Hydro Power
Contents:
Hydro Power
Like Wind Power, Hydro Power has been used in agriculture and industry for more than 3000 years. Essentially, Hydro Power is created by harnessing the force of moving water - whether the force is found in ocean tides, ocean waves, or rivers. The force of the moving water is typically converted to mechanical power through the use of water wheels, propellers, or specially designed water turbines.
Until the advent of electricity, Hydro power was rather limited. It required the user of the power to be located near the source. Thus the early examples of industrialism were invariably located near rivers where the force of moving water could be harnessed by use of water wheels. The rotating water wheels in turn would drive gears and drive belts creating mechanical power for use by mills involved in grinding, sawing, and other early industrial operations.
When the force of moving water is transferred through a pipe or other constraining device where the energy of the moving water or fluid can be concentrated under pressure, Hydro Power is normally called Hydraulic Power. In Northern California during the 1800’s hydraulic mining was used on a massive scale in placer mining of gold. It unfortunately had environmentally devastating results which can still be seen today. We should always remember that just because a power source is renewable, it does not mean it should be used without restraint.
Hydroelectric Power
Hydroelectric Power should not to be confused with Thermo-hydroelectric Power. Thermo-hydroelectric power is derived from the use of Power Plants which use either fossil fuels or nuclear power to convert water to steam. The steam is then used to drive steam turbines which drive electric generators. Thermo-hydroelectric plants use substantial amounts of water to both generate steam and cool equipment. Thermo-electric power plants also produce a significant amount of pollutants both in the form of carbon emissions and heat. In contrast, hydroelectric power plants use water which is almost immediately available for irrigation and public consumption purposes. Very little if any pollutants are generated.
Hydroelectric Power is derived from converting hydraulic power into electricity by directing pressurized water through a turbine which in turn drives an electrical generator.
Hydroelectric Power is mostly associated with enormous dams and large hydroelectric plants. However, much smaller dams and plants are becoming increasingly popular in the developing world. Even in North America and Europe if the circumstances allow it, the use of micro hydroelectric plants can be a very sound investment for a small community. Moreover, hydroelectric power like wind power complements solar power as it is typically more dependable during winter months when power from solar photo voltaic sources are less reliable.
Pros:
- Proven and dependable method of generating electrical power
- The electrical power is renewable
- Relatively inexpensive method of generating electricity after initial costs are paid off
- Dams also store water for seasons when rain is not available
- Dams are also useful to control flooding
- Lakes formed by dams provide a significant recreational resource
- In a time of crisis, hydroelectric plants can be shut down instantly, thermal electric plants take hours, and nuclear plants days
- Hydroelectric plants produce no chemical or waste heat pollution
- The life span of a hydroelectric plant is up to 3 times that of a thermal hydroelectric plant
- Hydroelectric facilities have the potential for incorporating fisheries and other aquatic base enterprises.
Cons:
- There are few locations available for the installation of a large hydroelectric dam
- The lakes formed by dams may inundate significant areas of wild life habitat and scenic areas
- The areas to be inundated by the dam’s lake must be cleared of built improvements and plant materials to prevent massive amounts of green house gases from developing.
- Damming a river disrupts its seasonal changes and ecosystems
- Turbines can kill fish
- Dams can cause a major loss of habitat for migratory or spawning fish such as trout and salmon
- Dams can cause silt build up in rivers by restricting the normal seasonal flow of water
- Dams are expensive to build
- In times of drought the hydroelectric plant may need to reduce its power output to conserve water
- Though very rare dams can break causing catastrophic flooding
Want to learn more about hydroelectric power:
- Hydro Research Foundation: http://www.hydrofoundation.org/index.html
- Mannvitt Engineering / Hydro Power Plants: http://www.mannvit.com/HydroelectricPower/HydroelectricPowerPlants/
- Northwest Hydro Power: http://www.fwee.org/nwhydro.html
Micro Hydroelectric Power
For the small scale developer, Micro Hydro Power provides the opportunity of generating electricity without the use of large dams. In fact, most micro hydroelectric installations require very little or no reservoir storage. Considered a “run of the river” system, micro hydroelectric power is dependent on the river or stream’s flow rate, volume and drop in elevation. It is also important to consider the distance between the power generator and where the power is going to be used. If located properly on a stream with sufficient flow rate during the non rainy season, micro hydroelectric power can be very dependable. In remote areas it can be even more dependable than the power received from the grid as utility companies in these areas notoriously have poor service. Like wind energy micro hydroelectric power complements solar voltaic power. In winter months when there is cloud cover and the photo voltaic system is undependable the hydroelectric system can provide most of the power. Then is summer months when the amount of water may be limited the solar voltaic system can be relied upon. Both systems can feed the same batteries.
