SCIENCE 30

Unit D: Energy and the Environment

Focusing Questions

How can Canadians and other members of the international community conserve energy and maintain quality of life?
What are the benefits and costs of available nonrenewable energy sources and of developing renewable energy sources?
What is our energy future?

Chapter 1: Dreams of Limitless Energy

General Outcome D2 - Students will describe the sun as Earth’s main source of energy and explain the functioning of some conventional and alternative technologies that convert solar, nuclear, tidal and other energy sources into useable forms.

Students will:
30–D2.1k explain how Hess’s Law, ∆H° = ∑∆ f H° (products) – ∑∆ f H° (reactants), leads to prediction of heats of combustion
30–D2.2k contrast the proportion of solar energy that creates wind and drives the water cycle with the small proportion captured by photosynthesis as chemical potential energy
30–D2.3k describe the conversion of solar energy into renewable forms (e.g., wind, hydropower, chemical potential energy by photosynthesis) and nonrenewable forms (e.g., coal, oil and gas) and further conversion into electrical and thermal energy
30–D2.4k describe the functioning of renewable energy technologies and assess their advantages and disadvantages, including active and passive solar-heating technologies, wind turbines, hydroelectric power, biomass energy, geothermal energy, hydrogen fuel cells
30–D2.5k explain the difference between fission and fusion and balance simple nuclear reaction equations to show the conservation of nucleons; e.g.,

1	n +	235	U →	141	Kr + 3	1	n	and	2	H +	2	H →	3	He +	1	n
1		235		141		1			2		2		3		1

30–D2.6k describe the main types and sources of radioactive decay and resulting ionizing radiation; i.e., alpha (α), beta (β) and gamma (γ) decay
30–D2.7k describe mass-energy changes in fission and fusion reactions, as represented by the formula E = mc²
30–D2.8k describe, in general terms, the operation of a fission reactor (e.g., the Canadian Deuterium Uranium [CANDU] Reactor) and the current state of fusion research
30–D2.9k trace the relationship between nuclear energy and geothermal energy
30–D2.10k compare and contrast conventional coal, oil-fired or hydroelectric power stations with nuclear power stations, in terms of purpose, process of energy conversions, design and function
30–D2.11k contrast, quantitatively, the orders of magnitude of energy produced by nuclear, chemical and phase changes
30–D2.12k explain the source of tides, in terms of gravitational attraction and the relative motions of the sun, moon and Earth
30–D2.13k describe the energy transformations involved in converting tidal energy to electrical energy and compare tidal power to hydroelectric power; e.g., tidal generating stations at the Bay of Fundy, Canada and La Rance, France.

1.1 Energy on Demand

Some Common Expressions For Energy

Unit	Symbol	Definition	Joules Equivalent	Example
Joule	J	energy needed to apply a force of 1 N over a distance of 1 m	1 J	Drawing a 25 cm line requires about 1 J of energy.
	TJ	terajoule	1 × 10¹²	This is equal to the energy in 24 tonnes of oil.
	PJ	petajoule	1 × 10¹⁵	This is equal to the energy in 24 000 tonnes of oil.
	EJ	exajoule	1 × 10¹⁸	This is equal to the energy in 24 million tonnes of oil.
calorie	cal	energy needed to raise the temperature of 1 g of water 1^oC	4.19 J	A foraging humming bird consumes 15 cal of energy per minuter
food calorie	Cal or kcal	energy needed to raise the temperature of 1 kg of water 1^oC	4190 J	A human walking 33 steps consumes 1 calorie
British Thermal Unit	BTU	energy needed to raise the temperature of 1 pound of water by 1^oF	1054 J	A typical barbecue has an energy output of 8 BTU for each second of operation
kilowatt hour	kW˙h	equal to the work done by one kilowatt acting for one hour	3 600 000 J	This is equal to the work done during 5 h of vigorous cycling

Joules are used by scientists and the metric system.
Calories are used to measure food energy. We used kilocalories (kcal) even though most containers say cal or Cal.
BTU are used for heating systems (furnaces and BBQ).
kWh are used to measure electricity use, your electricity bill. You will also see kWAh or mWAh (milli watt amp hours)

Canadians use a large amount of energy per capita:

Spread out population (lots of transportation)
Primary industries (natural resource based: mining, oil/gas, farming, forestry)
Cold weather (lots of heating)

Alberta’s oil sands use HUGE amounts of energy to mine oil, process it. Far more than many other countries due to different chemical composition. Farmers use a lot of fuel and energy working large fields with heavy machinery.

