Heat can't be converted losslessly to useful energy, but converting to heat to other forms of energy is extremely common. What do you think a steam turbine, boiler, internal combustion engine, etc. do?
But all the examples you give have a heat source of high temperature and dense energy, and a lot of energy is lost in it's transformation, as illustrated by the combustion engine. How can heat be a good energy storage if so much is lost when you want to use it?
But all the examples you give have a heat source of high temperature and dense energy, and a lot of energy is lost in it's transformation, as illustrated by the combustion engine. How can heat be a good energy storage if so much is lost when you want to use it?