Hydroelectricity

Question 1

What are the two categories of hydro-turbines? And exampled of each?

Answer 1

Impact (Pelton Wheel) and Reaction (Francis and Kaplan)

Question 2

Describe Kaplan

Answer 2

Both the blades and the wicket gates are adjustable, allowing for a wider range of operation.

Question 3

Describe Francis

Answer 3

Has fixed buckets. Besides the runner, the other major components are the scroll case, wicket gates, and draft tube.

Question 4

Issue with Francis

Answer 4

Pressure change (which itself is good) can cause bubbles in the fluid, if water pressure then increases toward atmospheric, the bubbles can burst and damage the blades. Called ‘Cavitation’.

Question 5

Are hydroelectricity systems difficult or easy to integrate into the grid

Answer 5

Easy

Question 6

Whats good about hyrdroelectricity

Answer 6

If catchment area large enough and/or river flow is very consistent, then approximately constant power can generated day and night

Question 7

When is ‘stored’ hydropower most useful

Answer 7

During peak utility when demand is high. it has rapid start up time and is relatively easy to control.

Question 8

Advantages and Disadvantages of ‘Run of the River’ power generation

Answer 8

A: No reservoir so no flooding, other than pre-existing risks of natural flooding. Most of river is un-diverted so does not bother fish.
D: Larger projects do have environmental concerns. Little or no capacity for storage so considered ‘un-firm’

Question 9

Pumped storage

Answer 9

Pump water up to high point and when needed let it flows back down through a turbine.

Question 10

What is the efficiency of pumped hydro storage

Answer 10

Energy out to energy in is about 70%

Question 11

Is pumped storage renewable?

Answer 11

No, as electricity is needed to pump the water. This can be supplied by excess wind electricity though.

Question 12

What is good about pumped storage

Answer 12

Can provide large amount of energy very quickly and has capability of restarting itself in case of full blackout, this can then be used to kickstart the grid

Question 13

benefits of three-gorges

Answer 13

• flood control
• year round shipping above dam
• ship lifts/locks beside dam
• 190 million tonnes/year of fossil carbon abated by using river transport instead of road

Question 14

negative impacts of three-gorges

Answer 14

1.3 million displaced
1300 archaeological sites drowned
removal of silt increases flood risk upstream
built on an earthquake region.. huge potential risk

Question 15

Disadvantages of hydropower

Answer 15

built on silt laden rivers, resulting in depleted reservoirs
debt burden - very big investment
can have effects on trees nearby resulting in emissions
DAM collapses!!