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Environmental Science A2 > Renewable energy resources > Flashcards

Renewable energy resources Flashcards

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1
Q

Describe how photothermal systems work

A
  • use light to increase temperature
  • used to heat water
  • you pump water into cells, run it up and down into a pipe
  • exposes more water to sunlight which releases energy
  • this increases SA:VOL
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2
Q

Key things to remember about how photothermal systems work

A
  • never boils the water - used for bathing and washing clothes
  • does not produce electricity
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3
Q

Describe how passive solar architecture can heat and cool buildings

A
  • can have lots of windows on the south facing walls
  • big, long walls south facing, shorter on the other sides
  • light reflective surface - lose heat (white buildings
  • dark absorbant surfaces - retain the heat
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4
Q

Describe how solar associated heat pumps work

A
  • heat pump contains a liquid with very low boiling point
  • that liquid can turn into a gas at low temps
  • the liquid raises its temperatures in the panel
  • the gas produced goes to a compresser
  • heat goes to a heat exchanger
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5
Q

Describe how photovoltaic systems work

A
  • N type is doped with phosphorus and this adds electrons so is electron rich (very negative)
  • the p side is doped with boron electron poor - lacks negative electrons
  • excess electrons on the n type layer gain energy
  • they move to the p type sode
  • continuous movement of electrons = a current
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6
Q

Advantages of using solar power

A
  • renewable energy source
  • job creation
  • doesn’t release CO2 upon combustion
  • safer than others
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7
Q

Disadvantages of solar power

A
  • intermittent
  • high initial costs
  • weather dependent
  • made with rare and finite materials
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8
Q

What is a heliostat

A
  • an apparatus containing a movable mirror, used to reflect sunlight in a fixed direction
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9
Q

What is a parabolic reflector

A
  • a reflective surface used to collect or project energy such as light, sound or radio waves
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10
Q

What is concentrating solar power with thermal storage

A
  • operation on a large scale
  • mirrors that reflect suns energy to a central point
  • producing salt - retain heat thats able to boil water through the night
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11
Q

What is anti-reflective surfaces

A
  • cells with a-rs are textured and bumpy
  • some structures mimic corneas of moth eyes because they are very efficient at absorbing light
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12
Q

What is multi-juction photovoltaic cells

A
  • has multiple layers that each absorb different wavelengths of light
  • meaning more energy can be released
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13
Q

What are photvoltaic/thermal hybrid systems

A
  • mix up of old-style photothermal and are producing electricity with photovoltaic sandwich
  • heating water and producing electricity
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14
Q

What are transparent pv cells

A
  • can use them as windows
  • increase surface that we can utilise
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15
Q

What are self-cleaning panels

A
  • hydrophobic layer on them - repels water
  • helps carry dust and particles with it
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16
Q

Define gravitational potential energy

A
  • the energy an object has due to its position above earth, energy due to its height
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17
Q

What features of the environment allow for the development of a HEP scheme

A
  • large river catchment area
  • high and regular rainfall
  • valley with steep sides
  • want the water to have low turbidity
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18
Q

Define what high head means

A
  • how high the water falls
  • might include fast flowing upland stream schemes
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19
Q

Define what low head means

A
  • water falls from a lower distance
  • may include old mill sites with a weir
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20
Q

Define run of the river

A
  • operating the flow of the river without modification by upstream storage
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21
Q

What are the advantages of HEP

A
  • renewable energy source
  • flood control + water supply
  • creation of freshwater habitats
  • use for recreational use
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22
Q

What are the disadvantages of HEP

A
  • environmental impact - construction
  • displacement of communities
  • dependent on weather
  • cause sedimentation
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23
Q

How is wind generated

A
  • from difference in temperature pressure (caused by the sun’s energy)
  • air moves in an attempt to reach equilibrium
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24
Q

What locational factors are needed for wind farms

A
  • ^ winds for a lot of the year
  • local constraints - may impact construction
  • public opposition - providing incentives
  • they interfere with telecommunications
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25
Q

What does HAWT stand for

A
  • horizontal axis wind turbines
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26
Q

What are advantages of HAWT’s

A
  • renewable energy source
  • lower maintenance costs
  • efficient
  • simple technology
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27
Q

What are disadvantages of HAWT’s

A
  • intermittent
  • noise pollution
  • visual impact - ruins aesthetic
  • bird and bat strike (deaths)
  • soil boots can be impacted by the vibrations when turbines are turning
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28
Q

