3-12 Sustainable energy knowing more (3.4)

• Natuurkunde
• Middelbare school
• havo, vwo
• Leerjaar 2

Sustainable energy (knowing more)

Efficiency

You wnat to collect the maximum 

amount of energy from the sun.

At a powerstation only a small amount of the energy of fossil fuels is converted to  electricity.

A lot of energy is transported away with the waste water 

(60% of energy is lost)

Efficiency

Efficiency is how well energy is being used.

example:

Of 100J only 70J is used.

The efficiency is thus 70%

The efficiency of a powerstation is therefore 40%

Efficiency

The efficiency of a high-efficiency boiler is 95%

Less than 5% goes lost

The quest for greater efficiency...

• Solar cells in 1954 had an efficency of 4%.
  
• In 2010 a solar cell was made with an efficiency of 42%
  

Also importnat: - It must be cheap to produce

 - Materials needed for production must not be in short supply

Sustainable from start to finish

You heat up water with an electric kettle. So you dont produce CO₂ . Is this sustainable?

Explain if driving an electric car is sustainable.

Calculating efficiency:

If a solar collector converts 14 MJ energy of the possible 45MJ energy into heat, what is the efficiency?

Make question 64

p 144

Using efficiency in calculations:

If the efficiency of an electric central heating system is 82%, and 15 m³ of natural gas is burnt, how much energy is then converted into heat by the electric central heating system? 

Make question 65

Using ration tables:

If the efficiency of a central heating system is 76%, and 56MJ of energy is converted into heat during one shower, how much energy is needed in total for one shower?

Make question 66a

Homework:

66 b,c

67

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