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(- ) Tampere University Joni Markkula

EE.EES.460 Electrical Energy Storages and Electric Vehicles, 5 cr.

Answer all the five (5) questions. The use of calculator is allowed. Answers in Finnish or English.

1. Answer TRUE or FALSE (+0.5 for correct answer, -0.5 for incorrect, 0 for empty, total max 6 p.)

New battery technologies are commercially available every year
C-rate states the li-ion battery temperature rating

LFP is safer than LCO

Specific energy is rated in Wh/kg or Wh/litre

Lead-acid battery has higher cell voltage than li-ion

Mode 4 always means DC charging in case of electric vehicles
Schuko and type 2 are common plugs in European EV markets
Electric vehicles consume about 20 kWh/100 km

Smart charging can cause problems for TSO

10. P2X2P process efficiency is ca. 50-60 %

11, Sensible heat storage the highest energy capacity of heat storages
12. Global EV fleet size is over 10 million vehicles

POnanesawne

2. Energy storages (6 p.)

a) Explain what a flywheel energy storage is, how it works and where it could be used. (3 p)
b) What are the three heat energy storage methods and how are they different from each other?

3. Lithium-ion batteries and supercapacitors(6 p.)

Explain in detail what is the difference between lithium-ion batteries and supercapacitors and how
they operate.

 

4. Electric vehicles (6 p.)
a) What has been the enabler of current wave of electric vehicles? What is still slowing down adoption of
electromobility?
b) How are electric vehicles charged at homes and on public charging stations? What are the equipment
needed and what they do?

PLEASE TURN THE PAGE
Lifetime costs (6 p.)

Consider operating a city bus line with one of the two possible electric buses: first with large battery and
slow charging, and second bus with small battery and quick charging station (expensive). They differ in
investment costs, operating costs and battery lifetime (which will need replacement at year X). Which one
is financially better option?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

eBus 1 (LFP) eBus 2 (LTO)
Bus price (body) 100 000 €
Battery size 250 kWh 50 kWh
Battery price 500 €/kWh | 1500 €/kWh
Charging station cost 10 000 € 100 000 €
Battery cycle life [ 1500 10 000
Bus energy consumption 1.1 kWh/km 1.0 kWh/km

Values that apply for both:

Distance per year | 60 000 km
Electricity cost | 0.4 €/kWh
Internal discount rate | 11%

 

 

£

(Hint : discount coefficient is i
1%
(2+;b0%)

 

))