Science 30 – Unit D: Energy and The Environment – Chapter 7 Worldwide Energy Demand Page 1

Science 30 Unit D - Energy and the Environment

Chapter 7 – Worldwide Energy Demand

Name _____________________________________

Table of Contents

7.1 – Global Energy Demand 7.2 – Fossil Fuels (Non-Renewable Resources) 7.3 – Combustion and Chemical Energy 7.4 – Environmental Effects

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7.1 – Global Energy Demand

What is Energy Measured in? (p. 471)

World Use of Energy

*EJ = exajoule = 1 X 1018 J

Per capita – for each person

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50.0

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450.0

1850 1900 1950 2000 2050

Wo

rld

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erg

y U

se (

EJ)

World Energy Use (EJ) from 1850-2000

0.00

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7.00

1850 1900 1950 2000 2050

Wo

rld

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illio

ns)

World Population from1850-2000

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1840 1860 1880 1900 1920 1940 1960 1980 2000 2020

Per Capita Energy Use from 1850-2000

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Gross Domestic Product (GDP) – the total market value for all goods and services produced by the country in one year. Considered a countries economic output. Energy Intensity – The ratio of energy input (in joules) to economic output (in US$) World Bank – Updated Info and GDP Graphs – Latest Values and Energy Intensity What Factors Affect Energy Use in a Country? Looking at Home – p.472 (Percent of New Car Sales). Why are Canadians buying more light-duty trucks than more efficient smaller cars? Energy Use in Alberta Alberta major sector are development of non-renewable energy resources of coal, petroleum, and natural gas. More focus in recent years on wind and hydroelectric power. Fossil fuels make up over half of the province’s exports. Royalties – paid to the Alberta government by energy companies that extract and process natural resources.

** Major focus in the past 10-15 years has been to improve efficiency in our technologies

in the energy sector. How does improving efficiency improve consumption?? **

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Energy Efficiency: The percent of input energy that has been transformed into useful output energy.

Example Problems

Calculate the energy efficiency of a toaster that uses 300 J of energy to increase the thermal energy of water 240 J. If an automobile engine is 15% efficient, calculate the useful output energy form 1 kg of gasoline containing 50.0 MJ of chemical potential energy (Answer to 3 significant digits).

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7.1 Homework Comparing Energy Use – Canada and Other Countries (p,473)

p.477-478 #9-12

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Lesson 7.2 – Fossil Fuels (Non-Renewable Resources)

Definitions – Types of Energy

____________________ Energy –heat

____________________ Energy – Motion

_________________________________ Energy – Stored energy from the position in a system.

________________________Energy – Potential and Kinetic Energy (when machines do work – think

of a turbine spinning)

_________________________ Energy – Stored in the bonds of compounds (mostly hydrocarbons)

Remember Energy is not created or destroyed only converted.

Non-Renewable Resources (Textbook 1.2) – The BIG THREE

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Coal

Society shifted from burning wood as a primary fuel source to burning coal during the

industrial revolution.

Coal is a combustible black or brownish-black sedimentary rock composed mostly of carbon

and ______________________________________. It is the most abundant fossil fuel produced

in the United States. Coal is a nonrenewable energy source because it takes millions of years

to create. The energy in coal comes from the energy stored by plants that lived hundreds of

millions of years ago, when the Earth was partly covered with swampy forests.

Coal is cheap to surface mine and generates about half of the electrical power for North

America. Coal surface mining can have negative impacts on the environmental landscape.

Emissions produced from coal are _________________________________________________.

Research is going into scrubber technology to reduce the amount of pollutants going into

the atmosphere.

Petroleum (Crude Oil)

Today by far, petroleum is the ____________________________________________________

Over millions of years, the remains of animals and plants were covered by layers of sand

and silt. Heat and pressure from these layers helped the remains turn into what we today

call crude oil. The word "petroleum" means "rock oil" or "oil from the earth."

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Crude oil is a smelly, yellow-to-black liquid and is usually found in underground areas

called reservoirs. Oil derricks are built on an oil well that will bring a steady flow of oil to

the surface.

The Athabasca Oil Sands are not crude oil, but petroleum stuck in sand. It needs to be

separated into useful ____________________________________________________________

There is an excellent source of energy; however there are a number of drawbacks. Pollutants form

emissions include CO2, CO, SO2, NOx, VOC’s, lead, benzene, and acetaldehyde. In addition to

harmful effects to reclamation of the land, problems can ensue at oil wells.

