字幕表 動画を再生する 英語字幕をプリント Who of us hasn't left the TV on, even though we are not watching? Who hasn't left the lights on, even though we are not in the room? Nowadays, electric power is regarded as a common commodity. Just as the sun rises every day, we believe that electricity simply is there. Electricity appears to be a straightforward issue. You press a button and we have instant electricity. It's as if it's hidden in the socket. But is this really how it is? Just one look out of the window reminds us that Electric power comes from somewhere. It travels along the cables on the pylons of the Hellenic Public Power Corporation. If we follow these cables, we might be able to discover where it comes from. In Greece, the largest amount of electrical power is generated in Western Macedonia. Six in ten houses get their electricity from the electric power stations in this area. Western Macedonia is the heart of electrical energy in our country. Let's look then at how electrical energy that we take for granted, is generated. In Western Macedonia, there is a large quantity of coal known as lignite. With the use of large machines it is mined from the ground. Some of the machines are taller than an eighteen-storey building and weigh more than five thousand cars. After lignite is mined, it is taken to the electricity generating power plants on conveyor belts. In all of Western Macedonia, there are 270 km of conveyor belts. This is one and a half times the distance from Florina to Thessaloniki! When the lignite arrives at the station, the process of energy production begins. First, it goes into a furnace burner where it is burnt. From the combustion, smoke is produced which escapes through the stacks of the power station. The burner generates heat which heats up a large water tank known as the boiler. The water that is heated in the boiler becomes steam. The high pressure steam goes into a turbine. The turbine has large bladed rotors, like the sails of a windmill which pushed by the steam, rotate at a high speed. In turn, these bladed rotors activate a magnet that generates the electric current. This magnet is part of a device known as an electric generator. Lastly, the steam is separated: Some of the steam is distributed to the surrounding cities and villages via a network of pipes to provide heating. This process is known as district heating. The remaining steam cools and condenses into water and goes back to the boiler for reheating. Steam is used for chilling by spraying the pipes which convey it with water. The water evaporates and is released into the atmosphere through those characteristically large, thick cooling towers that appear to be forming clouds in the sky! Combustion, steam, turbine, electrical generator, electricity. Once electricity is generated in the power plant, it is distributed all over Greece through cables, which are found on the transmission line towers. It is through these that it arrives in our houses. Highly-trained personnel are involved at every stage of the process of generating electrical power. When at some point a conveyor belt tears, the welders are called in. They join additional pieces onto the conveyor belt to make it operate again. When a machine breaks down, the electrician fixes it. Thanks to them, the machines in the plant operate like clockwork! The Rope Access Technicians work is very difficult. They climb the electric power pylons to fix them. They change the destroyed cables and join the cut ones. They undergo special training in order to climb the pylons safely. Apart from all the highly-trained personnel, there are also the machine-operators, the excavator drivers, and the technicians. All of these people work hard so that the power plant operates non-stop the whole day. We saw that in order to have electrical power in our homes, hard work is required by both people and machines. However, the generation of electricity also affects the environment. When lignite is mined from the ground, the natural landscape is destroyed. When lignite combusts, the air we breathe is polluted. The towers that transmit electric power to our homes are dangerous at close distances. Furthermore, at some time the lignite resources will finish. We estimate that up to now half of the reserves in Western Macedonia have been used up. This means that in a few years from now we will run out of lignite. We have already started using other sources of energy such as, the sun, water, wind and waves. Definitely, the sun will be around for many years, rising daily without our help. In contrast, electric power generation, as we have seen, is a most demanding process. Each time we press a button, let's not forget the long journey made by electric power to our homes.