Learn about nine new clean and green energies

Clean energy refers to environmentally friendly energy sources, indicating eco-friendliness, minimal emissions, and low pollution levels. However, this concept is not precise enough and can easily lead people to misunderstand it as a classification of energy sources, believing that there is a division between clean and dirty energy sources, thereby misconstruing the true meaning of clean energy. Clean energy, or green energy, refers to energy sources that do not emit pollutants and can be directly used for production and living. It includes nuclear energy and ‘renewable energy.’ Let’s explore nine major new types of clean green energy.

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1.Solar Energy

Solar energy as a clean energy source converts solar radiation into other forms of energy such as thermal energy, electrical energy, and chemical energy without generating harmful gases or solid waste during the energy conversion process. It is an environmentally friendly, safe, and pollution-free energy source.

Current comprehensive life cycle assessments (LCA) of solar energy utilization show that traditional solar photovoltaic conversion methods, relying on the production of high-pollution, high-energy-consuming materials such as solar panels, result in high utilization costs and environmental costs. Current research focuses on thermoelectricity in solar thermal utilization.

Current applications of solar energy include:

(1) Conversion of light to heat, such as solar water heaters, solar cookers, and solar thermal power generation systems.

(2) Conversion of light to electricity, such as solar panels, solar-powered vehicles, and boats.

2.Biomass Energy

Biomass energy is a form of energy stored in organisms in the form of chemical energy, directly or indirectly derived from the photosynthesis of plants. Among various renewable energy sources, biomass is unique. It stores solar energy and is a renewable carbon source that can be converted into conventional solid, liquid, and gaseous fuels.

Advantages of biomass energy include:

(1) Providing low-sulfur fuels.

(2) Providing affordable energy (under certain conditions).

(3) Converting organic matter into fuel can reduce environmental pollution (e.g., garbage fuel).

(4) Compared with other non-traditional energy sources, it has fewer technical challenges.

Its disadvantages include:

(1) Plants can only convert a small amount of solar energy into organic matter.

(2) The energy content of organic matter per unit land area is low.

(3) Lack of suitable land for planting.

(4) High moisture content of organic matter (50%-95%).

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3.Hydrogen Energy

(1) Among all gases, hydrogen has the best thermal conductivity, ten times higher than that of most gases, making it an excellent heat transfer medium in the energy industry.

(2) Hydrogen is the most abundant element in nature, constituting 75% of the mass of the universe. In addition to being present in the air, hydrogen is mainly stored in the form of compounds in water, the most abundant substance on Earth. It is estimated that if all the hydrogen in seawater is extracted, the total heat generated will be 9000 times greater than the heat generated by all fossil fuels on Earth.

(3) Apart from nuclear fuel, hydrogen has the highest calorific value of all fossil fuels, chemical fuels, and biofuels, at 142,351 kJ/kg, three times that of gasoline.

(4) Hydrogen combustion performance is good, ignites quickly, has a wide flammable range when mixed with air, and has a high ignition point and combustion speed.

(5) Hydrogen itself is non-toxic. Compared to other fuels, hydrogen combustion is the cleanest, producing only water and small amounts of nitrogen hydride, without producing harmful pollutants to the environment such as carbon monoxide, carbon dioxide, hydrocarbons, lead compounds, and dust particles. A small amount of nitrogen hydride, when properly treated, will not pollute the environment. Moreover, the water generated by combustion can be used to produce hydrogen, continuing the cycle of use.

4.Wind Energy

The kinetic energy generated by the movement of a large volume of air on the Earth’s surface. Due to differences in temperature changes and water vapor content in various places on the Earth’s surface after being irradiated by the sun, differences in air pressure occur, and high-pressure air flows horizontally to low-pressure areas, forming wind. Wind energy resources depend on wind energy density and the number of cumulative hours of available wind energy per year. Wind energy density is the power of wind that can be obtained per unit area of the windward surface, proportional to the cube of the wind speed and the air density. It is estimated that the total wind energy in the world is about 1.3 trillion kilowatts. Wind energy resources are greatly influenced by terrain, and wind energy resources worldwide are concentrated in coastal areas and contracted belts of open continents. In nature, wind is a renewable, pollution-free, and vast energy source. With global warming and energy crises, countries are accelerating the development and utilization of wind power to minimize the emission of greenhouse gases such as carbon dioxide and protect our planet, which we rely on for survival.

The utilization of wind energy mainly includes wind energy as power and wind power generation, with wind power generation being the main application. Wind energy as power utilizes wind to directly drive various mechanical devices, such as driving water pumps for water lifting. The advantages of wind power generation are low investment, high efficiency, and durability.

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5.Marine Energy

Marine energy refers to renewable energy attached to seawater, which absorbs, stores, and disperses energy through various physical processes such as tides, waves, temperature differences, salinity gradients, and ocean currents. Marine energy includes tidal energy, wave energy, ocean thermal energy, salinity difference energy, and ocean current energy.

6.Geothermal Energy

Geothermal energy is a natural energy extracted from the Earth’s crust, which comes from the internal heat of the Earth’s core and exists in the form of thermal energy. It is the energy that causes volcanic eruptions and earthquakes. The temperature inside the Earth reaches 7,000 degrees Celsius, and at depths of 80 to 100 kilometers, the temperature drops to 650 to 1200 degrees Celsius. Through the flow of underground water and magma to the crust, heat is transferred to places closer to the surface. High-temperature magma heats nearby groundwater, and this heated water eventually seeps out of the ground. The most straightforward and cost-effective method of using geothermal energy is to directly use these heat sources and extract their energy. Geothermal energy is a renewable resource.

