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Renewable Energy > Final Review > Flashcards

Final Review Flashcards

1
Q

Units of energy

A

kW, mW

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2
Q

Nameplate capacity (kW)

A

The maximum rated output of a generator, prime mover, or other electric power production equipment under specific conditions designated by the manufacturer.

(Percent of Building Load * Annual Building Load (kWh)) / (8760 * Capacity Factor )

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3
Q

kWh (per day/month/year)

A

kW x #h

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4
Q

Sectors impacting climate change

A

Energy and agriculture

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5
Q

Sectors under energy

A
  1. transport
  2. heating and cooling
  3. electricity
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6
Q

Sectors under agriculture

A
  1. food production
  2. land use change
  3. deforestation
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7
Q

Parts of a solar panel

A

cell
forms module
forms array

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8
Q

Energy efficiency of solar PV (2020)

A

15%-24% of solar energy is converted to electricity

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9
Q

Transforming solar radiation energy into electrical energy

A

Solar array -> inverter DC -> AC, grid
Transforming solar radiation energy into electrical energy

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10
Q

Solar economies of scale

A

Bigger is better
Prefer commercial rather than residential buildings
Prefer old derelict sites to green fields
The sky is the limit

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11
Q

Solar collector loop

A

Hot water, underfloor heating and central heating → boiler → mains for cold water feed → solar thermal twin coil cylinder → pump → flat panel or evacuated tube collector → pump → boiler → hot water

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11
Q

Poly-crystalline vs mono-crystalline solar cell

A

Mono-crystalline is more efficient and more expensive

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12
Q

Solar district heating (SDH)

A

Consist of large fields of solar thermal collectors feeding their produced solar heat into block or DH networks in urban quarters, smaller communities, or large cities

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13
Q

Solar collector

A

Pipes with water heated by the sun, no electricity/moving parts
Should work even on a cloudy day (contrary to photovoltaics)
Low-tech, cheap, materials are widely available

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14
Q

Closed loop water

A

Closed loop, no waste of water
Very little electricity needed
Very cheap to install and run

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15
Q

Need hot water but no sun?

A

Insulated storage tank
Insulated pipes (hot and cold)
Large holes in the ground that is insulated and sometimes has black balls for covers

16
Q

Hot water infrastructure costs

A

Hot water network is expensive to install but very cheap to run (low maintenance costs)

17
Q

Summary of solar thermal

A

Bigger is better: economies of scale
Significant surface needed (competes with farm land)
Meets only a portion of the demand
Cheap technology
A number of barriers to overcome

17
Q

Main components of a wind turbine

A
  1. blade
  2. rotor
  3. brake
  4. gearbox
  5. nacelle
  6. anemometer
  7. controller
  8. generator
  9. yaw drive
  10. yaw motor
  11. power cable
  12. computer system
18
Q

Price of solar

A

Biggest drop in electricity production cost between 2009 and 2019 – 89% in these 10 years

19
Q

What is the capacity factor?

A

The ratio of the actual energy produced in a given period, to the hypothetical maximum possible, i.e. running full-time at rated power.

It is geographically relevant

20
Q

Capacity factor formula

A

Energy output (kWh/year) = nameplate capacity x capacity factor x hours of use per year

Average power generated by wind/peak capacity
ex. 5MW wind turbine, if it produces an average of 2 MW, then its capacity factor is 2/5=40%

21
Q

Trias Energetica

A
  1. Limiting the demand for energy
  2. Use as much sustainable energy as possible
  3. (When necessary) deploying fossil fuels as efficiently and cleanly as possible, reducing the use of fossil fuels
22
Q

Difference between energy and electricity

A

Electricity is a specific form of energy that you use to power your home/vehicle.

23
Q

Basic principle of wind turbine

A

Transforming kinetic energy into mechanical into electrical energy

24
Q

Betz Law

A

Maximum theoretical energy efficiency of a wind turbine
MAX of 59.3% efficiency

25
Q

Pros and cons of bioenergy

A

Pros
-renewable
-waste reduction
-reliability

Cons
-expensive
-space requirements
-some adverse environmental impact

26
Q

Limitations of bioenergy

A

Storing and processing of biomass requires large amounts of space (which limits the location options). Some fuel sources are seasonal, may compete with food production in specific cases, large footprint

27
Q

Constraints of biomass

A

-lack of sustainable supply of biomass
-biomass production competes with food production
-bio-energy may not always be low carbon on a life-cycle basis

28
Q

District heating in Copenhagen

A

The district heating system is supplied by heat from combined heat and power (CHP) plants and from waste incineration plants in the region.

A system for distributing heat generated in a centralized location through a system of insulated pipes for residential and commercial heating requirements such as space heating and water heating.

29
Q

Hydrogen formula

A

2H2 + O2 = Energy +2H20
Hydrogen + oxygen = energy + water

30
Q

Basics of H2

A

Most common element in the universe
Can be produced anywhere you have electricity and water
Generates heat OR electricity
Produced, stored, transported, used without pollution/CO2
3x energy density of oil
Fuel cell can reach 60% efficiency

31
Q

Challenges of H2

A

Does not exist in nature
Requires a lot of energy to separate
Needs to be stored at high pressure (700 atm)
Needs to be refrigerated (-253ºC)
25% of energy for the same volume of gas, big tanks needed
Fuel cells need maintenance (moving parts)
Subject to leaks (very small gas)
Exposive

32
Q

Green H2

A

Only sustainable way, produces zero carbon emissions
Electrolyzers split water into hydrogen and oxygen (electrolysis)
May compete on cost vs blue/brown H2 in 2030

32
Q

Demand side of H2

A

Industry: 50% efficient, worse than batteries, potential use in industries such as chemical production
Heating: space heating out-competed by heat pumps (efficiency and cost)
Transport: 20% more expensive than EV, hopefully for planes and ships
Potential for large power plant

Fertilizer, hydrogenation, methanol, hydrocracking, desulphurization, shipping, off-road vehicles, steel, chemical feedstock, long-term storage, etc.

33
Q

Summary of H2

A

Large public funding
Big expectations: small achievements
Can help resilience in a fluctuating wind/solar economy
Good when large excess wind power available (unconnected island)

Renewable Energy (1 decks)

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