Hydro power currently suffices one fifth of the global electricity supply

The word hydro comes from a Greek word meaning water. The energy from water has been harnessed to produce electricity since long. It is the first renewable energy source to be tapped essentially to produce electricity.

Hydro power currently suffices one fifth of the global electricity supply, also improving the electrical system reliability and stability throughout the world. It also substantially avoids the green house gas emissions, thus complimenting the measures taken towards the climate change issues.

Hydro projects below a specified capacity are known as small hydro. The definition of small hydro differs from country to country, depending on the resources available and the prevalent national perspective. The small hydro atlas shows that the largest of the projects (30 MW) is in US and Canada. Small hydro power has emerged as one of the least cost options of harnessing green energy amongst all the renewable energy technologies.

According to the power generated, small hydro power is classified into small, mini/micro and pico hydro. In India, it is being classified as follows.

Small hydro - 2 MW - 30 MW
Mini - 100 kW - 2 MW
Micro - 10 kW - 100 kW
Mico hydro - 1 kW - 10 kW

Projects with the range of 100 kW and above feed power into the grid. They are commercial by nature. Projects below 100 kW are mostly off grid options being harnessed for rural village electrification. They come under the social sector.


Hydro Power


The basics of power from water is the result of conversion of potential energy (the water body at a certain height which is known as the "Head") to kinetic energy (a flow which is known as "Discharge" down the pipe) which is transferred to the buckets in the turbine (mechanical energy). It is the prime mover for the generator (electrical energy) which produces electricity.

Essentially power from a small hydro potential site is derived from two parameters, head and discharge .

Where "head" is the vertical height from which the potential energy of water is converted into electricity after the fall and discharge is the flow rate of the water in the stream/river.

Power (kW) = H * Q * Y

Where
H = Head in m(meter)
Q = Discharge in m3/sec (cumecs) Y = Specific weight of water, being the product of mass and acceleration due to gravity (9.81 kN/m3).

An altimeter is used for head measurement and various methods are used for discharge measurement based on the site conditions. Limited civil works is carried out for the development of the site for small hydro power. To maintain the power quality controllers and electrical equipments is used.

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Efficient energy use

Efficient energy use, sometimes simply called energy efficiency, is the goal to reduce the amount of energy required to provide products and services. For example, insulating a home allows a building to use less heating and cooling energy to achieve and maintain a comfortable temperature. Installing fluorescent lights or natural skylights reduces the amount of energy required to attain the same level of illumination compared with using traditional incandescent light bulbs. Compact fluorescent lights use one-third the energy of incandescent lights and may last 6 to 10 times longer. Improvements in energy efficiency are generally achieved by adopting a more efficient technology or production processes [2] or by application of commonly accepted methods to reduce energy losses.

There are many motivations to improve energy efficiency. Reducing energy use reduces energy costs and may result in a financial cost saving to consumers if the energy savings offset any additional costs of implementing an energy efficient technology. Reducing energy use is also seen as a solution to the problem of reducing carbon dioxide emissions. According to the International Energy Agency, improved energy efficiency in buildings, industrial processes and transportation could reduce the world's energy needs in 2050 by one third, and help control global emissions of greenhouse gases.[3]

Energy efficiency and renewable energy are said to be the twin pillars of sustainable energy policy[4] and are high priorities in the sustainable energy hierarchy. In many countries energy efficiency is also seen to have a national security benefit because it can be used to reduce the level of energy imports from foreign countries and may slow down the rate at which domestic energy resources are depleted.
Energy efficiency has proved to be a cost-effective strategy for building economies without necessarily increasing energy consumption. For example, the state of California began implementing energy-efficiency measures in the mid-1970s, including building code and appliance standards with strict efficiency requirements. During the following years, California's energy consumption has remained approximately flat on a per capita basis while national U.S. consumption doubled.[5] As part of its strategy, California implemented a "loading order" for new energy resources that puts energy efficiency first, renewable electricity supplies second, and new fossil-fired power plants last.[6]

Lovins' Rocky Mountain Institute points out that in industrial settings, "there are abundant opportunities to save 70% to 90% of the energy and cost for lighting, fan, and pump systems; 50% for electric motors; and 60% in areas such as heating, cooling, office equipment, and appliances."[citation needed] In general, up to 75% of the electricity used in the U.S. today could be saved with efficiency measures that cost less than the electricity itself. The same holds true for home-owners, leaky ducts have remained an invisible energy culprit for years. In fact, researchers at the US Department of Energy and their consortium, Residential Energy Efficient Distribution Systems (REEDS) have found that duct efficiency may be as low as 50-70%. The US Department of Energy has stated that there is potential for energy saving in the magnitude of 90 Billion kWh by increasing home energy efficiency.[7]

Other studies have emphasized this. A report published in 2006 by the McKinsey Global Institute, asserted that "there are sufficient economically viable opportunities for energy-productivity improvements that could keep global energy-demand growth at less than 1 percent per annum"—less than half of the 2.2 percent average growth anticipated through 2020 in a business-as-usual scenario.[8] Energy productivity, which measures the output and quality of goods and services per unit of energy input, can come from either reducing the amount of energy required to produce something, or from increasing the quantity or quality of goods and services from the same amount of energy.

The Vienna Climate Change Talks 2007 Report, under the auspices of the United Nations Framework Convention on Climate Change (UNFCCC), clearly shows "that energy efficiency can achieve real emission reductions at low cost."[9]

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