Natural Gas (Methane)

Formation of natural gas is similar to petroleum, except natural gas requires more

__________________________ _______________________________________. It is used to heat

our houses (furnaces), hot water, and the kitchen stove.

Natural gas produces fewer emissions of sulphur, carbon, and nitrogen than coal or oil. It

still produces ________________________________________________

_______________________________. The footprint from natural gas is much less, but still

impacts the land and marine habits where drilling occurs.

Fossil Fuels – Main source ________________________. In fossil fuel reactions the following occurs:

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Fossil-Fuel Power Station

https://www.duke-energy.com/about-energy/generating-electricity/coal-fired-how.asp

In a coal-fired steam station water is turned into steam, which in turn drives turbine generators to produce

electricity. Here’s how the process works.

1. Heat is created

The coal is crushed and mixed with hot air and blown into the firebox of the boiler. Burning in suspension, the

coal/air mixture provides the most complete combustion and maximum heat possible.

2. Water turns to steam

Highly purified water, pumped through pipes inside the boiler, is turned into steam by the heat. The steam

reaches temperatures of up to 500 degrees Celsius and is piped to the turbine.

3. Steam turns the turbine

The enormous pressure of the steam pushing against a series of giant turbine blades turns the turbine shaft. The

turbine shaft is connected to the shaft of the generator, where magnets spin within wire coils to produce

electricity.

4. Steam turns back into water

After doing its work in the turbine, the steam is drawn into a condenser, a large chamber in the basement of the

power plant. In this important step, millions of gallons of cool water from a nearby source (such as a river or

lake) are pumped through a network of tubes running through the condenser. The cool water in the tubes

converts the steam back into water that can be used over and over again in the plant.

The cooling water is returned to its source without any contamination, and the steam water is returned to the

boiler to repeat the cycle.

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7.2 - Homework

p.490 #1-6

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7.3 – Combustion and Chemical Energy

Terms

Combustion –occurs in the presence of oxygen and results in the release of energy, carbon dioxide

and water vapour.

YOU MUST KNOW THIS REACTION!

Exothermic – release of energy.

Endothermic – absorbing energy.

Temperature – a measure of the average kinetic energy of the atoms or molecules of a substance.

Heat – the transfer of energy from molecules at a higher temperate to lower temperature.

During a combustion reaction, the stored potential energy of a reaction decreases and the kinetic

energy of the reaction increases. Like all chemical reactions, this reaction conserves energy (often

released as heat).

Since heat is just the transfer of energy, we can calculate how much heat was generated by

measuring the temperature difference. This device is known as a calorimeter. This will allow us to

find out exactly how much energy was generated during the reaction.

∆cH° = ∆fH° = the heat of combustion (how much heat is released during a combustion

reaction)

Unit is often given in kJ/mol (Data book – p. 5)

What is the ∆fH° of:

Potential Energy

Progress of Reaction

This reaction is EXOTHERMIC

because energy was released

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Glucose?

2 mols of Sucrose?

Ethene?

Water (l) and ethane combined?

Single elements (i.e. Al, Ni, O2, H2, Ne, etc…) have a ∆fH° = 0. (If it’s not listed, just give it a zero!)

Hess’ Law – Theoretical Heat of Combustion

If we use the standard heats of formation from the data book – we can calculate the energy

generated by the products and the reactants. The standard heats don’t equal one another – where

has the missing energy gone?

In short, to find the heat generated by a chemical reaction

Heat of reaction = (Theoretical Heat of Products) – (Theoretical Heat of Reactants)

Or

(Data book – bottom p.5)

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Example Problem 1.1 (p.497)

1. Calculate the energy change of the reaction of methane gas. (Balance the equation and then use

the formula)

Practice

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7.3 - Homework

p.498 #22-23 and p.501 #1-5, 10

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7.4 – Environmental Effects of Combustion

(textbook reference – section 1.1, 1.3, 1.4 of Chem)

Objectives:

• B1.8k outline the chemical reactions (e.g., combustion reactions) that produce air pollutants (i.e., sulfur dioxide and nitrous oxides) that, when combined with water, ultimately result in acid deposition

