You're right, I was not factoring in the effiency of the generation process. 100 W is definitely moderate or higher for most people.
This was the first time I had seen a cycle desk and I find the idea really interesting.
Having done a little more reading on the subject, my sense is that you may have a better handle on the ergonomics than the existing cycle desks on the market. It seems like most people are using cycle desks to do a pretty limited amount and type of work while doing a short workout, whereas you are using it for a long time each day, which I imagine means you can do most types of work comfortably.
If that's true, and it's true for a sizeable number of people, not just you, I think that's what I would focus on.
Are the other people for whom you've built one able to use it as much as you?