But aggressive depreciation of hardware is in part a function of how much the electricity costs. If you're running off what is in effect "waste", then that would change the amortisation significantly.

May well be that it won't change the cost structure enough - I treat this as the president deciding an announcement like this, which amounts to little more than "I've asked them to look into it", as a way to get some publicity. It could very well end up being silently put aside if the costs don't stack up.