4.1 Non-renewable and renewable energy sources 103-108 of...4.1 Non-renewable and renewable energy...

Chapter 4 Using Energy in Our Lives 103© Edvantage Interactive, 2010 978-0-9864778-0-5

4.1 Non-renewable and renewable energy sources

We rely on non-renewable energy sources to meet most of our energy needs in our homes, businesses, and schools. For this reason, they are known as conventional sources or traditional sources of energy. Non-renewable energy sources cannot be made or renewed.

Someday, we will use up non-renewable energy sources. Because of this and because non-renewable energy harms the environment, more and more we are using renewable energy sources. Renewable energy sources can be easily made or renewed. They are alternative sources because they are not based on burning fossil fuels or splitting atoms.

Non-renewable energy sources

Coal

Coal is the most plentiful fossil fuel found on Earth. In Canada, coal is mostly found in the western provinces. About 20% of Canada’s electricity is fuelled by coal.

Coal is removed from the ground using either surface mining or underground mining. Coal buried less than 70 m underground is surface mined by removing topsoil and layers of rock to expose the large beds of coal. Underground mining removes coal buried deep underground.

Once the coal is separated from rocks, dirt, and other unwanted materials, it is transported to electric utility companies and other industries. Power plants burn coal to make high-pressure steam. The force of the steam is then used to turn the rotating blades on engines called turbines. The mechanical energy of the spinning blades is then converted into electricity by devices called generators (see Figure 4.1).

Transmissionlines

Transformer

Generator

CondenserCondenser cooling waterRiver

Steam

Water

Boiler(furnace)

Coal

Turbine

Figure 4.1 Coal-fi red power plants burn coal to make steam, which is used to turn turbines to make electricity.

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Unit B Energy Conservation in the Workplace104 © Edvantage Interactive, 2010 978-0-9864778-0-5

Check Your Understanding

1. Defi ne a non-renewable energy source and give an example.

2. Describe two methods of extracting coal from the ground.

Crude oil and natural gas

Crude oil comes out of the ground as a yellowish black liquid. Natural gas is normally a colourless, odorless gas. Crude oil and natural gas are fossil fuels that are drilled from underground areas called reservoirs or traps found either on land or offshore deep under the sea fl oor.

After they are removed from the ground, crude oil and natural gas are transported to refi neries. Crude oil and natural gas are made up of many different hydrocarbon molecules. A refi nery is an industrial plant that heats oil and gas to sort, split, and reassemble the molecules so they can be made into different products. For example, crude oil can be made into diesel fuel, jet fuel, and gasoline (see Figure 4.2). Processed natural gas mostly consists of methane, but fuels such as butane and propane are also made from natural gas. Natural gas is an energy source for electricity, steam heat production, industry, and domestic uses like furnace fuel.

Gasoline

Diesel fuel

Jet fuelRefining processLight fuel oil

Other products

Heavy fuel oil

Figure 4.2 Many different products are made from crude oil. However, the majority of crude oil is made into gasoline.



Nuclear power

Nuclear energy is the energy in the nucleus or central core of an atom. It can be released through nuclear fusion or nuclear fi ssion. Energy is released during nuclear fusion when the nuclei of atoms join together to form larger single atoms. Energy is released during nuclear fi ssion when an atom’s nucleus breaks apart to produce smaller nuclei and subatomic particles, or particles that are smaller than atoms. Nuclear power plants use nuclear fi ssion to make electricity.

Nuclear power plants primarily use uranium-235 (U-235) as fuel to make energy through fi ssion. This is because the atoms in U-235 are easy to split apart. Uranium is a common metal that is found in most rocks. However, it is non-renewable, and U-235 is quite rare. It makes up only about 0.7% of the naturally occurring uranium on Earth.

Nuclear power plants make electricity much like other power plants that burn coal or natural gas (see Figure 4.3). In nuclear power plants, reactors control the chain reaction that makes electricity. Nuclear reactors are the structures in which nuclear fi ssion occurs.

Electric powerto grid

Transformer

Generator

Fuellingmachine

Cooling water fromlake/ocean/river

Watermoderator

Fuel(uranium)

Reactor

SteamSteamgenerator

Pump

FeedwaterWatercoolant

Turbine

Figure 4.3 This diagram shows how nuclear power plants make electricity.


1. Name three products produced from crude oil.

2. What is the fuel used in a nuclear power plant?



Renewable energy sources

Hydroelectric power

Hydroelectricity is electricity that is generated from falling or fl owing water. Hydroelectric power plants or hydropower plants use turbines like coal, natural gas, or nuclear power plants. But they use the force of moving water to turn the turbines that drive generators to produce electricity. The best places to build these plants are along fast-moving rivers or streams, in mountainous areas, or in areas with consistent rainfall. Canada’s geography is well suited for hydropower. As a result, it is the source for most of the electricity used by Canadians.

Most hydropower plants use either the natural drop of a river, such as a waterfall, or a dam built across a river to create a driving force of water. Two things determine the amount of electricity produced: the amount of water moving through the turbines (water fl ow) and the height from which the water falls from the upper reservoir in the dam or from the waterfall. The more fl ow, the more electricity can be generated.

Solar power

Solar power is power generated by harnessing the energy of the sun’s rays. It can be used to heat houses and water, and generate electricity.

Solar power is generated through several different methods:

Photovoltaic (PV) cells• (photo = light; voltaic = electricity) are grouped together in panels. They are made out of semi-conductive materials, such as silicon and glass. When light strikes the cells, an electric current is produced.

Active solar • technology uses collectors, such as mirrors and metal plates, to capture solar energy to heat air or water. Active solar energy is often used for space heating or water heating.

Passive solar • technology uses basic building materials like windows and insulation to control the amount of solar energy that is absorbed or lost in a building.

Concentrating solar • technology uses mirrors arranged in towers, troughs, or dishes to concentrate solar energy to drive generators or engines to generate electricity (see Figure 4.4).

Wind power

Wind power uses the kinetic energy or the energy of motion in moving air. It is mainly used to generate electricity or as mechanical power to grind grain or pump water.

Turbines are used to capture the power of the wind. Large turbines are often grouped together in wind farms that provide power to an electrical grid that services homes and businesses. Wind turns the turbines’ blades, which spin a shaft that connects to an electric generator that makes electricity. Wind turbines come in different sizes but can be grouped into two types (see Figure 4.5):

Horizontal-axis turbines• look like windmills that can stand 20 storeys tall, with three blades that can measure longer than a football fi eld. Most of the wind turbines used today are of this type.

Figure 4.4 A solar dish is a concentrating solar energy system.



Vertical-axis turbines• have two blades that go from top to bottom. They look like large egg beaters.

Figure 4.5 Horizontal-axis wind turbines look like windmills (left). Vertical-axis wind turbines look like egg beaters (right).

Tidal power

A tide is the alternate rising and falling of the ocean on a shore or coastline caused by the gravitational pull of the moon and sun and the rotation of Earth. Tides can also be used to generate electricity.

The Annapolis Tidal Power Plant in Annapolis Royal, Nova Scotia, is one of only three tidal power plants in the world. A common form of tidal power involves building a large dam called a barrage across a river or outcropping of land. The barrage funnels water into a generating plant and through a large turbine as it fl ows in and out with the tide.

Instead of barrages, tidal turbines can also be used to generate electricity. Tidal turbines take advantage of natural tidal fl ows. They can be anchored to the ocean fl oor or fl oated offshore. Nova Scotia is also experimenting with this new form of tidal technology (see Figure 4.6).

Geothermal power

Geothermal energy is heat that is generated within Earth’s core. Temperatures hotter than the sun’s surface are produced deep inside Earth because of the slow decay of radioactive particles. Large areas of geothermal energy called geothermal reservoirs are found mostly deep underground.

In Canada, near-surface geothermal energy occurs at fairly low temperatures. Right now its primary use in Canada is to heat and cool homes and offi ce buildings. Heat pumps extract near-surface geothermal energy from buried pipes to provide heat or air conditioning to buildings. For example, more than 100 buildings in Toronto’s downtown core are air conditioned using a geothermal heat pump system that draws 4°C water from Lake Ontario at a depth of 83 m.

Figure 4.6 In 2009, a tidal turbine, as pictured above, was anchored to the sea fl oor in the Minas Passage of the Bay of Fundy in Nova Scotia. The turbine looks like a giant jet engine and is 10 m in diameter.



Biomass energy

Biomass is organic plant material and animal waste. Biomass contains stored energy from the sun. Through photosynthesis, plants convert the sun’s energy into chemical energy that they store in their leaves and stems. This chemical energy is passed on to the animals and people that eat them. Examples of biomass include:

wood and wood products like bark and sawdust;•

agricultural crop leftovers;•

animal manure and food processing wastes;•

organic portions of municipal solid waste.•

There are three main ways to convert biomass into energy:

Biomass can be burned to create heat. This can be used to create steam to drive • turbines that generate electricity or to heat homes and industries.

Biomass can be heated (not burned) to break it down into gases, liquids, and • solids. These can be processed to make fuels, such as methane.

B• iomass can be fermented or broken down by micro-organisms like yeast and bacteria to create biofuels such as ethanol. Biofuels are mainly used in vehicles, but can be used to power other engines and fuel cells.

Hydrogen fuel cells

The hydrogen fuel cell is a relatively new energy source. It can be thought of as a cross between an electrochemical cell, as used in fl ashlights, and a generator. Electrochemical cells convert stored chemical energy into electrical energy. However, unlike regular cells and batteries, fuel cells do not wear out over time. Hydrogen and oxygen power fuel cells to make electricity. The only by-product is water (see Figure 4.7). The hydrogen and oxygen are provided from external sources, so as long as they are supplied to the cell, it will produce electricity.

Hydrogen fuel cells can be used:

to power electric • vehicles;

to provide emergency power in remote places or at hospitals;•

to provide• portable sources of energy for laptop computers and cellphones;

to power space vehicle electrical systems.•


1. Identify seven different renewable energy sources.

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Hydrogen Fuel Cell

Waterout

Hydrogenin

Energy out

Oxygenin

Figure 4.7 Hydrogen and oxygen power fuel cells to make electricity.


4.1 Non-renewable and renewable energy sources 103-108 of...4.1 Non-renewable and renewable energy...

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