"What does "net zero" mean ? "
Net zero means, that you can have emissions, as long as you also have sufficient greenery, which absorbs it, so they balance out.
If we shut down half of our industry and plant trees in their places, we will be doing just fine, according to Kyoto.
Of course Kyoto also says that countries like China and Russia do NOT have to control their emissions, because they are "developing nations", so we need to cut back more, to make up for their pollution.
The problem is that power demand and solar/wind/hamsterwheel power production don't match, so Seattle uses regular "dirty" power to make up the difference, then dumps excess "clean" power into the system whenever possible.
This is, of course, nonsense. They're trying enjoy the benefit of dirty power plants (power whenever you need it) and also claim the moral high ground (we don't increase emissions).
I seem to remember hearing about some city "buying credits" from somewhere else.
I'm not sure about this, but perhaps someone else knows something else about it.
Low cost internet access - don't you read the ads.
Maybe they're doing some sort of carbon sequestration program. I would be curious to know myself.