What does VAWT stand for

A
  • vehicles axes wind turbines
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29
Q

What are the advantages of VAWT

A
  • smaller footprint
  • spin no matter the wind direction
  • start turning at lower wind velocities
  • have them in more built up areas
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30
Q

What are the disadvantages of VAWT’s

A
  • lots of disadvantages are similar to previous
  • produce less energy compared to HAWT’s
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31
Q

What are some advantages of wind power

A
  • abundant
  • predictable
  • renewable energy source
  • lower maintenance cost
  • reliable
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32
Q

What are some disadvantages of wind power

A
  • weather dependent
  • noise pollution
  • visual impacts
  • intermittent
  • space requirement
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33
Q

How has blade tip fins improved energy production

A
  • curved tips
  • reduce air resistance
  • reduce turbulence
  • blades move faster
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34
Q

What are blade tip fins an example of

A

biomimetics

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35
Q

How has nacelle brushes improved energy production

A
  • reduce air escaping from the base of the blades to the nacelle
  • increase kinetic energy that can be absorbed by the blades
36
Q

How has direct drive turbines improved energy production

A
  • increases revolutions per minute
  • generates electricity at low wind speeds
37
Q

How has helical VAWT blades improved energy production

A

-reduce air resistance because turbines are curved
- generate electricity at low wind speeds

38
Q

How has wind-assisted ships improved energy production

A

-harness the power of wind to supplement the propulsion of a vessel by generation of aerodynamic forces

39
Q

What type of energy is harnessed from waves

A
  • kinetic energy
  • vertical wave movement
40
Q

What factors produce large waves

A
  • strong winds
  • movement of water
41
Q

What are the best sites to harness wave power

A
  • the further out to sea = the larger the waves
  • large fetch = big area of wind and wave speed can increase
42
Q

What is a point absorber

A
  • have a floating structure which rises and falls as waves pass
  • this is attached to a non-moving base located on the seabed
  • movement of the floating part turns a generator
43
Q

What is a overtopping device

A
  • breaking waves force water into a storage reservoir which is above sea level
  • the water flows back to the sea passing through a turbine which generates electricity
44
Q

What is a oscillating wave surge converter

A
  • water moves both horizontally and vertically, producing a cycle
  • pushes a flat plate which means pistons to pump fluid over a turbine to generate electricity
45
Q

What is a surface attenuator

A
  • a hinged floating device
  • moving sections push and pull pistons which force a fluid over a turbine
  • this generates electricity
46
Q

What is an oscillating water column

A
  • rise and fall of water = forces water up and down in a submerged chamber
  • the air that is forced in and out flow over turbines
  • generates electricity
47
Q

What are some advantages of wave power

A
  • renewable energy source
  • predictable
  • minimal enviro impacts
  • useful in more coastal, remote areas
48
Q

What are some disadvantages of wave power

A
  • high initial costs
  • limited locations
  • maintenance challenges
  • intermittent
49
Q

What crops are deliberately grown for their energy value

A
  • wood (convert it to charcoal)
  • miscanthus (grows really quickly, low maintenance)
  • ethanol (from corn and sugar cane)
50
Q

Waste materials from other activities used as biofuels

A
  • burn domestic and commercial waste in an incinerator
  • methane from landfill sites - combusted
  • crop waste (roots etc) - burn it
51
Q

What are some disadvantages of biofuels

A
  • still release CO2
  • public opposition
  • impact on biodiversity
  • seasonal variability
51
Q

What are some advantages of biofuels

A
  • renewable energy source
  • reduced greenhouse gas emissions
  • waste reduction
  • predictable
52
Q

How to achieve hydrogen from algae

A
  • specific algae produced
  • mimics sunlight with LED’s
  • algae absorbs CO2 + H2O + energy and builds up hydrocarbons and proteins
  • extract H+, pressurise and can store it
53
Q

Where does geothermal energy come from

A
  • residual heat from formation of solar system
  • heat rises and is transferred to earth’s crust
  • radioactive decay of isotopes of thorium,uranium and potassium in the earth’s mantle releases heat
54
Q

What are 2 low temperature schemes

A
  • geothermal springs
  • geothermal aquifers
55
Q

What are geothermal springs

A
  • groundwater that has been heated by hot rocks underground may come to the surface in hot springs. This can be used for district heating
56
Q

