The world is now moving towards renewable energy

AB Siddique

-AB Siddique

The oil and gas crisis is getting bigger and bigger. This crisis is all over the world. In this situation, the world is now leaning towards renewable energy. Renewable energy is a source of energy that can be reused over a short period of time and thus the energy source does not run out. Various natural sources such as: sunlight and heat, wind currents, water currents, bioenergy (biomass), geothermal energy, ocean waves, ocean heat, tides, urban waste, hydrogen fuel cells, etc. are considered renewable energy sources. The production of renewable electricity is increasing day by day all over the world. By 2050, 85 percent of people’s electricity needs will be met from renewable energy. Most countries have set targets for the use of renewable energy to meet their electricity needs.

Renewable energies are environmentally friendly and carbon-free. The United Nations and global environmental movements continue to promote the use of renewable energy to combat climate change and achieve a sustainable energy system. Most of the world’s fossil fuels are used for power generation, motor vehicles and home heating. For this reason, various researches are underway internationally to introduce sustainable power systems using renewable energy, sustainable vehicle systems and energy-efficient household products rich in green technology. The Sun is the central star of our solar system, which is a giant gaseous body. Fusion reactions at its core produce enormous amounts of energy that reach Earth in the form of light and heat. Energy can be harvested from the sun mainly in two ways. Firstly, it collects light energy from the sun, secondly, it collects thermal energy from the sun. The photoelectric effect is used to harvest light energy. Solar panels are made using photovoltaic (PV) cells made of light-sensitive semiconductors. Direct current or DC electrical power is harvested from light energy by creating large arrays or arrays of these panels.

Concentrated solar power or ‘concentrated solar power system’ is used to collect thermal energy. Sunlight is reflected onto the front of a tower or minaret with the help of many mirrors. The heat generated by this concentrated reflection of all the mirrors is used to generate steam which is then used to generate electricity.

Solar water heaters or solar water heaters can also be used to heat water on the roof of the house. It is used in cold countries or to meet the hot water demand of factories.

The amount of solar energy that reaches the earth in one hour every day can meet the electricity demand of the whole world for two years. Airflow is caused by temperature differences. It is basically another form of solar energy. Wind speed contains kinetic energy. This kinetic energy is usually converted into mechanical energy by means of a turbine. Electrical energy is obtained from that mechanical energy. The higher one goes in the atmosphere, the more constant velocity air flow is found. Therefore, electricity is generated by installing wind turbines on top of tall towers. Wind turbines are usually arranged hierarchically.

Before installing the wind turbines, the wind flow speed of about two to three years is reviewed to see if there is sufficient wind flow throughout the year. Wind turbines installed on land are called on-shore-wind or onshore-wind-power. And in the sea, where relatively high wind currents are available, it is called 'off-shore-wind' or marine-wind-power. Currently, China is the leader in electricity generation from wind power. USA, Germany, India are also leading in the use of wind power. Biogas can be produced from human or animal excrement and decomposing garbage. Which is used in cooking or power generation. Biofuels can be made from certain types of sugar producing crops such as soybeans, sugarcane etc. Fermentation can produce methanol, ethanol or direct fuel hydrocarbons from sugars. This fuel can be directly used as fuel in vehicles. Research is also underway to produce biofuels from seawater, atmospheric carbon dioxide and sunlight using seaweeds].

Plants that can grow into full-fledged trees within twenty-five to thirty years of planting can also be used to generate electricity. Wood is burned in high-efficiency furnaces to provide heat. That heat produces electricity by steaming the water and running the turbine. In a managed forest or planned forest, trees are felled and planted in such a way that the total number of trees in that forest never decreases, but rather increases. This type of power plant is called biomass power plant. This type of power plant can also be made using the residue of different crops, straw, sawdust. It is a carbon neutral process. Most of the earth’s surface is covered by seas and oceans. This vast ocean is a storehouse of wealth and energy. Renewable energy can be harvested from the ocean in a number of ways. Among them, some of the common descriptions are - Ocean waves have kinetic energy and mechanical energy. Using it, electricity The expansion of liquids such as ammonia produces electricity by turning turbines. The height of sea water goes up and down twice a day during ebb and flow of tide. Using this height difference across the dam turns a turbine to generate electricity. The amount of power generation from the sea is now quite low. But Portugal, United Kingdom, Australia are using sea power. Geothermal energy is energy from the Earth’s interior. The center of the earth is a lump of molten metal with a temperature of about 6000 degrees centigrade. That temperature travels down to the Earth's surface by convection. Moreover, the heat generated by the decay of radioactive materials such as thorium and uranium inside the earth is also conducted to the bottom of the earth's surface. This heat can be used to generate electricity. In general, where there are tectonic plate edges or hot springs, water is piped about a kilometer or two below the surface to evaporate. From which electricity is obtained by running a turbine. About one-fourth of Iceland’s electricity needs come from geothermal energy. There are several types of geothermal power plants. For example, the most well-known source of renewable energy is hydropower. Generally, the height of water is increased by making huge dams on the banks of rivers in hilly areas. By allowing the water to fall down in a controlled manner, the turbine is turned by its pressure. Thus electricity is obtained. Apart from hilly areas, ‘run-of-the-river hydropower’ can also be created by damming downstream rivers. There are also systems such as micro hydro or pico hydro where small amounts of electricity are generated by running turbines on small mountain streams. Municipal waste to power or ‘Municipal Waste to Energy’ is a very popular renewable energy generation method in the present era. Every megacity or big city generates hundreds of thousands of tons of solid-waste or garbage every day. These wastes can be used to generate electricity. Combustible materials such as plastic, wood-straw etc. are separated from the garbage. They are burned in efficient furnaces to generate steam and generate electricity. The produced gas is released into the atmosphere after purification in various ways. Electricity is generated by producing biogas from the city’s decomposing garbage and sewage sludge.

Hydrogen is the most abundant element in the universe. 75 percent of all the elements in the universe are hydrogen. Hydrogen can be used as fuel to generate electricity. This method is called hydrogen fuel cell. It produces direct current like a battery. But to run this battery, pure hydrogen is given to the cathode and oxygen from the air is given to the anode. They react with each other to produce water and heat. Electrons flow from the cathode to the anode. Electricity can also be co-generated from a small steam engine by harnessing the thermal energy from a large-scale fuel cell. In such cases, the efficiency of the fuel cell is about 80-90 percent. Three types of methods can be used to harvest hydrogen – fuel cells are used in automobiles and in applications where uninterrupted power is required. It is a renewable nuclear power under research]. Hydrogen is an abundant element that can be used to produce large amounts of energy through fusion reactions (which occur inside the Sun). Conventional fission nuclear power is not called renewable because its fuel reserves of uranium, plutonium, thorium are limited. They are called alternative energy. But hydrogen fusion nuclear fuel is easily obtained from hydrogen water and the universe is about 75% hydrogen element, so it is a renewable energy.

The countries with the highest carbon-dioxide emissions in the world are also the largest users of renewable energy. Because of pressure from people in their own country and pressure from international environmentalists. USA, China, Germany, Russia, India are the most renewable energy users in the world. Many US states have separate legal obligations and feed-in-tariffs for renewable energy use.

China has the largest hydropower plant in the world. China is also building the largest wind and solar power plants. More than 100 coal power plants have been shut down in China. India currently has the world’s largest solar power plant with a generating capacity of 648 MW. Germany has the highest number of solar panels installed. The Nordic countries are helping to promote renewable energy by enacting friendly legislation. Most developed and developing countries worldwide have adopted policies to promote renewable energy.

(The author is a journalist.)