12.1 Sustainable energy supply Flashcards
(25 cards)
Hydro-electric power (HEP)
Fast flowing water, from river or released from dam, is directed through turbines.
Force of water spins turbine’s blades, generating electricity.
HEP advantages
Once operating, they are cheap and efficient to run.
Emits no GHG.
Reliable - little flux in water supply.
Flexible - can adjust water flow and output.
Safe - no fuel involved
HEP disadvantages
Building structures on rivers and dams may harm wild life.
Expensive to build: Bakun Dam costed 2.3 billion pounds
May overflow or experience silt build up.
Construction releases CO2: 0.9 pounds of CO2 produced per pound of cement produced.
Impede salmon migration BUT fish ladders can assist this.
Can lead to droughts: Ataturk dam cut flow of Euphrates river by 1/3.
Slope instability: Vajont Dam disaster in October 9, 1983.
Affecting surrounding areas: 10,000 people had to relocate
Areas suitable for HEP
Mountainous region with high rainfall.
Small-scale HEP schemes successful in LICs on a local but not national scale.
How many percent of Costa Rica’s energy is produced by HEP?
95%
How is nuclear energy created; Nuclear Fission
Through splitting of atoms.
Releases heat energy through radioactive decay of fuel rods, heat turns water into steam, steam turns turbines, turbines turn generators, generators make electricity.
Uranium ore is the most used.
Plutonium and Thorium can also be used.
All of today’s nuclear plants use fission to generate electricity
Two types of nuclear power
- Nuclear Fission
- Nuclear Fussion
Nuclear fusion generation
Energy released by joining of nuclei of small atoms
E.g., Deuterium and Tritium
Advantages of nuclear power
- Reduced reliance on imported fossil fuels, important for countries concerned about energy security
- Nuclear capability, is still useful threat to keep world peace
- Not as vulnerable to fuel prices as oil and gas; uranium is relatively plentiful and most mines are in politically stable countries
- Tech developments have improved reliability and efficiency
- Zero emissions of GHG when opertating
- Very efficient: 1 station = wind farm the size of Luxembourg
Disadvantages of nuclear power
- Power plant accidents could release radiation into air, land and sea
- Disposal of radioactive waste is major problem as it generates heat and corrodes all containers. Sites used for disposal of nuclear waste can never be used for anything else, uranium takes millions of years to lose radioactivity
- Rogue states and terrorists may gain access to nuclear fuel and develop nuclear weapons
- Decommissioning and constructing costs are very high; ~$6.3 billion and takes long time
- Possible increase in certain types of cancer near nuclear plant
- Not available in developing nations
Hinkley C, UK (nuclear energy)
In North Somerset
Contribute 3.2GW to UK’s total of 16GW
Provides 7% of UK’s power (6m homes) and 25,000 jobs
How many % of world’s energy needs is by Nuclear power?
11%
What are fast breeder reactors
A nuclear reactors that uses fast neutrons to generate more nuclear fuels than it consumes.
Greatly increases energy generation.
Disastrous if the plutonium got into wrong hands, as it is key for nuclear weapons
Nuclear power formula
Energy released =
mass of matter lost X speed of light2
E= mc2
Nuclear compared to coal
Costs about the same
Nuclear do not produce smoke or CO2, many see it as solution to environmental issues caused by energy production.
Storing of Nuclear waste in UK
UK’s intermediate and high level waste is encased in concrete and stored above ground.
Most low level waste is stored in sealed concrete vaults in Drigg, Cumbria
Fuel reprocessing
Fuel rods remain in reactor for several years before being removed by refuelling machine.
It is left in cooling pond for 3 months to allow the short half-life radioactive waste e.g., iodine, to decay.
The fuel rods are then transported in steel flasks to a reprocessing plant and dissolved in acid.
Reprocessing allows the most radioactive materials to be concentrated and produce some material that can be reused.
Quantities of waste are small compared to other forms of power generation, but are more dangerous.
Waste disposal depends on whether it is liquid, gas or solid.
Disposal of nuclear waste in UK
UK, like many other developed countries, is currently identifying sites for geological disposal of nuclear waste.
Sites will be 200m below ground and in geologically stable rocks
Factors considered for disposal sites for nuclear waste
- Availability of land
- Local unemployment
- Transport to site
- Farming
- Technology and design
- Need to ensure the site is safe
- Strength of local pressure groups
How long does a nuclear power station last?
20-40 years.
Short compared to coal-fired stations which last over 50 years.
After retirement, it will need to be decommissioned, ridding of radio active material etc.
The biggest producer of uranium
Kazakhstan
The biggest consumer of uranium
France
Did not want to rely on oil
Results of 1973 Yom Kippur war
Increased oil prices, nuclear became more popular
How many percent of world’s energy is by nuclear?
10%
