature Communications, he and his team calculated the amount of greenhouse gas emissions created by PV panel production all the way back to 1975 to see how long it would take before they made back their debt.

I didn’t even mention the other type of solar energy, concentrated solar thermal plants.

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%.
https://www.geothermal-energy.org/pdf

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…

(zoom in)
Earthquakes. In Oklahoma.

A geothermal well that was drilled in Switzerland set off an earthquake that measured a 3.4 on the Richter scale.

(pained)
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.

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