when you conquer sigil of the storm, it says recycle 1 power. when you do this, can you still gain the power from recycling? or does it cost 1 power?

No — the recycle doesn't give you Power, and it doesn't cost Power from your pool either. Sigil of the Storm says "recycle one of your runes," not "pay 1 Power" — it's a required effect, not a [C] payment.

Power only enters your pool when you activate a rune's own "Recycle this: [Reaction] — Add [C]" ability (Rule 164.2.b). Sigil's recycle is a separate instruction, so the same recycle can't both satisfy Sigil and produce Power. The rune just goes to the bottom of your Rune Deck (Rule 416).

What you can do: tap that rune for [1] Energy before Sigil's trigger resolves, and keep that Energy floating for the rest of the turn (FAQ 2810). And if you have no runes at all, the trigger resolves and simply does nothing (FAQ 6863).