When we talk about learning robotics there is no clear line as from where robotics starts, robotics is about automation of any process where human judgement can be simulated by a machine logic. So starting off with robotics is not really a defined line, most hobbyists that make autonomous bots are having a long history of tinkering around with basic electronic circuit, basic mechanical designing, types of motors, etc After the basic knowledge about electronics a familiarisation with basic IC's drivers and sensors. Now after playing around with all this one can get on microcontrollers basics to learn to program it, understanding memory, register, etc. It gave an overview of the process and skills that a robotics hobbyist is most likely to have in general, coming to the point of what is the eligibility, the answer is as we need to learn many basics and these basics can even be practiced as early as a 9 - 10 yr old. The road to the actual learning is fueled by interest and driven by the passion for learning, this whole thing is fun. To start off as a newbie it can be more fun by start learning basic electronic and very general DIY projects no need for classes.

Geothermal energy is the heat inside of earth, earth has molten high temperature core, we use this huge amount of heat to harness energy in a usable form for us. We usually use this heat to convert water to steam then run turbines with the high pressure steam and get electricity. This is how we use geothermal energy. GEO is Earth, THERMAL is heat.