In Mexico we use 110 volt electricity in our homes, but in industry and other activities are used, in certain cases, 220 volts and even higher voltages to move large equipment and machinery. In European countries typically use 220 volts for all electrical household appliances. How they are measured and weighed the things that we use or consume normally, also electric power is measured in Watts-time. The Watt is a unit of power and is equal to one Joule per second. For practical purposes, our electrical energy consumption Bill we charged for the amount of kiloWatts-hour (kWh) that we have consumed over a given period (normally two months). A kiloWatt-hour is equivalent to the energy consumed: A focus of 100 watts on for ten hours 10 bulbs of 100 watts lit for an hour an iron used for one hour a TV on for twenty hours a small refrigerator in a day a computer used a little more than 6 hours and half remember that kilo means thousand, so a kiloWatt – hour is equivalent to thousand Watts-hour. Used in the fields of generation and consumption of electricity, the megWatts (MW), equivalent to millions of Watts; the gigWatts (GW), billions; and the terWatts (TW), trillions of Watts). How is electricity generated? So far we have seen that electricity flows through cables, usually of copper or aluminium, reaching our lamps, televisions, radios and any other device that we have in house. But how electricity is produced and from where comes? We see, therefore, how to generate the electricity we consume at home, but first is convenient noted that there are several sources that are used to generate electricity: the movement of water that runs or falls, heat to produce steam and move turbines, geothermal energy (the heat inside the Earth), nuclear energy (of Atom) and renewable energies: solarwind (of the winds), and biomass (wood, coal, trash and stubble of the) field).