Home

Large-Scale Hydropower

Large-scale hydropower makes use of dams, impoundments and large turbines to create electricity.  These types of hydropower plants account for about sixteen percent of our worlds electricity.  Hydropower is a clean and renewable power source but it is losing some of it's popularity with the rise of technology in other forms of alternative energy.

While large-scale hydropower is the best know in the field of water power but there are a few others worth mentioning.  Hydropower can be produced from diversion systems.  Diversion systems use only a portion of the river to create electricity.  They are less productive power wise but are more environmentally friendly.

Hydropower Dam

A pumped storage systems is capable of generating power during peak hours and then pump the water back into a holding tank during off peak hours.  These are actually negative energy systems, they use more energy than they produce.  They are, however, useful.  The power can be generated during peak hours when a utility company would otherwise need to use more expensive back up generators.  You could say these are similar to very large batteries.

A river run system uses the flow of river water to create electricity.  While not as productive as a impoundment and dam system they are less damaging to the environment.  The river water is slowed down when it passes through the the generator but it is not dammed or diverted.

Small-scale hydropower describes generators placed into small steams or rivers to create power for a landowners home.  These units are available for do-it-yourselfers to install with a little help from your friends.  Dollar for dollar this can be an excellent alternative investment.

The subject of large-scale hydropower is not complete without talking about oceanic systems.  These include tidal hydropower and wave hydropower.  Tidal power is similar to a pumped storage system except a pump is not used to the system is a positive power source.  The rising tide fills a dammed reservoir and at low tide the water is released through a power generating turbine.  Wave hydropower is a little trickier.  It involves placing the generators into the ocean in ways to capture the waves to turn the turbines to create the power.  There is a more complicated generating system used in these units and they are barely visible in the water, causing possible problems with boats.  These two types of hydropower deliver only a small portion of our nations total output.  They do have promise, and with the increasing cost of fossil fuels, are being  developed.  The encouraging thing is there minimal environmental impact, far less than the more conventional types of large-scale hydropower.

Impoundment

Impoundments are created when a dam is built.  The process of blocking a river and creating a lake where there was once dry land has environmental issues on many different levels.  The large area of land submerged by new water is called the riparian zone.  The riparian zone can encompass millions of acres and displace animals and possibly humans.

Creating the dam gives us the power to regulate the flow of water.  This control, in most cases, prevents flooding downstream.  This flooding at one time occurred naturally when nature dumped strong rains on the area.  This periodic flooding used to enrich and irrigate the surrounding land, when that natural occurrence becomes disturbed bad things can happen.  One of the widest publicized issues caused by the dams is the disruptions of seasonal migrations.  This effects many different types of fish, some of them becoming extinct.  In some cases ladders are built next to the dams to allow fish access to their upriver spawning waters.

As dams get older they need more maintenance, if that is not kept up they are prone to failure.  When a dam breaks, entire downstream communities, can get wiped out.  Dams also restrict the flow of the water in the river below.  What used to be a strong, fast current becomes much slower.  This causes sediment to build up in the river often contaminating the water with toxic heavy metals.  These are just a few of the environmental issues associated with dams and impoundments.  With other forms of alternative energy coming to light as being cost effective, the further production of these large power production plants is at a standstill.

Hydropower does have many advantages over other types of energy production.  The storage systems used for hydropower are safe and clean.  They have none of the dangers associated with fossil fuel storage.  The water reservoirs can be used for recreation and usable water for nearby communities.  Hydropower plants have the unique ability of being able to control the production of power.  To change the output they simply raise or lower the dam gates.  One of the biggest advantages is the cost competitive nature of hydropower compared to all other sources of power.  As much as ninety percent of the energy offered by the water is transformed into electricity.  Fossil fuel plants seldom see 50 percent efficiency.

Another huge advantage of large-scale hydropower is how clean it is.  Like solar and wind, hydropower produces no pollutants, carbon dioxide, greenhouse gases or toxic wastes.

Are you wondering just how hydropower works?  Large gates control the flow of water through the dams.  The water near the bottom of the dam is pressurized by the weight of the water above it.  This pressurized water is forced into a pipe where it is shot through a turbine that creates the electricity.  The depth of the water effects the head pressure of the flow hitting the turbines.  As a rule of thumb, the deeper the dam the more power it can produce.

Top of Large-Scale Hydropower