If you have a DOE Q or L clearance, you know you have it. It takes a long time to get it. You have to be working in a job that requires it. When you leave that job, your clearance goes inactive unless your new employer picks it up. If it is picked up it is because the new employer put you in a job that requires it.
People with Q clearances are in high demand due to the length of time it takes to get the clearance (1-2 yrs). Unfortunately, you cannot start the process yourself.
These clearances are different from power plant clearances and DOD clearances, although the paperwork looks the same for DOD and DOE.