Topic: Alternative energy sources

Target group

High school / technical school student

Core curriculum:

New core curriculum:

High school and technical high school. Chemistry – basic level:

XXII. Elements of environmental protection. Pupil:

4) indicates the need to develop branches of the chemical industry (drugs, energy sources, materials); indicates problems and threats resulting from improper planning and conducting of chemical processes; justifies the need to design and implement chemical processes that reduce or eliminate the use or manufacture of hazardous substances; explains the rules of the so‑called green chemistry.

High school and technical high school. Chemistry – extended level:

XXII. Elements of environmental protection. Pupil:

4) indicates the need to develop branches of the chemical industry (drugs, energy sources, materials); indicates problems and threats resulting from improper planning and conducting of chemical processes; justifies the need to design and implement chemical processes that reduce or eliminate the use or manufacture of hazardous substances; explains the rules of the so‑called green chemistry.

Old core curriculum:

High school and technical high school. Chemistry – basic level:

XXII. Elements of environmental protection. Student:

5) indicates the need for development of chemical industry branches (medicines, energy sources, materials); indicates problems and threats resulting from improper planning and conducting chemical processes; justifies the need to design and implement chemical processes to reduce or eliminate the use or production of hazardous substances; explains the principles of green chemistry.

General aim of education

The student discusses ways to gain energy in terms of benefits and risks.

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• to classify energy sources into renewable and non‑renewable;

• to name alternative energy sources;

• to analyse possible uses of alternative energy sources;

• to determine positive and negative effects of using particular types of energy;

• to predict the effects of using different energy sources;

• to analyse various energy sources in terms of benefits and threats associated with them;

• to analyse how energy generated in various manners affects the environment.

Methods/techniques

• activating

  • discussion.

• expository

  • talk.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in pairs;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• notebook and crayons/felt‑tip pens;

• interactive whiteboard, tablets/computers.

Lesson plan overview

Introduction

1. The teacher hands out Methodology Guide or green, yellow and red sheets of paper to the students to be used during the work based on a traffic light technique. He presents the aims of the lesson in the student's language on a multimedia presentation and discusses the criteria of success (aims of the lesson and success criteria can be send to students via e‑mail or posted on Facebook, so that students will be able to manage their portfolio).

2. The teacher together with the students determines the topic – based on the previously presented lesson aims – and then writes it on the interactive whiteboard/blackboard. Students write the topic in the notebook.

Realization

1. The teacher uses the text of the abstract for individual work or in pairs, according to the following steps: 1) a sketchy review of the text, 2) asking questions, 3) accurate reading, 4) a summary of individual parts of the text, 5) repeating the content or reading the entire text.

2. The participants of the classes, working in pairs, ask each other about the knowledge of the abstract..

3. The teacher initiates a discussion about the advantages and disadvantages of alternative energy sources..

4. Students, working individually or in pairs, carry out interactive exercises to check and consolidate knowledge learned during the lesson. Selected people discuss the correct solutions for interactive exercises. The teacher completes or straightens the statements of the proteges.

5. The teacher plays the abstract recording for all students. Participants listen carefully and give feedback on the difficulty of the text being heard using the traffic light method. Students are provided with green, yellow and red cards. While listening to the recording, they display the appropriate color for self‑assessment and to inform the teacher: green - I'm fine, I understand everything; yellow - I have some doubts; red - I do not understand anything, please help. The teacher responds depending on the needs of the students, deciding to repeat the recording, listen to the recording while following the text or translate the text.

Summary

1. The students consolidate the acquired information, discussing it with their nearest neighbors („tell your neighbor” method.

2. The teacher displays the criteria for success and asks the students to assess their skills acquired during the classes.

Homework

1. Imagine that you have the opportunity to interview an academic - a specialist in the field of today's lesson. What questions would you like to ask him? Write them down.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Alternative energy sources

Nowadays more and more energy is needed. Population growth, the high rate of economic development and progress in developing and using new technologies – all these make the demand for electricity growing all the time. Current energy sources cause substantial environmental pollution, contribute to climate change and furthermore their resources are limited and found only in certain regions of the world. Besides the limited supply and high demand for fossil fuels make their prices higher. That is why, it is necessary nowadays to increase the amount of energy produced from renewable sources.

