[natas]

It's a good idea, but it's probably cheaper and, from an ecological standpoint better (than e-waste) to sharpen knives; a top-quality professional electric knife sharpener will set you back $170 and last you a lifetime; which is a third of the cost of the Ultrasonic's knife. Cool idea though.

[ahofmann]

I don't get it. How is buying a "top-quality professional electric knife sharpener" more ecological than buying a knife with a bit of electronics in the handle? Both are used by one person in your proposal and I would think, that it needs more energy to build the sharpener.

[AgentElement]

One does not even need a top-quality professional electric knife sharpener to produce an edge for kitchen work. An inexpensive 1500 grit whetstone suffices.

[natas]

yes, you are right. Basically $15 is all you need, and certainly better for the environment.

[samuli]

..and if you don't like sharpening knives, you can buy a serrated vegetable knife for cutting fruit like tomatoes.