Solar collectors supply us with solar energy in the form of heat, and solar or photovoltaic systems convert the solar energy into electricity with the help of solar cells. Although these solar plants work very well and supply electricity to many parts of the world, it is worthwhile to establish them only in areas with regular and abundant sunlight. Till now, only one-thousandth of the electricity consumed all over the world comes from such plants. The reason is that the sun does not always shine in many European countries and a single solar cell is not sufficient to provide adequate electricity. Research is being carried out to develop them further because the advantages are tremendous. For instance, the generation of ‘solar current’ will make a pollution-free environment.
A discussion on solar sails on the television often implies the umbrella-like stretched surfaces around the satellites or the International Space Station (ISS). These are solar plants, which provide energy to the objects in space flight. Strictly speaking, the solar sail is a new technology, which uses the pressure of the solar radiation to drive the space probes.
Like the ‘solar sail’, the magnetic sail is also a new possibility for using the solar energy to power spaceships or space probes. This would become possible through the solar wind, a stream of electrically charged particles, coming from the sun. However, this method is still under research.
There are a lot of strong forces in the nuclei of atoms, which keep the particles together. There are two ways to release the energy hidden in the atomic nuclei. We can fuse them with one another, as occurs in the core of the stars, or we can split them, which is done in at nuclear power plants. To split an atom to release energy, a chain reaction is required in a reactor. Many people consider the atomic power plants also called nuclear power plants dangerous because radioactive material is released in this process. 
Atoms are made up of a nucleus and a shell of electrons. The nucleus contains protons and neutrons. The protons are positively charged and repel each other like magnetic poles. At the same time, there is also a strong force of attraction, the nuclear force. This force prevents the nuclei from flying apart. The origin of this force is complicated and nuclear physicists have been studying this phenomenon.
Radioactivity is a property of the atomic nuclei to decay and thereby release radiation. Many atoms split when they are bombarded with neutrons, and others decay spontaneously. In both the cases, the radiation of radioactive material takes place. This radiation occurs in three forms. The alpha rays can reach only up to a few centimetres. The beta rays are made of electrons resulting from the splitting of atomic nuclei. They can go up to 1m and are stopped by metallic foils. The gamma rays are bundled energy released in the decay and are very dangerous. Even thick lead plates can only partly stop them. They can penetrate the cells of our body and can modify or destroy them. 
Chain reactions are modifications in the composition of the atomic nucleus. The nucleus of a uranium atom, for instance, can be split by bombarding with neutrons. A lot of energy is released in the process. The fragments that arise as a result of the initial reaction fly off at a high speed and collide with the neighbouring nuclei, which get split in turn. The whole process takes place as long as the present mass of uranium is split. An enormous amount of heat is released when several nuclei are split at once. This can lead to explosions. For this reason, this chain reaction is initiated in a controlled way in nuclear power plants. 
In atomic power plants – APP in short – the chain reaction of the uranium decay is allowed to run in a controlled way. The uranium rods in the reactor, which are bombarded with neutrons, are dipped in water, which slows down the neutrons and helps achieve a controlled nuclear fission. In addition, the fuel rods heat up the water to about 330°C. This heat is transferred in a heat exchanger to a second, non-radioactive water circulation, where the hot water evaporates and drives steam turbines. The energy is converted into electricity by means of the connected generators similar to other power plants. 
We need to manage our natural resources very carefully to ensure that the Earth remains in a habitable condition for future generations. We must preserve the greatest treasure of the Earth, the nature. Water should be judiciously used in regions where it is scarce. After all, in many parts of the world, people are still fighting for this valuable commodity. We need to make sure that we use non-renewable natural resources like coal, petroleum sparingly and use renewable resources like wind and solar energy more for our daily needs. A research to develop a harmonious way of living is very important for our future.