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Alternative energy sources

Link to the lesson

Before you start you should know
  • that the amount of fossil fuels is limited;

  • that prices of traditional fuels are rising;

  • that conventional energy sources cause substantial environmental pollution.

You 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 make a choice according to your beliefs and values;

  • 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.

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Nagranie dźwiękowe abstraktu.

Why are we searching for new 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

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 engineeringwater‑power engineeringwater‑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.

Advantages and Disadvantages of HYDROPOWER

advantages

disadvantages

- Harmless for the environment if operating properly;
- Does not have adverse effect on landscape;
- Geothermal energy resources are always available (regardless of the weather conditions);
- Plants are characterized by relative low operating costs.

- There are few places where they can be constructed (this is particularly relevant to tidal power stations); - The are more expensive to construct than conventional power plants;
- They affect natural environment (topography, climate, fauna, flora);
- Large hydropower plants need adequate water damming which often requires flooding large areas of land and resettlement of people;
- A dam is a barrier, e.g. for salmon;
- The operation of wave power stations depends on weather conditions.

Wind power

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 farmswind farmwind 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.

Advantages and Disadvantages of WIND POWER

advantages

disadvantages

- Wind can be a source of clean energy;
- It is renewable energy source;
- Following the installation of a wind turbine – it practically does not generate costs;
- Possibility to use small wind turbines and produce electricity on the areas where supply current is not available;
- The wind energy is suitable for immediate use and its conversion into electricity is relatively easy.

- Its usability is limited to the areas with strong and constant winds;
- Wind is changeable;
- Wind farms take a lot of place and are detrimental to landscape;
- They contribute to the death of birds and bats;
- They negatively affect TV and radio signal reception;
- Use of very high quantities of construction materials and high construction costs of wind turbines;
- Turbines may be the source of noise and cause the stroboscopic effect;
- Short lifetime (max 20 years).

Solar power

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:

6CO 2 + 6H 2 O light C 6 H 12 O 6 + 6O 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.

Advantages and Disadvantages of SOLAR POWER

advantages

disadvantages

- A clean source of energy;
- Solar cells do not require particular maintenance;
- They are cheap to operate;
- Their impact on the environment is low;
- Versatility of applications, long lifetime of the installations.

- Photovoltaic cells are produced with the use of toxic elements (cadmium, arsenic, selenium, tellurium); - The installation often occupies large areas;
- The possibilities of installation are limited to the sunniest areas;
- Low concentration of the produced energy and the necessity to store it;
- Very high costs relating to the production and installation of solar panels and collectors.

Energy in the Earth

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.

Advantages and Disadvantages of GEOTHERMAL POWER

advantages

disadvantages

- Harmless for the environment if operating properly;
- Does not have adverse effect on landscape;
- Geothermal energy resources are always available (regardless of the weather conditions);
- Plants are characterized by relative low operating costs

- Favorable conditions for its use are present only in few places;
- Plant construction requires high investment outlays;
- There is a risk that the geothermal reservoir will move away;
- Low concentration of the produced energy;
- During operation, greenhouse gases (COIndeks dolny 2,CHIndeks dolny 4) and toxic substances (HIndeks dolny 2S, SOIndeks dolny x) are emitted.

Nuclear power

Nuclear power is generated as a result of fission of atomic nuclei of heavy elements such as: U,92235U,92238Pu,94239Th90232. In nuclear reactors, fission takes place as a result of collision of a neutron with a nuclei of: U92235 It is reflected by the following equation:

U + 92235n → 01Kr + 3692Ba + 356141n + γ01

The resulting neutrons make more uranium nuclei disintegrate U92235, 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.

Advantages and Disadvantages of NUCLEAR POWER

advantages

disadvantages

- High amount of energy is obtained from low amount of fuel (1g of uranium equals 2.5 tons of coal);
- Low and stable price of the produced electricity;
- No emission of pollutants and COIndeks dolny 2 and very low amount of waste;
- Location of nuclear power plants does not depend on the location of raw materials;
- Area for power plant construction is small as compared to RES;
- Very low risk of failure;
- Ensures energy security.

- There is a danger of radioactive contamination in case of failure, natural disaster, terrorist attack;
- Necessity to apply expensive measures to ensure nuclear safety and radiological protection;
- Technically complex and quite expensive methods of storing radioactive waste;
- Changes in ecosystems caused by hot water disposal;
- High costs of power plant construction and demolition.

Biomass

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):

C6H12O6 enzyme2C2H5OH + 2CO2

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:

CH3OH + vegetable oil  cat./temp. C3H5(OH)3 + 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.

