Use of power / authority is very common at work space. Compelling subordinate to do a task out of their job description and firing them in case they fail to do so is use of power. Same is mentioned in the question statement that Marietta's boss may fire her for not doing something which is not in the job description.
Geothermal energy is the energy given off by lava or magma. And since it is heat energy inside the earth it makes sense that it would have an effect on the environment