Energy is the capacity to do work and is required for life processes. An energy resource is something that can produce heat, power life, move objects, or produce electricity. Matter that stores energy is called a fuel. Human energy consumption has grown steadily .throughout human history. Early humans had modest energy requirements, mostly food and fuel for fires to cook and keep warm. In today's society, humans consume as much as 110 times as much energy per person as early humans. Most of the energy we use today come from fossil fuels (stored solar energy). But fossils fuels have a disadvantage in that they are non-renewable on a human time scale, and cause other potentially harmful effects on the environment. In any event, the exploitation of all energy sources (with the possible exception of direct solar energy used for heating), ultimately rely on materials on planet Earth.
Some of the questions we want to answer in this discussion are: What sources of Energy are available?
How do the energy sources rely on resources available on Earth?
Which energy sources are renewable on a human time scale?
Since fossil fuels (oil, natural gas, coal) are our main source of energy, how are they formed, how do we find them and exploit them?
What is the future for our energy needs?
There are 5 fundamental sources of energy: Nuclear fusion in the Sun (solar energy) Gravity generated by the Earth & Moon. Nuclear fission reactions. Energy in the interior of the Earth.Energy stored in chemical bonds.
Solar EnergySolar Energy arrives from the Sun by electromagnetic radiation. It can be used directly for heat and converted to electricity for other uses. It is a nearly unlimited source, it is renewable, and largely, non-polluting.Gravity Generated by the Earth & Moon.
Gravitational pull of the Moon on the Earth causes tides. Tidal flow can be harnessed to drive turbines. This is also a nearly unlimited source of energy and is largely non-polluting.
Combining both both solar energy and gravity provides other useful sources of energy. Solar radiation heats air and evaporates water. Gravity causes cooler air to sink and condense water vapor. Gravity then pulls condensed water back to Earth, where it flows downhill. The circulation of the atmosphere by the process is what we call the wind. Energy can be extracted from the wind using windmills. Water flowing downhill has a result of gravity can also be harnessed for energy to drive turbines and generate electricity. This is called hydroelectric energy. This sources of energy are mostly renewable, but only locally, and are generally non-polluting.Nuclear Fission Reactions Radioactive Uranium is concentrated and made into fuel rods that generate large amounts of heat as a result of radioactive decay. This heat is used to turn water into steam. Expansion of the steam can then be used to drive a turbine and generate electricity. Once proposed as a cheap, clean, and safe way to generate energy, Nuclear power has come under some disfavor. Costs of making sure nuclear power plants are clean and safe and the problem of disposing of radioactive wastes, which are unsafe, as well as questions about the safety of the plants under human care, have contributed to this disfavor.Energy in the Interior of the Earth Decay of radioactive elements has produced heat throughout Earth history. It is this heat that causes the temperature to increase with depth in the Earth and is responsible for melting of mantle rocks to form magmas. Magmas can carry the heat upward into the crust. Groundwater circulating in the vicinity of igneous intrusions carries the heat back toward the surface. If this hot water can be tapped, it can be used directly to heat homes, or if trapped at great depth under pressure it can be turned into steam which will expand and drive a turbine to generate electricity. Energy Stored in Chemical BondsEnergy stored in chemical bonds drives chemical reactions. When the reactions take place this energy is either released or absorbed. If it is absorbed, it is stored in the chemical bond for later use. If it is released, it can produce useful heat energy. electricity, and light. Hydrogen Fuel Cells are one example: A chemical reaction occurs wherein Hydrogen reacts with Oxygen in an electrolyte bath to produce H2O, and releases electricity and heat. The reaction is non-polluting, but currently has problems, such as safely storing and distributing compressed hydrogen gas, and producing hydrogen efficiently.