Describe a process in which energy changes forms at least twice. are there any unwanted forms of energy that are produced during the energy transformations?

Heating your food on a gas stove.

The thermal potential energy within the flammable gas is released due to the electric spark that is produced by a voltage or potential difference if automated. And if manual, a spark ignites the flame due to friction of abrasive metals releasing ionic bonds and creating a spark. The flame heats the underside of the pan and trasmit thermal energy to heat increasing temperature and therefore unlocking the potential energy of the food into thermal energy. and so on.