The times are changing – the world is changing
What is energy? It’s a power (ability) to do work. Energy makes everything go. There are many forms of energy, such as mechanical, heat, gravitational, chemical, electrical. We need energy enough to keep development of industry. Each type of energy comes from a power source. There have been invented several types of power stations. Thermal power stations pollute the air, release smog, oxides of sulphur, oxides of carbon. The main source is coal. Today the power plants must use soft coal often contained with sulphur. When the smoke from this coal is dissolved (rozpustit) by precipitation (srážky), it results in „acid rain“. Burning coal products carbon dioxide as well, which can act as a blanket, trapping solar heat in our atmosphere.
This could contribute (přispět) to global warming, the greenhouse effect. Coal also contains a surprising amount (množství) of radioactive material. Indeed, a coal-fired electric plant spews (vyplivne) more radioactive pollution into the air than a nuclear plant. => disadvantages of coal: polluted air, acid rain, radioactive material. Water (hydro) power stations destroy the landscape, fish can’t get through and there are not many rivers suitable for water power stations. Water power station can produce mechanical and electrical energy. It’s the cleanest and the cheapest practical source of electricity, but there’s no opportunity (příležitost) to dam (přehradit) all rivers. When it is need for electrician, it is no problem to start this plant in few seconds. Wind power is cheap and it could be used as a big supplement (doplněk) of energy, where wind is strong enough. Wind power can be used to turn a turbine to generate the electricity. It’s non-polluting. Oil and natural gas can run engines. It is waste of oil to use it for making electricity.
The reserves are limited and it is very important for traffic. Nuclear power stations are very expensive but they don’t pollute the air. The fuel is used uranium, a heavy metal, which contains a great deal of energy. Now let’s look at the advantages of nuclear power. Many people think that nuclear power stations aren’t safe but nuclear power is secure. The reserves of uranium are inexhaustible. Through a process called „breeding“ a reactor can convent uranium into plutonium on even better fuel. The nuclear power is cheap and clean. If you burn 100 000 tons of coil, you need for the same deal of electricity only1 ton of radioactive fuel. The waste material makes the biggest problem of power stations but nuclear waste is not a technical problem and it is easy to control it. The best place to store it is deep underground, because the Earth provides excellent shielding. The waste is packaged in metal and ceramic containers for easy retrieval (nalezení). As its radioactivity ebbs (úpadek), future generations may want to recycle the unspent fuel. Of course there were some catastrophe – the biggest was in 1986 in Chernobyl.
The system of Chernobyl power station was out of date (zastaralý) but it was functional!!! There was fail of human factor (selhání lidského faktoru). The staffs tested the reactor and therefore they switch off the control security system and now started an unorganised chain reaction…
We must find new sources of energy. The first alternative is sun power (solar power) which give us light and heat energy. Solar energy could be obtained from the sun using orbital stations. But the scientists must find the way, how to transport this energy to the Earth. It is difficult to change it into power we can use, because it is expensive, but energy itself is free. Quite modern are the solar panels. It is some flat (plocha) which absorbs the solar energy and it makes electricity. The biggest disadvantages are that we need great area of solar panels for small performance (výkon) and that it doesn’t work at night and when it is very cloudy.
Other, more exotic energy schemes (plány) would harness (využítí) ocean tides and waves. It seems that it is the most ecological way how to get electricity. Nuclear fusion is the process that powers the sun or heat from the earth’s crust or the sea. But even proponents (míra) admit (připustit) that none of these will become a major source of energy soon.