Henry M
Tidal Renewable Energy – Is it a Cost-Effective Renewable Energy Option?
There are several reasons to use tides renewable energy. They're inexpensive and natural, and they are renewable. However, they're not yet cost-effective. The strength of a tide fluctuates over time, and scientists are struggling to find ways to harness the energy from the tide.
Additionally, the system can only provide power for about 10 hours a day – not enough time to meet peak electricity demand. But scientists say it's a possibility and are working on ways to make it cost-effective.
Tidal energy
Tidal energy is one of the most promising emerging sources of renewable energy, and despite a few setbacks, the industry is poised to make a significant contribution to clean energy production.
Until the 19th century, incoming tidewater was retained in storage ponds and the outgoing tide's movement was used to turn waterwheels to mill grain. With the introduction of falling water and spinning turbines, this technology has the potential to generate 10%-20% of the world's electricity demand.
Although the tidal movement can cause turbines to generate electricity, the tidal energy produced so far is insufficient to power a conventional electrical grid. However, a project like this one proposed by Tidal Energy Corp. has already received approval from the Federal Energy Regulatory Commission.
If approved, the project will generate enough clean power to power the entire Alaska Railbelt grid and supply clean power to all Bush communities in Alaska. In addition to electricity production, tidal energy will also help in the creation of green hydrogen, a fuel that is both renewable and environmentally friendly.
Although not an efficient source of energy, tidal power can help generate a great deal of electricity. The tides are 12 hours long, and create an enormous amount of energy. Scientists have theorized that this energy can be harnessed using dams.
Those dams have a turbine connected to a generator, which turns when water flows in and out. This process is similar to wind turbines, but in this case, the water flows outward and spins the turbine, producing electricity.
Tidal stream generators
A tidal stream is a tidal current that travels in waves. Because the water is shallow near the coast, the movement of the tide is amplified.
The energy of these currents is captured by turbines and transmitted through underwater cables to the grid. Tidal stream generators can capture energy in places where land constrictions make land construction impossible. The MeyGen project is the world's largest tidal stream-generating station.
Current technologies for tidal energy generation are advancing slowly. While some companies have left the market before developing a viable product, others are now leading development and deployment of tidal power arrays.
Because the technology is still in its infancy, there are limitations to where the devices can be placed. Many locations don't experience the tidal conditions that make them effective for power generation. Additionally, these installations may not be near a power grid, which means additional investments for cables.
In terms of aesthetics, tidal stream generators offer significant advantages over other forms of renewable energy. The turbines are submerged and thus have less visual impact. They produce little noise and are less susceptible to wind-related noise pollution.
Additionally, they can be smaller than traditional wind turbines and use the Venturi effect to move water faster through their turbines. Tidal stream generators are currently installed in 19 countries, including the U.S., Canada, Australia, and South Korea.
Tidal barrages
Tidal barrages, also known as tidal power plants, are marine renewable energy systems that harness water's kinetic energy to create electricity.
Like hydroelectric power plants, tidal barrages use the water's two-way flow to convert energy into electricity.
These systems are also relatively inexpensive to build and maintain, but they do have some disadvantages. A 2010 US National Oceanic and Atmospheric Association report, Environmental Effects of Tidal Energy Development, identified several negative impacts from this marine renewable energy technology.
Tidal barrages, or tidal dams, are very effective in harnessing the energy from the tides. Barrages are constructed across river estuaries and have tunnels with turbines.
The barrages' lifespan is about 100 years, though one barrage, La Rance in France, has been operating for over fifty years and continues to generate a significant amount of electricity every year.
In order to produce electricity from tidal barrages, a large reservoir is flooded during incoming high tides. The resulting tidal reservoir will become empty when the tides recede. A similar structure, known as a tidal lagoon, operates in a similar fashion.
Unlike a tidal barrage, a tidal lagoon does not span the tidal estuary itself. The lagoons function in conjunction with a breakwater and create a constrained body of water.
