In a world where both social and environmental instability are increasingly on the rise as they are today, the issue of energy is a very hot topic of concern.

In a world where both social and environmental instability are increasing day by day, energy is a hotly debated issue. Fossil fuels, which have long been considered the key source of energy, are becoming scarce and causing numerous disputes among countries worldwide.

According to scientists' predictions, with the current rate of exploitation and use of fossil resources, our future generations will have to bear serious consequences within a few centuries. Therefore, the demand for alternative energy sources is becoming more urgent, and more and more alternative energy research projects are being initiated and developed. However, not all of them are suitable for development in the future. In this article, we will discuss some of the most feasible alternative energy sources at this time.

Nuclear energy
Nuclear energy is a nuclear technology designed to extract useful energy from atomic nuclei through controlled nuclear reaction furnaces. The only method currently used is nuclear fission, although other methods may include nuclear fusion and radioactive decay. In 2007, up to 14% of the world's electricity production came from nuclear energy, of which the United States, France, and Japan accounted for 56.5% of electricity production. There are currently nearly 450 nuclear power reactors operating in 31 countries worldwide. In the entire European Union, nuclear energy provides 30% of the electricity demand. Nuclear energy policies differ between European Union countries, and some other countries such as Australia, Estonia, and Ireland have no nuclear power plants in operation. Compared to other countries, France has the most nuclear power plants, with a total of 16 complexes in use. Nuclear energy advocates believe that nuclear power is a sustainable energy source, reducing carbon emissions, and enhancing energy security by reducing dependence on oil. They also emphasize that risks can be further reduced with the latest technologies. However, some critics argue that nuclear power is a dangerous energy source. However, for Western countries, it is seen as a feasible way to achieve energy independence.

Compressed natural gas
Compressed natural gas (CNG) is a combustible gas mixture consisting of methane, which is compressed to less than 1% of the volume it occupies at standard atmospheric pressure. It is stored and distributed in hard containers at high pressure, usually 200-248 bar (2900-3600 psi). CNG is considered a cleaner burning fuel than gasoline or diesel and is currently used in vehicles, buses, and even ships. It can also be used to generate electricity and heat homes and businesses. However, the limited availability of CNG infrastructure and the high cost of conversion are still significant challenges for widespread adoption.

Biomass energy
Biomass is a form of biological material from living things, or recently living organisms, mostly from plants or materials derived from plants. It is considered a renewable energy source, and can be used directly, indirectly once or converted to other forms of energy such as biofuels. Biomass can be converted to energy in three ways: thermal conversion, chemical conversion, and biochemical conversion. Historically, humans have utilized products derived from biomass energy when they began using firewood and dried grasses for heating. Nowadays, the term can be understood in two senses. The first sense, biomass is the plant material used to generate electricity (using steam turbines or compressed air), or to produce heat (through direct combustion). Biomass may also include biodegradable waste that can be burned as fuel. Industrial biomass sources are developed from a variety of plants including Miscanthus, grasses, jatropha, corn, poplar, willow, miscanthus, sugarcane, and some other plant species.

Biomass production is a growing industry and is becoming increasingly important. Currently in the United States, biomass energy produces approximately 0.5% of the electricity output annually. The New Hope Power Plant is the largest biomass power plant in North America. Developing biomass energy will help reduce dependence on fossil fuels in the future.

Geothermal energy
Geothermal energy is energy extracted from heat inside the Earth. It originates from the initial formation of the planet, radioactive decay of minerals, solar energy absorbed at the surface, and other sources. Extracting this energy is not difficult. Since ancient Roman times, it has been used for heating, bathing, and cooking. Nowadays, it is primarily used for electricity generation. It is considered an efficient, reliable, and environmentally friendly energy source. Its only drawback is its dependence on geographical areas near tectonic plate boundaries. Recent scientific and technological advances have gradually expanded the scope and scale of this potential resource, particularly direct applications such as home heating. Geothermal wells tend to release greenhouse gas emissions that are trapped deep underground, but these emissions are much lower than those from conventional fossil fuel burning.

The world's largest geothermal power plant is located in California, USA. By 2004, some countries such as Kenya, the Philippines, Iceland, and Costa Rica had generated 15% of their electricity output from geothermal sources.

Hydropower
Hydropower is a source of energy derived from the power of water. It is largely obtained through the potential energy of water stored in dams, which turns water turbines and generators. Small-scale hydropower systems can be installed in small rivers, streams, and large-scale facilities are usually located in areas with large water currents, such as fast-flowing rivers. Hydropower plants also have a longer lifespan than thermal power plants, and some operating hydropower plants were built 50 to 100 years ago. Labor costs are also low because these plants are highly automated and require fewer workers to operate. Currently, hydropower accounts for about 19% of the world's electricity production and is a key source of fuel. Most hydropower projects supply electricity to the public power grid, but some are also created to serve specific industrial businesses. The downside of hydropower is that, although it does not consume fuel or emit harmful emissions into the environment, it also severely damages the ecological environment in various ways.

Wind power
Wind power is the conversion of wind energy into useful energy for humans through wind turbines. Large-scale wind farms are typically connected to local power transmission grids. In some isolated areas, this is also a form of primary energy supply, and some residential areas even have private production for household use. Wind farms are often built on large areas that combine agriculture or animal husbandry. It is considered a renewable energy source with minimal impact on the environment. Although wind power currently only produces about 1.5% of the world's electricity, it is growing rapidly, especially in recent years. In Denmark, wind power accounts for about 19% of electricity production, 11% in Spain and Portugal, and about 7% in Germany. Historically, wind energy was used directly to propel ships or converted into mechanical energy to grind grain, pump water, etc. In modern times, its main application is to produce electricity. As of 2008, Europe was the world leader in offshore wind energy development. In addition, the United States and China are also promoting strong development of this energy source in potential areas such as the Great Plains in the US and Inner Mongolia in China.

Solar Energy
This is one of the most well-known, used, and advocated sources of energy in the world. Humans have been harnessing this energy since ancient times to the present day. This energy source is renewable, and until now we have only used a very small part of the available solar energy. Currently, solar energy exploitation technology is developing rapidly. Electricity can also be obtained from the sun by directly using photovoltaic panels (PV), or indirectly by using concentrated solar power (CSP). CSP systems use lenses, mirrors, and tracking systems to focus a large area of sunlight onto a small beam. PV converts light into electricity by using the photoelectric effect.

Looking to the future, solar energy can be said to be one of the most applied and highest-replaceable energy sources. Currently, some types of cars that use solar energy have also been developed and are fully capable of being used in daily life. In addition, many places in the world have utilized solar heat sources to warm up, boil water, cool spaces, cook food, and more.

Wave Energy
Although it originates from the ocean, wave energy is not exploited underground like tidal energy but on the surface of the sea where there are the strongest waves. This energy source is very useful, it can be used to generate electricity, desalinate water, pump water into reservoirs, etc. However, the main problem lies in the difficulty of exploiting this energy source. We are still struggling to predict wave direction and behavior on the sea surface. A wave energy farm has been created and used in Europe. It uses the Pelamis floating converter - a device that will generate energy through the mechanical motion from the peaks and bottoms of waves. However, waves do not have the regularity of tides or the stable circulation of ocean currents, so even though people have known about it for a long time, it has not yet been widely exploited.

The world's first wave energy farm is in Portugal, where it includes 3 Pelamis 750-kilowatt devices. In the United States, there is also a project to build a wave energy farm in Reedsport, Oregon. This new project will use PowerBuoy technology, which consists of energy conversion buoys. The up and down motion of the waves will create mechanical energy, which will be converted into electrical energy through a specialized device.