Energy Efficiency

energy efficiency =	useful energy output	× 100%
	energy input

Example: How efficient is a furnace that converts 2500 J of natural gas chemical energy into 2375 J of heat in hot air?

Given: Input = 2500 J, Output = 2375 J

energy efficiency =	energy output	× 100%
	energy input
energy efficiency =	2375 J	× 100%
	2500 J
energy efficiency =	95 %

Example: A solar panel is 30% efficient. You need 3500 J of output energy,
A. How much input solar energy do you need?
B. If each 1.0 m² of panel absorbs 1000 J, what area of panels do you need?

Given: %Eff = 30 %, Output = 3500 J

energy efficiency =	energy output	× 100%
	energy input
input =	output	× 100%
	% Eff
input =	3500 J	× 100 %
	30 %
input =	11 666.66666... J

You need an input energy of 1.2 × 10³ J of input energy to produce 3500 J of output energy.

If each 1.0 m² of panel absorbs 1000 J, what area of panels do you need?
Given: area = 1.0 m², E = 1000 J, E = 1.2 × 10³ J
Set up the ratio as two fractions. Make sure the units on top of both fractions are the same, and the units on the bottom of both fractions are the same.

1.0 m²	=	Area	or	1.0 m²	=	1000 J
1000 J		1.2 × 10³ J		Area		1.2 × 10³ J
Area			=	12 m²

Often more efficient devices cost more up front (cost more to buy), because they use newer technology (new materials, production methods) so initially they cost more. As more factories make the device and companies sell more, the price will decrease.
As the purchaser, over the life (use) of the item you will save money (electricity cost, maintenance, works longer, etc…)
For example when LED lights first came out they cost hundreds of dollars per light bulb, now they only cost $3 each and $20 for a color changeable Wi-Fi enabled smart bulb.
For example an AMOLED superthin foldable/rollable flat screen TV 12 inches (large tablet sized) cost $120 000 in 2018. There are projections that by 2030 you will be able to buy jackets made of AMOLED screens (video screen jacket) with touch screen controls on the sleeve.

1.2 Solar Fuel from the Past

From Wood to Coal

All of our energy come from the sun.
Initially people used that energy as burning wood.
The problem with wood fires is that they produce a lot of smoke especially indoors. People discovered that you can “pre-burn” wood in a low oxygen environment to produce charcoal. Charcoal burns and doesn’t produce as much smoke.

Coal

When people discovered coal on the surface of the ground or in holes they realised they could mine it.
Coal produces more heat and less smoke making it excellent fuel for forges (metal working), cooking and heat.
Coal became the fuel of steam engines and the industrial revolution.
Alberta has a lot of coal deposits for the same reason that there is lots of oil, gas and fossils. Millions of years ago Alberta was an sea with lots of aquatic plants and animals. As organisms died, they sank and were buried. Over time the organic material was compressed and heated causing it to chemically change into coal, oil and/or natural gas depending on the exact conditions.
You could take organic material, which mostly made of hydrogen and carbon, heat and compress it and change it into coal, oil and/or natural gas.
Coal was one of the most common fuels for electrical power generation. There used to be lots of coal electrical power plants in Alberta. As of 2023, they are all decomissioned or converted to natural gas.
China, India and the United States are the three largest users of coal for power plants.
Alberta has higher quality coal (harder and less impurities) so it is sold around the world.
Coal use has be leveling out. However due to the large amount of pollution produced by coal plants (soot, acid deposition and green house gases) many countries are looking for other ways to generate electricity.
Most contries are phasing out coal power plants.

Petroleum—Today’s Dominant Fuel

As this graph shows Traditional fuels (wood) has been decreasing since the invention of the steam engine in the mid 1800s.
In the early 1900 liquid petroleum fuel (diesel, gasoline) engines were invented as well as the invention of oil drilling.
It took time to develop for the technology to deal with natural gas which is it is lowest.
In the future it is expected that petroleum use will continue for vehicles. Natural gas (methane) is the fuel of choice for heating and more electricity plants are changing from coal to natural gas because it releases less pollution.
Renewables are more popular as the environmental choice as better technology is developed.
On the left (west) side of the province the hydrocarbons are coal (shallow) and natural gas (deeper).
On the right (east) side of the province the hydrocarbons are oil sands that are shallow.
To get more liquid or gas petroleum out of the ground often water is pumped into the ground to force the petroleum into an adjacent pumping well.
The water is permanently stuck underground. Some companies are experimenting with using liquid carbon dioxide to help with greenhouse gas emission reduction (CO₂ sink).

Natural Gas (Methane) & Propane

Natural gas (methane) is CH₄. It is a colorless, odourless gas. Gas companies mix in small amounts of mercaptan (methanethiol) which is easy to smell as a safety feature. This way people can easily notice methane leaks.
Methane is used for heating, cooking and generating electricity, occasionally vehicles.
Many places are changing from coal to methane electricity production because it releases less carbon dioxide into the atmosphere.

1.3 Harvesting Chemical Energy

Heat of Combustion

The difference in the potential energies of the reactants and products corresponds to the energy released during the combustion reaction.
The symbol Δ_CH^o, the heat of combustion, is used to represent the quantity of energy released during the combustion reaction.
To find the heat of combustion scientists us a bomb calorimeter. The fuel is burnt and the energy heats the surrounding water. A lot of insulation is used to prevent outside energy from affecting the results.
This is how they determine the energy of food.

Theoretical Heat of Combustion—Hess’s Law

Δ_rH^o = Σ nΔ_rH^o products - Σ nΔ_rH^o reactants

Δ_rH^o = energy change of reaction (kJ)
Σ = the sum of
n = amount (number of moles) represented by the coefficient from balanced chemical equation
Δ_rH^o = standard heat of formation

Example: Determine the energy released when octane is combusted.

Skeleton Equation: C₈H₁₈ + O₂ → CO₂ + H₂O
Balanced Equation: 2 C₈H₁₈ + 25 O₂ → 16 CO₂ + 18 H₂O

Δ_rH^o	=	ΔH_products - ΔH_reactants
Δ_rH^o	=	n ΔH_CO₂ + n ΔH_H₂O - n ΔH_C₈H₁₈ + n ΔH_O₂
Δ_rH^o	=	16 mol × -393.5 kJ/mol + 18 mol × -241.8 kJ/mol - 2 mol × 250.1 kJ/mop - 25 mol × 0 kJ/mol
Δ_rH^o	=	- 10 148.2 kJ

The energy released by combusting one mole of octane is 10 148.2 kJ.

Example: Calculate the energy released by combusting one mole of ethane.

Skeleton Equation: C₂H₆ + O₂ → CO₂ + H₂O
Balanced Equation: 2 C₂H₆ + 7 O₂ → 4 CO₂ + 6 H₂O

Δ_rH^o	=	ΔH_products - ΔH_reactants
Δ_rH^o	=	n ΔH_CO₂ + n ΔH_H₂O - n ΔH_C₂H₆ + n ΔH_O₂
Δ_rH^o	=	4 mol × -393.5 kJ/mol + 6 mol × -241.8 kJ/mol - 2 mol × -84.0 kJ/mop - 7 mol × 0 kJ/mol
Δ_rH^o	=	- 2 856.8 kJ

The energy released by combusting one mole of octane is 2 856.8 kJ.

1.4 Harvesting Nuclear Energy

Describing the Nucleus

Chemical reactions are all about how atoms share and transfer electrons.
Nuclear reactions involve the nucleus of the atom.

