> It requires less maintenance (no moving parts)

They are no rotating parts, but some parts are moving.

see here: https://vortexbladeless.com/technology-design/

I'm skeptical about the cheaper per KWh. A 100W conventional turbine can be purchased for around $200 and has 3 blades around 50 cm in length. The 100W vortex device is 2.7m tall and I doubt can be purchased for less than $600 since the structure is much wider and weighs around 3 times more. 14kg vs 5kg for a conventional turbine.

A 100W conventional turbine also only has a couple of moving parts, won't kill birds and is effectively silent. I'm unsure on wether these claims are still true as the device scales up. A device 100m or so tall will have a fast velocity at the tip perhaps as much as 50m/s at a few Hz which is similar to the blade tip speed of a conventional turbine thus having similar potential to kill birds and make noise.

While I also doubt their claims - the price you want to look at is :

(purchase + installation) / average_life_span + maintenance per time unit

So, even at triple the cost it could still be worthwhile.

> It's silent (no frequencies >20 Hz)

I hope there also isn't much noise below 20 Hz, as infrasounds are uncomfortable and potentially dangerous.