Board Thread:Questions and Answers/@comment-137.200.0.112-20180509190813/@comment-454133-20180509200328

You keep your unspent energy each round, so even though your slowest maneuver only produces 3 energy, if you have 1 or more saved up you'll reach the cap at 4.

Also some cards can generate extra energy, or have it in reserve for when you need it.

Also some titles will change your energy cap.