Gold seems to be the least worst thing to hang on to for a central bank. Funny that it is rarely used as cross border settlement, and is rarely verifiably audited.

I guess the only metric to assess whether you'd trade energy reserves for something else, besides central bank holdings of gold, would be state-owned bank loans, which everyone is fudging fast as they can.

Otherwise why would you sell energy for paper? Better to trade/sell energy for tangible goods and commodities.