There are other not so obvious ways in which we use fire. Such as what? you ask. Well where does your electricity come form? No you can't just say "electricity comes from those little wires running into my house". Those wires go somewhere and that's where the use of fire becomes important. It turns out that the vast majority of the electricity produced in the United States (and throughout the world) comes from burning something. In the U.S. the "someting" that is burned is usually coal, oil or natural gas - fossil fuels!! So how does it work? The heat produced from burning something is a form of energy and electricity is also a form of energy. The trick is to be able to convert one form of energy into another form.
To make electricity, the heat from burning something is used to heat water and make steam. The expanding steam can be used to move things like the blades of a turbine. The turbine turns a shaft holding coils of wire that sit inside a magnet. The moving coils of wire inside the magnet produce an electrical current - electricity!! This device is an electricial generator. The diagram of a simple electricial generator is given here.