Mass = protons + neutrons; Changes with isotopes →	9	Be
Atomic number = protons; stays 4 for beryllium →	4	Be

Nuclear reactions occur when the nucleus of the atom changes and the atom transmutes into another element.
Just like chemical reactions the nuclear reaction is balanced.
Nuclear reactions often release dangerous ionizing radiation: alpha particles (α), beta particles (Β), gamma rays (γ), X-rays

Alpha Radiation

This when a nucleus releases an alpha particle (helium nucleus).

4 nucleons = 2 protons + 2 neutrons →	4	He or	4	α
2 protons →	2	He or	2	α

Example: the alpha decay of uranium 238

238	U →	4	α +	234	Th
92		2		90

Beta Radiation

This when a nucleus releases an beta particle (electron).

0 nucleons = -1 protons + 1 neutrons →	0	e or	4	Β
-1 protons, a proton changes to a neutron →	-1	e or	-1	Β

Example: the beta decay of potassium - 42

42	K →	0	Β +	42	Ca
19		-1		20

Gamma Radiation

Gamma radiation is a high energy wave of energy. It is dangerous because it can cause chemical reactions in your DNA causing mutations in children or disrupt cell membranes causing radiation poisoning.

0 nucleons →	0	γ
0 protons →	0	γ

Example: the gamma decay of potassium - 42

42	K →	0	γ +	42	K
19		0		19

Shielding

There are two ways to protect yourself from ionizing radiation:

Move away – different types of radiation can go different distances.
Alpha – 10 cm, Beta – 3 m, Gamma – 2 km
Shielding – put enough material between you and the source
Alpha – paper, Beta – mm Al foil, Gamma – 1 m leaded glass

Example: When you get a dental X-ray the technician leaves the room to increase the distance away (they do this regularly) You as a patient get the big lead blanket (shield) that protects your organs from X-ray exposure.
Example: Nuclear reactors have very thick walls made of materials that will absorb radiation. Due to the amount of shielding, if you live near a coal power plant you will get a higher dose of radiation than living the same distance away from a nuclear power plant

Nuclear Energy

Nuclear reactions are nuclear powered kettles. The steam runs the generator.

Mass-Energy Equivalence
In all nuclear reactions a very small amount of mass is lost by conversion directly into energy.
E = mc²
E - energy, J
m - mass, kg
c - speed of light, 3.00 × 10⁸ m/s

Example: In a nuclear bomb, 700 mg (7.00x10-4 kg of matter is changed into energy. How much energy is released?

Given: m = 7.00 × 10^-4 kg

E = mc² E = 7.00 × 10^-4 kg × 3.00 × 10⁸ m/s E = 6.30 × 10¹³ J
This is the energy released from a bomb used during WW2. 700 mg of matter (1/3 of a dime) released as much energy as exploding 15 000 tons of dynamite. Nuclear power is a very dense source of energy.

Example: What is the energy released by the following equation:

226	Ra →	0	γ +	4	α +	222	Rn
88		0		2		86

Find the masses on page 8 in the data booklet.
From the table: Ra-226 m = 226.02540 × 10^-3 kg/mol, He-4 m = 4.00151 × 10^-3 kg/mol, Rn m = 222.01757 × 10^-3 kg/mol. Note the × 10^-3 in the table.
Δm = m_daughter - m_parent
Δm = 4.00151 × 10^-3 kg/mol + 222.01757 × 10^-3 kg/mol - 226.02540 × 10^-3 kg/mol
Δm = 0.00632 × 10^-3 kg/mol

E = mc²
E = 0.00632 × 10^-3 kg/mol × (3.00 × 10⁸ m/s )²
E = 5.88 × 10¹¹ J/mol
For every mole of radon 226 that reacts 5.69 × 10¹¹ J is released.

Nuclear Fusion

Fusion is when two small atom nuclei are combined to form a larger nucleus. Fusion releases huge amounts of energy and powers the sun. It is too hot for nuclear reactors. (25 million ^oC)

2	H +	2	H →	0	γ +	1	n +	3	He
1		1		0		0		2