One of the AI players was short on energy for the last 4-5 rounds. My buddy and I were selling some of our excess at over $100 per energy, but the AI player didn't have enough cash to buy all he needed.
But to your point, collectively there was a surplus of energy being produced, but none was sold to the store. I guess the game must just use the over all production and demand numbers to set the store price, not what energy is actually trading for amongst players.
That's because the current version of the game is not doing post-auction valuation like the original is.