Renewable sources of energy

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II. Types of Wind Turbines
1. Reading

     Read the text ‘Electricity from the wind’ and answer the questions.

     1- What factors does the amount of energy produced by a wind turbine depend on?
     2- At what wind speeds do wind turbines operate?
     3- Why do wind turbines automatically shut down at high wind speeds?
     4- Why is the rotor mounted on a turntable?
     5- What advantages do vertical axis wind turbines have? (See diagram on the next page)
     6- What disadvantages do wind turbines have?

      Electricity from the wind

      Modern wind turbines are now a familiar sight – like giant propellers with two or three blades,
      called rotors, mounted on top of tall towers of steel or concrete. The rotors turn a shaft which
      drives an electric generator.
      The size of the blades and the height of the tower determine how much electricity the turbine
5     can generate. Wind generally gets stronger as you go higher and the power of the wind you
      capture depends on the swept area of the blades. Double the length of the blades and the power
      increases four-fold. More important still is the speed of the wind because the power that can be
      extracted goes up as the cube of wind speed – if it blows twice as hard, there is eight times as
      much power to be had.
10    However, wind generators neither need nor want stormy weather. Most machines are designed
      to operate at wind speeds between Force 3 and up to Force 10 on the Beaufort Scale (21 to 97
      kph). Above Force 10 the machines automatically shut down to prevent themselves from flying
      apart. Most machines are designed to produce much the same power throughout their working
      range. The blades automatically ‘feather’ or twist as the wind strengthens so that the machine
15    does not accelerate too violently. It is better to have a steady output over a wide range of wind
      speeds than to be able to take advantage of the few really strong gusts.
      Wind generators must point in the right direction, either directly towards the wind or directly
      away from it. For this reason the rotor is mounted on a turntable and controlled by an electric
      motor connected to sensors which tell it which way to face.
20    This problem of wind direction can be completely avoided, however, if the blades are mounted
      on a vertical rather than a horizontal axis. Then it does not matter where the wind is blowing
      from. Furthermore, these vertical machines*, called Darreius turbines, have other advantages.
      Since the heavy generating machines that convert the power into electricity can be placed on the
      ground, instead of at the top of the tower, the rotor is subjected to less stress than in horizontal
25    axis generators. A disadvantage, on the other hand, is that they often need a push to get started,
      either manually or with an electric motor.
      Although wind turbines utilize so-called renewable energy, they do pose environmental
      problems. Turbines can be noisy and the Nimby principle operates with wind parks as well as
      with conventional power stations. Also, turbines lose efficiency when placed too close together
30    as they stand in each other’s wind shadow. Serious consideration has been given to placing
      turbines out at sea. But there would be problems anchoring them and in transmitting the power
      back to land.
      (*see wind turbine configurations on the next page)

Words:
swept area – area within the reach of the blades            to twist – verdrehen
             (überstrichene Fläche, Erntefläche)            to accelerate – beschleunigen
four-fold – um ein Vierfaches                               gust – Böe
the cube – dritte Potenz                                    turntable – Drehtisch
to feather – to move the blades into the wind so that       to be subjected to – ausgesetzt sein
            they provide less resistance
                                                    2




2. Grammar

2.1. Short-form relative clauses ( = reduced relative clauses)

a) Relative clauses with a relative pronoun:

Translate these sentences:
       A computer is a machine which/that processes information.
       A programmer is someone who writes computer programs.
       We must gain access to the data that is stored on the hard disk.

b) Short-form relative clauses (no relative pronoun)
    We can cut the above relative clauses shorter by using participles:

Translate these sentences:
       A computer is a machine processing information.
       A programmer is someone writing computer programs.
       We must gain access to the data stored on the hard disk.

When you translate short-form relative clauses into German, use a relative pronoun.
Example: Ein Computer ist eine Maschine, die Informationen verarbeitet.

