Class 2: concepts and global picture

Question 1

energy vs power

Answer 1

energy: ability to carry out work, measured in Joules
power: work done per unit of time, measured in Watts

Question 2

Joules

Answer 2

1 Joule: energy needed to lift 100g by 1m

Question 3

Watts

Answer 3

Joules per second

Question 4

exergy vs anergy

Answer 4

exergy: energy that is actually usable
anergy: share of energy that cannot be transformed into work (i.e. gets lost as heat)
energy = exergy + anergy

Question 5

different forms of energy

Answer 5

mechanical, chemical, thermal, nuclear, radiant (light), etc.

Question 6

2 theorems of thermodynamics

Answer 6

1st: within a closed system, energy is not consumed, only transformed
2nd: within a closed system, over time entropy increases (energy is transformed into less usable/concentrated form of energy, e.g. thermal heat spreads until evenly distributed)

Question 7

primary, secondary and tertiary energy

Answer 7

primary: fossil fuels, solar radiation, waves, wind, uranium, trees
secondary (primary but more processed): firewood, gasoline, electricity
tertiary (usable energy): light, heat, cold, mechanical energy

Question 8

efficiency formula

Answer 8

ƞ = output/input = exergy/energy

Question 9

Carnot efficien cy

Answer 9

ƞ Carnot = 1 - (T low / T high)
T is temperature in Kelvin, T low is usually environment’s room temperature
gives the highest theoretical possible efficiency

Question 10

efficiency of different energy types

Answer 10

heat generation has very high efficiency because energy isn’t “lost” as heat (80-100%)
lightbulbs: 5%
fluorescent lights: 20%
diesel/gas engines: 25-50%
electric engines: 80-90%

Question 11

what do kJ, CE, OE, and BTU stand for?

Answer 11

kilojoule, coal equivalent & oil equivalent (how much energy you get from 1kg of each), British thermal unit

Question 12

10 to the power of 1, 2, 3, 6, 9, 12, 15 and 18

Answer 12

deca, hecto, kilo, mega, giga, tera, peta, exa

Question 13

10 to the power of negative 1, 2, 3, 6, 9, 12, 15 and 18

Answer 13

deci, centi, milli, micro, nano, pico, femto, atto

Question 14

globally most used energy sources yearly

Answer 14

oil, coal, natural gas (160 EJ each), bioenergy (wood, 60EJ), nuclear (30EJ), RES uncommon (15EJ all together)

Question 15

what are different energy types used for?

Answer 15

oil for transport, mostly fossils for manufacturing, mix of RES and fossil fuels for heating/lighting

Question 16

problem with “we use 50% renewables!”

Answer 16

input ratio could be 75/25 fossils/RES, whereas output is 50/50 (because RES are more efficient)
varies depending on what stage of energy flow you’re looking at

Question 17

global energy efficiency

Answer 17

useful energy about 55 EJ, lost in conversion about 420 EJ
ƞ = 55/420 = 13%

Question 18

Switzerland energy consumption, where electricity comes from

Answer 18

Still mostly fossil fuels overall (especially transport), but electricity very clean
electricity: 60% nuclear, 30% hydro, rest RES

Question 19

when did different fossil fuels take off globally?

Answer 19

until industrialization: only biomass (wood)
industrialization after 1850: coal used for manufacturing
WW2: oil used for war transportation, lots of technologies developed
post WW2: oil for cars/trucks, international trade by planes/ships

Question 20

when did nuclear and RES take off globally?

Answer 20

around 1970 started being used, but slow growth

Question 21

which energy types’ shares of total consumption have declined/increased since 2000?

Answer 21

oil, coal and nuclear declining
natural gas and RES increasing

Question 22

how does each region’s energy consumption look? (North/ South America, Europe, CIS, Asia Pacific, Middle East, Africa)

Answer 22

graph in word
North America: mostly oil and gas, some coal, 20% RES and nuclear
South America: most RES globally (about 1/3), lots of hydro
Europe: 70% fossils, most nuclear globally (10%)
CIS: almost 90% fossils, over 50% natural gas
Middle East: almost 100% fossils, about 50/50 oil & gas
Africa: 90% fossils, rest mostly hydro
Asia Pacific: most coal globally (50%), about 15% RES and nuclear

Question 23

areas with highest/lowest energy use per person

Answer 23

highest: US, Canada, Saudi Arabia (then Russia, Australia)
lowest: Central African countries

Question 24

where is coal/gas/oil production highest?

Answer 24

oil and gas: US, Middle East, Russia (then China, Brazil, Canada)
coal: China, then Russia, US, India, Australia

Question 25

what is the global energy demand trend? how did covid affect it?

Answer 25

on the rise constantly as poor countries industrialize, covid temporarily decreased demand but we’re back on track

Question 26

what is the Swiss energy demand trend?

Answer 26

overall demand actually decreasing since 2010, electricity and gas shares increasing, oil decreasing

Question 27

what is the German energy demand trend?

Answer 27

high demand but decreasing over time (efficiency gains), more gas, less coal, small RES increase