I am no expert in science but basic rational suggests that you cannont achieve more than 100 % energy conversion rates.
Btw the foumula you given above is just a basic formula to measure efficiency it doesn't suggrst that you can achieve more than 100 % efficiency in energy/mass conversions.other experts can better expain it i guess.
Neither am I. I am a science enthusiast, though.
The basic formula of calculating efficiency is the ratio b/w output to input multiplied by 100. The ratio will always be less than 1, so efficiency is always less than 100. Forget it, even the most of those claimed efficient engines only convert 30% of initial energy to work.
Anyway, what looks somewhat appealing in the above case is, he is not literally generating electricity, he was somehow able to convert the initial supply to extricate energy stored in isolated electrons in the vacuum.
The facts are
1. There are electrons in the vacuum that store considerable energy.
2. It is possible to manipulate them through electric or magnetic fields.
3. He didn't break any law then.
The fiction is
1. How he was able to extradite the energy of the electrons