Note:
Short-form relative clauses are relative clauses that do not have a relative pronoun, i.e. words
like that, which or who have been omitted. Very often participles are used.
They are mainly used in written English.
When translating these clauses into German, we usually use a relative pronoun.

c) Translate these sentences into German. Underline the short-form relative clauses.
1- These local reversible effects are in stark* contrast to the worrying global uncertainties of
   acid rain and the greenhouse effect associated with gaseous emissions from fossil fuel
   combustion, and the risk of radioactivity pollution associated with the nuclear industry.
   (*clearly obvious)


2- Studies undertaken by the CEGB and others have shown that wind energy could provide at
   least 20% of the UK’s electricity needs.


3- In 1989 the 2,690 million kWh of electricity generated by wind turbines throughout the
   world prevented the release of nearly 3 million tonnes of carbon dioxide.
                                                     3

2.2. Der Subjektkasus mit Infinitiv (NcI-Konstruktion)

1) Examples:
1- The transformer is known to be a useful apparatus.
        Translations:   a) Man weiß, daß der Transformator ein nützliches Gerät ist.
                        b) Es ist bekannt, daß ...
                        c) Bekanntlich ist der Transformator ein ...
                        d) Der Transformator ist als nützliches Gerät bekannt.
                        e) Der Transformator is bekanntlich ein ...

2- After this treatment, the material is then said to be magnetic or magnetizable.
        Translations:   a) Man sagt, daß das Material nach dieser Behandlung magnetisch oder
                           magnetisierbar sei.
                        b) Nach dieser Behandlung nennt man das Material ...
                        c) Das Material wird nach dieser Behandlung als ... bezeichnet.

2) Translate these sentences into German.

1- This computer is believed to be the most powerful in our laboratory.
2- For a long time the atom was thought to be indivisible.
3- The new turbine is reported to go into operation next year.
4- A vacuum is assumed to be a perfect non-conductor of heat.
5- The heat loss is taken to be negligible.
6- The completion date is the date on which the wind project is considered to be
   operational.
7- The wind turbine is said to have a yaw error, if the rotor is not perpendicular to the wind.

3) Translate these sentences into English.

1-   Windkraft ist als umweltfreundliche Energiequelle bekannt.
2-   Man sagt, daß sehr viele Windturbinen an einem Ort visuell störend sind.
3-   Es ist bekannt, daß Windturbinen sicher für die Umwelt sind. (environmentally safe)
4-   Man sagt, daß Windturbinen die Umwelt nicht verschmutzen. (be non-polluting)
5-   Die Lärmemission wird als ein mögliches Problem erkannt. (to perceive)


2.3 Connectives

1) Study this table.

Connectives that are separated from the rest             Connectives that are not separated by commas
of the sentence by commas                                because they introduce a subordinate clause
Therefore,                                               although
Consequently,                                            since
However,                                                 as
on the one hand / on the other hand,                     because
moreover,                                                in order for / in order that (damit)
that is to say,                                          while
indeed,                                                  whereas
in this case / in that case,
                                               4

2) Arrange the following connectives in groups to show their function.

although              regarding              while                moreover
lastly                but                    according to         as a result
with regard to        furthermore            in conclusion        in addition
also                  concerning             thirdly              for this reason
therefore             consequently           whereas              in other words
next                  however                first(ly)            on the other hand
thus                  thereby                to conclude

Function/Meaning               Connectives
additions

contrasts

conclusions

listing/sequencing

restating

effect

reference


3) Choose the best connective to complete the sentences.

1- Modern wind turbines can be aesthetically pleasant machines. However,/ Consequently,/
   Therefore, there is understandable concern that large numbers of wind turbines may be
   visually intrusive.
2- An advantage of wind turbines operating offshore is that wind speeds are generally higher.
   Therefore,/ This means / Because that more energy is generated than would be if the
   identical machines were based onshore. Consequently,/ Although/ However, the costs of
   the underwater foundations ... result in higher costs.
3- Although / But / Moreover, the machines would be spread over an area of 650 square
   kilometres they themselves would only occupy 7.2 square kilometres.
                                                   5

3. Types of wind turbines
3.1 Reading
3a) Read the texts about the one-armed wind turbine and the vertical axis wind turbine and
    answer the questions.




