Science 30: energy and the environment unit exam

how has the demand for fossil fuels changed

demand for coal, oil and natural gas has been increasing exponentially, partly due to the population explosion that occurred throughout the 20th century

what do albertans use fossil fuels for

coal: electricity and power

oil: fuel

natural gas: heating homes

per capita use

energy used / population

developing countries

make up 75% of the world's population, but only uses 30% of the world's energy

developed countries

make up only 25% of the world's population, but use 70% of the world's energy

factors that affect a country's energy consumption

- geography

- industries, GDP

- lifestyle and population

- technology

calculating energy efficiency

percent efficiency = (output / input) x 100%

solar energy sources

solar energy from the sun is converted to chemical potential energy (starch, glucose) by producers during photosynthesis

the sun is the ultimate energy source - most energy sources on earth are linked to the sun

0.023% is used for photosynthesis

1% is used to drive air currents

23% is used to drive the water cycle

where do fossil fuels come from

- provide most of our energy

- 54% of our electricity comes from coal

- created by an indirect use of solar energy

- with the heat of the earths core and pressure coal, petroleum and natural gas formed

harvesting chemical energy

energy stored in fossil fuels can be released by combustion

combustion of hydrocarbons always required oxygen and produces carbon dioxide and water vapour as products

greenhouse effect and global warming cause

- CO2 from the combustion of fossil fuels

- CH4 from anaerobic waste decomposition, from cattle farming and the production of oil and gas

greenhouse effect and global warming effects

- CO2 traps thermal energy within the earths atmosphere

- increased global temperatures

- sporadic weather pattens

- glaciers are melting -> more water and flooding

- changing vegetation

- species extinction

greenhouse effect and global warming solutions

- drive less

- replant trees

- carbon capturing and storage

- hold companies accountable for emissions

- invest in alternative energy sources

heat of reaction

the energy absorbed or released during a chemical reaction

- the energy change of a reaction is represented by ^rH

- exothermic reactions release energy to the environment and are negative

- endothermic reactions absorb energy from the environment and are positive

combustion is an exothermic reaction

energy released

to calculate the heat released during combustion we will use Hess' law along with the standard heats of formation for different compounds

coal fired generating station

convert chemical potential energy into electricity

- coal is crushed into a fine dust

- the coal is burned in a boiler and the energy produced is used to heat water within a network of tubes

- water boils and turns into steam which turns a turbine

- the turbine is connected to a generator which generates electricity

solar energy > chemical potential energy > thermal energy > kinetic energy > electrical energy

renewable and non renewable energy sources

our energy use has shifted from renewable to non renewable but with the impacts that fossil fuels have on the environment, we are slowly shifting back to an increase in renewable resources

nuclear energy

relies on radioactive material (a substance that emits energy in the form of EMR)

- said to be ionizing because some forms of radiation and particles released can penetrate solid material and damage living cells

isotopes

become unstable when the force of repulsion in the nucleus is greater than the nuclear force of attraction holding the nucleus together

- will change into another substance and release energy in the form of radiation and particles

three types of radiation

- alpha rays

- beta rays

- gamma rays

alpha radiation

made of 2 protons and 2 neutrons with a net charge of 2+

not very penetrating

4/2 He

beta radiation

a high speed electron

more penetrating

0/-1 e

gamma radiation

high energy photon with no mass or charge, used to treat cancers

most penetrating

0/0 y

nuclear fusion

when 2 smaller nuclei with high energy join to form a larger nucleus while releasing energy

nuclear fission

when a large nucleus splits into smaller nuclei while releasing energy

this reaction is difficult to control

the CANDU reactor

Canadian deuterium uranium reactor

intranuclear potential energy > thermal energy > kinetic energy > electrical energy

the energy from nuclear fission is used to heat water and produce steam with turns a turbine, spins a generator which creates electricity

mass energy equivalence

E = mc^2

- this formula says that mass can be converted into energy

- a tiny loss in mass results in a gigantic gain in energy

alternative energy sources

non renewable energy resources are running out and we need to reduce our impact on the environment

environmental concerns

carbon dioxide and methane contributes to global warming

NOx and Sox contributes to acid deposition

sustainable development

won't run out in the near future and will last for generations to come

ecological sustainability

having minimal impact on the environment

societal sustainability

able to maintain our current standard of living

economic sustainability

able to provide jobs and generate revenue. the way we generate energy is efficient

geothermal energy

- earth and heat

- this heat is renewable and originates from the radioactive decay of uranium in earths core

- geothermal energy tends to collect at plate countries in the earths crust

intranuclear potenial energy > thermal energy > kinetic energy > electrical energy

tidal energy

tidal waves are natural movements of water due to the gravitational force of the moon and sun acting with the earth

- depending on the location of the moon, there will either be low or high tides

- there is a turbine that spins in the water which is connected to a generator which produces electricity

hydrogen fuel cells

similar to a battery, but use hydrocarbon and oxygen instead of battery acid/chemicals to produce electricity

- H2 reacts with a catalyst to produce electrons

passive solar energy

- using sunlight without using mechanical devices

- solar energy is converted into thermal energy

- available everywhere, free and renewable

active solar energy

converting solar energy into usable electricity using some type of mechanical equipment

photovoltaic cells

- converts sunlight directly to electrical energy

- these are used as a major source of power in space and in homes and buildings

- energy can be used immediately or stored for later use in batteries

- when light strikes the surface of the cell, atoms lose electrons and the moving electrons in a wire generate electricity

hydroelectric power

- when radiant energy from the sun heats up water it will evaporate

- this water is then carried by winds and will eventually fall as precipitation at higher elevations and flows downstream or down mountains due to gravity

- dams are built to control the flow of water

- as water flows, it turns a turbine, connected to a generator to produce electricity

solar energy > gravitational potential energy > kinetic energy > electrical energy

wind energy

- thermal energy from the sun heats up air molecules causing them to move and take up more space

- the movement of air has kinetic energy which can be turned into electricity

solar energy > thermal energy > kinetic energy > electrical energy

biomass energy

- using plant materials or biodegradable animal wastes as fuel

- released by burning the material directly and by converting it to a biofuel

- carbon neutrality is one of the major advantages of biomass energy

- during photosynthesis, plants absorb carbon present in the atmosphere and it is released again when it is burned

- bioethanol is produced by fermenting plants in organic matter such as corn

solar energy > chemical potential energy > thermal energy > kinetic energy > electrical energy

this sequence of energy conversions is identical to fossil fuel combustion