Advantages and Disadvantages of BIOMASS ENERGY PRODUCTION

advantages

disadvantages

- Renewable energy source;
- Its production and combustion cause less environmental pollution than the extraction of fossil fuels;
- Growing market of agricultural products;
- It ensures energy security;
- The use of biomass from forest and pasture areas reduces the risk of fires;
- Cultivation for energy production allows to manage agricultural wasteland and remediate post‑industrial areas;
- Reduction of the quantity of stored municipal and agricultural waste.

- Plant cultivation for biomass production takes large areas which might be used for other crops;
- Reduced crop biodiversity;
- May cause the rise in food prices;
- Relatively low density of raw material which makes it transportation, storage and dosage difficult;
- Lower energy value than in the case of fossil fuels;
- The availability of certain raw materials is seasonal.

Other energy sources

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

 2H2 + O2 → 2H2O + 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.

2H2O → 2H2 + O2

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

2H2 + O2 → 2H2O

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.

Advantages and Disadvantages of FUEL CELLS

advantages

disadvantages

- High efficiency of chemical energy conversion into electricity;
- Low level of noise;
- They can work continuously subject to the supply of fuel and oxidant;
- Easy to expand as the need arises;
- They do not cause environmental pollution;
- Their construction is easy and quick.

- Catalyst materials are expensive;
- High costs of fuel and membrane;
- A single cell generates low voltage, therefore in order to obtain adequate voltage, several hundred cells must be linked, which increases the mass;
- In case of hydrogen‑oxygen fuel cells, hydrogen is an element which is difficult to store and its preparation and storage involve high costs;
- Sensitivity to operating parameters (including ambient temperature).

Task 1

After learning about alternative energy sources, answer the question below.

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Wykonaj ćwiczenie zgodnie z poleceniem.
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Fiszki zawierają informację o odnawialnych źródłach energii. Są wybierane losowo: 1. Water-power plants- They convert potential energy of water into kinetic energy, which in turn is converted into electric energy in generators. 2. Wind farms - The amount of energy produced by wind farms is determined not only by the wind power driving the wind turbine, but also by the frequency of this phenomenon at given area. 3. Solar energy- Collected by--- solar panels using photothermal conversion,-- photovoltaic panels using photovoltaic conversion,--- photosynthesis, also known as photochemical conversion. 4. Biomass-Biomass is present in three states: --- solid (such as piece wood, straw, hay, energy crops, wood chips, briquette, pellet), --- liquid (such as bioethanol, biodiesel), and gaseous (such as mixtures of gases produced as a result of dry and wet anaerobic fermentation, gasification and pyrolysis).
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Exercise 1
Indicate true statements. Możliwe odpowiedzi: 1. Coal power plants or power plants using gas or crude oil are one of the causes of acid rainfall and greenhouse effect., 2. Solar collectors may be used only to heat water and homes., 3. Solar energy, geothermal energy, biofuels, uranium, water and wind energy are renewable energy sources., 4. The following greenhouse gases emitted during combustion of fossil fuels: CO2, N2O, CO, O3, freons, 5. Nuclear power is generated as a result of fission of atomic nuclei of heavy elements such as uranium, plutonium and thorium.
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Exercise 2
Wysłuchaj nagrania abstraktu, ułóż do niego pytania i zadaj je koledze.

Summary

  • 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.

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Grafika przedstawiająca tablicę szkolną, na której znajdują się zdania do dokończenia. Finish selected sentences. 1 It was easy for me (uzupełnij). 2 It was difficult for me (uzupełnij). 3 Today I learned (uzupełnij). 4 I understood that (uzupełnij). 5 It surprised me (uzupełnij). 6. Today I found out (uzupełnij). 7. I was interested in (uzupełnij). 8. I still have to repeat (uzupełnij).
Source: GroMar Sp. z o.o., licencja: CC BY-SA 3.0.

Keywords

wind farm, water‑power engineering, chain reaction, photothermal conversion

Glossary

wind farm
wind farm
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Nagranie dźwiękowe słówka.

farma wiatrowa – zespół położonych w niewielkiej odległości od siebie wiatrowych urządzeń prądotwórczych, grupujący od ponad 10 do nawet 100 turbin wiatrowych

water‑power engineering
water‑power engineering
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Nagranie dźwiękowe słówka.

hydroenergetyka – termin określający wytwarzanie energii elektrycznej przez elektrownie wodne

chain reaction
chain reaction
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Nagranie dźwiękowe słówka.

reakcja łańcuchowa – reakcja, która przebiega w następujących po sobie etapów, nazywanych „łańcuchem reakcji”; produkt każdego z etapów pośrednich jest jednocześnie substratem kolejnego etapu

photothermal conversion
photothermal conversion
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Nagranie dźwiękowe słówka.

konwersja fototermincza – proces polegający na przetwarzaniu energii słonecznej na energię cieplną