index > Today's Earth, Our Future > 5. Clean energy > Do You Know How to Produce Electricity?
 
Do You Know How to Produce Electricity?Making electricity is called "power generation." Ways of generating power are roughly divided into four types: 1) Thermal power is generated using steam from water boiled by burning oil and coal. As you may know, oil and coal are fossil fuels, so the thermal power generation emits the greatest amount of carbon dioxide (CO2) of all types of generation. Also, if the power plant is too old, it could leak harmful chemicals. In order to reduce the emissions of CO2 and other hazardous chemicals, people make various efforts, such as using natural gases instead of fossil fuels and improving the facilities of the power plants with new technologies. 2) Hydropower generation uses energy from water, so that it doesn't emit that much CO2. However, building dams (strong walls across rivers to stop the water from flowing, especially to produce electricity) in the mountains damages the surrounding environment. Major rivers in Japan already have so many hydroelectric dams that more and more people think that there are enough. Nowadays, what draws an increasing interest is a "micro-hydropower system." It generates electricity by making use of the head drop (the difference created when water can fall from a certain level to a lower level) in agricultural water supply and sewage treatment plants. Japan has thousands of possible locations available for micro-hydropower use. 3) Nuclear power generation makes electricity with the heat produced in uranium nuclear fission. It doesn't emit CO2 as nothing is burned during the power generation. (Of course when nuclear reactors are built or dismantled, CO2 is emitted.) It is said that uranium can be found throughout the world and will never run out. So, unlike petroleum, we don't have to depend on its supply from a limited number of countries.? On the other hand, however, it also has some problems: the raw material concentrated uranium requires to be treated with the greatest of care, we don't have a concrete answer to how to treat nuclear waste which emits radiation, and concerns about safety still remain since our world has experienced nuclear power plant accidents. Just because nuclear power generation does not emit CO2, we cannot say yes to it, can we? In fact, almost all countries in the world are planning to stop constructing new nuclear power stations, or to decrease the number of plants. Today, around 50% of the electricity used in Japan is generated by thermal power, about 33% by nuclear power and 8% by hydropower. Meanwhile, renewable power generation that uses solar power, wind power, geothermal power and so on produces only a small amount of electricity at present. The ratio of the types of power generation differs from country to country. Even within a country, the ways of power generation have changed according to the policy or the technologies and resources that can be used at that time. This means we can change the types of power generation if we want to. 4) Compared with thermal power and nuclear power generation, renewable power generation using natural energy sources (such as solar, wind, wave and tidal power, as well as biomass and geothermal heat) is rather new. Japan has just started using them although renewable power generation produces a high proportion of the total electricity in some countries. We will introduce you "rookie players," who are expected to play key roles for stopping global warming in the following sections.
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   5. Clean energy
   
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