How to use tidal power?

Although oil often triggers wars and conflicts, spawns consumer slavery, and petroleum fuels emit large amounts of carbon dioxide, we still have to say that oil plays a major role in human beings and that human society is rapidly developing. However, oil is a non-renewable resource and its reserves are limited, which means that one day the oil on Earth will be depleted.

Because of this, in order to find new alternative energy sources, humans have racked their brains to come up with a variety of bizarre methods, such as switchgrass ethanol, biodiesel, wind power and solar power. However, due to their own obstacles, these methods cannot be put into operation on a large scale. Therefore, researchers are still looking for more efficient ways of generating electricity on the human planet.

Some researchers turned their eyes to the night sky. The results prove that there is indeed a huge energy body in the night sky. That is the moon. We can use the tidal power generated by the moon's gravity to generate electricity. The Earth is also gravitationally affected by the Sun and the Moon. Although the Sun is much larger than the Moon, the Moon is closer to Earth (the Moon is about 240,000 miles from Earth, and the Sun is 93 million miles from Earth). Therefore, the moon's gravitational effect on the Earth is more than twice the gravity of the Earth's gravity, and the resulting tidal movement also contains great energy.

We can imagine the Earth as a capsule, and the water on Earth is the rubber shell of the capsule. When the moon's gravity pulls the rubber shell horizontally, the side of the rubber shell expands, and the tide rises here. At this time, the top and bottom of the rubber shell become very thin, and there will be ebb tide here, and vice versa. The gravitational pull of the moon is constant. The periodic rotation of the earth causes periodic high tides and low tides at different locations on the earth. Because this tide is regular, people in many places have begun to use tidal dynamic power.

1. Underwater turbine power generation

The moon's gravitational force on water creates tides, and it also gives the tide a huge amount of kinetic energy. All moving objects have kinetic energy. For example, the wind or a ball rolling down has kinetic energy. Humans can already capture the kinetic energy of the wind through windmills. According to this principle, researchers are now trying to capture the kinetic energy of the tidal water using a windmill-like device. This device is an underwater turbine.

Compared to some high-end technologies, the principle of underwater (or tidal) turbines is relatively simple. It is actually a windmill installed on the seabed or riverbed. Its impeller is designed like an airplane propeller. A gear box is connected behind the turbine and a gear box is connected to the generator. When tidal power drives the turbine to rotate, it also drives the gear to rotate, which in turn drives the generator to run. The electrical energy generated by the generator is transmitted to the shore via the submarine cable, which is then sent to the grid and sent to millions of households.

Although underwater turbines and windmills are essentially the same, underwater turbines have some advantages over windmills. First, the bottom turbine does not need to occupy the floor space, and the windmill farm needs to occupy a large amount of land. In the future, the issue of land use will be a hot topic. For an Earth with 600 million people, ground space is particularly valuable. We need to use limited floor space for building housing, planting crops and other production. The underwater turbines resolve the space problem intangible.

Another advantage of underwater turbines comes from the high density of water. The density of water is greater than the density of air, which means that at the same speed, the same area of ​​force, the bottom turbine produces more electricity than a windmill. What's more, the amount of wind blowing in a given area is unpredictable, and the tidal kinetic energy in a given area is predictable. Since the ebb and flow of tidal waves have regular patterns, the amount of electricity each turbine can produce can be accurately calculated in specific tidal areas.

Scientists have been measuring the energy changes in tidal pools during a one-month cycle. The two most important measurements are two, one is the average peak velocity and the other is the average bottom velocity [source: Carbon Trust]. These two measurements help to estimate the maximum speed and minimum speed at which the tide can occur within a month.

In addition to the gravity of the Earth, there are other factors that affect the flow velocity. For example, whether the surrounding terrain is a rocky or a sandy landform determines the flow of water. In addition, the width of the tidal area also affects the water flow rate, and the narrow area of ​​the water flow is faster.

When calculating the water flow velocity, factors such as the tidal movement and the characteristics of the water body can all be represented on the paper surface, and the turbine's own influence on the water flow can only be known after actual measurement is performed.

2. Do I need to test before installing a tidal turbine?

Water researchers have a good understanding of currents in the tidal zone, but there are still many unknown factors. Therefore, some researchers believe that humans should not put the turbine into the water prematurely, but should first fully study the possible impact of the turbine. When a large number of turbines are put into a tidal area, what impact will it have? We know that energy cannot be created nor destroyed, but can only be transformed from one form into another form that can be used by us, for example, from kinetic energy. Become electrical energy. However, water mobility may also affect the underwater environment in a way that we do not quite understand.

One reason why many people worry about putting turbines under water prematurely is that this technology is really attractive. Underwater turbines do not emit carbon dioxide, and they are benign compared to other methods of generating electricity: turbines are passive in energy production, capturing only the kinetic energy of some tidal motion and converting it into electricity.

The effects of underwater turbines on the marine ecosystem are hardly verifiable, but a fast-rotating turbine blade is likely to roll in small fish. However, people who love the fish are relieved that the tidal turbines are slow, about 10 to 20 rpm. A turbine that moves only a few feet a second does not cause much damage to the fish, but what if the next-generation turbine speeds up?

Of course, the role of the turbine and the underwater environment is mutual, and we must also consider what effect the underwater environment will have on the turbine. For example, will barnacles like barnacles adhere to turbine blades and engines, slowing down or even stopping them?

In order to clarify these issues, underwater turbine pilot projects have been established in many parts of the world. The first tidal turbine put into production is located at the bottom of the Kvalsund Channel in Norway. The turbine is 20 meters high and its blades are 10 meters long at a rate of 7 revolutions per minute. In September 2003, the turbine was connected to a local village, Hammerfest, which generates 700,000 degrees per year, equivalent to the annual electricity consumption of 35 households in the area.

Another group is evaluating the impact of turbines on underwater organisms. The United States Ford Power Company installed five 35-kilowatt turbines on the water bottom and installed special equipment to monitor the surrounding marine life. These devices will detect, track and record fish within 54 feet (18 meters) of the turbine. So far, no fish have been caught in the turbine.

Ford Power Company also participated in a project in East River, New York. They installed six 35 kilowatt tidal turbines at the bottom of a river with a speed of 4 knots (about 46 miles per hour). These six turbines currently power the surrounding grocery stores and parking lots. The company also plans to install more turbines at the bottom of the river and plans to supply 4,000 homes.

The United Kingdom is also studying underwater turbine power generation. British Marine Power Company has installed two large turbines in the water. Each of its blades is 18 meters long and can generate 1.2 million watts of power when it is rotated. The currents generated by the two turbines were all brought into a pole that stood at the bottom of the North Sea not far from the Irish coastline.