Hydro-electric Power Stations

One of the more widely used renewable energy sources used today is hydro-electricity. The hydro-electric power plant gives off very little emissions and no direct waste. Hydropower currently generates 20 percent of electricity globally, accounting for almost 88 percent of the electricity that comes from renewable sources.

However, there are still environmental issues with regard to the construction of hydro-electricity power stations. Most stations are built by blocking a river to create a reservoir. Power is then generated from the potential energy of water gushing down the hill under pressure from the dam and passing a water turbine.

A water wheel can also power up smaller hydro-electricity systems, which can produce as little as a couple of kilowatts of electricity to 10MW (megawatts), which can then be purchased from different power manufacturers – or the system can be installed at a desired site in as little as a couple of weeks time. Micro-hydro power stations have grown popular in China, with hundreds of units being constructed in recent years.

The many advantages of power stations using hydro-electricity are:

• Lower ongoing cost, as no fuel is involved
• No emissions of any kind
• An extremely long life; those built 80-100 ago are still operating efficiently
• Easy increase and decrease of power production with the turning of a tap, making hydro-electric power stations a very flexible power source

There are also secondary uses that can be utilized with a lot of hydro-electric power stations, like managing water flow; stopping downstream flooding; and for creating tourist attraction sites, with the reservoir’s waters used for general recreation and water sports. They can also be used for agricultural purposes. In India, hydro-electric power stations are used to irrigate rice fields.

Pumped Storage

Producing electricity on a large scale can be a big challenge, as it is extremely hard to store the extra electricity generated during low demand so that it can be later used during times of high demand. This lack of storage capability can turn into a bigger challenge when wind turbines are introduced for generating electricity, since this type of energy depends on the wind’s strength and not on user demand. Pumped storage may be the solution to the problem, as it stores the excess energy until it is needed to be released as required and demanded. This system works by depending on two hydro-electric reservoirs: one on top of the hill and the other at the bottom.

When there is extra electricity being generated, such as at low peak hours in the nighttime, water can be pumped to the top reservoir from the lower one. When the demand is at normal or high (daytime hours), water is released to the lower reservoir via a water turbine so that it can generate the needed electricity.

If two lakes exist, a pumped storage system is usually built, whether the lakes are natural or man-made.  These systems are usually found alongside the conventional hydro-electric power station.

Pumped storage systems may generate just enough electricity for use, but they can store extra energy that is