Jumat, 18 Januari 2008

Micro hydropower


What’s Micro hydro power
Hydropower is energy from water sources such as the ocean, rivers and waterfalls. “Micro hydro” defined as a plant between 10 kW and 200 kW means which can apply to sites ranging from a tiny scheme to electrify a single home, to a few hundred kilowatts for selling into the National Grid. Small-scale hydropower is one of the most cost-effective and reliable energy technologies to be considered for providing clean electricity generation. The key advantages of small hydro are:

  • High efficiency (70 - 90%), by far the best of all energy technologies.
  • High capacity factor (typically >50%)
  • High level of predictability, varying with annual rainfall patterns
  • Slow rate of change; the output power varies only gradually from day to day (not from minute to minute).
  • A good correlation with demand i.e. output is maximum in winter
  • It is a long-lasting and robust technology; systems can readily be engineered to last for 50 years or more.

It is also environmentally benign. Small hydro is in most cases “run-of-river”; in other words any dam or barrage is quite small, usually just a weir, and little or no water is stored. Therefore run-of-river installations do not have the same kinds of adverse effect on the local environment as large-scale hydro.

Why Micro hydro

Micro hydro are one of renewable energy sources. Renewable energy sources can be replenished in a short period of time. The five renewable sources used most often are, biomass, water (hydropower), geothermal, wind, solar .Five generations (125 years) ago, wood supplied up to 90 percent of our energy needs. Now, some biomass that would normally be taken to the dump is converted into electricity (e.g., manufacturing wastes, rice hull Historically, low fossil fuel prices, especially for natural gas, have made growth difficult for renewable fuels. The use of renewable sources is also limited by the fact that they are not always available (for example, cloudy days reduce solar energy, calm days mean no wind blows to drive wind turbines, droughts reduce water availability to produce hydroelectricity). Despite these limitations, renewable energy plays an important role in the supply of energy. When renewable energy sources are used, the demand for fossil fuels is reduced. Unlike fossil fuels, most renewable sources do not directly emit gasses, and black liquor from paper production). Theirs energy sources outdoes of micro hydro ;

  • Nature produce by continue till the existence of relative awake.
  • Conversion process of becoming electrics energy do not generate pollutant.
  • Production cost of cheaper relative compared to fossil energy.
  • Most of all places in Indonesia have the source of this energy.

Water power for micro hydro.

Hydropower is using water to power machinery or make electricity. Water constantly moves through a vast global cycle, evaporating from lakes and oceans, forming clouds, precipitating as rain or snow, then flowing back down to the ocean. The energy of this water cycle, which is driven by the sun, can be tapped to produce electricity or for mechanical tasks like grinding grain. Hydropower uses a fuel water that is not reduced or used up in the process. Because the water cycle is an endless, constantly recharging system, hydropower When flowing water is captured and turned into electricity, it is called hydroelectric power or hydropower. There are several types of hydroelectric facilities; they are all powered by the kinetic energy of flowing water as it moves downstream. is considered a renewable energy.

Turbines and generators convert the energy into electricity, which is then fed into the electrical grid to be used in homes, businesses, and by industry.

Site configurations.

The objective of a hydro power scheme is to convert the potential energy of a mass of water, flowing in a stream with a certain fall (termed the head.), into electric energy at the lower end of the scheme, where the powerhouse is located. The power of the scheme is proportional to the flow and to the head. According to the head, schemes can be classified in three categories:

High head: 100-m and above, Medium head: 30 - 100 m, Low head: 2 - 30 m.

Schemes with the powerhouse at the base of a dam ( low head system )

A small hydropower scheme cannot afford a large reservoir to operate the plant when it is most convenient; the cost of a relatively large dam and its hydraulic appurtenances would be too high to make it economically viable. But if the reservoir has already been built for other purposes . flood control, irrigation network, water abstraction for a big city, recreation area, etc, - it may be possible to generate electricity using the discharge compatible with its fundamental usage or the ecological flow of the reservoir. The main question is how to link headwater and tail water by a waterway and how to fit the turbine in this waterway. If the dam already has a bottom outlet., the solution is clear. top of the dam or on the downstream side. The unit can be delivered pre-packaged to the works, and installed without major modifications of the dam.

Schemes integrated with an irrigation canal( high head system )

The canal is enlarged to the required extent, to accommodate the intake, the power station, the tailrace and the lateral bypass. To ensure the water supply for irrigation, the scheme should include a lateral bypass, as in the figure, in case of shutdown of the turbine. This kind of scheme must be designed at the same time as the canal, because the widening of the canal in full operation is an expensive option.

If the canal already exists, a scheme like the one shown in figure 5 is a suitable option. The canal should be slightly enlarged to include the intake and the spillway. To reduce the with of the intake to a minimum, an elongated spillway should be installed. From the intake, a penstock running along the canal brings the water under pressure to the turbine. The water, once through the turbine, is returned to the river via a short tailrace. As generally, fish are not present in canals, fish passes are unnecessary.