What are geothermal aquifers

A
  • hot groundwater may be pumped to the surface from underground aquifers to be used in district heating schemes
57
Q

What are 2 high temperature schemes

A
  • geothermal steam systems
  • hot dry rock systems
58
Q

What are geothermal steam systems

A
  • groundwater at very high temps may be brought to the surface using an extraction borehole, producing high temperatures
  • the steam at the surface can be used to generate electricity by turning a turbine
59
Q

What are hot dry rock systems

A
  • water is pumped down an injection in the borehole and steam is recovered using a second borehole
  • fracturing the rocks underground may increase permeability if rock and the surface area exposed for heat absorption
60
Q

What factors are needed to harness geothermal energy

A
  • areas of hot rock
  • under the surface
61
Q

What are advantages of geothermal power

A
  • renewable energy source
  • low intermittency
  • predictable
  • low technological developments
62
Q

What are disadvantages of geothermal power

A
  • high initial costs
  • local constraints
  • releases CO2
  • difficult to transport
63
Q

What are some new future developments for geothermal

A
  • geothermal fluid extraction
  • heat exchange
  • vaporization
64
Q

What is the source of energy used for tidal power

A
  • gravitational attraction between the water and the moon
  • gravitational attraction of the moon, is dependent on the sun’s position, near the moon
65
Q

What factors make harnessing tidal power viable

A
  • being able to harness it close to coastline
  • topography of the sea bed
66
Q

What can be done to increase the velocity of water flow caused by tides

A
  • tide moving into a more narrow space
  • this increases velocity of water
67
Q

What is a tidal barrage

A
  • water flows over it at high tide
  • close the gates until the tide has lowered
  • open the gates and water escapes and turns turbines that are built in the barrage
68
Q

What is a tidal lagoon

A
  • build a pool shape
  • at high tides the water enters the pool
  • once ride has gone down the water is then released and flows over turbines
69
Q

What is a in-stream turbine

A
  • fixed to the seabed + absorb kinetic energy of the natural tidal flow
  • they harness much less energy than the others
  • enviro impacts are very low
70
Q

What is advantages of tidal power

A
  • renewable
  • low emissions
  • long lifespan
  • predictable
71
Q

What is disadvantages of tidal power

A
  • possible migration barrage
  • high initial costs
  • intermittent
  • potential for erosion
72
Q

What are tidal reefs

A
  • formed by an accumulation of sediments, rocks or coral in areas where tidal currents are strong
  • they provide habitats for marine species
  • protect shoreline from erosion
73
Q

What is a primary fuel

A
  • type of energy source that is extracted from natural resources and used directly to produce energy
  • typically raw materials that haven’t been processed
74
Q

What is a secondary fuel

A
  • energy source that is derived from the processing or transformation of primary fuels
  • they have undergone some form of conversion
75
Q

What is the most common example of the use of a secondary fuel

A
  • converting primary furl to electricity
76
Q

How does a coal fired power station work

A
  1. pulverising (increase SA)
  2. combustion
  3. steam generation
  4. turbine operation
  5. electricity generation
  6. cooling system
  7. electricity distribution
77
Q

Which energy resources can produce steam which can be used in a steam powered turbine to produce electricity

A
  • coal
  • oil
  • gas
  • uranium
78
Q

Explain how other energy sources produce electricity via kinetic energy

A
  • tidal
  • wind
  • wave
  • HEP
79
Q

What is a fuel cell

A
  • a chemical battery
  • uses a chemical reaction to produce energy (electricity)
80
Q

How does a fuel cell work

A
  • feed the cell with hydrogen and oxygen
  • hydrogen loses electrons and are now H+ ions
  • H+ ions move through the membrane to meet O2- ions and produce H20
  • electrons are forced to take a different route
  • only waste - water
81
Q

Define peak shaving

A
  • storing energy at times of excess for a later time of high demand
82
Q

Explain how electricity can be transported

A
  • electricity goes to a step up transformer
  • increases voltage
  • travels further - travels through cables
  • reaches a step down transformer
  • decreases voltage
  • electric energy is moved through a grid system
83
Q

Advantages of using electricity

A
  • versatile
  • ease of transport
  • storage options
  • reduced pollution upon use
84
Q

Disadvantages of using electricity

A
  • infrastructure costs
  • energy losses
  • dependence on non-renewable sources
  • health and safety risks

Environmental Science A2 (2 decks)

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