Fig. 1 Single-blade turbine                                      Fig. 2 Vertical axis wind turbine

1- What advantages do one-bladed wind turbines have over multiple blade turbines?
2- What characteristics does the rotor blade have? Why?
3- What advantages does the vertical axis wind turbine have?

The one-armed wind turbine
According to traditional conceptions, a wind turbine must have at least two blades. However, MBB is
now working on a single-blade configuration which was developed using expertise obtained from its
helicopter design activities. The aerodynamic characteristics of this configuration are superior to those
of multiple blade designs because its cardan blade suspension can cope easily with gusts of wind and
changes in wind speed, its design is lightweight and exerts less load. The Monopteros 50, which is
equipped with many innovative components which will secure its future as an energy-producing
machine. Constant changes in load, for example, place heavy demands on the rotor blade. It is
therefore made of fibre composite material and suspended from a flapping hinge similar to the type
used on helicopters.
The adjustable blade angle makes optimum use of wind power. The generator is accommodated in the
housing. It converts mechanical energy into electrical energy and supplies up to 2,000 MWh annually
at an average wind speed of 7.5 m/s, i.e. 27 km/h.

Words:
suspension (to suspend) – Aufhängung
flapping hinge – Schlaggelenk
adjustable – verstellbar
angle – Winkel

The Dornier vertical axis wind turbine
The wind turbine which Dornier has been developing since the mid-70s has an unorthodox design
based on a vertical axis. This principle is attributed to the Frenchman Jean Marie Darrieus who
patented his design in 1929.
The decisive advantage of this wind turbine compared with other models is that it need not be turned
into the wind. Wind power can therefore be optimally used no matter which way the wind is blowing.
The rotor has a diameter of 15 m and a blade area of 200 m2. It reaches a nominal power output of 55
kW and is designed for a life of 20 years.
                                               6

3.2 Language functions - Classifying

1- To classify from general to specific (i.e. from the top to the bottom) the following
   expressions can be used:

         CPU                    is/are divided into           fall into
                                can be divided into           consist of
                                is/are split into             include
 central     main               is/are composed of            comprise
 processor   memory             is/are made up of             contain

   Example: The CPU comprises the central processor and the main memory.
           The CPU is composed of the central processor and the main memory.

2- To classify from specific to general (i.e. from the bottom to the top) the following
   expressions can be used:

          CPU                      constitute
                                   make up
                                   form
 central          main             are classified as
 processor        memory           are the (three) parts/types of

    Example: The central processor and the main memory make up the CPU.
3- One way to identify objects is to classify them according to type,
       e.g.: Mainframes, minis and micros are types / kinds of computers.

  If we want to focus on only one of the items, we use the singular,
       e.g.: A mainframe is a type of computer. A monitor is a kind of TV screen.

4- State the classification criterion when talking about types. To do this, use:

   according to   with regard to       regarding
   referring to   with reference to    depending on

1) Complete the sentences below using the above phrases. Give different possible options.

1. A computer’s hardware _______________________ a CPU and peripheral equipment.
2. Input, output and storage devices are _____________________ peripheral equipment.
3. Storage devices ____________________________ 2 categories - tape or disk.
4. We can __________ a printer and a VDU __________ output devices.
5. We ______________________software __________ 2 types - systems and applications
   software.
                                              7


2) Pair work

Student A:

1- Talk to student B. Describe this diagram from top to bottom. Use different verbs.

       Start here                     CPU


               central processor                   main memory


        control unit            ALU               RAM          ROM



2- Listen to student B and complete the diagram he/she is describing.

                                             Computer system




Start here        input devices      …………… devices …………… devices
                                                                8

Student B:

1- Listen to student A and complete the diagram he/she is describing.

