What is energy.
    Everything in the universe is either energy or matter. For us humans, energy is the means for doing work. Picking up a book, watching TV or launching a Space Shuttle all needs energy. Without it there would be no life, for all life uses energy.
    Energy, so far as we are concerned, comes from only two sources: the Sun and the decay of radioactive elements inside the Earth. The Sun radiates its warmth out to all the planets, but ours happens to be about the right distance away to be able to support Life. In fact, Life seems to control the temperature of the planet like a thermostat.
    But what about oil, gas or coal, which also come from inside the Earth? They were formed because of the energy from ancient sunshine from millions of years ago driving life on Earth. These have formed 'fossil fuels' or 'non-renewable' energy sources.
    Energy is the power that we use to do things, whether it is thinking about building a ship or actually building it. Building it needs large amounts of energy to power blast furnaces to make the steel, mills to roll it and electricity to weld it to form the ship's structure. That ship, when built, has engines, which push it through the water. Most energy is not available to us in a usable form. We have to convert it into another form to make it work for us.
    Here are two examples: A fast-flowing river is full of energy we can't use. If you dam it and install turbines, you get electricity. Coal is just black rock with one odd property ... it burns. If you burn it, you can warm your home, cook food or raise steam in a boiler - to make electricity.
    Life needs energy. Life's energy is self-perpetuating only so long as there is sunshine. Plants can convert it and store it for their next generation (as in potato tubers, groundnuts, rice or peas). Animals eat the plants or each other, die and decompose, freeing nutrients for plants again. It is a sustainable cycle. For hundreds of thousands of years, humans have merely been a part of this cycle. Then we got clever and discovered that we could use energy other than from our own muscles to do work for us.
    First we discovered that wind could drive our ships and water could power our mills. Later, we found that coal could make heat and steam for machinery. Then came oil and gas and nuclear power, all needed in increasingly large amounts to fuel our endless appetite for being comfortable and doing things with as little effort as possible. So we heat our homes, schools and workplaces in the winter. In the richer countries, most people have a car (or several) so that they can travel about. Transport guzzles huge amounts of energy - all so that we can have goods and services when we want them. Kinds of energy resources. Almost all of the energy we use comes from non-renewable sources. All non-renewable energy sources create pollution, in part due to their extraction from the crust of our planet but mainly from their burning. Only two types exist: the fossil fuels (coal, oil and natural gas) and nuclear fuels (uranium, plutonium and, for the future, unusual types - isotopes - of hydrogen such as deuterium and tritium).
    Fossil fuels are useful to us only because they liberate heat energy when we burn the carbon they contain. "Burning" - combustion - is really oxidation; making carbon and oxygen combine to liberate heat. Unfortunately for us, the principal byproduct is carbon dioxide, CO2. Most scientists believe that this is an important contributor to global warming. The heat from coal, gas and oil we can use either directly or indirectly to raise steam in boilers and generate electricity using steam turbines to drive generators. By contrast, properly managed nuclear fuels liberate no pollution to the atmosphere at all. Accidents are rare in the nuclear power industry but when they occur, their potential for long-lasting damage is horrific. The disaster at Chernobyl on April 26, 1986 was by far the world's worst nuclear accident. Phytoplankton are tiny floating plants called algae. The commonest are golden or brown colored diatoms and din flagellates. Zooplankton are tiny animals, which eat the phytoplankton but are themselves the main food for fish and some whales. Oil (petroleum) and natural gas formed by complex decay processes from microscopic life forms called phytoplankton (phyto=plant) which floated in the world's oceans millions of years ago. Just like today's phytoplankton, they harnessed the Sun to photosynthesis and store energy. When these myriads of tiny floating plants died, they sank to the sea floor and became mixed with muds from distant rivers, and were gradually buried. Over immense periods of time, the soft sediments became ever more deeply buried and slowly hardened into rocks. Heat from the Earth's interior and the weight of the overlying rocks gradually changed the energy-containing substances in the accumulated plants into hydrocarbon liquids and gases. Hydrocarbons are simple molecules made up of carbon and hydrogen atoms joined together in chains or in rings. These molecules, being light and mobile, migrated upwards through the rocks but eventually became trapped beneath impermeable rock structures in the Earth's crust. The oil and gas companies around the world know how to find these trapped reservoirs and release their contents by drilling holes into them. As everyone knows, crude oil and gas from these deposits form the basis for the world's largest energy industry: oil and gas. Much oil and gas production now comes from underneath the seabed. As the technology for extraction continues to advance, production becomes possible from deeper and deeper waters. This means that new oil and gas fields will continue to be found for some years yet so the early forecasts of oil running dry have proved to be wrong. ............