Solutions for visualizing, understanding, and streamlining carbon emissions from various angles, such as business sites and products, corporate activities, and consumer behavior.
Efforts to conserve energy have been underway for several decades, but in recent years, the methods used have become more sophisticated, including AI and other technologies and billing methods based on usage. These solutions optimize energy usage.
Solutions related to batteries and hydrogen, such as electrification (EV) of mobility (means of transportation) such as cars and buses, which used to be fueled by gasoline, to reduce CO2 emissions, and to extract hydrogen for industrial use and to encourage its practical application.
Solutions related to batteries and hydrogen, such as electrification (EV) of mobility (means of transportation) such as cars and buses, which used to be fueled by gasoline, to reduce CO2 emissions, and to extract hydrogen for industrial use and to encourage its practical application.
Solutions that contribute to the fixation and absorption of CO2 in the atmosphere through forest protection and forest management, and offset the amount of greenhouse gas emissions that cannot be fully reduced through the purchase of carbon credits.
One solution is to reduce emissions in society as a whole by recycling metals, plastics, and other resources and products at various stages of economic activities.
Hydroelectric Power Generation - Mechanisms, Types and Advantages
Hydroelectric power generation is a method of storing the potential energy of water by installing dams on rivers and other means, and using this energy to rotate water turbines to generate electricity. This article explains how hydropower works, its advantages and disadvantages, as well as the classifications of hydropower.
Easy-to-understand diagrams of how hydropower works
Hydroelectric power generation is a power generation method that uses water power, such as running water or falling water, to rotate a water wheel and convert the power of the wheel into electricity.
They can be divided into several types depending on the method of water fall, the structure of the turbine, and the method of water use (using a river or dam), but the part that converts the potential energy of water at high altitudes into electrical energy remains the same.
Like thermal power generation and wind power generation, which rotate turbines, generators are machines that use electromagnetic induction to obtain electrical energy from rotational force.
Electromagnetic induction is a physical phenomenon in which a potential difference (voltage) is generated in a conductor such as a coil when the magnetic flux penetrating the conductor changes.
When a magnet is rotated around a coil connected to a conductor, the magnetic flux through the coil changes, generating an induced current.
Generators use this mechanism to convert rotational power into electrical power.
Introducing the advantages and disadvantages of hydroelectric power generation
As an advantage, hydropower is one of the renewable energy sources that has attracted much attention due to its high energy conversion efficiency and low administrative costs.
Energy obtained from resources that are replenished by nature on a steady and repetitive basis is called renewable energy.
Because it is a renewable energy source, there are some carbon dioxide emissions in the installation and operation of the equipment, but no carbon dioxide emissions during power generation.
Hydroelectric power has the highest energy conversion efficiency of all renewable energy sources. While wind and solar power have energy efficiencies ranging from 10% to 40%, hydroelectric power has an energy efficiency of about 80%.
In addition, Japan's mountainous terrain and abundant water resources make hydroelectric power generation a suitable power generation method for Japan.
On the other hand, one disadvantage is that because it has been utilized for a long time, land favorable for dams and hydroelectric power plants has already been developed, making it difficult to find new large-scale land, and new facilities tend to be relatively small.
Hydroelectric power generation and management costs are low compared to other renewable energy sources, but new dams are expensive to build. Another disadvantage is that the amount of electricity generated by hydropower depends on the amount of precipitation, and in cases of extremely low rainfall, it may not be possible to generate electricity.
Explains the different types of hydropower generation and how each works
Hydroelectric power generation can be classified according to how the water fall is created, how the water is used, and the type of turbine.
Below is a summary of hydropower "classification by structure," "classification by water use," and "classification by type of turbine, " respectively.
Classification by structure
Hydroelectric power generation can be classified into three types depending on the structure : "dam type," "canal type," and "dam canal type.
In the dam type, a dam is constructed on a river or other body of water to store water, and the water potential energy is stored by the water fall created by the storage of the water.
