Solar furnaces <a href="https://en.wikipedia.org/wiki/Solar_furnace" rel="nofollow">https://en.wikipedia.org/wiki/Solar_furnace</a> have been useful for reaching especially high temperatures since at least Trombe's 1949 furnace, which can hit 3500°, without computer vision or even closed-loop control. So why is a 1500° solar furnace being touted as a groundbreaking innovation and a new high-temperature landmark?<p>A friend asked me what I thought about this earlier, based on a somewhat better reprinting of their press release:<p><a href="https://www.geekwire.com/2019/company-backed-bill-gates-claims-breakthrough-concentrated-solar-energy-promising-replace-fossil-fuels-industrial-plants/" rel="nofollow">https://www.geekwire.com/2019/company-backed-bill-gates-clai...</a><p>Scroll back to 2010, when Bill Gross started working on this. That's when he got funded by that dude whose futurism book about the Information Superhighway, <i>The Road Ahead</i>, didn't mention <i>the internet</i>. In 1995. In 2010, photovoltaic modules cost €1.62 per watt. Concentrating solar power was a promising alternative; it uses the same steam engines used by coal and nuclear power plants, so at scale it should be just as cheap as they are, as long as you can get the cost of the heliostats under control somehow and scale up. It also didn't have that pesky intermittency problem PV modules have: you can store the heat overnight.<p>Since then, though, heat engines have become economically uncompetitive relative to PV, because PV modules now cost €0.19 per watt, where they've been stuck all year. And steam turbines, almost a century and a half old, aren't improving or getting cheaper rapidly the way PV has been. Being just as cheap as coal isn't a blessing anymore; it's a handicap.<p>So, if you've been working on CSP and filing patents for a decade before getting your pilot plant up and running, a decade during which the PV market has left your product's price in the dust, what do you do? You look for a possible use where CSP is still viable, such as process heat; you hire a good PR firm; you announce that you won't be building any plants, but you're "willing to partner with" companies that want to build your design; and you hope to God nobody says "Solyndra".<p>But what's the actual invention? It seems like the actual news is that Bill Gross has patented some aspect of his closed-loop control system using webcams and GPU-accelerated CV to figure out where the mirrors are pointing to improve your concentration factor. The key improvement that made it possible was better GPUs, according to the press release, anyway.<p>So what happened, from the point of view of anyone outside Idealab, is that now Idealab and Intellectual Ventures will sue you if you do this fairly obvious thing of using high-resolution webcams for precise heliostat control.<p>So, when would this be a sensible thing to do?<p>Trombe's solar furnace and similar devices are able to compete quite effectively in the "market" for process heat at the 2500–3500° level, since, as I said, 1949. (I guess Bill's PR firm didn't know this, or hopes you don't.) That's a level almost impossible to achieve using fire (oxy-acetylene burns at 3500° under ideal conditions), and difficult even with arc furnaces. But Bill's thing is designed for a more prosaic 1000–1500° level, where it's competing not only with fire but also Kanthal or SiC fed from PV, wind, hydro, and nukes, as well as induction, dielectric heating, and microwave heating.<p>The potential advantage of CSP for process heat at these lower temperatures is that it's cheap and abundant. If you fill a field with mirrors, they can harvest 6× as much power than PV modules covering the same field can. But if land area is your limiting factor, your cement plant or steel mill or whatever probably isn't in the middle of a big field; it's using a lot more energy than your land receives in sunlight. In that case, you probably want to pull your power from someplace further off, whether in the form of coal, oil, gas, biomass, or electricity. Probably electricity from PV panels if we're talking about anything post-2030.<p>But suppose you <i>can</i> put your factory in the field where the mirrors are, and the limiting resource isn't land but money. In that case, it might be a reasonable approach. PV modules cost €30 a square meter now. That's probably more expensive than mirrors, if you take into account that mirrors give you 6x as much energy: €180 per square meter is the price mirrors have to beat, and that seems doable.<p>But now you are on notice: if you do that, make sure it's in a country where Intellectual Ventures's shell companies haven't gotten a patent on it, or you have to deal with patent trolls. The press release reprinted above is clear: as with IV's laser mosquito swatter, they aren't going to make it happen themselves, but they'll definitely "partner with" you if you try.<p>I think we're about to see a giant boom in shitty "do well-known thing X, but with computer vision" patents similar to the shitty "do well-known thing X, but on a computer/on the internet" patents that plagued us in the early 2000s. The availability of massive GPU power means that many things that used to be impractical to do with video data have become possible.