16-4 What are the Advantages and Disadvantages of using hydropower?Katie BrumbaughSydney Lenzotti

Section ConceptWe can use water flowing

over dams. tidal flows, and ocean waves to generate electricity, but environmental concerns, limited availability of suitable sites may limit our use of these energy resources.

Hoover Dam, Neveda

Syncrude Tailings Dam, Canada

We can produce Electricity from Flowing and Falling water Uses kinetic energy of falling and

flowing water to produce electricity An indirect form of solar energy (based

an evaporation of water or water cycle) http://

www.youtube.com/watch?v=StPobH5ODTw&feature=related

Water deposited at higher elevation where it can flow to lower elevations in river

How to HarnessMost common approach is to build

a high dam across a high dam to create a reservoir (artificial lake formed when a stream is dammed)

Some of the stored water flows through large pipes at controlled rates to spin turbines that produce electricity

World Leading Renewable Energy Source used to Produce electricity2007- 20% of the worlds electricity

99% Norway, 75% New Zealand, 59% Canada, 21% China, 6% US (but about 50% used on west coast)

Top 5 producersCanada, China, Brazil, United

States, Russia

Untapped Potential According to the UN, only about 13%

of hydropower has been developed Especially China, India, South America,

Central Africa, and parts of the former Soviet Union

2020 China plans to double hydropower output, build/fund more than 200 dams around the world

Brazil has 4 dams and plan to build about 70 more

Untapped Potential cont. If goals completed, current and planned

hydropower projects around the world will have the electrical output of several thousand large coal burning power plant, but without the high emissions of greenhouse gases

Criticism Some analyst the use of large scale hydropower

plants to fall over the next several decades as existing reservoirs fill with silts and become useless faster than new dams can be built

Growing concern over the emission of methane from the decomposition of submerged vegetation in hydropower reservoirs especially in warm climates.

Dams are the single largest source of human produced methane

As glacier melt and less water is flowing through rivers and streams less electricity will be able to be produced

Microhydropower Generators Floating turbines, each about the size of

an over night suitcase May become an increasingly important

way to produce electricity Use power of flowing water to turn rotor

blades, which spin a turbine to produce electric current

Advantages Be placed in any stream or river without

altering its course Can provide electricity at very low cost Low environmental impact

We can use Tides and Waves to Produce Electricity Tides can cause water levels to rise and

fall up to 6 meter (20 feet) or more between daily high and low tides

Dams built across costal bays and estuaries to capture energy

Operating Tidal Energy Dams La Rance on the

northern coast of France Nova Scotia’s Bay of

Fundy Several more countries

plan to build tidal energy dam

Disadvantages include: high costs and few global sties

New and Developing Technologies 2006-2008 Verdant Power built and

installed 6 underwater turbines which tapped into the tidal flow of the East River near NYC

Turbines resembled underwater wind turbines because they swivel to face the incoming and out going tides

Produce electricity efficiently Next phase involves installing 30 turbine, if

successful up to 300 more could be installed

New and Developing Technologies cont. Next phase involves installing 30

turbine, if successful up to 300 more could be installed

System similar to this powers a town in Norway

Disadvantages- systems limited to limited amounts of rivers with adequate tidal flow

The Future Trying to capture the water energy of

waves along sea costs where there is almost continuous waves

Portugal- large snake-like of floating steel tubes

the up and down motion of the chains creates electricity

Powered 15,000 homes Disadvantages: few suitable sites, high

costs, and equipment could be easily corroded

TradeoffsAdvantages

Moderate to high net energy yield

Large amount of untapped resources

Low CO2 emissions

Disadvantages

Large land disturbance

High CH4 emission from rapid biomass decay in reservoirs

Disrupts downstream aquatic ecosystems

Summary Water flowing in rivers and streams can be trapped

in reservoirs behind dams and released to spine turbines and produce electricity

Hydro power is an indirect form of renewable solar energy. It produced 20% of the world’s electricity in 2006

Advantages: many untapped potential resources, high net energy yield, low CO2 emissions

Disadvantages: large land disturbance, High CH4 emission from rapid biomass decay in reservoirs, disrupts downstream aquatic ecosystems

Ocean tides and waves can be used to generate electricity but the costs are high and limited locations for this technology