Bond energies at Inveraray

Looking at the supermarket trolley stack at Inveraray, it finally occurred to me that this is a good analogy for calculating bond energies in Chemistry. I teach that energy is needed to break bonds and that energy is given off when bonds are remade. So I put in money to break the chain and get a trolley but I get money back when I remake the bond between the trolleys. The view was better round the corner though...