To cut this short and for your understanding, ionic bond is formed between metals (mostly right column in periodic table). Covalent bond is formed between non-metals (mostly left column in periodic table). So polar covalent is also a covalent bond but it is polar, which means the shape of molecules are not symmetrical hence maybe an atom in a molecule has most of the electron attracted to it causing itself to be partial negative (since electron are negatively charged) and the other atom has its electron being attracted by others became partial positive. Polar covalent can also be when H atom is binding either to F, O or N (also known as hydrogen bond).
Energy that comes from the heat of the Earth's core is known as geothermal energy.
Solar energy comes from the Sun, hydro energy from water, and wave energy from wind and waves.
Hydroxide ion is a strong and would react with H+ to form water
OH-+H+---->H2O
Fusion occurs constantly on our sun, which produces most of its energy via the nuclear fusion of hydrogen into helium. Neither do fusion reactions produce the large amounts of dangerous radioactive waste that fission reactions do. That's why it's such a dreamy source of energy.