Pros:
- Efficient and Reliable source of electrical energy
- Under the proper conditions could be considered a primary source of electricity
- Water reservoir is not required
- Relatively inexpensive to install per KW produced when compared to other technologies
- Excellent for remote locations
- Excess electricity could be sold to the local power company
Cons:
- Critical that an appropriate site be well researched
- A typical Micro installation may not be expandable
- Diversion of even a small amount of stream water could have an ecological impact
- Months when the river or stream or low in volume could impact the ability to produce electricity
Want to learn more about micro hydroelectric power:
Alternative Energy / Micro Hydro Power: Renewable Energy Bug / Hydropower: No Outage.Com uc / hydroelectric information: Tidal Power
In certain places around the globe there are coastal regions which are subject to a rather large tidal range. This tidal range is directly in response to the gravitational pull on the Earth mainly by the Moon but also partially by the Sun. Together, with the rotation of the Earth, these forces are the reason behind the twice a day ebb and flow of tides found throughout the world. The variation in height and strength of tides are completely predictable. By placing tidal dams in river inlets and bays it is possible to direct the tidal water through tidal turbines which are actuated by the tide flowing in both directions. However, as the tide ebbs and flows the flow rate changes markedly. It may be fast during one part of the cycle then slow as it transitions to flow in the other direction. Therefore, though the generation of electricity is reliable it is not consistent. The key to developing tidal power is to find naturally occurring areas of either high tidal flows or large tidal basins that can be easily dammed to direct water through the water turbines. Despite the difficulties, Nova Scotia and France have successfully developed and built these types of facilities. Other countries are planning to join the list.
Pros:
- Proven and dependable method of generating electrical power
- Good secondary source of electrical power.
- The electrical power is renewable
- Relatively inexpensive method of generating electricity after initial costs are paid off
- Unlike thermal electrical plants in a time of crisis, water turbines can be shut down instantly
- Clean source of power; there are no carbon emissions
- Unlike wind and solar power, tidal power produces electricity at predictable times and levels
- Except for possible severe storms, tidal power is not affected by weather conditions
Cons:
- Though predictable tidal power is not consistent enough to be a good primary source of electrical power for the power grid, it can only be used to supplement other sources of energy
- Installing a tidal dam on a river disrupts its seasonal changes and ecosystems
- Tidal dams can inhibit the migration fish such as trout and salmon
- Turbines can kill fish
- Dams can cause silt build up in rivers by restricting the normal seasonal flow of water
- Tidal dams can only be located in certain areas of the world where the conditions are optimum
- Dams are expensive to build, locating them require careful consideration
- Periods of diminished electrical production during the tide cycle
- Tidal dams can be more expensive than hydroelectric river dams per KW produced.
- Salt water environment is not easy on metal equipment; corrosion can be a major problem
- Heavy storms are particularly fierce in the tidal zone; these storms can be problematic in maintaining electrical generating equipment.
Wave Power
Wave Power attempts to capture the up and down vertical force of waves. This can be accomplished by an extraordinary variety of methods. The applicability of the various methods depends on a number of variables. The most important being the consistent availability of waves which possess a significant range of motion. Scotland is the country that comes to mind when we think of fierce powerful waves. And it is Scotland where we find the most promising methods being considered. In fact, it is on the Scottish island of Islay that we find the world’s first commercial wave power station.
Pros:
- Off shore wave energy generators are normally considered beneficial to sea life as they provide surface area and habitat for marine life
- Submerged off shore wave generators have no visual impact and have been shown not to be detrimental to boat traffic or marine life
- Relatively inexpensive to maintain
- Low negative impact on ecosystems
Cons:
- High initial investment
- The Ocean can be extremely hostile at times; the equipment must be very durable
- Ocean waves are intermittent and variable like wind
- On shore wave generators can occupy extensive lengths of scenic coastline
- Many coastlines throughout the world appropriate for wave energy generators are coincidently already developed for prime real estate or are protected pristine wilderness
- Off shore wave energy generators still need to transfer the electricity to the shore
Want to learn more about Wave Power:
Earth Science Australia / Water Power Devices: http://www.earthsci.org/mineral/energy/wavpwr/wavepwr.html#Salter
Tidal Stream Power
A fairly new approach to hydro power is Tidal Steam Power. It basically approaches the generation of power in the same manner as wind power – except under water. A tidal stream power generator is very similar to a wind turbine generator except it transfers the force of moving water found in tides or currents. This is a new technology and several prototypes have been developed. In theory the potential for developing power should be even greater than that for wind turbines. Water has 800 times the density of air; therefore moving water should be able to transfer its force through a turbine more readily than air even at relatively low velocities. Moreover, marine currents which depend on the gravitational pull of the Moon & Sun and the rotational force of the Earth are more reliable than wind. Tidal Stream Generators will work best where the current is fast. Normally currents flow more rapidly between two land masses where an existing ocean current is forced through. It is in these areas that tidal steam generators will be located.
Pros:
- Tides are more predictable than either wind or solar
- No significant impact to the environment
- Underwater turbines typically turn slow enough not to damage wild life
- Conceptually tidal stream generators should not be prohibitively expensive
- Renewable resource
- Tidal steam power can be incrementally expanded simply by adding generators
- Tidal stream generators are not dependent on dams
Cons:
- Tidal stream generators are still experimental
- No particular design has been proven as a true leader
- Not practicable for micro applications
- Electrical distribution is required to transfer energy to the shore.
Want to learn more about Tidal Stream Power:
EPRI Tidal In Stream Energy Conversion (TISEC) Project
http://oceanenergy.epri.com/streamenergy.html
Marine Current Turbines
http://www.marineturbines.com/
The Ocean Renewable Energy Group Links
http://www.oreg.ca/research.html
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First and only Tidal Dam in North America
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