                                        CPU




2- Talk to student A. Describe this diagram from bottom to top. Use different verbs.

                                        computer system


                      hardware                                         software


       CPU         main memory             peripherals


Start here  input devices                output devices            storage devices


3) Classify these devices into types using a classification criterion. Complete the sentences.
1- power and size – computers – mainframes, minicomputers, microcomputers
   According to their power and size, computers ………………………………………….
   ........................................................................................................................
  (Nach ihrer Leistung und Größe werden Computer eingeteilt in …)

2- purpose – peripheral devices – input, output and secondary storage devices
   …………………………………………………………………………….
   ………………………………………………………………………….
3- design and operation – monitors – CRT , LCD and TFT screens
   ………………..……………………………………………………………………………..
  ……………………………………………………………………………………………….
                                                 9

4) Speaking / Writing
Describe the classification of wind turbines. Match the names for the different types with the
pictures.
                                     Wind turbines


              Drag turbine                                      Lift turbine


   Vertical axis t.     Horizontal         Horizontal axis t.                  Vertical axis t.
   e.g.                 axis t.            e.g.
   Savonius             e.g. farm          one-bladed t.
   turbine,             and ranch          two-bladed t.
   Persian                                 three-bladed t.            Darrieus t.      T. with
                        turbine
                                                                                       straight blades
   windmill                                multiple blades




Fig. 1: …………….         Fig. 2: ……………          Fig. 3: ……………          Fig. 4: ……………
        ……………..                ……………                  ……………                ……………




Fig. 5: ……………         Fig. 6: ………………..               Fig. 7: ……………             Fig. 9: ………………….
      ……………                …………. (top view)                   …………….                   ………………….

Use the gap filling text to write a description of the classification of wind turbines.
Wind turbines are ……….. into 2 main types. According to their operating principle they are …….
into …………………………………………………… . Depending on the position of their axis they
are …………………. into …………………………………………………………………………….
An example of the vertical ……………………………. turbine is ………………………………..
which is illustrated in ………………
Examples of horizontal ……………………………….. turbines are ………………………………….
which are ……………………. in Fig. …. . The …………….. turbine which is illustrated …………..
is an example of …………………………………………………….
Fig. … shows / depicts / illustrates a ……………………………………….. which is a ……………..
………………………………….. turbine.
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4. Listening (General Engineering, Unit 4E)

4a) Listen to this lecture on wind turbines. Look at the incomplete notes first and try to
   complete them as the lecturer gives his talk.

1. Title of the lecture: ____________________________________ (design and operation)

2. Basic design: Rotor or rotors on _____________________________ rotate
                 to convert wind into power via __________________________________

3. Rotor materials: Wood, glass reinforced plastic, ________________________________

4. Rotor types            (a) ______________________________
   and position           (b) _______________________________
                          (c) two or more sets of blades on the same shaft

5. Horizontal axis: two types of blades:
   turbines         (a) have _____________________ with aerofoil section to produce
                        _____________________
                    (b) Blades rely on ________________________ to extract energy from
                        wind.

6. Lift turbines:         (a) Small rotors turn at ___________ rpm (revolutions per minute)
                          (b) Large rotors turn at _______________ but blade tips reach speed of
                              _____________________

7. Drag turbines:         (a) Turbines turn _____________________________________
                          (b) Not suitable for _________________________________
                          (c) Used for __________________________

8. Control techniques:             (a) Rotors have _______________ to slow them down.
                                   (b) Rotors are made from ______________________________
                                   (c) Most machines have __________________ to stop rotation.

