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    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.

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