They claim that "Caltrain is running its service on 100% renewable energy", but they are connected to the same grid as everyone else. It doesn't really make sense to say, half of our electricity is green, so customer X is renewable, but customer Y is not renewable.
Power is pooled. If I buy from a supplier or group of suppliers that (1) procures only from renewable resources (2) isn’t reselling power from non renewable sources, (3) hasn’t sold the power more than once, and (4) is capable of providing my energy demands at any given time, then I am buying green power from the pool. It doesn’t matter if the actual electrons come from Ng or coal because I bought enough for the pool (the electrons I added to the pool will be used by someone else if I am using ng electrons).
Not 100% sure this is how Caltrain works but the fact that everyone is physically using the same pool does not imply that you cannot be 100% renewable if you buy from suppliers to the pool with the above properties.
It doesn't physically, but it does financially. Power generation is not free after all, so any power station, be it renewable or non-renewable, will only be producing as long as people are buying electricity from it.
Out of the 25GW being generated right now only 3GW are renewable. There is a corner where there is more demand from "100% renewable" customers than there actually is available renewable energy. There is no point at which this gets made up.
I’m not sure where your figures are coming from, did you mean at the moment of posting your comment? If you look at the integral over the year, California does decently well[1] on renewables, and the people paying for it help blunt the competitive edge of the tremendous federal subsidies enjoyed by fossil fuels.
Technically it does decently well on combined "non greenhouse gas + renewables." This is a rather self serving categorization of generation sources and might not be what people buying "100% renewable" energy think they're actually getting.
In any case, subtracting Nuclear and Hydro, if more than half the kWh purchased in the state are purchased as "100% renewable", they cannot all be possibly served by renewables even in the aggregate.
The first is that at any given point in time, my instantaneous energy use is offset by renewables.
The second is that over some period of time (e.g., one month) my aggregate energy use is offset by renewables.
The second is MUCH easier. When people say things are 100% renewable, I generally think they mean the second thing. This is a bit of a fudge (not wrong but not 100% level).
Yes, electrons are electrons are electrons. But customer X is paying for the renewable sources and customer Y is paying for the non-renewable sources, so customer X can say that they are renewable.
