physics topic 8

Renewable energy

a fuel that is created faster or equally fast as it is consumed

Non-renewable energy

a fuel that is consumed faster than it is created

Primary energy

all types of unprocessed energy sources (e.g., crude oil)

Secondary energy

processed or exploited to mechanical work or electrical forms (e.g., a battery)

Specific energy, ES

is the amount of energy that can be extracted from a unit mass of fuel

Energy density, ED

is the amount of energy that can be extracted from a unit volume of fuel mass

Fossil fuels

are produced by the decomposition of buried animal and plant

material due to pressure and bacteria. Examples of fossil fuels are coal,

oil and natural gas

advantages of fossil fuels

• Cheap

• High power output

• Ease of use

disadvantages of fossil fuels

Non-renewable

• Environmental hazards

Nuclear power

a nuclear reactor is a machine in which nuclear fission

reactions take place producing energy

advantages of nuclear power

• High power output

• Large reserves of nuclear fuels

• No greenhouse gases

disadvantages of nuclear power

• Disposing of radioactive waste

• Uranium mining

• Risk of nuclear explosion

Solar panels

collect heat, from which water in pipes underneath is heated

Photovoltaic cells

convert light directly into electricity.

two methods to harness energy from the sun

• solar panels

• photovoltaic cells

Hydroelectric power

power derived from moving masses of water.

Wind power

power derived from moving masses of air.

Solar constant S

is the amount of solar radiation at the mean distance from

the sun to the Earth

Greenhouse effect

Greenhouse gases strongly absorb infrared radiation

from the atmosphere, when re-radiated in all directions, these gases

account for additional warming. These gases include water vapour,

carbon dioxide, methane and nitrous oxide.