dams

Tajikistan Nurek is the tallest.

Brazil's Itaipu is the most powerful.

Damn dams are everywhere and they're getting bigger all the time dammit!

Hydropower is one of the oldest methods of power generation in the world.

Today, we often think of Hoover dam, but ancient Greeks used the power of turning waterwheels

to grind grain.

with enough drop to run waterwheels.

Today, instead of a waterwheel on a creek, hydropower often involves building a massive

dam to hold back a water source.

With enough water pressure and drop, the water can turn giant turbines and generate electricity.The

Department of Energy says "70 percent of Washington State’s electricity comes from hydropower…

and 11 states get more than 10 percent of their electricity from hydro."

The thing is, only 3 percent of the 80,000 dams in the U.S. generate electricity, and

even if they do, dams inevitably alter thousands of square miles of waterways in both directions,

affecting fish and wildlife, forests, farms, and (of course) human populations.

China is the largest producer of hydroelectricity, followed by Canada, Brazil, and the United

States, according to the Energy Information Administration.

The Xayaburi dam is a three-and-a-half billion dollar project on the Mekong river in northern

Laos scheduled to be completed in 2019.

It's one of 11 dams planned to be completed by 2025.

Though they'll provide 8 percent of the region's electricity, and 3.7 billion a year in income;

it will affect more than 200-thousand people in the region and result in "possible extinction

of fish species, reduced fish populations, inundation of river bank gardens, and loss

to a 2011 International Rivers report.

Plus, construction of the dams could expedite the extinction of these cute but weird-looking

Irrawaddy dolphins.

Most people are aware of the impediments these dams make for spawning and migrating fish,

but it's not just that...

Water in a reservoir is stagnant, gathering more sediment and growing more aquatic weeds

and algae -- causing problems with downstream life.

Fish are used to certain temperatures and levels of oxygen in their river water.

Dams not only block the fish, but the deep reservoirs held by the dam result in damn

cold water with VERY little oxygen.

Opening the reservoir to respond to a sudden demand for electricity causes this cold, barely

oxygenated water to rush into rivers, suffocating and killing fish, this is according to the

Union of Concerned Scientists.

On top of all that, the river itself suffers, because sand, rocks, wood and other natural

sediment builds up in the reservoir rather than spreading downriver.

On top of ALL THAT, The Union of Concerned Scientists found large hydroelectric dams

DO pollute with greenhouses gases.

As the reservoir behind the dam grows or floods over plants; that material decomposes releasing

CO2 and methane; especially in tropical areas.

Emissions vary, but are just underneath the lowest levels from a natural gas plant.

The Balbina hydroelectric dam in Brazil flooded over 900 square miles (2360 sq km) of land

-- an area the size of Delaware, that's a lot of decomposing vegetation.

Dams are considered symbols of human achievement and national willpower, but that can come

at the expense of our national resources and still cause pollution and destruction.

We didn't even talk about earthquakes or the construction of the dams themselves -- which

can take as long as a decade.

So what can we do?

Two, century-old, dams on the Elwha River in Washington state are blocking a key salmon

spawning channel -- and they generate very little electricity -- so they're being demolished!

Aside from tearing them down, some hydropower plants simply divert water rather than daming

a whole river, and you can even generate power using natural wave surge in the ocean!

Another way companies are using nature to power our appliances is with wind energy,

but what about when the wind's not blowing?

Then you just capture the wind in a cave and use it later!