While the green angle on this story is definitely good to highlight, I wonder if they're seeing any cost savings too?
Solar and wind on the grid increase supply, which should drive down price per KwH (of course, the equation isn't quite that simple, since demand in most of the world near human population centers is also highest during the day).
I don't think the electric grid follows a traditional supply-and-demand curve. Every kilowatt used must be generated at the same time. Generation comes in tiers: cheap baseload (coal or nuclear, each with their issues), expensive peaker plants (nat. gas), and cheap but unpredictably intermittent renewables. Prices are highly regulated and agreed to in long-term contracts that take into account peak usage and minimal generation capacity. If demand increases, it is really expensive to supply until the level is enough to build a new baseload plant, but even those are expensive now.
Big users such as Google with its datacenters will of course negociate their own electricity contracts. I think renewables are the cheapest to buy right now, so by moving load around to be able to maximize use of cheap renewable electricity, they will definitely save money.
I think this has very little to do with a carbon tax and everything about external and internal marketing. They are committed to using renewable power.
Solar and wind on the grid increase supply, which should drive down price per KwH (of course, the equation isn't quite that simple, since demand in most of the world near human population centers is also highest during the day).