Comments by "Peter Lund" (@peterfireflylund) on "Asianometry" channel.

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  26. ​ @kngharv  Yes. But when you zoom in, some of those incremental improvement are not that simple. There are lots of total shifts of technology in delimited areas. The improved power electronics did not come about because power MOSFETs became better (which they did) but because of a different type of "transistor", the IGBT. And that's just one example. If you zoom out, it looks like incremental improvement but if you zoom in, you can see it is a new technology which happens to share most of its "ecosystem" with preexisting semiconductors and which is compatible with preexisting electronics. Here's some background reading... https://en.wikipedia.org/wiki/Insulated-gate_bipolar_transistor (just look at the table if you are in a hurry) Our grids are AC for one reason only: it makes it a lot easier and cheaper to transform the electricity down from high voltages (and low currents) to lowish voltages and high currents close to the consumers. The power lines are really just very, very long resistors and the loss in a resistor is proportional to the current. The power (energy per unit of time) equals the voltage times the current, so if we can step the voltage up and the current down, we get lower losses. Transformers are good at this job but they require alternating current. Other methods have been used, for example electric motors that drive dynamos, but they are not as efficient. With modern power electronics, we finally have something that can do it better than transformers and without the alternating current. HVDC is useful for transmitting electricity with smaller losses = it's practical go much longer distances + underwater in more cases than before. The DC part also means that the connected subgrids don't have to be synchronized, which they do for AC. That's a huge deal. It makes it much less risky to connect up gigantic powernets because the risk of cascade failures is much lower. And we want our nets to become bigger because wind and sun are intermittent power sources but hopefully the wind will be blowing somewhere and the sky will be clear *somewhere*. It also makes it easier to use pumped storage for "peak shaving" -- pumped storage usually requires mountains and low population densities but the usefulness requires industry/cities. Better electronics (computers) and communication (internet) also makes it easier to keep synchronized grids running. https://en.wikipedia.org/wiki/High-voltage_direct_current We have a big connected grid in Europe and we are trying to make it bigger (but less synchronized): https://en.wikipedia.org/wiki/Synchronous_grid_of_Continental_Europe https://en.wikipedia.org/wiki/European_super_grid https://en.wikipedia.org/wiki/List_of_HVDC_projects#Europe Pumped storage: big lakes (possibly artificial) at high elevations + a big height drop + turbines that can turn into pumps. https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity It's currently the best/cheapest energy storage method but it is not feasible everywhere + we have more or less built what we can in the West and some of them do have a local environmental impact. Other options for energy storage is batteries, of which lithium-ion is clearly the technology to bet on. Lead iron used to be cheaper (and might still be cheaper for a couple of years more) but lead is really unpleasant whereas lithium-ion batteries are safe enough to put in landfills (but can also be recycled). Lithium-ion have had a superior energy density for a long time but the prices have been too high, particularly when taking the low cycle count into account. Every single charge-discharge cycle wears a little on the battery and lithium-ion used to have a limit of a few hundred cycles. This has been improved immensely in recent years, mainly through the use of better additives. The technological enabler for this was a better measurement device that could measure microscopic wear on a battery over a single cycle. It's basically a really, really, really good amp meter. Prior to that, researchers had to perform many(!) cycles in order to compare their additives. This device was developed in Jeff Dahn's lab at Dalhousie University: https://www.dal.ca/diff/dahn/about.html There's a reason why Tesla has been working closely with him for about a decade... Tesla sells huge batteries commercially and expect that part of its business to grow a lot: https://en.wikipedia.org/wiki/Tesla_Megapack Tesla had a "Battery Day" event last year to tell investors about their battery technology, both current and upcoming. The press mostly ignored it but they showed several things that will change the world because they promise to make lithium-ion batteries much cheaper to produce (and also better than they are now). The official stream (140 minutes): https://www.youtube.com/watch?v=l6T9xIeZTds Much shorter version (16 minutes): https://www.youtube.com/watch?v=HK79ioBW8Mg The main competition for lithium-ion batteries for the grid is flow batteries. Unfortunately, they tend to use big tanks of really nasty chemicals (which may have to be heated to work properly). They are also unlikely to be able to compete with future lithium-ion batteries. https://en.wikipedia.org/wiki/Flow_battery
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