[fulafel]

Incidentally, this is close to how it works (at least around my part of the world) when you as a residential customer choose to buy solar/wind generated electricity. The retail electricity providers sell you electricity from a spot market (see https://en.wikipedia.org/wiki/Electricity_market#Wholesale_e...) and you pay the local power comapny to send you the electricity over the national grid.

BTW there's a big difference here between GW (power) and energy - do they contract 3 GW 24/7 or are they buying 24*3 GWh per day whenever the spot prices are lowest, or are they paying companies to average 3 GW per day over a multi year contract? In the first scenario there will be surplus over 3GW for most of the day.

[allenz]

3 GW measures average power. Google just buys the entire output of wind or solar farms, so supply is not matched with demand.[1] This is a known problem with renewables. Elon Musk claims that he can solve it with a relatively small area of batteries like the Powerpack, but he's sold less than 1 GW so far because batteries are expensive.

[1] https://environment.google/projects/announcement-100/

[fulafel]

I guess that accounting is natural for marketing numbers.

I don't generally think it's a problem, it's just a feature of those generation methods and just means we need overprovisioning. Whereas fossil fuels have unsurmountable problems and cause untold human suffering, famines and damage to the environment.

[allenz]

I think that Google has made a fantastic step forward. However, solar and wind require some form of energy storage, such as pumped hydro or batteries (which Google hasn't addressed). Overprovisioning by itself isn't sufficient.