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CIVE40010 - Energy and environmental engineering > Hydropower > Flashcards

Hydropower Flashcards

1
Q

What are the main characteristics of HP?

A
  • Renewable
  • Sustainable
  • Flexible (storage and fast response)
  • Economic
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2
Q

How long have dams existed for?

A

5000 years

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3
Q

What allowed HP to become a key component of the energy grid?

A

Industrial revolution 100 years ago

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4
Q

What allowed electricity to be deployed along long distances?

A

Alternating current

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5
Q

When was there major dam development?

A

1960s-1980s

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6
Q

How many large dams are there in the world?

A

60,000

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7
Q

How many of the 60,000 large dams are in China?

A

Half

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8
Q

What is the role of hydropower in the share of renewable energy capacity?

A

Hydropower is a major player within the top 3 sources of renewable energy capacity, known for being dispatchable but experiencing declining growth

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9
Q

When it comes to renewable energy generation, how does hydropower compare in productivity?

A

Hydropower is more productive compared to other forms of renewable energy generation

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10
Q

Historically, why has hydropower been able to compete with fossil fuels?

A

Hydropower has traditionally been the only top renewable energy source able to compete in price and scale with fossil fuels due to its low cost

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11
Q

What factors have made hydropower more expensive in recent times?

A

Hydropower has become more expensive because most of the most productive projects have already been built, leaving less profitable sites, facing small sites, and more environmental regulations

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12
Q

What is hydropower’s role in energy storage as of 2017?

A

Hydropower was dominating the share of energy storage in 2017

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13
Q

What is the status of hydropower in the UK?

A

Hydropower in the UK is marginal, contributing to 1.7% of electricity generated, largely due to the requirement of specific conditions such as topography and gradient

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14
Q

What are features of a run-of-the-river dam?

A
  • Weir
  • Spillway
  • Settling tank
  • inlet canal
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15
Q

How can power be calculated?

A

P=𝜂𝛾QH

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16
Q

How does run-of-the-river hydro projects work?

A

Use the natural downward flow of rivers and microturbine generators to capture the kinetic energy carried by water

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17
Q

What are the characteristics of an impoundment hydropower system like the Aldeadávila Dam?

A

Impoundment systems stir water, have significant storage, and allow control over both the flow rate (Q) and the head (H)

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18
Q

How does the volume of water elevation (V) relate to the height of a dam (H)?

A

The volume of water elevation is proportional to a certain power of the height of the dam (V ~ H^a)

19
Q

What is the purpose of pump-storage in hydropower?

A

Pump-storage systems use excess electricity production to pump water to a high elevation for later use, especially when electricity is needed

20
Q

What is the efficiency of the turbine section in a pump-storage system?

A

90%

21
Q

What are the drawbacks of hydropower regarding land use?

A

Hydropower requires a lot of land, which means obtaining permits can be a complex process

22
Q

What is the energy production capacity of hydrokinetic turbines and where are they well suited?

A

Hydrokinetic turbines have low energy production but are well suited for small, isolated communities with low environmental impact, such as those in the Amazon

23
Q

How does hydropower production affect the climate?

A

Through evaporation, which is proportional to the surface area of the water

24
Q

Hydropower

What is energy generation affected by?

A
  • Highly seasonal, for instance: subject to snow/glaciers or dry periods.
  • Droughts (annual and interannual).
  • Floods
25
Q

What competing interests must be balanced with hydropower during droughts?

A

During droughts, the competing interests include environmental flows, water supply, flood storage, and irrigation

26
Q

How are dams designed in terms of flood protection?

A

Dams are designed to survive floods that happen, on average terms, once every 1,000 years

27
Q

How can past floods be used in relation to hydropower dams?

A

By examining floods in the past 30 years and their respective discharges, one can estimate the potential for future floods

28
Q

What are the stages of the dam life-cycle?

A
  1. Planning: 3-30 years
  2. Design: 1-2 years
  3. Construction: 2-10 years
  4. Operation → monitoring & maintenance → Refurbishment, uprating or decommissioning : +50-150 years
29
Q

List the multi-purpose functions of dams.

A

Dams serve purposes such as irrigation, hydroelectric power generation, water supply, recreation/river regulation/navigation, and flood control

30
Q

What are the two main types of dams according to the material, and what is their prevalence?

A

There are embankment dams (80%), which use materials available on-site, and concrete dams (20%), which need materials to be transported

31
Q

What are the components of dam infrastructure?

A
  • water management
  • flood safety
  • hydropower generation
  • environmental impact reduction facilities
32
Q

Identify the key parts of a hydropower dam.

A

The key parts include the reservoir, control gate, penstock, powerhouse, spillway, and fish ladder

33
Q

What principle is energy extraction based on in a hydropower dam?

A

Energy extraction is based on the net head and the conversion of mechanical energy into electrical energy, taking into account losses of energy

34
Q

What is the function of the penstock as indicated in the diagram?

A

The penstock is a pipe that carries water from the reservoir to the turbines in the powerhouse

35
Q

What are the three main types of hydropower turbines?

A

Francis turbines for heads over 10 meters, Pelton turbines good for high heads, and Kaplan turbines good for low heads

36
Q

What does the term “per cent of full load” mean for turbines?

A

“Per cent of full load” refers to the operating capacity of a turbine compared to its maximum potential capacity

37
Q

According to the graph, which turbine shows the highest efficiency at full load?

A

The Kaplan turbine shows the highest efficiency at full load

38
Q

What are the common impacts of hydropower systems?

A
  • Everyday water losses due to evaporation and infiltration
  • Alteration of the hydrological regime downstream
  • Hydropeaking/residual flow impacts
  • Sediment and nutrient disruptions
39
Q

How does the lack of sediments downstream affect the environment and infrastructure?

A
  • lead to the scouring of bridges
  • lead to nutrient depletion in water
  • lead to loss of dam storage capacity
  • lead to loss of sediment discontinuity
40
Q

What is the impact of a lack of dissolved oxygen (DO) in water bodies?

A

A lack of dissolved oxygen can negatively affect aquatic organisms and water quality

41
Q

Why can excess of gases be a problem in hydropower systems?

A

Excess gases, particularly total dissolved gas (TDG), can become supersaturated under high pressures and lead to fish mortality

42
Q

What greenhouse gases are emitted by hydropower dams during construction and operation?

A

CO2 is emitted during construction due to cement use and transport, while CH4 is emitted during operation, which can be mitigated by reducing organic material in the reservoir

43
Q

What is the frequency of dam collapses mentioned?

A

It is mentioned that on average, 3 dams collapse per year

44
Q

What design principle is recommended to mitigate the hazards associated with dam failures?

A

Dams should be designed with a low probability of failure, as it is noted that 0.1% of dams fail

CIVE40010 - Energy and environmental engineering (21 decks)

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