Hydroelectric Energy Pros and Cons
20% of the world’s electricity consumption in 2006 was generated with hydroelectricity (generating electricity from hydropower), the most used renewable energy source in the world. We all know that hydroelectricity is both renewable and green, but what are the other advantages this technology offer? Are there any disadvantages? Read the hydroelectric energy pros and cons list below to find out!This article is solely about the pros and cons of hydroelectricity. If you don’t know how hydroelectricity works yet I suggest you first read through
How Does Hydroelectric Power Work?
Advantages of Hydroelectric Energy
Hydroelectric energy is renewable. This means that we cannot use up. However, there’s only a limited number of suitable reservoirs where hydroelectric power plants can be built and even less places where such projects are profitable.
Generating electricity with hydro energy is not polluting itself. The only pollution occurs during the construction of these massive power plants.
Hydroelectricity is very reliable energy. There are very little fluctuations in terms of the electric power that is being by the plants, unless a different output is desired. Countries that have large resources of hydropower use hydroelectricity as a base load energy source. As long as there is water in the magazines electricity can be generated.
As previously mentioned, adjusting water flow and output of electricity is easy. At times where power consumption is low, water flow is reduced and the magazine levels are being conserved for times when the power consumption is high.
Compared to among others fossil fuels and nuclear energy, hydroelectricity is much safer. There is no fuel involved (other than water that is).
Disadvantages of Hydroelectric Energy
1 Environmental Consequences
The environmental consequences of hydropower are related to interventions in nature due to damming of water, changed water flow and the construction of roads and power lines.
Hydroelectric power plants may affect fish is a complex interaction between numerous physical and biological factors. More user interests related to exploitation of fish species, which helps that this is a field that many have strong opinions on.
Fish habitats are shaped by physical factors such as water level, water velocity and shelter opportunities and access to food. Draining would be completely devastating to the fish. Beyond this, the amount of water may have different effects on the fish in a river, depending on the type and stage of the lifecycle. Not all unregulated river systems are optimal in terms of fish production, because of large fluctuations in flow.
Building power plants in general is expensive. Hydroelectric power plants are not an exception to this. On the other hand, these plants do not require a lot of workers and maintenance costs are usually low.
Electricity generation and energy prices are directly related to how much water is available. A drought could potentially affect this.
4 Limited Reservoirs
We have already started using up suitable reservoirs for hydroelectric power plants. There are currently about 30 major power plants that are expected to generate more than 2.000 MW under construction. Only one of these projects was started in the last two years.
Small hydro-power Hydropower, large and small, remains by far the most important of the “renewables” for electrical power production worldwide, providing 19% of the planet’s electricity. Small-scale hydro is in most cases “run-of-river”, with no dam or water storage, and is one of the most cost-effective and environmentally benign energy technologies to be considered both for rural electrification in less developed countries and further hydro developments in Europe. Hydropower on a small-scale is one of the most cost-effective energy technologies to be considered for rural electrification in less developed countries. The development of hydro-electricity in the 20th century was usually associated with the building of large dams . Hundreds of massive barriers of concrete, rock and earth were placed across river valleys world-wide to create huge artificial lakes. While they created a major, reliable power supply, plus irrigation and flood control benefits, the dams necessarily flooded large areas of fertile land and displaced many thousands of local inhabitants. In many cases, rapid silting up of the dam has since reduced its productivity and lifetime. There are also numerous environmental problems that can result from such major interference with river flows . Small-scale hydro power generation Small hydro is in most cases ‘run-of-river’; in other words, any dam or barrage is quite small, usually just a weir, and generally little or no water is stored. The civil works purely serve the function of regulating the level of the water at the intake to the hydro-plant [2,3. Therefore, run-of-river installations do not have the same kinds of adverse effect on the local environment as large hydro. Hydropower has various degrees of ‘smallness’. To date there is still no internationally agreed definition of ‘small’ hydro; the upper limit varies between 2.5 and 25 MW. A maximum of 10 MW is the most widely accepted value worldwide, although the definition in China stands officially at 25 MW. In the jargon of the industry, ‘mini’ hydro typically refers to schemes below 2 MW, micro-hydro below 500 kW and pico-hydro below 10 kW . These are arbitrary divisions and many of the principals involved apply to both smaller and larger schemes. Current Scenario Hydropower, large and small, remains by far the most important of the ‘renewables’ for electrical power production worldwide. The World Hydropower Atlas 2000 , published by the International Journal of Hydropower and Dams, reported that the world’s technically feasible hydro potential is estimated at 14,370 TWH/year, which equates to 100% of today’s global electricity demand. The economically feasible proportion of this is currently considered to be 8080 TWH/year. The hydropower potential exploited in 1999 was 2650 TWH/year, providing 19% of the planet’s