I shouldn't have used "sunk cost;" I should have said "fixed cost."
Google builds datacenters to N-year-long plans that are expensive to modify. Whether they're running their batch jobs on solar energy or coal energy, the carbon footprint of the datacenter build plan is not going to change. They want those datacenters anyway (mostly for the non-batch work and whatever the next big thing is that hasn't been invented yet but can only be done by putting a beach's worth of thinking sand on the problem).
Google builds datacenters to N-year-long plans that are expensive to modify. Whether they're running their batch jobs on solar energy or coal energy, the carbon footprint of the datacenter build plan is not going to change. They want those datacenters anyway (mostly for the non-batch work and whatever the next big thing is that hasn't been invented yet but can only be done by putting a beach's worth of thinking sand on the problem).