Energy and Energy Resources Part 3 Flashcards
From specific heat capacity to power from the sun and earth
What is specific heat capacity?
The energy needed to raise the temperature of 1kg of the substance by 1 degree Celsius.
For something that changes temperature, what is the equation for energy transferred?
Energy transferred (J) = Mass (M) x Specific Heat Capacity x Temperature Change ( degree Celsius)
How do you work out specific heat capacity?
c = energy transferred / (mass x temperature change)
How does mass affect specific heat capacity?
The greater the mass of an object, the more slowly its temperature increases when it is heated.
What measures can be taken to reduce energy transfer out of the home? (Stop heat getting out)
Loft insulation -fibreglass. Is thick and traps air between its many fibre layers.
Cavity walls- traps air in small air pockets reducing heat loss by conduction.
Aluminium foil- behind radiators reflects heat.
Double glazed windows- have vacuum between the sheets of glass and so reduces conduction and convection. All measures lower thermal conductivity.
How do solar panels work?
Absorb infrared radiation from the sun and are used to generate electricity directly or heat water.
Which fuels meet society’s energy demands?
Burning oil, coal and gas. Some energy is also provided by nuclear power, biofuels and renewable resources.
How does a coal power station work?
The burning fuel heats water in a boiler, producing steam that turns a turbine which turns a generator. Oil and gas powered stations also work this way.
What is a biofuel?
Any fuel taken from living or recently living organisms. Examples are animal waste, methane gas, biodiesels, ethanol from fermented sugarcane. Biofuel can be used instead of fossil fuel.
What are the two main features of biofuels?
Biofuels are renewable as biological sources can be regrown or are continually produced at the same rate it is used. Biofuels are carbon neutral as the living organism can take in the carbon dioxide produced when the biofuel is burnt.
What is the power source of nuclear stations?
Uranium or plutonium
How does a nuclear reactor work?
The uranium is sealed in the reactor’s core. The uranium atom splits in two and releases heat. The energy of the core’s reaction is transferred by a coolant solution that goes to a heat exchanger before returning to the core. The energy transferred by the coolant is used to turn water into steam in the heat exchanger. This steam turns turbines generating electricity.
Compare advantages and disadvantages of a nuclear station
It does not produce greenhouse gases ( but burning fossil fuels do). But it produces radioactive waste that needs to be stored for years.
What is a wind turbine?
A wind turbine is an electricity generator at the top of a tower. Wind forces the blades to turn, which then turns a generator. More power is generated at higher wind speeds.
What is a wave generator?
A generator uses the waves to make it move, the movement turns the generator so it generates electricity. Wave generators are not active constantly and a lot of cables are needed to connect to shore.
What is hydroelectric power?
Power is generated when rainwater that’s collected in a reservoir flows downhill and turns a turbine that turns a generator to produce electricity.
What is tidal power?
A tidal power station traps each high tide and uses it to turn generators.
What is the difference between a solar panel and a solar cell?
A solar cell is a small single panel that converts sunlight directly into electricity. A solar panel is a collection of solar cells working together to produce more power.
List the advantages and disadvantages of solar panels/solar cells
They are useful when only a small amount of energy is needed. They are expensive but don’t have any running costs. Lots of solar cells are needed and can be less effective when there isn’t much sunlight.
What is a solar heating panel?
A panel that heats water passing through it for home use.
What is a solar power tower?
A tower with thousands of flat mirrors that face the sun to reflect sunlight on to a big tank at the top of the tower. The water in the tank is turned to steam by the solar radiation. The steam turns electricity generators by the ground.
What is geothermal energy?
Energy that comes from radioactive substances deep in the earth. The energy transferred heats surrounding rocks and makes its way to the surface over time.
How does a geothermal power station work?
Water is pumped down to the hot rocks in the ground to produce steam that turns electricity turbines at ground level.
