Hydropower Flashcards
What are the main characteristics of HP?
- Renewable
- Sustainable
- Flexible (storage and fast response)
- Economic
How long have dams existed for?
5000 years
What allowed HP to become a key component of the energy grid?
Industrial revolution 100 years ago
What allowed electricity to be deployed along long distances?
Alternating current
When was there major dam development?
1960s-1980s
How many large dams are there in the world?
60,000
How many of the 60,000 large dams are in China?
Half
What is the role of hydropower in the share of renewable energy capacity?
Hydropower is a major player within the top 3 sources of renewable energy capacity, known for being dispatchable but experiencing declining growth
When it comes to renewable energy generation, how does hydropower compare in productivity?
Hydropower is more productive compared to other forms of renewable energy generation
Historically, why has hydropower been able to compete with fossil fuels?
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
What factors have made hydropower more expensive in recent times?
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
What is hydropower’s role in energy storage as of 2017?
Hydropower was dominating the share of energy storage in 2017
What is the status of hydropower in the UK?
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
What are features of a run-of-the-river dam?
- Weir
- Spillway
- Settling tank
- inlet canal
How can power be calculated?
P=𝜂𝛾QH
How does run-of-the-river hydro projects work?
Use the natural downward flow of rivers and microturbine generators to capture the kinetic energy carried by water
What are the characteristics of an impoundment hydropower system like the Aldeadávila Dam?
Impoundment systems stir water, have significant storage, and allow control over both the flow rate (Q) and the head (H)
How does the volume of water elevation (V) relate to the height of a dam (H)?
The volume of water elevation is proportional to a certain power of the height of the dam (V ~ H^a)
What is the purpose of pump-storage in hydropower?
Pump-storage systems use excess electricity production to pump water to a high elevation for later use, especially when electricity is needed
What is the efficiency of the turbine section in a pump-storage system?
90%
What are the drawbacks of hydropower regarding land use?
Hydropower requires a lot of land, which means obtaining permits can be a complex process
What is the energy production capacity of hydrokinetic turbines and where are they well suited?
Hydrokinetic turbines have low energy production but are well suited for small, isolated communities with low environmental impact, such as those in the Amazon
How does hydropower production affect the climate?
Through evaporation, which is proportional to the surface area of the water
Hydropower
What is energy generation affected by?
- Highly seasonal, for instance: subject to snow/glaciers or dry periods.
- Droughts (annual and interannual).
- Floods
What competing interests must be balanced with hydropower during droughts?
During droughts, the competing interests include environmental flows, water supply, flood storage, and irrigation
How are dams designed in terms of flood protection?
Dams are designed to survive floods that happen, on average terms, once every 1,000 years
How can past floods be used in relation to hydropower dams?
By examining floods in the past 30 years and their respective discharges, one can estimate the potential for future floods
What are the stages of the dam life-cycle?
- Planning: 3-30 years
- Design: 1-2 years
- Construction: 2-10 years
- Operation → monitoring & maintenance → Refurbishment, uprating or decommissioning : +50-150 years
List the multi-purpose functions of dams.
Dams serve purposes such as irrigation, hydroelectric power generation, water supply, recreation/river regulation/navigation, and flood control
What are the two main types of dams according to the material, and what is their prevalence?
There are embankment dams (80%), which use materials available on-site, and concrete dams (20%), which need materials to be transported
What are the components of dam infrastructure?
- water management
- flood safety
- hydropower generation
- environmental impact reduction facilities
Identify the key parts of a hydropower dam.
The key parts include the reservoir, control gate, penstock, powerhouse, spillway, and fish ladder
What principle is energy extraction based on in a hydropower dam?
Energy extraction is based on the net head and the conversion of mechanical energy into electrical energy, taking into account losses of energy
What is the function of the penstock as indicated in the diagram?
The penstock is a pipe that carries water from the reservoir to the turbines in the powerhouse
What are the three main types of hydropower turbines?
Francis turbines for heads over 10 meters, Pelton turbines good for high heads, and Kaplan turbines good for low heads
What does the term “per cent of full load” mean for turbines?
“Per cent of full load” refers to the operating capacity of a turbine compared to its maximum potential capacity
According to the graph, which turbine shows the highest efficiency at full load?
The Kaplan turbine shows the highest efficiency at full load
What are the common impacts of hydropower systems?
- Everyday water losses due to evaporation and infiltration
- Alteration of the hydrological regime downstream
- Hydropeaking/residual flow impacts
- Sediment and nutrient disruptions
How does the lack of sediments downstream affect the environment and infrastructure?
- 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
What is the impact of a lack of dissolved oxygen (DO) in water bodies?
A lack of dissolved oxygen can negatively affect aquatic organisms and water quality
Why can excess of gases be a problem in hydropower systems?
Excess gases, particularly total dissolved gas (TDG), can become supersaturated under high pressures and lead to fish mortality
What greenhouse gases are emitted by hydropower dams during construction and operation?
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
What is the frequency of dam collapses mentioned?
It is mentioned that on average, 3 dams collapse per year
What design principle is recommended to mitigate the hazards associated with dam failures?
Dams should be designed with a low probability of failure, as it is noted that 0.1% of dams fail