A power station is built near the dam, and electricity is generated by rotating a water wheel.
In the water channel type, a power plant is installed downstream of a river, and a water intake weir is built upstream to divert the flow of the river.
The water is channeled at a slower gradient than the original river flow, and the water is allowed to flow and fall at a steeper gradient at the power station to rotate a water wheel and generate electricity, after which the water is returned to the original river flow.
The dam channel type uses a dam and waterway to rotate a turbine to generate electricity.
This method allows for separate water storage and power generation, making it easy to adjust the site conditions.
Classification by water use
They can be classified into "flow-in type (self-flow type)," "regulating reservoir type," "reservoir type," and "pumping type," depending on the method of water use.
The inflow type (self-flow type ) is a method that draws on the river flow as it is.
Although it is difficult to adjust the output of the flow-in type, it can generate electricity on a steady basis as long as the river is flowing, so it is often responsible for the base portion of demand.
The regulating reservoir and reservoir systems use dams to store water when demand for electric power is low, and when demand for electric power increases, more of the stored water is allowed to flow, thereby responding to fluctuations in demand for electric power.
The regulating reservoir type is a relatively small-scale type used to adjust load on a daily or weekly basis, while the reservoir type is a large-scale type in which a dam is installed to make adjustments between seasons.
The pumped storage type is also used to respond to fluctuations in electricity demand.
In the pumped storage type, dams are installed downstream and upstream of the power plant, and water is exchanged between the two dams to adjust the demand for electric power.
During low-load periods when demand for electricity is low, surplus electricity is used to fill up the upstream regulating reservoir, and when demand for electricity is high, the water is used to increase the amount of electricity generated.
The pumped storage system can be said to be a type of storage battery that uses hydraulic power.
Types of water wheels
Various types of water turbines have been developed to improve the energy conversion efficiency of hydropower generation.
Water turbines for hydropower generation can be broadly classified into two types: reaction turbines, in which the mechanism is filled with water and water pressure is maintained for rotation, and impulse turbines, in which rotation is achieved by accelerating and applying running water.
One example is the " Francis turbine" and "propeller turbine" for reaction turbines, and the "Pelton turbine" and "cross flow turbine" for impulse turbines.
Francis turbines can handle a wide range of water drops from tens to hundreds of meters, are used in 70% of hydraulic power plants in Japan, and are easy to maintain due to their simple structure.
Propeller turbines are reaction turbines in which water flows in and out longitudinally, and of these, those that can move their blades in response to changes in water pressure are called Kaplan turbines.
Kaplan turbines are suitable for drop-offs from 5m to 80m and feature higher power generation efficiency than Francis turbines.
The Pelton turbine is rotated by applying a jet stream of water from a nozzle to the turbine.
The output can be easily adjusted and is suitable for high drop-offs of 200 m or more.
Cross-flow turbines are mainly used in small-scale hydroelectric power plants.
The flowing water is divided into two parts by guide vanes, and each part is applied to the turbine for rotation.
Current Status and Future Prospects of Hydroelectric Power Generation
Hydroelectric power has been an important support for Japan's economic growth to date.
As a result, much of the land that is favorable for the construction of large hydropower plants is already developed, and construction costs are high, making it difficult to build new large-scale power plants.
In place of large-scale hydropower plants, relatively small-scale micro-hydropower (small-scale hydropower ) installations are gaining ground.
Small-scale hydroelectric power plants may play an even more important role in the future because of their high potential and the flexibility of their installation sites as long as a certain amount of water is available.
This article summarizes the structure, advantages and disadvantages, classification, and future prospects of hydropower.
Hydroelectric power generation is a method of generating electricity by utilizing changes in water elevation caused by running water or falling water to rotate a water wheel, and is characterized by extremely high power generation efficiency.
There are several classifications depending on the method of water use, altitude difference, and type of turbine, and it has been used in Japan for a long time.
