**1. Introduction**

Our daily life on Earth requires the production of large amounts of energy. The energy is produced mainly in the forms of electrical energy and mechanical energy as a result of liquid fuels and gases combustion in engines in various types of vehicles. Unfortunately, the various types of useful energy also cause the production of a huge amount of heat. Moreover, these useful energies are eventually converted to heat energy in machines, vehicles, and devices. An important question arises here—whether this release of a large amount of thermal energy is comparable to solar energy and can it significantly affect the global temperature and climate change. In this paper, the thesis was verified whether the heat emission, which is the final result of energy generated by our civilization, has an effect comparable to that of greenhouse warming. The greenhouse effect is well known and is comprehensively presented in many papers—among others [1–4]. However, the effect and greenhouse gas emission have not been discussed in the presented work so far.

Nuclear and fossil fuel power plants are thermal power stations and have a maximum efficiency of around 40%. It means that during the production of electrical energy, around 60% of nuclear or chemical energy in fossil fuel is converted to heat energy and is emitted directly into the atmosphere and water (seas, lakes, rivers). Thus, most of the energy contained in any fuel is lost, but there is currently no technically more efficient way to generate electricity. Unfortunately, that also applies to the combustion of biofuels. Wind and water power plants have much higher energy efficiency, and the production of electricity is accompanied by a low heat emission. Much more information about the energy conversion efficiency in thermal power stations is presented in the papers [5–7].

However, regardless of the way how electricity is produced, almost all electricity is ultimately turned into heat. It may seem surprising, but the following analysis proves this thesis. Electrical energy is distributed to different electricity consumers—factories, buildings, hospitals, railway electrification systems, etc. For example, any computer consumes electrical power and uses it to perform calculations, which is accompanied by heat production in semiconductor components (microprocessors, transistors, diodes, resistors). In practice, considering the field of physics, all the electric power in any computer is finally converted to heat. In a fridge, an electric motor drives a heat pump, which pumps out heat from inside the fridge to the outside. According to the principle of energy conservation, the heat energy released into the atmosphere (outside) is equal to the sum of heat energy collected from the fridge interior and the consumed electricity. A very similar situation occurs in any device. While an electrical train moves, electric motors cause acceleration driving at a constant velocity and partial energy recovery during braking. When the velocity of the vehicle is constant, all the consumed electrical energy compensates the work of friction forces in mechanical components (in bearings, etc.) and of air resistance forces. The friction in the components causes their heating, and air resistance causes the heating of the train's surface and air. The same situation occurs in cars. In a modern petrol engine, the chemical energy in the fuel is converted to heat (about 60%) and useful mechanical energy (about 40%). All mechanical energy is used to compensate friction forces and air resistance, so always a heat is produced. Thousands of various devices and machines can be considered in which the energy would finally be converted into heat—similar to what it is shown in Figure 1.

**Figure 1.** Electrical energy changes into other forms of energy and makes useful work, but almost 100% is finally converted to heat energy (own study).

Consequently, sooner or later, almost 100% of electrical energy or chemical energy in fuels is finally converted to heat energy. To determine the global heat production, it is necessary to calculate the global production of electricity and petrol fuels.