• 30–B1.9k describe impacts on the biotic and abiotic components of the environment caused by acid deposition

Emissions Can React

• Products of combustion reacts, released as emissions can react with the water present in the atmosphere

– Oxides of carbon greenhouse gases – Oxides of sulfur acid deposition – Oxides of nitrogen acid deposition

• Note: rain water is naturally acidic and oxides of carbon, sulfur and nitrogen do exist naturally as well as anthropogenically (human produced)

Dioxides react with water:

• SO2 + H2O ==> H2SO3 (sulphurous acid) • NO2 + H2O HNO3 (nitric acid)

Look at p. 161 – where are the majority of sulphur dioxide and nitrogen monoxide emissions from?

• The main acid-forming pollutants are sulphur dioxide (SO2) and oxides of nitrogen (NOx). These substances interact with water in the atmosphere to form mild acids that return to the earth in wet (rain or snow) or dry (being absorbed in the atmposhere) deposits.

Where do the Acids come From?

• Sulphur dioxide comes from electrical power stations, smelters (such as the nickel smelters in Sudbury, Ontario), gas processing plants, oil sands plants, coal-fired power plants, and transportation (trains and vehicles).

• Oxides of nitrogen come from the same sources with nearly half of it coming from transportation sources (cars, trucks, airplanes, etc.).

• The largest source of acid pollution in Alberta is from ______________________. It is a natural gas,

which contains hydrogen sulphide (H2S) that must be removed before the gas can be used for other purposes or burned as fuel. In the process, large amounts of sulfur and sulfur dioxide can be produced.

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Acid Deposition in Canada

• Acid deposition has different effects in different areas of Canada.

– Many parts of Eastern Canada and Western B.C. have naturally acidic soils. Acidic soils

cannot neutralize acid; therefore acids build up faster in these soils.

– Other areas including parts of British Columbia, central and Alberta have large amounts

of limestone in the rock beds and lakes. These lakes “buffer” the acid…

Effects of Acid Rain

• Limestone is (CaCO3). What would happen when limestone reacts with H3O+ ions of an acid?

(Use acid-base reaction in data book)

• Minerals like calcium, magnesium, potassium and sodium are leached from the soil and carried

away. (leaching – loss of nutrients through dissolving with the liquid in soil)

• Toxic metals like aluminum, manganese, mercury, cadmium and lead become more soluble by

the chemical action of the acids. This allows the toxic metals to be absorbed by the plant roots

and can cause serious damage or death to the plant or microorganisms.

• Toxic metals like aluminum, mercury, lead, and cadmium are washed into the lakes from the

soil.

• Collect in fish and other aquatic animals

making them unsuitable or dangerous for

people to eat (biomagnifcation).

– Ex. At a pH of 5.9, aluminum can start

damaging the gills of some fish species

and may eventually kill them. If the pH

reaches 4.5, most of the fish, frogs, and

insects will have died.

• Acid rain even affects historical monuments,

such as the Parthenon in Greece, Westminster

Abbey in England and the Taj Mahal in India by

turning the marble into a crumbly rock called

gypsum.

• Modern day works like steel bridges, vehicles and other metallic structures corrode or rust at a

much faster rate because of acid rain.

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Learning from Acid Deposition

• Reducing emissions is necessary for areas exposed to extreme acid deposition to recover • The road to recovery is a LONG process • Ability to be exposed to an acid or base and not change pH

• Soil/Limestone in lakes carbonate ion • Blood hydrogen carbonate and carbonic acid

• Once too much of an acid/base is added, the buffering capacity is exceeded and the pH changes

Titration Curves and Buffering

• The pH changes slowly in a titration due to buffering. Once the capacity is reached, a sharp

change occurs.

Smog

Photochemical smog – brownish-red haze produced by reaction of sunlight and automobile

exhaust. Occurs in the atmosphere. Reaction of nitrogen oxides.

Toronto, Montreal and Vancouver are cities where the ozone air quality objective is exceeded an

average of 10 or more days in the summer.

Reducing Emissions

Process that removes one or more harmful components from a mixture of gases or liquids

o See examples of electrostatic precipitator, scrubbers, and catalytic converters.

(textbook)

Different treaties and societal changes are needed to further reduce emissions.

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Homework Questions ???