Why It Was Almost Impossible to Make the Blue LED

I was watching a YouTube video from a Scottish YouTuber recently and heard him refer to a light as being a LED bulb. He, however, pronounced LED as if it were the element lead. I, an American, pronounce those bulbs as their three separate letters El Ee Dee, like an acronym. 

Neither, of course, is correct, nor is it at all relevant to this video.

This video, just over half an hour long and produced by Dr Derek of Veritasium, goes through the quantum mechanic explanation of how semiconductors conduct at room temperature which also explains how LEDs produce light and - eventually in the video - how LEDs can be tuned to produce different colors.

This video is also a great exploration of how doped semiconductors conduct electricity. 

I'm really happy that I don't have to teach this concept in my chemistry - or material science - classes because this really pushes my understanding of quantum mechanics and electronics. I didn't thoroughly understand it when I first heard about it back in 1993 or 1994, and I don't entirely understand it now. I do, however, fully accept that there are people who do understand these concepts and that we owe those people a massive debt because the widespread use of LEDs has been a huge revolution in energy savings for our world.

Plus it lets people wrap their cars in Christmas lights.

Reusable handwarmers that get hot by freezing

The title of this video is wrong.

There is no freezing happening. There is recrystallization happening from sodium acetate dissolved in solution.

That's not freezing - a pure liquid turning into a solid like ice turning into water. The host seems to understand that distinction, but he's sloppy on using the term freezing and freezing point somewhat misleadingly. He also is sloppy on liquid versus solution and melted versus dissolved.

Most of this video is an explanation and comparison of the two types of hand warmers - the reusable sodium acetate solution and the single-use iron rusting type. The video host explains the science behind what's happening and judges the single-use to be the better choice - something that I'll leave up to you.

I use both in class for different purposes and different chapters.

Wind energy has a massive waste problem. New technologies may be a step closer to solving it...and...How can companies recycle wind turbine blades?

 

From the CNN article

Wind energy might be the solution - or at least part of the solution - to our energy problems. We absolutely need to stop burning things (methane, oil, coal, wood, trash, retired Beanie Babies) to make energy. That is not in dispute.

One of the things that is in dispute, however, is how to deal with the waste from retired wind turbine blades. From the same article, "[b]lade waste is projected to reach 2.2 million tons in the US by 2050. Globally, the figure could be around 43 million tons by 2050." The blades are, as a CNN article writes, "made from fiberglass bound together with epoxy resin, a material so strong it is incredibly difficult and expensive to break down." 

Recycling the themoset resin is challenging, though a company named Vesta "has been working on in partnership with Aarhus University, the Danish Technological Institute and US-based epoxy company Olin, uses a liquid chemical solution to break down the blade into epoxy fragments and fibers. The epoxy resin is then sent to Olin which can process it into 'virgin-grade' epoxy"

There are other possible solutions mentioned in the article - pyrolitic separation of the resin and fibers allowing both to be reused, chopping the composite blades into fragments to then mix into cement, and...well...not much else.

A C&EN article explores the same issue and adds in an option of repurposing the blades rather than recycling them, showing an image of a playground made of decommissioned blades in the Netherlands and saying that they have also been turned into bus shelters and other public structures. The article also reports that there are companies exploring making the blades out of more easily recycled materials, though little detail of what those materials could be are provided as the materials and processes are still being devloped.

The Future Of Energy Storage Beyond Lithium Ion

I've watched enough videos about renewable energy to know that one of the biggest issues with increasing our use of renewables isn't necessarily the actual energy production but rather the storage of the energy from times when it's produced to times when it's needed.

There's lithium ion storage batteries...3:15-4:05...

...flow batteries...4:10-7:50...

...pumped hydroelectric...8:15-8:40...

...energy vault (the most entertaining storage method if you ask me)...8:40-10:15...

...thermal storage...10:20-11:40...

...compressed air...11:50-12:00...