electricity from an installed capacity of 674 W. 135 W of new hydro capacity is expected to be commissioned in the period 2001 to 2010. All other renewables combined provided less than 2% of global consumption. As illustrated in Fig 1. North America and Europe have developed most of their economic potential, but huge resources remain in Asia, Africa and South America. Small hydro (10 MW) currently contributes over 40 GW of world capacity. The global small hydro potential is believed to be more than 100 GW. China alone has developed more than 15 GW, and plans to develop a further 10 GW in the current decade . Small hydro offers today one of the most promising energy resources for long term sustainable development in rural areas of many of the world’s poorer countries.However, with a few notable exceptions, progress to date has been disappointing relative to both the potential and the need. Low-cost micro-hydro systems were developed and tested in Nepal from the mid-1970s onwards, with long-term funding from mainly Swiss and German aid programs. Simplified designs 020014-2 of cross flow and peloton turbines were transferred to local manufacturers and workshops and the technology was soon also adopted in Sri Lanka, Peru, and Indonesia.In parallel, Electronic Load Controllers (ELC’s) using solid-state power electronics were developed in the UK and transferred to these countries in the early 1980’s. ELC’s were a low-cost means of running off grid turbines at a fixed speed so as to guarantee 50 Hz generation regardless of the increase or decrease in load. The ELC concept has since been copied worldwide and has greatly improved the long-term sustainability of micro- hydro projects in developing countries . FIGURE 1: Current Scenario of Hydro Power Generation in World [EIA] FIGURE 2: Range of Costs for small hydro projects [2, EIA] The economic success of these early micro-hydro schemes depended largely on achieving a high load factor and using the scheme for income-generation activities. The first expressed demand for power is usually domestic lighting (plus TV and radio), but lighting alone is rarely enough to justify a new micro-hydro plant because the load 020014-3 factor rarely exceeds 10% and further demand only builds up slowly (typically less than 20%/year) . Increasing commercial and industrial end-uses, i.e. raising the productivity of local labor, is the most direct way of justifying a new scheme on economic grounds. Hence if lighting is wanted by night, then this must be ‘paid for’ by using hydropower for productive activities by day. Studies in Nepal have shown that rural electrification alone has had minimal impact on agricultural or industrial production. The most cost-effective use of hydropower in Nepal has been through mechanical end-uses . Innovation, development and cost-cutting Although manufacturers rightly pride themselves in the high efficiency and quality of their turbines, these are irrelevant if the machinery is unaffordable. In the final analysis, it is the energy delivered versus the investment cost which is the key parameter . Much of the technical effort to develop small hydro in recent times has therefore focused on measures to improve cost-effectiveness of the technology. To this end, several developments show promise, which can only be summarized very briefly here . Standardization: Moving away from designing a new system for every site by offering standard sizes of turbine, which share components wherever possible. Innovative use of existing civil works: designs are emerging which avoid much of the civil construction costs by cleverly utilizing the civil works already in place at existing river structures, for example symphonic turbine designs. Variable speed operation of low head turbines: Recent developments in power electronics allow a turbine and generator to be run at varying speeds (instead of synchronous speed needed to produce the mains standard of 50 Hz AC). This permits simpler propeller turbines to be used instead of Kaplan’s. Electronic control and telemetry: Permits unattended operation of hydro-plants. Submersible turbo-generators: These run usually as a ‘bulb’ propeller turbine with the generator submerged and sealed in the flow; this can eliminate the need for a power house. New materials: Plastics, new anti-corrosion materials, etc. offer possibilities for more cost- effective turbines, penstock pipes, bearings, seals etc. Computer optimization of small systems: Permits more accurate and rational sizing of a system to maximize the financial return from a site (rather than maximizing energy capture). Inflatable weirs: Water-filled rubber weir crests are being used to raise the available head on low- head sites; they can deflate to allow flood waters to pass through. Innovative turbines: Various novel types of turbine, or modifications to existing types, have been trialed, and significant work has been done on using mass-produced pumps running backwards as turbines. Simplification and improvement of trash racks: Innovations such as self-cleaning trash racks or self-flushing intakes are being developed to reduce the problem of intake screens becoming clogged with debris. Improved techniques to avoid interference or damage to fish: 020014-4 Perhaps the most common objection to new hydro systems is that they may harm fish. Novel forms of fish ladder and physical or ultra-sonic screening promise more cost-effective solutions. DISCUSSION Every day the sources of non-renewable energy are decreasing. The overall energy situation now mostly depends on renewable energy. All most all country are trying to generate and use renewable energy instead of non-renewable energy. They are trying with wind, wave, hydro etc. But the ration of hydro power is less than others. But it is a great source to produce energy. The overall cost is more efficient than other energy system. And it is also environment friendly. It can be a great source for developing country to overcome their energy crisis. This energy sources can be used both electrically and mechanically. It can become a great support for world energy resource.