In our last post, we talked about the concept of green energy as well as its history. To jog your memory, green energy is the energy that obtains from sources that are natural, environment-friendly, and infinite.
However, green energy is still under research all around the world and newer applications coming almost daily. Scientists share intensive studies explaining their operations, advantages, and disadvantages. So, let’s take a look at the different types of green energy and their efficiencies.
The energy released by the sun is known as solar energy. This energy converts into electricity using photovoltaic (PV) solar cells. To understand the process, let’s begin with photons. Solar panels catch that photons present in the sunlight hit them instead of the ground. These panels contain semiconductor material which helps in absorbing the photons. Then release electrons from the material and they start traveling in the panel which produces electricity. Inverters convert this direct current into alternating current to supply the commercial or industrial use. It is an efficient and reliable source of energy because it is completely environment-friendly. Sunlight is unlimited and easy to access which means the input for solar power plants is free. However, currently, their rate of efficiency is almost 20% and they are quite expensive for day-to-day use. The biggest market player in solar energy in China.
Wind is a green energy source that generates electricity using wind turbines. The blades on a turbine are part of a generator spin due to the flow of the wind. The generator, in turn, converts the acquired energy into electrical energy. The winds are stronger at greater heights as compared to the ground, so the turbines built are around 330 feet tall. Similarly, winds are stronger offshore, which is why some countries like Denmark, the UK, and China have built turbines accordingly. Just like the sun, the wind is a free and natural source of energy. It is clean and poses no harm to the environment. However, winds are stronger depending on the location and the cost of building a wind turbine is high.
Water is also a source of green energy because rain, tides, and flowing water generate power. The most famous use includes the generation of hydroelectric power where the moving energy of water into electricity. These power plants are part of dams to store water until it is ready to generate energy. The water falls down a slope so that its higher speed can turn the turbines which then turn the generator. So, a greater amount of energy can be produced by using steeper slopes. It takes many years and a great deal of money to build a power plant. However, it can run for up to 50 to 100 years. It is also cheaper than other renewable sources because it costs around 9 cents per kilo-hour in the US and generates almost 3,500 terawatts of power.
To begin explaining the process, let’s talk about the heated and molten rock under the earth’s surface called magma. Magma produces heat in the layer of this rock due to radioactive decay. Regions where the heat is maximum also result in volcano activity and are also prone to earthquakes. However, geothermal energy is available 10 to 100 feet below the surface of the earth anywhere in the world. Dry steam, flash steam, and binary cycle power plants capture hot water/steam from the heat source which turns turbines to generate electricity and then return it back to the heat source. Kenya, the Philippines, and Iceland have already started generating more than 15% of their electricity from geothermal energy. However, geothermal energy is highly dependent on location and might be costly for countries with less seismic activity.
Biomass refers to organic material obtained from plants, animals, and their waste. It is possible to dry and burn it. Biomass power plants burn organic matter to produce steam and then turns the turbine to produce electricity. The steam can also provide heat for commercial and industrial use. Biomass can also be converted to biogas to be used as an energy source. Animal and food waste or sewage when decomposed in an oxygen-free environment, releases biogas. It can be used for cooking or burned to power vehicles. Biomass is a long-lasting source because of the nature of its input.
Overall, biomass energy is not entirely green considering greenhouse gases are still produced as a result. However, they are still less than the amount released by burning fossil fuels. Biomass energy is almost 75 to 80% efficient in a combination of Heat and Power (CHP) plants and its generation of electricity is 20 to 25% efficient.
Green energy sources are still trying to balance factors such as cost-effectiveness, maintenance, efficiency, and lessening environmental impacts while delivering a balance in the supply of energy. However, we should keep in mind that in the long run, these energy types are still ‘greener’ when we compare them to the currently available environmentally destructive sources.