...cryogenic storage...12:00-12:15

Oh, and I absolutely love the joke at 1:28...energy storage methods all have 'serious potential'...

See, because stored energy is potential...it's funny.

The Mystery Flaw of Solar Panels

I find myself digging the shift that has taken place on the Real Engineering channel.

Brian McManus - the host of Real Engineering - has been putting in a ton of work to step up the video's quality and the content's depth. I find myself learning a whole bunch of new stuff in every video that he's posting.

In this one, McManus details the reasons that the solar energy striking most photovoltaic solar cells is only turned into electricity at a lab-tested 20% efficiency - and even lower 18% real-world efficiency.

This is due to light being reflected, the threshold energy necessary for silicon to release electrons, heat build up, adding metal contacts which block light hitting the cell itself, oxygen defects in the silicon wafers itself.

...and there's some awesome explanation (along with animation) of how p-type and n-type semiconductors are used to produce voltages in solar cells.

The Real Engineering videos do tend toward higher level concepts nowadays, but they're brilliantly cited and clearly explained.

They're good stuff, man.

TRANSPARENT Solar Panels?!

We can maybe back off with the question mark-exclamation point ending on the title, folks.

I'll take 'not 100% transparent' any day of the week if it means that we can turn our windows into solar panels. That would be outstanding.

I am a little curious, though, about just how 'not 100% transparent' they would be. The whole <640 nm thing would be around red/orange, and their explanation that longer wavelengths would travel right on through seems odd. Longer than red/orange doesn't leave a whole lot of colors because the rest of the colors are shorter wavelengths than red/orange.

Misconceptions about heat

In today's video Dr Derek Muller of Veritasium takes a few minutes to again tell people that they're wrong. He seems to do that a lot. I'm not saying, but I'm just saying...

The informality of the testing that he does is one of Muller's great advantages since it leaves the viewer fairly well able to reproduce many of the experiments that he does. Yeah, he uses an infrared thermometer here, but that's not radically out of the realm of expenses for most folks.

The testing today is looking at whether a book - apparently an Asimov tome - is warmer or cooler than an aluminum-cased hard drive. The trick is that they're both at room temperature...the same temperature. It's just that the two materials transfer heat very differently.

There's a similar video with slightly higher production value also by Dr Muller over on the Catalyst, an ABC Australia program, website. The video there is downloadable but not embeddable, and it does have a nice transcript of the prettier video. They also have a larger version of the downloadable video, but it's not viewable in the US. It does, however, come with some teacher material.

Proteq Starpath

I'll admit to being intrigued by this material, a coating that apparently phosphoresces throughout the night once the sun goes down.

I do have a few questions, though:

• What's the durability of the coating?
• How inert is it, particularly to surrounding flora and fauna?
• Does the light produced by the Proteq coating cause any problems with nocturnal animals and their navigation/courtship?
• Can I get it in cornflower blue?

Red Hot Nickel Ball Has Finally Met Its Match!

You might not have been know that Red Hot Nickel Ball has its own YouTube channel, but it does.

Well, almost. RHNB has its own playlist of thirty-two videos from among carsandwater's uploaded videos.

Things all got started with a mute, never-appearing user putting the eponymous red hot nickel ball into a cup of water (a demonstration that I love doing - with slight adjustments - in class when I'm introducing thermochemistry in chemistry class) and continues through honey, pop rocks (surprisingly cool to watch), a steak, and - most recently - aerogel.

Man, aerogel is cool.

I wish I had some.

Wait, I did have some.

Until another master teacher broke it.

Which makes me sad...

A better solar-powered water splitter

Metals are just ceramic wanna-be's.

It's something that summarizes so much chemistry, so much material science understanding, and so many problems that we run into with using metals - and apparently with metalloids (semi-metals if you're British).

I'd never thought of the problem of corrosion with metalloids, though it's understandable that even metalloids would 'want' to react with oxygen since all metals do, too.