Turn Heat or Weight into Power

I have been given a mind that asks questions constantly. Not many of us would ever think to ask if heat or pressure could be turned into electricity. Both of these are very large store houses of energy.
How do we produce heat? We cut down trees and haul the firewood. We dig the coal and put into the furnace. Likewise, we drill for oil/gas to make gasoline, diesel or propane/LNG. We put the nuclear rods together to make steam to make electricity. All of these are labor intensive and require moving giant amounts of stuff around to make our heat. Even our own bodies need lots of food, water and shelter to keep us going. We are fortunate that our civilization/technology has made it so easy for us to enjoy this bountiful heat. My point is that our heat is a store of large amounts of effort/work; heat is a very dense form of energy.
Pressure is very similar. Anything that we pick up and carry takes effort. We have many things to help us move and carry things; some are very heavy and require trucks and ships. To make a building, we bring in concrete to pour a slab; got to have the foundation. Then, there is the steel or wood; it must be manufactured and shipped in.
My point is that anything that is heavy takes a lot of energy to get that way. Think of a tree; a mighty oak from an acorn. So, pressure is also a very dense form of energy.
This is obvious, but most of us do not think this way.
By asking the questions, can heat and/or pressure be turned into electricity, you are reading about this now.