Tidal energy converters
One of the biggest obstacles to commercializing tidal energy is its high cost. The technology is in its infancy and requires large tidal ranges and narrower waterways with stronger tidal currents.
With worldwide energy demands on the rise, researchers have recognized the potential of ocean currents to produce energy. The DOE estimates that the energy generated by ocean currents could power millions of homes.
The main environmental concern with tidal energy converters is the risk of marine organisms being pulled by the turbine blades. Moreover, the higher the speed of the water, the greater the risk of organisms being entangled near or even pulled through the turbines.
In addition, the turbine blades are exposed to electromagnetic fields and acoustic outputs that may affect marine organisms. This issue can only be solved by further testing.
The first challenge is how to design a tidal energy converter that can be installed and operated without a large capital investment. While it may be expensive to build and maintain a large-scale tidal array, it is possible to construct one that is cost-effective.
The design process includes a mathematical model to calculate the rotor blades' hydrodynamics and a computational algorithm to optimize the turbine's blades for maximal annual output. The experimental data from full-scale tests of the turbines were used to validate the results. The predictions agreed with the experimental data.
Tidal power plant
A tidal power plant uses tides to generate electricity. Typically, it uses a series of small turbines that are installed along the barrage. These turbines can harness the energy available much more efficiently than larger turbines.
The design of a tidal power plant also depends on its location. The water level is usually at its lowest along the coast. The water level also varies significantly during tidal events.
While tidal power generation is still in its infancy, the amount produced has been relatively small, with only two commercial-scale tidal power plants in operation. The biggest facility is located in South Korea, with a capacity of 254 megawatts.
The United States currently does not have a tidal power plant, but China, France, England, and Canada are considering using this renewable energy source.
In 2013, a marine energy developer, Atlantis Resources Corp., announced plans to build a 50-megawatt tidal power plant in the Gulf of Kutch. This project will replace coal in the grid in Digby Neck, which supplies around half of the province's electricity.
The tidal power plant resembles a dismasted trimaran and is the only one in North America operate. It is non-polluting and works in calm conditions.
Another major concern regarding the impact of tidal power is the effect it may have on marine life. The spinning blades of tidal turbines can accidentally kill swimming sea life.
Because of this, environmental monitoring has been conducted to ensure that these tidal energy generators do not have a negative impact on marine life. The Tethys database provides detailed information on the effects of tidal power on marine life.
Tidal energy cost
Tidal energy is a promising form of green energy. The tides are caused by the gravitational pull of the sun and moon and cause water levels near shore to rise and fall by as much as 40 feet.
As far back as more than a thousand years ago, Europeans began harnessing the movement of water to run mills. Today, tidal energy systems can generate electricity, but you'll need to locate a site where the tidal range is at least seven meters to be economically viable.
While tidal turbines are useful for generating electricity, they are harmful to marine ecosystems. They can disrupt sea creature movement, trapping them in the blades, and altering the levels of silt and salt.
Some research suggests that underwater noise turbines may interfere with sea creatures' communication, and electromagnetic fields emitted from power lines may harm sensitive species. And because of these turbines' erratic movements, fish cannot easily move between locations, which reduces their food supply.
Though tidal energy is greener than wind power, it has significant technology costs. Its components must be durable, corrosive-resistant, and well-insulated. Because tidal power plants are often located in the water, they must be built offshore.
They also require a barrage, which can disrupt the natural flow of water. The cost of installing a tidal power plant is high.
Sources:
- “Tidal Energy: A Primer” by the National Renewable Energy Laboratory https://www.nrel.gov/docs/fy12osti/53712.pdf
- “Tidal Energy: Pros and Cons” by Power Technology https://www.power-technology.com/features/featuretidal-energy-pros-and-cons/
- “The Pros and Cons of Tidal Energy” by Treehugger https://www.treehugger.com/pros-and-cons-tidal-energy-4869314