Water power has been used for centuries to irrigate fields, drive turbines or water‑wheels in mills, forges and industrial plants. For the first time water was used to generate electricity in the 19th century. Contemporary water‑power engineering is based on potential of rivers and open water reservoirs on which river hydro‑plants and dams are constructed or uses the potential of seas and oceans – energy generated by waves, tides and sea currents.

Wind power production is the fastest growing branch of energy industry. Wind, that is a horizontal or nearly horizontal air movement in relation to earth’s structure, is caused by differences in the atmospheric pressure and temperature. Wind turbines are used to generate electricity using wind. Nowadays they are often found in the so‑called wind farms. In Poland there are favourable conditions for the construction of wind farms mainly in coastal areas and mountain passes. In Western Europe, this energy is used to the greatest extent in Germany and Spain.

Sun is the greatest and most important source of energy on Earth. It has practically always been used by humanity. Nowadays, it is used to power calculators, watches, surveillance cameras, road signs. Solar energy can be processed into heat using solar collectors and use to produce electricity by means of photovoltaic cells constructed using silicon. The third solution involves conversion of solar energy into chemical energy. This process takes place in green plants and is called photosynthesis:

${\text{6CO}}_{\text{2}}\text{+}{\text{6H}}_{\text{2}}\text{O}\stackrel{\text{light}}{\to }{\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}\text{+}{\text{6O}}_{\text{2}}$

Solar energy can be used on a small scale at private homes or public institutions. Solar cell batteries are mounted on roofs of these buildings. Solar energy is used on a larger scale at solar power stations. Germany is the leader in using energy of this type.

Geothermal energy is heat originating from radioactive decay of isotopes, such as uranium, thorium and potassium in the Earth’s mantle. Explosions of volcanoes, outflows of superheated steam (fumarole) or hot water (geysers) remind us of the huge potential of energy in the Earth. Hippocrates, the Greek physician, had already used geothermal energy to treat his patients. Water at a temperature of 40–90°C is used to generate heat, in balneology, agriculture and horticulture (for crops cultivated in greenhouses), fish farming and in the industry (for example to pasteurize milk or dry wood). On the other hand, water at a temperature of at least 150°C can be used to generate electricity. The US is the leader in using this type of energy.

Nuclear power is generated as a result of fission of atomic nuclei of heavy elements such as: ${}_{\text{92}}{}^{\text{235}}\text{U,}$${}_{\text{92}}{}^{\text{238}}\text{U,}$${}_{\text{94}}{}^{\text{239}}\text{Pu,}$${}_{\text{90}}{}^{\text{232}}\text{Th}.$ In nuclear reactors, fission takes place as a result of collision of a neutron with a nuclei of: ${}_{\text{92}}{}^{\text{235}}\text{U}$ It is reflected by the following equation:

${}_{\text{92}}{}^{\text{235}}\text{U + }{}_{\text{0}}{}^{\text{1}}\text{n → }{}_{\text{36}}{}^{\text{92}}\text{Kr + }{}_{\text{56}}{}^{\text{141}}\text{Ba + 3}{}_{\text{0}}{}^{\text{1}}\text{n + γ}$

The resulting neutrons make more uranium nuclei disintegrate ${}_{92}{}^{235}U$, leading to a chain reaction accompanied by emission of approx. 80,000 MJ of energy from 1 g of uranium (compared with 30 MJ of heat generated during combustion of 1000 g of hard coal). There are 455 operating atomic energy reactors in the world (status as 1.01.2018). The share of nuclear power plants in global electricity production amounts to around 10.5%.

