Part of the point of NFV is the lower power use vs. the current state of equipment. How is this done?

in the first paper on NFV here is the part that explains how the power savings will be achieved.

Reduced energy consumption by exploiting power management features in standard servers
and storage, as well as workload consolidation and location optimisation. For example,
relying on virtualisation techniques it would be possible to concentrate the workload on a
smaller number of servers during off-peak hours (e.g. overnight) so that all the other servers
can be switched off or put into an energy saving mode.

The number of telecom equipment that goes into lower power mode is probably amazingly low.

Besides saving power this same feature makes it easier for maintenance operations.

Option to temporarily repair failures by automated re-configuration and moving
network workloads onto spare capacity using IT orchestration mechanisms. This
could be used to reduce the cost of 24/7 operations by mitigating failures
automatically.