Words
lift turbine      - Auftriebsläufer (alle modernen Windräder, z.B. mit 3 Rotorblättern)
drag turbine      - Widerstandsläufer (z.B. Savonius Rotor) The blade design creates a pressure difference in
                  wind – high pressure on one side and low pressure on the other – that causes the blades to turn.
operation         - Betrieb, Einsatz
to mount          - montieren
to convert        - umwandeln
composites        - Verbundwerkstoffe
glass-reinforced plastic - glasfaserverstärkte Plaste
carbon fibre      - Kohlefaser
strength          - Festigkeit
aerofoil section - Blattprofil
drag forces       - (Luft)widerstandskräfte
to spin           - drehen
blade tip         - Blattspitze
swept area        - überstrichene Fläche
to prevent        - verhindern
to slow down      - bremsen, Geschw. verringern
to bend           - biegen
brake             - Bremse
                                                   11

4b) Writing – Post-listening activity
Using the information in the table, write a short text about
common features and differences of the two main types of
turbines.
Start with a short introduction and then continue with the
gap-filling below the table.
The dotted gaps should be filled in by information from the
table. The straight lines should be filled in by connectives
and other phrases for expressing contrast or common
features.
Use this structure:       - introduction
                          - two types of wind turbines
                          - common features (with introductory sentence)
                          - differences (with introductory sentence)

Introduction:
- Commercial wind turbines – design – generate electricity
- most turbines utilize aerodynamic lift – provide their driving force

Two main types: horizontal and vertical axis turbines (position of their axis)

Horizontal axis turbines                             Vertical axis turbines
- typically – two or three blades                    - typically two or three blades
- rotors – mount – high tower                        - can receive wind – any direction
 this arrangement – allow – turbines –               require no aligning devices
    exploit best winds                               - not exploit – increasing energy of wind
- require – turntable – turn – turbine into            with height
  wind – and mechanism – control – alignment          must operate in more turbulent regions
   (Ausrichtung)                                     - strong wind – cause – severe alternating
                                                       stresses in blades – because – rotate about
                                                       vertical shaft
                                                      require – careful fatigue (Dauerhaltbarkeit)
                                                         design
- all components – arrange – great height            - generator – arrange – ground level
 more difficult – maintain                           simplify servicing

Both types of turbines _____________________________, e.g. …………………………
…………………………………………………………………………..
However, there are also_______________________.
The rotors of horizontal axis turbines ………………………………………………………….
____________ this arrangement ……………………………………………………………….
____________, they …………………………………………………………………………….
…………………………………………………………………………………………………..
__________________, vertical axis turbines ………………………………………………….
……………….. . _____________, they ………………………………………………………
_______________, they cannot ……………………………………………………………….
______________ they must …………………………………………………………………..
____________, strong …………………………………………………………………………
…………………………………………………………………., ___________ requiring …….
…………………………………………………………………
In horizontal axis turbines, all …………………………………………………………………..
_____________ they ………………………………………………………. . _____________,
the generator of vertical axis ………………………………………………………………….,
___________ simplifying …………………..
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4c) Speaking / Writing

Use the information below to give a short presentation on the advantages and disadvantages
of horizontal axis wind turbines (HAWT).
Add missing words like articles, prepositions etc. Use the correct verb form.

Use introductory sentences: ... have some advantages.
                              ... have some disadvantages.
Use linkers: - contrast: however, on the other hand, whereas
              - addition: moreover, in addition, furthermore, also
              - numbering: first, second ... lastly
              - reason: because, as, since
              - effect: consequently, therefore, as a result
              - modality: thus, thereby

HAWT advantages
      Turbine – use – variable blade pitch – give – turbine blades – optimum angle of attack
       Remote adjustment of – angle of attack – allow effective control  turbine – collect
       maximum amount of wind energy for the time of day and season.
      Tall tower base – allow access to stronger wind
      High efficiency – blades – always move – perpendicular – to wind – receive power
       through the whole rotation

HAWT disadvantages
      Tall towers and blades up to 90 meters long – difficult to transport
       Transportation can reach 20% of equipment costs.
      Tall HAWTs – difficult to install – need – very tall and expensive cranes and skilled
       operators
      Massive tower construction – required – to support – heavy blades, gearbox, and
       generator
      Their height – make – them obtrusive visible across large areas  disrupt –
       appearance of the landscape
      Require – additional yaw control mechanism – turn – blades toward the wind


(Source: http://en.wikipedia.org/wiki/Wind_turbine)
                                               13


4d) Speaking

In a similar way, describe the advantages and disadvantages of wind turbines.