In the future nuclear power engineering will probably become the main source of energy in the world. Failure of reactors in Chernobyl (1986) and Fukushima (2011) raised new concerns and provoked discussions on the safety of this energy source. However, undoubtedly it is the lest failure‑prone source of energy, the best ally in the fight for clean environment and the cheapest way to produce electricity.

Biomass consists of matter of plant and animal origin, mainly waste generated by agriculture, forestry, sludge, industrial and municipal waste. Biomass is the oldest and the most broadly used renewable energy source. It can be burned directly or processed into biofuels. Basket willow is a plant most commonly used in Poland for energy‑related purposes. Its yield from one hectare per year allows for getting on average so much energy as burning 10–13 tonnes of coal.

Liquid biofuels are used in cars. Potatoes or plant grains are fermented and this is how ethanol is obtained. Ethanol is more and more often used as a biofuel (bioethanol):

${\text{C}}_{\text{6}}{\text{H}}_{\text{12}}{\text{O}}_{\text{6}}\stackrel{\text{ enzyme}}{\to }{\text{2C}}_{\text{2}}{\text{H}}_{\text{5}}\text{OH + }{\text{2CO}}_{\text{2}}$

Its energy value is about 30 MJ/kg. This is why it can be added to petrol. A biofuel called biodiesel is obtained from rapeseed or sunflower oil, or from used cooking oil. It consists of fatty acid methyl esters, which are formed as a result of the esterification reaction of methanol and fats from oil plants:

${\text{CH}}_{\text{3}}\text{OH + vegetable oil}\stackrel{\text{ cat./temp.}}{\to }{\text{C}}_{\text{3}}{\text{H}}_{\text{5}}{\text{(OH)}}_{\text{3}}\text{ + biodiesel}$

This is how a natural biogas (called waste dump gas) is created in peat bogs and at waste dumps. It consists of methane, carbon dioxide, nitrogen and hydrogen sulphide. Combustion of biogas obtained in a controlled manner in biogas installations can be a source of energy that can be used to heat buildings, cook or power vehicles.

Fuel cells are devices in which electricity and heat are generated as a result of the following chemical reaction:

${\text{2H}}_{\text{2}}\text{ + }{\text{O}}_{\text{2}}\text{ →}{\text{ 2H}}_{\text{2}}\text{O + electric current}$

A fuel cell needs a substance that is easily oxidized as a substrate, such as hydrogen. They can also be fed with other substances, such as methanol or ethanol. Such energy sources supply ships, ferries and space stations, at the same time providing drinking water. The availability of different types of fuel cells means that the list of their possible applications can be extremely long, starting from portable devices such as cameras, mobile phones, laptops, tablets, through cars and other vehicles, ending with home heating systems. This would eliminate losses arising during the transmission of energy from the power plant to the recipient. A single fuel cell has little power, which is why they are combined in modules, the so‑called fuel cell stacks.

${\text{2H}}_{\text{2}}\text{O →}{\text{ 2H}}_{\text{2}}\text{ +}{\text{ O}}_{\text{2}}$

The hydrogen burns explosively in presence of oxygen. The process taking place can be described with the following chemical equation:

${\text{2H}}_{\text{2}}\text{ + }{\text{O}}_{\text{2}}\text{ →}{\text{ 2H}}_{\text{2}}\text{O}$

A mixture of hydrogen and oxygen at voluminal ratio of 2:1 or of hydrogen and air at voluminal ratio of 2:5 is a detonating gas.

• The main advantage of renewable energy sources (RES) is the protection of the natural environment against the emission of harmful chemicals. Furthermore, the use of RES allows for a significant reduction in the use of fossil fuels and oxygen consumption.

• The following alternative energy sources can be distinguished: water, wind, solar, geothermal, nuclear, biomass and hydrogen energy.

• Geothermal energy – is heat generated in the Earth which is accumulated in rocks and water filling rock pores and crevices.

• Nuclear energy – is released during nuclear transformation.

• Biomass -- is organic matter susceptible to biodegradation.

• It is possible to use alternative energy sources to a greater extent because new technological methods are being developed and the exiting ones are constantly being improved.