There are different classifications of types of energy. One is according to the form in which it enters the service of man. The amount of energy is a constant. What happens is its transfer from one form to another with the help of different kinds of energy carriers in the course of different chemical and physical processes. The main types of energy on earth are:
- chemical
- thermal
- gravitational
- kinetic
- electrical
- nuclear
The types of energy are also commonly divided into:
- potential (e.g. any body on the ground, even at rest, has potential energy, the source of which is the Earth’s gravity)
- kinetic (i.e. related to any kind of motion)
Energy can also be:
Primary (coming directly from the source, e.g. sunlight, heat) and secondary energy (arising in the process of transformation of primary energy, e.g. electric energy).
It should be noted that the conversion of one type of energy into another is not a human invention. Such processes have always been present in nature, they are the basis for the existence of all life and the planet itself. Man has only managed to learn the laws by which they develop and tried to put them to his service.
So, for instance, chemical energy arising in the process of consumption of vegetable or animal food by man, in the process of metabolism, is converted into heat, which maintains the temperature of his body, and into kinetic energy, which enables his organs to work and his body to move, again giving energy to nature in the form of heat and chemical processes.
This flow of energy is constant, and until a certain time man was unable to intervene in this process. That changed when he learned to consciously use its sources. For example, the use of steam energy was humanity’s greatest discovery before the invention of electricity and brought about a technical revolution in the 19th century. The thermal energy of burning wood, coal or petroleum products, by heating a boiler of water, was converted into the kinetic energy of steam, driving industrial machinery, steam locomotive engines and steamboats. The era of human impact on the environment began, but the consequences were not immediately clear.
The main types of energy sources
There are several such types, and it is possible that in the course of technological development new ones will be added to them. Their classifications can be based on different principles. The most global of these is the finiteness of the source, or its renewability. On that basis they are divided into two big groups:
- Renewable
- Non-renewable
Renewable sources include:
- Sun
- air (wind)
- water
- gravity
- geothermal sources (volcanoes, geysers and others based on thermal processes inside the Earth);
the planet’s biosphere (as a source of plant biomass)
Strictly speaking, it would be more correct to call almost all of these sources conditionally renewable, because nothing is eternal. The nuclear processes taking place in the sun and in the bowels of the Earth, which today are the most powerful sources of energy, are of course finite. The movement of water and air is only possible with these. The renewability of plant biomass is beyond question. However, for the foreseeable future, in the absence of global catastrophe, these sources do indeed seem inexhaustible. At least as a result of human activity.
With non-renewable sources the situation is quite different. Their depletion through human exploitation is taking place before our eyes. Their main types are:
- wood
- coal
- oil
- gas
- chemical elements that are a source of radioactive radiation
The use of wood has long ceased to be relevant due to the catastrophic depletion of its reserves. The destruction of forests is probably the first significant damage caused to nature by human energy activities. As far back as the 20th century it became clear that the depletion of oil, gas and coal reserves was not only a realistic prospect but also a fairly close one. Some scientists are already trying to calculate exactly when this will happen. Nuclear decay, the basis of nuclear power, remains a viable energy source for the foreseeable future, where sources will not be subject to depletion in the near future. Unfortunately, the current level of technology development and achievements in nuclear physics can’t yet guarantee the full safety of such processes.
It is precisely the systemic energy crisis, as well as the difficult environmental situation, that is causing mankind today to think more and more about a return to renewable natural sources.
Impact on the environment
The encroachment of mankind into the natural energy and ecological systems of the planet cannot but affect the environment. In some places this impact is almost imperceptible, but elsewhere it is catastrophic. It is commonly believed that almost all renewable energy sources are environmentally friendly. That is not entirely true. Yes, most of them are indeed environmentally friendly, and that is their great advantage. Many scientists believe that humanity’s very survival will depend on whether it manages to completely replace environmentally damaging species with them.
The sun, air, gravity and the Earth’s thermal energy are indeed “clean” energy sources whose use is perfectly safe for the environment. However, almost all of them are currently too inefficient to fully replace environmentally ‘harmful’ sources. The future is bright for solar power plants, once people learn how to convert star energy into electrical energy more efficiently, at all latitudes and in all weathers. It should be noted that positive developments in this direction are already underway. Solar panels, which used to be very expensive and exclusive installations for scientific and governmental needs, are now available to the average consumer, who is increasingly choosing this option for powering their homes.
Unfortunately, what has been said about renewables does not apply to hydroelectric and biofuel plants. The impact of the latter is still poorly understood, but there is no doubt that any human intrusion into the biosphere which disrupts the natural bio-balance can have dire consequences. Humanity is quite familiar with the consequences of using rivers for the construction of hydroelectric power stations.
The surge in popularity of this type of power plants dates back to the first half of the 20th century. At that time it seemed that turbine rotating water from a natural source (blocked by locks and, as a rule, greatly altered riverbeds) was the best option for environmentally friendly and almost eternal source of energy. The fact that the ecosystems of entire upstream and downstream regions were being destroyed by such a liberal treatment of rivers was not immediately noticed by people. The alarm was sounded when, as a result of dehydration or, on the contrary, swamping of vast territories, mass death of fish, animals and birds started, weathering of soils due to loss of forests, depletion of agricultural lands due to lack of water in arid areas, and many other things. Today, the construction of hydraulic structures is approached with much more caution, trying not to grossly disturb the existing ecosystem of rivers. However, it is very difficult to avoid adverse impacts completely.
But all the other dangers pale in comparison with what happens to the environment as a result of thermal power plants. Based on the energy derived from the combustion of fuels, they are still the main source of electricity on the planet today. They are truly efficient and unpretentious to use, and can run on oil, gas, coal and any other combustible material to produce the cheapest possible electricity. But the harm caused by thermal power plants to the environment is not comparable with the harm caused by all their other types combined.
Of course, the use of the listed energy carriers and products of their processing in other fields, first of all in transport and industry, also contributes to pollution. The combustion of coal, oil, gas and other fuels, whatever their use, in addition to directly polluting the atmosphere, soil and water, leads to enormous emissions of carbon dioxide, which are believed to be the main cause of the so-called greenhouse effect. In the longer term, the processes they trigger lead to catastrophic changes to the planet’s climate, with all the consequences that follow.
Many people today have high hopes for nuclear power plants. If they work properly, they are efficient, safe for people and the environment and provide relatively inexpensive electricity. If scientists succeed in taking full control of the nuclear fission process and putting it at the service of people, humanity will be provided with a clean, affordable and accessible source of energy for many centuries to come. Unfortunately, a huge disadvantage of this type of power plant is the catastrophic consequences, beyond human control, that any accident could entail.