Hydroelectric Energy

Introduction

Every day, the sun heats up the water on the Earth. The evaporated water rises as water vapour, condenses in the sky as clouds, and then falls back to the ground.

Some water falls into the oceans. Some water falls on parched land and is soaked up by the ground. Some water falls high up near streams, flows into the tributaries of major rivers and ends up flowing down the rivers and down into the oceans.

Hydroelectric power is all about harnessing water power. Waters in rivers are flowing downwards towards the ocean. When dams are built, the rivers are blocked up and water accumulates behind the dam, making a lake behind the dam. When the gates of the dam are opened, the water behind the dam flows quickly through the gates of the dam, through turbines, and downwards towards the ocean. The waters flowing through the turbines make the turbines spin at high speeds. The spinning of the turbines is used to drive electric generators – making electricity!

SUPPLY and AVAILABILITY

Like any other energy source, hydroelectric power needs a source of its energy. This source is the water built up behind the dam.? Dams need to be built at large rivers with a lot of water flowing through them. Therefore, any country that wants to build a dam must have a big river flowing in order to be able to use hydroelectric power. As not all countries have such rivers, hydroelectric power is not available to every country.

COST

The source of hydroelectric power is free, as flowing river water has no cost. However, dams are gigantic structures and take a lot of time and materials to build. The are extremely expensive to build. For example, the Three Gorges Dam in China cost more than 25 Billion US dollars to build! So any country wanting to use hydroelectric power must first pay a large sum of money to use the hydroelectric power, but after the dam is built the electricity generated will be practically free. In other words, hydroelectric power is very capital-intensive.

LEVEL OF TECHNOLOGY

Humans have been using water power for a long time. Waterwheels are an example of how water power was used last time – flowing water spun the waterwheels which turned a grindstone that ground grain to make flour. Technologies to get energy out of flowing water have been around for a very long time.

Currently, the technologies used to generate hydroelectric power are very advanced, with computer modeling able to design structurally sound dam structures and efficient turbine blade gradients to get the most spin out of the flowing water. With our advanced technology, hydroelectric power is something that we are able to harness on a large scale.

TRANSPORT AND ACCESSIBILITY

Countries without big rivers are unable to get hydroelectric power. However, in countries that have big rivers, the transport of hydroelectric power is not an issue. Electricity is generated at the dam itself, and then transported to cities through electric cables. Therefore, as long as a country has rivers suitable for building dams, the electricity generated will be accessible to everyone connected to the energy grid.

GOVERNMENT POLICIES

Most governments see hydroelectric power as a cheap way of getting electricity, and are supportive of building dams. However, some governments are unwilling to build dams because when a dam is built, the water that builds up behind the dam will flood large areas of land and drown villages along the river banks. The people who live in the villages will have to be relocated to live somewhere else. Therefore, before deciding to build a dam, governments will have to decide whether it is worth flooding so much land for a dam.

ENVIRONMENTAL CONCERNS

One large environmental advantage of hydroelectric power is that there is no need to burn fossil fuels to generate power, which means that there will be little carbon dioxide produced. As there will be little carbon dioxide produced, the atmosphere will not be polluted by carbon dioxide.

One obvious threat to the environment caused by dams is the flooding of habitats of animals. These animals that live in the areas flooded by the water needed will die as their homes will be destroyed.
The dam needed to generate hydroelectric power will also harm aquatic species. Some species of fish such as salmon swim up and down rivers to mate and spawn baby fish. With the dams in the way, these fish find it very hard to get to suitable breeding grounds. There have been some measures put in place to try and help these fish bypass the dam such as fish ladders and fish lifts, but studies have shown that these measures are largely ineffective and a lot of fish are killed by the exertion of getting to the breeding grounds and by getting torn up when they swim through the fast spinning turbines.

Also, large pools of water with biological material submerged inside are very good for anaerobic bacteria. These bacteria can survive in places with less oxygen, such as in lakes. These bacteria give out large amounts of methane – a powerful greenhouse gas. The methane given off by the bacteria in the lakes created by the dams will enter the atmosphere and contribute to global warming.

FEASIBILITY

Hydroelectric power as a power source for supplying electricity for countries with access to suitable rivers is quite feasible, as it can provide free power when the dam is built. The power can be generated continuously and is not intermittent like energy sources like tidal energy and solar energy. The technology used for hydroelectric power is quite advanced and dams are generally safe. Hydroelectric power also does not create as much greenhouse gases as the burning of fossil fuels to generate electricity.
However, there are considerable disadvantages such as ecological damage and the flooding or large amounts of land for the dam. The large amount of capital needed to start up the dam may also be a disadvantage.

Therefore, hydroelectricity is quite feasible for the countries who can afford it.