"Given level of power" is meaningless for data centers. If they can get 50MW of power, they'll obviously try to use it as efficiently as possible to generate as much compute/value.

But that's not what anyone means when they're talking about sustainability for data centers in terms of power usage: they're either talking less power (ie less value) or power from renewable sources, which can't compete with sources like gas turbines across a mix of setup time, consistency, and power/$.

If solar and batteries were available sooner than gas turbines, GE wouldn't have a multiyear waiting list. If solar/batteries were cheaper than gas turbines after accounting for land/permitting/maintenance, every DC would be buying the empty land next to them for an eventual switch to solar. Notably these many-million dollar investments aren't doing those things, and I guarantee you they have tried every angle imaginable to get power to the DC as quickly and cheaply as possible.