Tidal Energy

Introduction

The tide moves much water everyday, the energy that can be harnessed from it can be used to power a considerable bit our energy needs. The tide as an energy supply is reliable and also plentiful, yet however, converting it into electrical power to satisfy our needs is not easy.

How Is It Done?

Tidal energy is obtained from moving masses of water, known as tides. Basically, there is a dam or a barrage that is built across a delta, beach, estuary or any place that can be affected by the tide.

The dam has sluices and turbines, which are capable of holding the tide at high tide when the water comes in. When the tide is low, the dam will then release the water, which will then pass through turbines. These turbines harness the energy from the tide's kinetic energy which can then be converted into electrical energy for our use.

Analysis of Energy Source

Availability

Tidal energy requires fast flowing rivers and tides, which provide the kinetic energy for turning the turbines of the dam. Such rivers and water bodies are mostly available in most countries, except those which are like desert countries.

This source is also renewable, as due to the water cycle, the water is replenished. The gravitational pull from the moon pulls the water in the ocean, and thus causes a high tide two times a day.

As long as there is water, there will always be movement of waves which generates kinetic energy, which can then be converted into electrical energy.

Cost

The cost of tidal energy is rather inexpensive in the long run. The cost mainly comes from the building of the dam, and once the dam is built, there is not much cost other than the maintenance of the dam.

Also, as the basin of water or river is renewable and does not cost anything, tidal energy hardly requires any cost.

Tidal energy has also a relatively high efficiency rate. About 80% of the kinetic energy from the waves can be converted into usable electrical energy for our use.

Level of Technology

Modern day technology permits the building of dams and turbines which can harness kinetic energy from tides to be converted into electrical energy. Most countries have such technology, as it is not of the highest standard, or the cutting-edge type of technology.

The technology required for harnessing the energy from tides is probably known to most of the world, apart from possibly developing countries. This technology is quite efficient, as it can convert up to 80% of the tide's kinetic energy into usable electrical energy.

Transport and Accessibility

Tidal energy is obtained from the tidal movement which turns the turbines. The energy will be converted into electrical form, which can then be channeled off into electrical cables. Thus, there is no transport needed to bring the energy to other places, as the electricity can then pass through cables.

The source of tidal energy however cannot be moved, and it is rather permanent. It is usually situated in fast flowing rivers, or a basin of water. But as the converted form of the energy in electricity can be moved through cables, this would not pose a large problem.

Feasibility

Although tidal energy may be inexpensive, it however is not very feasible, despite that there are some governments who see much potential in tidal energy, and have invested and funded such projects, such as the British Wind Energy Association and the Western US governments.

Firstly, the cons outweigh the pros. Tidal energy may only be harnessed when there is water elevation, which thus makes it impossible for countries without a sea/ocean, like desert countries or inland countries.

Also, dams do not provide enough energy to satisfy the current energy needs that we require. As such, it is not much of a future source.

It also causes much environmental damage, which includes flooding upstream areas from containing all the water. This thus causes damage to villages and towns that are upstream, and also leads to loss of lives. The dams also cause water shortages downstream by containing all the water upstream.

Government Policies

As tidal energy is a renewable source, and it is relatively safe, governments do not really oppose the idea. In fact, the British Wave Energy Association is promoting wave and tidal current technology, and has funded the UK in this industrial sector.

Also, the government in Western US has invested much of their money into building dams for the purpose of harnessing energy from tides, as there is great potential in this industry.

However, due to the large amount of funds required to build a dam, tidal energy may not reap returns for years. As such, this has put off some investors and governments. Although they may have the financial power to fund such projects, they are largely unwilling to fund them because of how it may not reap returns in a short term perspective.

Environmental Concerns

There are a few environmental concerns regarding tidal energy. Firstly, as the water in the basin and sea hardly is exchanged, the salinity of the basin decreases, which would affect the ecosystem. Also, when the water is not exchanged, the turbidity (amount of matter in suspension in water) decreases, thus letting much sunlight get into the water, which would thus encourage phytoplankton growth, upsetting the ecosystem once again.

Also, pollutants in the basin will not be easily dispersed. This would result in a buildup of pollutants, and for biodegradable pollutants, this would thus result in bacterial growth.

Lastly, fishes that swim through turbine are highly susceptible to getting killed by the turbines. Fish mortality rate due to these turbines is approximately 15%, which is alarmingly high for the fish which pass through everyday. Alternative technologies, like fish lifts and fish ladders have failed to address this problem.

Examples

There are quite a few major dams which are used to generate tidal energy around the world. Most of them can be found in Europe and the North and South Americas . Also, there are a few of these stations in Asia, for example, China , India and Korea .

In terms of efficiency, this source of energy is rather efficient due to its high amount of energy converted from the raw kinetic energy. But however, as tidal energy does not provide enough energy for our needs, it is not a feasible source for the future.