Applications of geothermal energy include:

(1) Direct generation and comprehensive utilization of electricity at 200-400°C.

(2) Dual-cycle power generation, refrigeration, industrial drying, and industrial heat treatment at 150-200°C.

(3) Dual-cycle power generation, heating, refrigeration, industrial drying, dehydration processing, salt recovery, and canned food at 100-150°C.

(4) Heating, greenhouses, domestic hot water, and industrial drying at 50-100°C.

(5) Bathing, aquaculture, livestock breeding, soil warming, and dehydration processing at 20-50°C.

Many countries are adopting cascade development and comprehensive utilization methods to improve geothermal utilization rates, such as combined heat and power, tri-generation of heat, electricity, and cold, and heating before farming. Geothermal power generation, steam geothermal power generation, hot water geothermal power generation, geothermal heating, geothermal farming, and geothermal medicine are also being developed.

7.Hydropower

Hydropower is a renewable energy source and a clean energy source, referring to the kinetic energy, potential energy, and pressure energy of water bodies. Broadly speaking, hydropower resources include hydro energy, tidal energy, wave energy, ocean thermal energy, and ocean current energy resources; narrowly speaking, hydropower resources refer to the hydro energy resources of rivers. It is a conventional energy source and a primary energy source. Water can not only be directly used by humans but also serves as an energy carrier. Solar energy drives the water cycle on Earth, allowing it to continue. The flow of surface water is essential. In areas with large drops and large flows, hydropower resources are abundant. As mineral fuels diminish, hydropower is a very important and promising alternative resource. Currently, hydropower development worldwide is still in its infancy. Rivers, tides, waves, and surges, among other water movements, can be used for power generation.

This includes the clean use of conventional energy sources, such as coal gasification and liquefaction; the utilization of renewable energy sources such as solar energy, wind energy, hydropower, marine energy, geothermal energy, and biomass energy; and the development of new energy sources (such as hydrogen fuel). The calorific value of hydrogen fuel is four times that of the same weight of carbon, and the fuel produces water, causing no pollution to the environment, making it an ideal clean energy source.

8.Nuclear Energy

Nuclear energy (or atomic energy) is the energy released by converting the mass of an atomic nucleus, in accordance with Albert Einstein’s equation E=mc², where E=energy, m=mass, and c=the speed of light constant. Nuclear energy is released through one of three types of nuclear reactions:

(1) Nuclear fission, which breaks open atomic nuclei’ binding forces.

(2) Nuclear fusion, where particles of atoms fuse together.

(3) Nuclear decay, a much slower form of fission that occurs naturally.

Advantages:

(1) Nuclear power generation does not emit large amounts of pollutants into the atmosphere like fossil fuel power generation, so nuclear power generation does not cause air pollution.

(2) Nuclear power generation does not produce carbon dioxide that exacerbates the Earth’s greenhouse effect.

(3) The uranium fuel used in nuclear power generation has no other uses besides power generation.

(4) The energy density of nuclear fuel is hundreds of thousands of times higher than that of fossil fuels, so the volume of fuel used by nuclear power plants is small, making transportation and storage convenient. A 1,000-megawatt nuclear power plant only requires 30 metric tons of uranium fuel per year, which can be transported in a single plane trip.

(5) The cost of nuclear power generation is less affected by international economic conditions due to the low proportion of fuel costs in the overall cost of nuclear power generation, making the cost of power generation more stable compared to other methods.

Disadvantages:

(1) Nuclear power plants produce high- and low-level radioactive waste, or used nuclear fuel, which, although occupying a small volume, must be carefully handled and face significant political challenges due to their radioactivity.

(2) Nuclear power plants have lower thermal efficiency, resulting in more waste heat being discharged into the environment than general fossil fuel power plants, resulting in more serious thermal pollution from nuclear power plants.

(3) The investment cost of nuclear power plants is too high, resulting in higher financial risks for power companies.

(4) Nuclear power plants are less suitable for peak and off-peak operation.

(5) The construction of nuclear power plants is more likely to cause political disputes.

(6) The reactor of a nuclear power plant contains a large amount of radioactive material, which, if released into the external environment in an accident, can harm the ecology and people.

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9.Flywheel Energy Storage

Flywheel energy storage is a technology that stores energy using the high-speed rotation of a flywheel. During the energy storage phase, an electric motor drives the flywheel to accelerate to a certain speed, converting electrical energy into kinetic energy; during the energy release phase, the flywheel decelerates to drive the electric motor to operate as a generator, converting kinetic energy into electrical energy. Typical flywheel energy storage devices generally include a high-speed rotating flywheel, a closed housing and bearing system, and a power conversion and control system.

Flywheel energy storage has the advantages of high energy density, energy storage cycles and depths independent, high energy conversion efficiency, high reliability, easy maintenance, low environmental requirements, and no pollution. However, the large-scale development of flywheel energy storage systems still faces difficulties in high-speed, low-loss bearings, generators/motors, heat dissipation, and vacuum technology.

Currently, flywheel energy storage technology mainly has two branches: large-capacity flywheel energy storage technology represented by contact-type mechanical bearings, which are mainly characterized by storing kinetic energy and releasing large power. It is generally used for short-term, high-power discharge and power peaking occasions. The second is medium and small-capacity flywheel energy storage technology represented by magnetic suspension bearings, which are mainly characterized by compact structure, higher efficiency, and generally used for flywheel batteries and uninterruptible power supplies.

The concept of clean energy and sail-assisted of wind energy utilization technology

Development of wind power generation of wind energy utilization

Current status of wind power generation of wind energy utilization