Energy resources
50 exam-style questions with answers for 3.3 Energy resources in AQA A-level Environmental Science (spec 7447). Practise with flashcards, a topic quiz, a random quiz across the course, 5 crosswords, Five Degrees, Associations, or read every question and answer below. Not official AQA material.
All 50 questions and answers
Question 1
Explain how pumped-storage HEP meets fluctuating demand. [3 marks]
Answer:Surplus electricity pumps water to an upper reservoir, storing gravitational potential energy (peak shaving). Water is released through turbines at peak demand, giving a rapid response.Question 2
Describe how fertile fuels are used in nuclear fission. [3 marks]
Answer:Uranium-238 or thorium-232 is bombarded with neutrons and becomes fissile plutonium-239 or uranium-233. Fission releases heat, which makes steam to turn turbines.Question 3
State two features of energy resources that affect how they are used. [2 marks]
Answer:Any two from: intermittency, energy density, abundance, locational constraints, need for energy conversions.Question 4
Define the term ‘energy density’. [1 mark]
Answer:The energy per unit mass or volume of a fuel or resource.Question 5
Explain why low head turbines suit rural areas. [2 marks]
Answer:They work with a small drop or low flow, need no large dam or flooding, and have less infrastructure and lower environmental impact.Question 6
Describe how carbon capture and storage (CCS) works. [3 marks]
Answer:CO2 is removed from exhaust gases (for example by amine scrubbing), compressed and stored underground in depleted gas fields or aquifers.Question 7
Explain how hydraulic fracturing extracts shale gas. [3 marks]
Answer:High-pressure water and sand is pumped into shale, cracking it. The sand keeps the cracks open so gas flows to the well.Question 8
State two advantages of Combined Heat and Power (CHP). [2 marks]
Answer:Waste heat is used for heating buildings or greenhouses, so overall efficiency is higher and less fuel is needed.Question 9
Explain why double glazing reduces heat loss. [2 marks]
Answer:The air gap has low thermal conductivity and, if narrow enough, no convection.Question 10
Describe how regenerative braking (KERS) saves energy. [2 marks]
Answer:Kinetic energy drives a generator when braking, charging a battery so the energy can be reused.Question 11
Explain why intermittent resources need energy storage. [2 marks]
Answer:Supply may not match demand, so surplus is stored (peak shaving) and used when demand exceeds supply.Question 12
State two ways a wind farm may harm wildlife. [2 marks]
Answer:Bird and bat collisions, and noise or vibration affecting marine mammals offshore.Question 13
Define the term ‘embodied energy’. [1 mark]
Answer:The total energy used to manufacture and install equipment.Question 14
Explain how multi-junction photovoltaic cells increase efficiency. [2 marks]
Answer:Different layers absorb different wavelengths of light, so more energy is absorbed.Question 15
State two causes of fluctuations in energy demand. [2 marks]
Answer:Any two from: weather, season, weekday or weekend, night and day, TV pick-up.Question 16
Define the term ‘renewable resource’. [1 mark]
Answer:A resource that is rapidly reformed, so use does not affect its availability.Question 17
State two features of fossil fuels that make them widely used. [2 marks]
Answer:High energy density, easy to store, and available on demand.Question 18
Explain why fuel cells are useful. [2 marks]
Answer:Hydrogen is oxidised electrochemically to make electricity and water with low emissions, and hydrogen can store surplus energy.Question 19
Describe how a tidal barrage generates electricity. [2 marks]
Answer:Incoming and outgoing tides are channelled through turbines in the barrage.Question 20
State two ecological impacts of tidal barrages. [2 marks]
Answer:They change tidal range, turbidity and flow, and block migration of fish and mammals.Question 21
Explain the advantage of in-stream tidal turbines. [1 mark]
Answer:There is no barrier to water flow, so ecological impact is lower.Question 22
Describe how thorium reactors work. [2 marks]
Answer:Thorium-232 is bombarded with neutrons to produce fissile uranium-233, with less long-lived waste.Question 23
Describe nuclear fusion. [2 marks]
Answer:Hydrogen isotopes fuse to release energy, in toroidal reactors or by laser fusion, with no high-level waste.Question 24
Explain how directional drilling reduces environmental impact. [2 marks]
Answer:Many wells reach reserves from one platform, including under cities or sensitive areas.Question 25
Describe how tertiary oil recovery works. [2 marks]
Answer:Oil viscosity is reduced using steam, solvents or bacteria, so it flows more easily.Question 26
State two methods of energy storage. [2 marks]
Answer:Any two from: pumped-storage HEP, batteries, fuel cells, compressed gas, flywheels, thermal storage.Question 27
Explain vehicle-to-grid (V2G) systems. [2 marks]
Answer:Parked electric vehicles supply electricity to the grid during shortages and recharge when there is a surplus.Question 28
Describe how heat exchangers conserve energy. [2 marks]
Answer:They transfer heat from outgoing warm air or water to incoming flows.Question 29
Explain why a low surface area to volume ratio conserves energy in buildings. [2 marks]
Answer:Less surface area means less heat is lost.Question 30
State how wind power changes if wind velocity doubles. [1 mark]
