Well, I wouldn't call it simple. The term to google for is hydrocracker or cracker in general (uh, cracker in petroleum chemistry, specifically). For the first 50 years or so from 1890 to WWII they only did it thermally and since WWII its been all about exotic catalysts.

Its not viable to thermal crack other than weird situations (Like I don't care if its net energy positive, we need feedstock to produce methane to produce ammonia to produce fertilizer so if you want to eat next winter, get crackin' today said the Kaiser to .. somebody .. in WWI). If its ridiculously expensive to thermally crack and crude is cheap, its simpler to just refine more crude and kill the market price of asphalt by dumping it on the market. So thats how we get blacktop roads, which seems to be a stupid use of valuable crude, yet... So this is a gross generalization but you can't thermally crack as a primary energy source, you've gotta cat crack. Unfortunately catalytic cracking is still something of an art or craft rather than a science because its horrifically complicated. Since day one there has been slow continuous incremental improvement, to the point that in 2010-ish its finally reasonable to finally start cat cracking algae on an industrial scale, or at least kinda sorta.

The problem with cat cracking is the catalysts are sensitive to trace contaminants so just pitching in crap from a field is an excellent way to destroy the catalyst. It is almost exactly like how carbon monoxide kills people, in that "stuff" gets stuck in the important parts which jams the whole works up and then nothing works ever again. On the other hand algae grown in glass tubes can have all its inputs controlled to not destroy the catalyst... more or less... plus or minus required trace elements... some of which kill some catalysts...

The best HN analogy I can provide is its kind of like 3D FPS games in the early 90s, no one suddenly shockingly invented out of whole cloth "the 3d chip" and that's how we got endless WWII sequels, its more like the smooth and gradual ramp up in performance from 1800s punch card unit record equipment up to the present day, where a phase change or whatever happened in the market in 1990 where suddenly the state of the art in 1990 made 3D FPS video games a reasonable application. But nothing really "new" happened in 1990 other than a century of computational performance gains continued as usual. Its the market that shifted after a certain performance level was achieved.

True, you can point to the days before and after the bipolar transistor demonstrated amplification and say the world changed on a certain date. But smooth growth in computer performance or cat cracker performance means there is no such sudden change date for FPS video games or algae based feedstock for hydrocrackers. And thats why we've been hearing about algae crackers as a "new" thing for about two decades and probably have to keep hearing about them being "new" for at least another couple decades because it becomes commonplace for people to run their cars on algae based biofuel.

The difference in the situations makes it an interesting HN topic more so than the trivia about someones recent lab experiment.