I think its practical and Andy Prokopyk took a page from the recyclable or renewable energy playbook. The heat of the ASIC miners that could have gone to waste is being captured and utilised here to keep the pizza warm, Im guessing this will be able to warm some other fast foods or snacks.
Hello..... Practical in what essence? It's nothing really more than a fun project based off the concept mainly. If I had to warm my pizza I'd use the microwave... Besides I don't think you have this particular device in your home but I'm pretty sure you do have a microwave. So like a said the idea doesn't fix any problem but it's a fun project regardless..
This is really creative stuff he did here, Im just marvelling at the engineering he used to get this done.
Lol... The creativity here is from the idea not the engineering..... I don't think there's any major breakthrough here though the process is just basic heat transfer by conduction probably little convection.