Advantages and disadvantages of wind turbines

Advantages
   a- not generate air or water emissions + not produce hazardous waste
   b- not deplete natural resources (coal, oil, or gas)
   c- not cause environmental damage through resource extraction and transportation
   d- pollution-free electricity – use – wind turbines – can help – reduce – environmental
      damage – cause – by power generation from fossil fuels
   e- consume no fuel + emit no air pollution – fossil fuel power sources
   f- energy – consume – to manufacture and transport the materials – use – to build – wind
      power plant is equal to the new energy – produce by – plant within a few months of
      operation
Disadvantages:
   a- Wind power – intermittent power source = power production from a wind turbine may
      increase or decrease –dramatic – over a short period of time
       grid must be able to – quick – compensate for this change
   b- economics of wind turbines can be challenging (in economic terms, wind power –
      have – a low marginal cost and a high proportion of capital cost)
      high quality wind resources often – locate – in areas inhospitable to people, logistics
      and transmission capacity can introduce significant obstacles to new installations
      (offshore wind farms)
   c- impact on wildlife (can pose a danger to birds and bats)
      studies of modern monolithic tower structures – show – lower impacts on bird
      populations
   d- Visual impact (people – live – in very close proximity to large turbine installations –
      complain)
   e- complaints about noise

4e) Writing / Speaking

Write a technical text about or give a presentation on wind turbines. Include these points:

– advantages and disadvantages of wind power
  (See: http://en.wikipedia.org/wiki/Environmental_effects_of_wind_power)
– classification of wind turbines into types
– advantages and disadvantages of the different types of turbines, e.g. horizontal and vertical
  axis turbines
                                               14

5) Speaking/ Writing - Wind turbines

Use the keywords given below to talk/write about some aspects of wind energy and wind
turbines. Pay attention to the difference between written and spoken style.

1. Renewable energy – important role in energy balance of the future
- examples: solar energy, wind energy, water power, geothermal energy, energy from biomass
           and waste
- advantages: - not pollute environment
              - available for free
              - inexhaustible, i.e. resources are not limited

2. Wind energy
- advantages: - environmentally friendly;
              - prevent increase in release of carbon dioxide
- disadvantages (wind turbines):     - relatively noisy,
                                     - visually intrusive
                                     - cause shadow flicker (i.e. moving shadow)

3. Wind turbines
- use: convert mechanical energy (wind) into electricity
- classification:
        - position of axis:    a) vertical axis turbines, e.g. Darrieus turbine,
                               b) horizontal axis turbines, e.g. conventional turbines with
                                  three blades
        - operating principle: a) lift turbines, e.g. conventional turbines
                               b) drag turbines, e.g. farm and ranch turbine

- advantages of vertical axis turbines:
        - need not be turned into the wind;
        - generator – place on ground  rotor blades – subjected to less stress
- disadvantage of vertical axis turbines: less efficient

- main components: tower, set of blades, generator, control equipment; with/without gearbox

- operation:
        - to operate efficiently – require an area with relatively high average wind speeds;
        - wind turn blades; blades connect to generator and turn generator;
           generator produce electricity; electricity fed to the grid
        - pitch control: ensures – overload of plant cannot occur;
                        shut turbine down – automatic – when wind too strong
                                                    15

Key Enercon

B 3) 1- placed 2- support        3-connect       4-revolve     5-located           6-accommodates
     7-mesh
C 1) a- attached b-arranged      c- supported    d-installed   e-placed, support          f-connected
         g-accommodates h-located        i-mounted

Key: Writing Turbines 4b)
have some common features
some differences
As a result
Moreover
On the other hand
Consequently
In addition
Therefore
Furthermore
thus / thereby
For this reason
On the other hand
thus

				
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