Advantages: Tidal energy is an alternative energy. The energy produced is clean and non polluting. There is no carbon dioxide or any other by-products released. It produces no greenhouse gases or other waste.It is a renewable energy that will help reduce our reliance on the burning of fossil fuels. There are two tides every day and they can be relied on. The energy is there for the taking.So the electricity supply is constant and efficient.Once you've built it, the energy is free because it comes from the ocean's powerIt needs no fuel.It produces electricity reliably.Not expensive to maintain.Tides are definitely predictable. There are two tides every day and they can be relied on. So the electricity supply is constant. Offshore turbines and vertical-axis turbines are not ruinously expensive to build and do not have a large environmental impact.A plant is expected to be in production for 75 to 100 yearsUses an abundant, inexpensive fuel source (water) to generate powerMay protect coastline against damage from high storm tides and provide a ready-made road bridge

Holding back the tide allows silt to build up on the river bed.The dams and barrages sometimes interfere with shipping. You will need to find a way to connect the electricity to the grid.Pose same threats as large dams, altering the flow of saltwater in and out of estuaries, which changes the hydrology and salinity and possibly negatively affects the marine mammals that use the estuaries as their habitatTurbidity decreases as a result of smaller volume of water being exchanged between the basin and the sea.The average salinity inside the basin decreases, also affecting the ecosystemA barrage across an estuary is very expensive to build, and affects a very wide area - the environment is changed for many miles upstream and downstream. Many birds rely on the tide uncovering the mud flats so that they can feed.There are few suitable sites for tidal barrages.Only provides power for around 10 hours each day, when the tide is actually moving in or out.

It only provides about 7% of the power needed for England and Wales that means that some people get their energy close to free and some pay a lot of moneyWater is not replenished, it cannot flow away so any dirt or pollution lingers around the coast much longerNeeds a very big piece of sea to be cost effectiveCannot be used inlandBarrage systems require salt resistant parts and lots of maintenanceAffects the lives of the people who rely on fishing for a means of livingLimited because the tide never speeds up or slows down, and occurs on 6 hour cycles. It is also dependent on the fetch distance. The fetch is the distance the tide rises and falls, so some beaches have a very small fetch, and others have a big fetch but hardly any have a large enough fetch to support tidal energy

Tidal power is not used more widely because tidal barriers are expensive to build, often in remote locations, have high maintenance requirements, and generate relatively small amounts of power. This makes the cost of power very high, and correspondingly the return on investment capital quite low or even negative. In summary, it is promising but needs more development.

There are also three main ways that tidal energy is harnessed: Tidal Barrages - A tidal barrage works like a dam. When the tide goes high, the reservoir fills up. When the tide drops the dam lets the water out. In both directions the moving water can spin the blades of turbines to create electricity. Tidal Fences - These are smaller structures than a barrage. A number of vertical turbines form a fence between two land masses. When the tide moves in or out, the turbines spin and generate electricity. Tidal Turbines - These are individual turbines placed anywhere there is a strong tidal flow.

Tidal power to turn water wheels and grind grains was used as far back as Roman times and the Middle Ages. The idea of using tidal power for electricity is fairly recent, but the costs have been too high to make it a major energy source. Recent technological advances have shown that it could become a competitive and viable source

Tidal turbines are more expensive to build and maintain than wind turbines, but produce more energy. They also produce energy more consistently as the tide is continuous while the wind doesn't always blow.

Tidal energy is a type of energy that produces electricity and other forms of power through the use of water.

The tide moves a huge amount of water twice each day and although the tidal energy supply is reliable and plentiful, converting it into useful electrical power is not easy.

The first involves converting the power of the horizontal movement of the water into electricity. The second involves producing energy from the rise and drop of water levels

Tidal energy is the utilization of the variations in sea level caused primarily by the gravitational effects of the moon, combined with the rotation of the Earth.

Tidal energy is a clean, renewable energy resource, but its environmental impacts and accessibility, limit its potential to become a major provider of electricity. Where tidal energy is a viable resource, it may prove to be expensive at first, but economical in the long run if the technology improves.

We can use slow moving ocean and river waves for a new, reliable and affordable alternative energy source. A University of Michigan engineer has developed a device that acts like a fish that turns the potentially destructive vibrations in water into clean, renewable energy.

Tidal power is non-polluting, reliable and predictable.Tidal barrages, undersea tidal turbines - like wind turbines but driven by the sea - and a variety of machines harnessing undersea currents are under development. Unlike wind and waves, tidal currents are entirely predictable.

Green energy has never been more important than it is today with the looming threat of global warming. Every possible effort must be made to reverse the worldwide threat of climate change by subsidizing and switching to green energy. One often-overlooked source of clean, renewable energy comes not from solar, wind or geothermal power, but from the tides.

The collection of tidal energy is clean because it involves very little emission of carbon dioxide and other greenhouse gases

However, estuaries are among the world’s most productive and sensitive ecosystems, and barrages cause large disruptions to their natural processes. We will therefore not further consider barrage based tidal power as a truly sustainable energy resource.

The second type is based on utilizing the fast-flowing marine currents caused by tidal action. While there are non-tidal based ocean currents such as the Gulf Stream, those are usually too diffuse to be a practical energy source. The tides cause water to flow inwards from the ocean twice a day during flood tides, and outwards during ebb tides.

Nevertheless, it is a truly sustainable energy source which is also very predictable. It is not subject to the vagaries of weather or climate change, and while the energy varies, it follows a predictable pattern that is known many years in advance.