Solar Technology - The Next Generation

It wasn't so long ago that photovoltaic solar panels were expensive, hard—and dirty!—to produce, inefficient sources of very expensive power.

In the last little while, however, a flurry of advances have improved on all of those problems. So many announcements have come out lately that I've delayed this post repeatedly due to the sheer quantity of new information. But that's not going to stop, so I'll post what I have now, and I may post again later.

For a super-quick summary of first-generation photovoltaic power, the panels were made of silicon using a process that involves toxic chemicals and high temperatures, were very fragile, expensive, and had a low efficiency and limited lifespan.

But now they're becoming cheap, tough, flexible, easy to make, and remarkably efficient and durable.

Crystal habits

I am fascinated by crystals, particularly by their regularity. They basically consist of a unit cell that repeats over and over again, identically, across the whole span of the crystal. And if the crystal is big enough to see with the naked eye, that's a very large number of unit cells.

Very simple crystals, for example table salt (NaCl), have a tiny unit cell consisting of 4 atoms of Na and 4 atoms of Cl, arranged in alternating rows, a structure that is called face-centred cubic, because on each face of the cube, there's an atom in the centre of the same type as the atoms on the corners of the unit cell.

An interesting quirk of the simple 1:1 ratio cubic crystal structure is that you can define either Na or Cl as the corners of your unit cell, and it'll still be face-centred cubic.

Diamond's structure is also simple: every carbon atom has four links to four other carbon atoms, arranged in a tetrahedral shape around it. Because unit cells are defined as cubic or rectangular shapes, however, the diamond unit cell is less simple, even if the structure itself is simple.

Not a sunrise, but a galaxy rise

I just discovered the "Symphony of Science" series of music videos. Gorgeous visuals in this one, both on the screen and inspired in my head by the lyrics.

I don't really have much to say about it, except that it makes me happy when I watch it. This music video has lyrics made entirely from recordings of things said by Carl Sagan (with a verse by Stephen Hawking), with their tone digitally altered to fit the melody.

Surface tension

Here's a little random bit of fun for today: kitchen games with surface tension.

One of the things that changing surface tension does is determine how stable bubbles are. So, let's change the surface tension of boiling water with some common household items.

If you set a pot of water on the stove to boil, the lid will rattle when it gets going, and that's about the extent of it. The bubbles pop quickly and aren't very stable.

If, on the other hand, you set a pot of water with some white rice in it on the stove to boil (and forget to turn it down to low the instant it starts to boil) it'll foam up and boil over and make a great big mess of your stove. If you're one of the other three people left in the world who both cooks rice and hasn't got a rice cooker, you've probably had this happen to you at least once.

A while ago I noticed something interesting: there are certain additives you can put in a pot of white rice that changes the surface tension yet again, so it goes back to not boiling over. My favourite of these additives is ground coriander seed, stirred in while the water is still cold. Also, it makes for some really tasty rice. Garlic powder also helps: while the water still foams, it doesn't grow as tall and boil over as quickly.