Roughly 68% of the universe is dark energy. We know this because it affects the universe’s expansion by making it larger. The idea behind this is that the universe is getting bigger at a rapid pace because it seems that other galaxies are moving away from us in quick succession.
Normal energy is the ability to do work or the influence required to perform an action. Basically, no these two types of energy cannot be converted to each other because they act as opposites yet require the other one to exist in a stable form.
Dark energy cannot be turned into regular energy because they are opposite forces in the universe. Not a lot is known about dark energy and astrophysicists are still trying to figure out what the purpose of dark energy is in the universe.
We know that dark energy and regular energy occupy the same space. There are some theories that dark energy and regular energy need each other to exist in a stable way. There is no way to harness dark energy yet so we are unable to study the properties.