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A Level Environmental Science > Energy Resources - Secondary Fuels and Energy Storage > Flashcards

Energy Resources - Secondary Fuels and Energy Storage Flashcards

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1
Q

What are the main forms of secondary fuels?

A
  • Electricity
  • Hydrogen
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2
Q

What is a primary fuel?

A

An energy resource found in nature which can be directly used

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3
Q

What is a secondary fuel?

A

An energy resource produced by the conversion of a primary fuel

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4
Q

What types of energy can be converted to electricity?

A
  • Kinetic (generators)
  • Chemical (electrochemical cells)
  • Light (PV cells)
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5
Q

Why are secondary fuels more useful than primary fuels?

A
  • Easier to use
  • More applicable
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6
Q

How is chemical energy converted to electricity?

A
  • Electrochemical cells
  • Rechargeable batteries
  • Fuel cells
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7
Q

What is the main disadvantage of electricity?

A

Difficult to store

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8
Q

How does a coal-fired power station work?

A
  1. Coal is pulverised to coal dust
  2. Furnace used to produce steam
  3. Steam turns a turbine and drives a generator
  4. Condensing tower recycles steam
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9
Q

How do coal-fired power stations reduce environmental impacts?

A
  • Cooling towers remove heat from water
  • Limestone slurry removes sulfur from leftover coal deposits to prevent acid rain
  • Electrostatic precipitators remove particulates from the smoke
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10
Q

How is hydrogen produced?

A

Electrolysis of water using electricity from surplus primary energy resources

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11
Q

What is peak shaving?

A

Storing energy during periods of excess generation to be used in periods of high demand

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12
Q

How can chemical energy from hydrogen be released?

A
  • Combustion to produce heat (similar to natural gas)
  • Fuel cells
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13
Q

What is a fuel cell?

A

A chemical battery which produces energy through a chemical reaction

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14
Q

How does a hydrogen fuel cell work?

A
  1. H2 and O2 is fed in
  2. H2 loses electrons and become H+ ions
  3. H+ ions move through a membrane to produce H2O with O2- ions
  4. Electrons cannot pass through the membrane and take another route (produces a current)
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15
Q

Which waste product do fuel cells produce?

A

Water

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16
Q

How is electricity transported?

A
  1. Generation
  2. SU transformer (increases V and reduces R - travels faster)
  3. Cables and pylons at 400,000V
  4. SD transformer (reduces V and increases R)
17
Q

How can hydrogen be produced by electrolysis?

A
  1. Anode and cathode placed in water
  2. H2O is split
  3. O2- ions attracted to the anode (+)
  4. H+ ions attracted to the cathode (-)
18
Q

How can hydrogen be stored?

A
  • Compressed gas in pressurised storage tanks
  • Liquid hydrogen (high pressure, low temp)
  • Material-based storage (as ammonia - NH3)
19
Q

How can hydrogen solve the issue of intermittency with renewables?

A

Excess electricity can be used to produce hydrogen and be used in a fuel cell during periods of high demand

20
Q

What are the problems with hydrogen storage?

A
  • Low volumetric energy density
  • Easily lost to the atmosphere
  • Liquid hydrogen must be cryogenically stored
  • Requires pressurised containers
21
Q

How is hydrogen used for combustion?

A

Used like natural gas in existing networks

22
Q

What is the hydrogen economy?

A

The vision of using hydrogen alongside renewables to provide net zero energy security without intermittency

23
Q

What can cause surplus electricity to be available?

A
  • Wind farms at night
  • Solar farms on bright days
  • Increased energy efficiency
24
Q

Why might energy supply fluctuate?

A
  • Weather conditions (e.g. wind speed, sunlight hours)
  • Bulk delivery of non-renewable resources
25
Q

Why might energy demand fluctuate?

A
  • Periods of peak demand
  • Public events (TV ‘pickup’)
  • Climate and weather
26
Q

How does pumped storage HEP work?

A
  1. Excess electricity is used to pump water from a low to a high level reservoir
  2. Energy is stored as GPE
  3. Gates opened at periods of high demand and water flows over turbines
27
Q

How does compressed gas work?

A
  1. Excess electricity used to pump compressed gas into depleted gas reservoirs
  2. Compressed gas is allowed to escape through pressure turbines during periods of high demand
28
Q

How rechargeable batteries be used?

A
  • Small scale batteries for phones and domestic use
  • Large scale batteries for grid energy storage
29
Q

What are the disadvantages of rechargeable batteries?

A
  • Limited lifespan
  • High environmental impact when not recycled correctly
  • Long charging time
30
Q

What are V2G systems?

A

Vehicle to grid - energy is transferred from EVs parked for long periods to the grid

31
Q

What are P2G systems?

A

Power to gas - surplus electricity is used to produce gaseous fuel (e.g. H2 produced, converted to CH4)

32
Q

What are heat energy storage systems?

A

Short term storage of heat using materials with a high SHC

33
Q

What is high volume storage?

A

Very large heat stores which can be used for inter-season storage (reduces the rate of heat loss)

34
Q

What is molten salt?

A

Can be used in CSP - potassium nitrate can be heated up to 550C and used at night to produce steam

35
Q

What are thermal mass buildings?

A

Using construction materials with a high SHC reduce the need for heating as the building warms and cools slowly

36
Q

How can kinetic energy be used for energy storage?

A

Rotating flywheels can temporarily store Ek for later use (4 hours on average)

37
Q

What are electricity super capacitors?

A

Could be used for large-scale energy storage using an electrochemical process

38
Q

What is specific heat capacity?

A

The heat energy required for a 1C rise in temperature

A Level Environmental Science (22 decks)

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