Abstract : It has been known for many years that the lower chromosphere can be heated by the shock dissipation of acoustic waves. They can not be responsible for heating the upper chromosphere though because the energy is completely dissipated lower down. Various mechanisms for heating the upper chromosphere have been proposed, and many of them use Alfven waves as the mechanism to carry energy into the upper chromosphere. The question is how the energy is dissipated. Based on high resolution 2D MHD simulations the possible dissipation mechanisms are considered, coming to the conclusion that the primary heating mechanism is likely to be the dissipation of ponderomotively generated slow shocks.