Answer:Available power increases eight-fold because it is proportional to velocity cubed.Question 31
Explain how coal, oil and natural gas formed. [3 marks]
Answer:Dead organic matter (plants for coal; plankton for oil and gas) was buried (1); heat and pressure over millions of years converted the carbon compounds (1); in anaerobic conditions that prevented complete decomposition (1).Question 32
Explain why burning coal causes more pollution than burning natural gas. [2 marks]
Answer:Coal has a higher carbon content so releases more CO2 per unit of energy (1); coal contains sulfur and impurities, so releases more SO2, particulates and ash (1).Question 33
Describe coal gasification. [2 marks]
Answer:Coal is partially oxidised with limited oxygen and steam at high temperature (1); produces syngas (carbon monoxide and hydrogen) which burns more cleanly than coal (1).Question 34
Describe coal liquefaction. [2 marks]
Answer:Coal is converted to liquid hydrocarbons by reacting with hydrogen under high temperature and pressure (1); the liquid fuel can substitute for oil products such as petrol and diesel (1).Question 35
Describe methane hydrates and one concern about extracting them. [2 marks]
Answer:Methane trapped in ice-like crystals at low temperature and high pressure in ocean sediments and permafrost (1); extraction may release methane, a powerful greenhouse gas, or destabilise the seabed (1).Question 36
Describe how control rods and a moderator operate in a nuclear reactor. [3 marks]
Answer:Control rods (boron or cadmium) absorb neutrons to slow or stop the chain reaction (1); moderator (water or graphite) slows neutrons (1) so they are more likely to cause fission of uranium-235 (1).Question 37
Explain how a solar photovoltaic cell generates electricity. [2 marks]
Answer:Photons of light strike a semiconductor, usually silicon, and release electrons (1); the electrons are driven through a circuit as a direct current (1).Question 38
State two disadvantages of solar photovoltaic power. [2 marks]
Answer:Any two: intermittent (no output at night/cloud); large land area needed; high manufacturing energy and cost; low efficiency; pollution during panel manufacture and disposal.Question 39
Describe how geothermal energy is used to generate electricity. [2 marks]
Answer:Water is pumped down to hot rocks and heated to produce steam (1); the steam drives turbines connected to generators (1).Question 40
Explain why biomass is described as carbon neutral and why that may not be fully true. [2 marks]
Answer:Carbon dioxide released on burning is balanced by the CO2 absorbed during growth (1); not fully true because energy is used in growing, harvesting and transporting, and land clearance releases stored carbon (1).Question 41
Give an advantage and a disadvantage of biofuels made from crops. [2 marks]
Answer:Advantage: renewable and approximately carbon neutral (1); disadvantage: uses agricultural land that could grow food, may cause deforestation and raise food prices (1).Question 42
Explain how a hydroelectric dam generates electricity and one environmental impact. [3 marks]
Answer:Water stored behind the dam is released through turbines, converting gravitational potential energy to kinetic energy and then electricity (2); impact: flooding of habitats, altered river flow, and sediment trapped behind the dam (1).Question 43
Describe how an oscillating water column wave generator works. [2 marks]
Answer:Waves force water up and down inside a chamber, compressing and expanding the air above (1); the moving air drives a turbine and generator (1).Question 44
Explain why thermal power stations are limited in efficiency. [2 marks]
Answer:Much of the energy from the fuel is lost as waste heat at each stage (1); typical efficiency is only about 35–40%, so energy is lost in cooling water or cooling towers (1).Question 45
Describe how district heating works. [2 marks]
Answer:Heat (eg waste heat from power stations or incinerators) is used to heat water (1); the hot water is piped to homes and buildings, reducing the need for individual boilers (1).Question 46
State two ways industry can conserve energy. [2 marks]
Answer:Any two: recovering and reusing waste heat; insulating furnaces and pipes; using energy-efficient motors and lighting; Combined Heat and Power; optimising processes and recycling materials.Question 47
Explain how smart meters help to conserve energy. [2 marks]
Answer:Show real-time energy use and cost to consumers, encouraging behaviour change (1); allow time-of-use tariffs so demand shifts away from peak periods (1).Question 48
State two ways energy use in transport can be reduced. [2 marks]
Answer:Any two: more public transport/walking/cycling; lighter, more aerodynamic vehicles; more efficient engines/hybrid and electric vehicles; regenerative braking; car sharing; reduced speed limits.Question 49
State two advantages and one disadvantage of wind power. [3 marks]
Answer:Advantages: renewable, no CO2 during operation, low running costs (2); disadvantage: intermittent, visual and noise impact and wildlife collisions (1).Question 50
Explain why nuclear power produces little carbon dioxide yet remains controversial. [3 marks]
Answer:Fission releases no CO2 during operation (1); concerns include radioactive waste storage for thousands of years (1); accident risk, decommissioning costs and links to weapons (1).