>"1 square mile is available but not 4 square miles" (this is a different sentence than "there is not enough space").

how are these different? one is an example, one is general, but they communicate the exact same point. if you have something that requires 4 sq. miles, you cannot fit it into a place that is 1 sq. mile in size because there is not enough space to fit it.

>as they are still more compact per GWh.

i am really struggling here... if i cannot fit something large, whether the large thing is "more compact per GWh" does not matter. i only have so much physical space to work with. if its too big, its too big.

for a more easily visualized example, you cannot fit a reactor from three mile island into a submarine. efficiency doesnt come into the equation, because physical space constraints get in the way first.