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Energy and Environmental > First 2 guest lectures - introduction > Flashcards

First 2 guest lectures - introduction Flashcards

1
Q

What is an electricity grid?

A
  • Electricity grid that converts energy from one form to another
  • matches the amount of consumption to the amount produced
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2
Q

What are the main goals for an energy system?

A
  • convert energy
  • regular and continuous supply
  • efficiency
  • store excess eenergy
  • supply == demand
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3
Q

What is energy used for?

A

electricity - 10kwh/day
heating
transport

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4
Q

What are the challenges of building an energy system?

A
  • finite energy resources
  • sustainability
  • robustness/ reliability
  • cost
  • maintenance
  • land / resources available
  • accessibility/ equality
  • large scale of transformation
  • integration of renewables
  • economic cost
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5
Q

How much more energy are humans likely to need in the future?

A

50%

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6
Q

What is leading the increase for the demand of energy?

A

increasing industrialization - GDP growth

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7
Q

How much energy i used in the UK a day?

A

190 kWh/p/day

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8
Q

How much energy in the UK could theoretically be gotten from reneewables?

A

180 kWh/p/day

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9
Q

What is peak oil?

A

The point at which oil production reaches its peak value and after which enters a terminal decline

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10
Q

Why is predicting peak oil so important?

A
  • too late and we risk fuel shortages

- too soon, economic damage

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11
Q

What is Ohms law?

A 
V = IR
W = VI
W = I^2 R
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12
Q

What kind of energy do fossil fuels provide?

A 
1 barrel of oil - 6GJ 
1 tonne of oil - 42 GJ 
1 m^3 of gas - 40 MJ
1 tonne of coal - 29 MJ 
1 kcal - 4.22 kJ
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13
Q

What is the first law of thermodynamics?

A

Energy is neither created nor destroyed, but converted from one form to another

Q = q + work

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14
Q

What is the second law of thermodynamics?

A

A device operating continuusly cannot export only work from an isolated source of heat

1 =/ 0

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15
Q

What is the theoretical maximum extractable work called?

A

exergy

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16
Q

What types of work are usually treated as 100% exergy?

A

Mechanical, electrical, chemical

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17
Q

What does the maxiumum amount of exergy depend on?

A

the hot source temperature
the coolest heat sink temperature

As temp –> inf. the source tends to pure E, when the heat source temperature is close to that of the ambient, the energy is of low grade

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18
Q

What is primary energy?

A

the raw fuel enetering the economy

19
Q

What is secondary energy?

A

The energy reaching consumers

20
Q

What are some examples of secondary energy?

A
  • refined oil
  • town gas
  • electrical power
21
Q

What is the equation for the work dependent on temperature?

A

W = (1 - Tc/ Th) Q - carnot efficiency

22
Q

What kinds of impacts do fuels have on the environents?

A

Upstream: spoil at mines, oil extraction and transportation, gas extraction using fracking
E.g. Aberfan disaster, piper alpha, deepwater horizon

Getting energy from fuels: Wood or coal creates smoke

23
Q

What is temperature inversion?

A

When the raidative cooling of the ground or warmer layer is created by a warm fron 1-2 km above the surface

24
Q

What does temperature inversion lead to?

A

COnvection cannot disperse the emissions, become trapped in the cool air

1952 london smog - 8000 deaths

25
Q

What is the strategic solution to air pollution?

A
  • dispersing from urban centre
  • generating power at remote large power stations
  • omporving domestic fireplaces and fuel
  • distribution of heat via district heating
26
Q

What is district heating?

A

When heating is shared amongst buildings by a system of pipelines

27
Q

What is the ideal use case for district heating?

A

in residential or commercial propertires where they cna provide higher effciencies and better pollution control

28
Q

What are some of the environmental consequences of renewable technologies?

A
  • wind turbines effect bird migration
  • wildlife disruption
  • large amounts of resources needed
  • environmental considerations of geothermal energy (aquatic)
  • carbon footprint
  • noise pollition
  • land use (wind/ solar)
  • dams have consequences on river ecosystems
29
Q

What is the definition of weather in climatology?

A

the state of the atmosphere at any give pooint at a given time

30
Q

What is the definition of climate in climatology?

A

the set of weather statistics at a location averaged over a long period

31
Q

What is the definition of a greenhouse gas?

A

Tranpsarent to sunlight, absorb cooler, reflected radiation

32
Q

What is climate forcing?

A

The extra solar radiation that would be needed to obtain the same temperature elevation the absence of the effect

33
Q

What is the equation for climate forcing?

A

deltaF = 5.35(ln(C/Co))

Logarithmic variation comes from the fact that the adsorption of CO2 in the new atmosphere is already nearly saturated. Tis means te increase of forcing with concentration for other greenhouse gases is much sharper

34
Q

What is climate sensitivity?

A

the global average temperature rise resulting from the forcing equivalent to doublng the CO2 concentration over pre-industrial levels:

delta T = lamda*deltaF

lambda is the climate sensitivity

35
Q

What is albedo?

A

a measure of the reflection of sola radiation out of the toal rediation recieved by an astronommical body such as the earth

36
Q

What does an albedo = 0 mean?

A

the object is a blackbody (absorbs all light)

37
Q

What does an albedo = 1 mean?

A

The object is a pure reflector

38
Q

What is the average albedo of the earth from the upper atmosphere>

A

30-35%

39
Q

If the earth is treated as a heate engine what energy is it creating?

A

wind and ocean circulation between the equator and the poles

40
Q

What is the snowball earth?

A

the earth has been entirely frozen at least once

This state is associated with low GHG concentration

The hypothisis is that an ice-albedo feedbac would result in global ice

41
Q

What is the grounded/ floating ice and sea level model?

A

Floating ice displaces the same volume of sea water as when it melts, so makes no contribution to sea level

The ssea level depends on the amount of fresh water locked up in grounded ice, like glaciers - and the antarctic

42
Q

How much would the complete melting of the antarctic raise the sea level by?

A

60-70 metres

43
Q

What is the runaway greenhouse effect?

A

When the net positive feedback between surface temperature and atmospheric opacity increases the strength of the greenhouse effect on a planet until its ocean boils away

This is thought to have happened in Venus, where the increase in evaporation from the ocean produced large amounts of water vapour

Energy and Environmental (8 decks)

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