First 2 guest lectures - introduction

Question 1

What is an electricity grid?

Answer 1

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

Question 2

What are the main goals for an energy system?

Answer 2

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

Question 3

What is energy used for?

Answer 3

electricity - 10kwh/day
heating
transport

Question 4

What are the challenges of building an energy system?

Answer 4

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

Question 5

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

Answer 5

50%

Question 6

What is leading the increase for the demand of energy?

Answer 6

increasing industrialization - GDP growth

Question 7

How much energy i used in the UK a day?

Answer 7

190 kWh/p/day

Question 8

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

Answer 8

180 kWh/p/day

Question 9

What is peak oil?

Answer 9

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

Question 10

Why is predicting peak oil so important?

Answer 10

• too late and we risk fuel shortages

- too soon, economic damage

Question 11

What is Ohms law?

Answer 11

V = IR
W = VI
W = I^2 R

Question 12

What kind of energy do fossil fuels provide?

Answer 12

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

Question 13

What is the first law of thermodynamics?

Answer 13

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

Q = q + work

Question 14

What is the second law of thermodynamics?

Answer 14

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

1 =/ 0

Question 15

What is the theoretical maximum extractable work called?

Answer 15

exergy

Question 16

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

Answer 16

Mechanical, electrical, chemical

Question 17

What does the maxiumum amount of exergy depend on?

Answer 17

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

Question 18

What is primary energy?

Answer 18

the raw fuel enetering the economy

Question 19

What is secondary energy?

Answer 19

The energy reaching consumers

Question 20

What are some examples of secondary energy?

Answer 20

• refined oil
• town gas
• electrical power

Question 21

What is the equation for the work dependent on temperature?

Answer 21

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

Question 22

What kinds of impacts do fuels have on the environents?

Answer 22

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

Question 23

What is temperature inversion?

Answer 23

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

Question 24

What does temperature inversion lead to?

Answer 24

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

1952 london smog - 8000 deaths

Question 25

What is the strategic solution to air pollution?

Answer 25

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

Question 26

What is district heating?

Answer 26

When heating is shared amongst buildings by a system of pipelines

Question 27

What is the ideal use case for district heating?

Answer 27

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

Question 28

What are some of the environmental consequences of renewable technologies?

Answer 28

- 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

Question 29

What is the definition of weather in climatology?

Answer 29

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

Question 30

What is the definition of climate in climatology?

Answer 30

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

Question 31

What is the definition of a greenhouse gas?

Answer 31

Tranpsarent to sunlight, absorb cooler, reflected radiation

Question 32

What is climate forcing?

Answer 32

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

Question 33

What is the equation for climate forcing?

Answer 33

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

Question 34

What is climate sensitivity?

Answer 34

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

Question 35

What is albedo?

Answer 35

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

Question 36

What does an albedo = 0 mean?

Answer 36

the object is a blackbody (absorbs all light)

Question 37

What does an albedo = 1 mean?

Answer 37

The object is a pure reflector

Question 38

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

Answer 38

30-35%

Question 39

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

Answer 39

wind and ocean circulation between the equator and the poles

Question 40

What is the snowball earth?

Answer 40

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

Question 41

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

Answer 41

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

Question 42

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

Answer 42

60-70 metres

Question 43

What is the runaway greenhouse effect?

Answer 43

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