The law of conservation of energy states that energy cannot be created it can only change state. If that is the case then where does our energy come from?
Gravity is harvested every day in many forms. Hydroelectric power is generated when water travels down hill pulled by gravity, changing into kinetic energy. This kinetic energy is harvested by turbines and generators that transform part of that kinetic energy into electricity. Much geothermal energy is also a result of gravity pulling matter together and compressing it until it is transformed into thermal energy. Geysers and hot-springs are a very harvestable form of this energy. Notably deep sea vents driven by this geothermal energy are the only locations known on earth that colonies of animals, plants, prokaryote, and protists thrive without access to energy from the sun. Even wind power which we will touch later is derived from gravities effect on the atmosphere as it is acted upon by the sun's thermal energy.
Solar energy wraps up just about every other kind of energy we encounter. Our food chain, fossil fuels, and even wind energy are all driven by that giant burning ball of gas that we know as our sun.
Plants convert sunlight into energy using photosynthesis. Herbivores and omnivores eat the plants and store that energy in their tissues. Omnivores and Carnivores consume the flesh of other animals and store that energy in their tissues. all of those animals transform that energy stored in their tissues into thermal energy to keep them warm or kinetic energy to continue their fight for life. Food energy that the animal doesn't use is passed on in the form of waste where protists, prokaryotes, and fungi break them down further into kinetic, and thermal energy. A few animals actually turn the energy into electric and other forms of energy.
Fossil fuels are these same plant and animal energy broken down by protists, prokaryotes, and fungi, heated by geothermal energy and stored over hundreds of thousands of years like batteries. And just like the battery in your favorite electronic devices, they have a very finite amount of energy and then they are used up, unlike your ipod, these batteries cannot be quickly recharged by plugging them into your computer.
Wind energy is caused by the sun heating the atmosphere which converts that thermal energy into kinetic energy as they rise or more specifically are pushed up by the denser air around them which is drawn down by gravity. As this air absorbs thermal energy, expands and contracts and is pushed around it's kinetic energy can be harvested by turbines and converted into kinetic energy.
So, where does our energy come from? Gravity compresses items until they give off thermal energy in the form of geothermal energy from the earth or thermal energy from the sun which then are converted into all other forms of energy that we know of.
