Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Renewable Energy 4 > Past papers > Flashcards

Past papers Flashcards

1
Q

What is the conversion factor for Celsius and Fahrenheit?

A

Fahrenheit = (Celsius x 1.8) + 32

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the three main issues for commercial algal production?

A

Maintaining desirable species
Low yield of oil
High cost of harvesting

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How can issues with algae production be overcome?

A

Increasing algae oil content
Increasing growth rate
Robust growth systems
Coproduction
Increasing oil extraction efficiency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the average algae production of an open pond?

A

5-10g/m2-day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the average algae production of an enclosed bioreactor?

A

2-3g/L-day

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

List four carbon capture technologies

A

Post combustion capture
Direct air capture
Blue hydrogen
BECCS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How big is a hectare?

A

10,000m2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the power coefficient Cp of a wind turbine?

A

The fraction of available wind power in an area that is actually generated by a turbine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why does the stream tube of a wind turbine expand after passing through?

A

The mass flow rate must be maintained due to conservation of momentum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the theoretical relationship between wind turbine radius and output power?

A

Power is proportional to area so it is proportional to radius squared

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is a litre in m3?

A

0.001m3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a watt?

A

1 joule per second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why is 100% efficiency of a wind turbine impossible?

A

It would require the wind to have a speed of zero after passing the turbine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How to you find required fuel when given power output and efficiency?

A

Divide output by efficiency for max potential then divide this by energy content of the fuel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the reflectance of a material at the boundary between materials with refractive indexes of n1 and n2?

A

((n1-n2)/(n1+n2))^2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What material is best for PV where low weight, low size and high efficiency are needed?

A

Gallium Arsenide

17
Q

What is the most commonly used type of photovoltaic cell?

A

Polycrystalline silicon

18
Q

What are the benefits and drawbacks of a perovskite PV cell?

A

Cheap
Efficiency close to silicon
Short lifespan

19
Q

What are the benefits and drawbacks of an indium phosphide PV cell?

A

Potentially the highest electrical output
High material cost
Not at optimum efficiency

20
Q

Summarise the generations of biofuel

A

Produced from food crops
Growing on land where food cannot be grown
Derived from algae
Derived from genetically engineered microorganisms

21
Q

What are the benefits and drawbacks of a cadmium telluride PV cell?

A

Thin film application
Cheapest per W
Low efficiency compared to Si

22
Q

If asked for the environmental impacts of a renewable scheme, what can you always include?

A

The fact that it is a renewable technology that leads to lower carbon emissions

23
Q

What can be an ethical benefit of a new power source in a country that currently imports power?

A

Improved energy supply security

24
Q

What are some negative impacts of building a solar farm?

A

Land area use displaces wildlife and crops
Rare Earth element mining is destructive and materials are toxic

25
Q

What is the Betz Limit?

A

0.593

26
Q

What are the terms in the equation K v^3 A T?

A

K is a correction factor (usually 3.2)
v is average wind speed
A is Area
T is number of turbines

27
Q

How is the correction factor K calculated?

A

0.5 * density of air * power coefficient * hours in a year/1000
The last part is for unit consistency with kWh

28
Q

What is the conversion of ft to metres

A

1 ft = 0.3048m

29
Q

If a geothermal region is convection dominated with perfect mixing, what does this mean?

A

The temperature in this region is constant throughout

30
Q

If a geothermal power plant extracts 20•C from 65•C fluid, what is delta T in the power output equation?

A

20 K

31
Q

Why is growing algae at scale difficult?

A

Predators
Bioreactors improve growth rate but are much more expensive

32
Q

Why can dewatering algae have high electricity demand?

A

Current methods rely on centrifuging

33
Q

Why is dewatering more expensive if growth rate is low?

A

The proportion of biomass to water is less, so more water has to be removed

34
Q

What are issues with using a bioreactor to sequester CO2 from a fossil fuel burning energy source?

A

Problems with diluting CO2
Output gas is not only CO2 and can contain toxic compounds
Output gas is hot and could denature algae

35
Q

What rock type is best for carbon sequestration?

A

Porous basalt

36
Q

How do we know power is proportional to wind speed squared?

A

Kinetic energy is 1/2 mU^2
Power is energy over time
Mass over time is mass flow rate
Mass flow rate is rho A U
P = 1/2 rho A U^3

37
Q

What is a reasonable assumption for geothermal heat flow?

A

30•C/km

38
Q

What are the top 5 European countries for geothermal energy production

A
  1. Turkey
  2. Italy
  3. Iceland
  4. Germany
  5. Portugal

Renewable Energy 4 (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions