alt Hacker NewsIt's just carbon neutral, not "technically" carbon neutral.
The reason we even care about CO2 emissions is that industrial emissions reconnect carbon reservoirs that were disconnected from the atmosphere for millions of years, i.e. underground oil, gas and coal deposits, back to the atmosphere. Not that CO2 in itself is harmful in any way.
The fact that we have ~8 billion people now vs ~1 billion in 1800 does make a difference to the equation, in terms of our own respiration and not just our deliberate use of fossil fuels. Admittedly it's minor, and I don't know what's happened to other biomass in that time. But still. The point is: having people eat more so that they could pedal a stationary bike hooked up to an electric generator, would not give "clean" power at the margin.