Brunt fett

“The general impermeability of these membranes to H+is key to coupling the catabolism of molecules such as fats to the release of their stored energy in chemical form to make ATP. If the membrane becomes permeable to H+, by insertion of UCP1 in the inner mitochondrian membrane, this coupling is lost and the stored energy is released as heat.”

Jag förstår inte varför fri passage av H+ över membran skulle ge värme?