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Renewable Energy > TEST 1 > Flashcards

TEST 1 Flashcards

1
Q

list the power plants and their efficiencies

A

oil fied steam (33-37%)
coal fired steam (36-46)
integrated gasifiaction combined cycle (IGCC) (39-44)

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2
Q

what is the most efficient power plant

A

Hydroelectric (85 -90)
Tidal (70-80)
medium speed reciprocaing ICE engines (45-50%)

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3
Q

what is hydroelectric power’s distinct advantage?

A

it is far more flexible source of power, it can provide baseload power , peaking power, spinning reserve, and energy storage

it can meet minute by minute load fluctuations faster with greater range and flexibility

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4
Q

how does a hydropower work

A

water from the reservoir flows due to gravity to drive the turbine

turbine is connected to a generator

power generated is transmitted using power lines

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5
Q

what are the three types of hydroelectric power plants are available based on the way they interact with their resource?

A

Conventional plants
Run of the river plants
pumped storage

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6
Q

State two characteristics of the conventional plants

A

they serve multiple purposes besides power generation, including urban water supply, flood control irrigation and recreation

decouples the timing of precipitation from the constantly varying load that the grid must satisfy

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7
Q

describe the run of the river stating 3 characterstincs

A

portion of the river is diverted into a forebay that provides modest storage
water travels from the forebay in a pipeline, penstock that delivers water under pressure to a generate below the intake

for small off grid systems, it may contain a battery bank to help provide for peak demands that exceed the average generator output

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8
Q

describe the pumped storage plants

A

a reservoir serves to supply peaking power for the grid

water from a lower elevation source is pumped uphill during off peak times to the storage reservoir

round trip efficiency are above 80%

provides grid stability

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9
Q

what are the advantages of hydro power

A
  • once the dam is built, the energy is virtually free
  • a clean source of renewable energy
  • can be used baseload and peak load plant
  • has the capacity to follow demand fluctuations almost instantly
  • offers a quick response to failing power grids
  • no waster or pollution produced
  • much more reliable than wind solar or wave power
  • long lifetimes
  • low operating
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10
Q

what are the disadvantages of hydro power

A
  • dams are very expensive to build
  • building a large dam will flood a very large area upstream causing problems for animals there
  • finding a suitable site can be difficult since residential impact is unacceptable
  • water quality and quantity downstream can be affected which can have an impact on plant life
  • social impacts of displacing indegenous people
  • health impacts in developing countries
  • variable output
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11
Q

what are the ecological impacts of hydropwer

A
  • loss of forests, wildlife habitat and species
  • degradation of upstream catchment areas due to inundation of reservoir area
  • rotting vegetation also emits greenhouse gases
  • loss of aquatic biodiversity, fisheries and other downstream services
  • cumulative impacts on water quality, natural flooding
  • disrupt transfer of energy, sediment and nutrients
  • sedimentation reduces reservoir life, erodes turbines
  • creation of new wetland habitat
  • fishing and recreational opportunities provided by new reservoirs
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12
Q

what are the 6 different turbines

A

Francis turbine
fixed pitch propeller
turgo
pelton
kaplan
crossflow

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13
Q

How do impulse turbines work

A

impulse turbines capture the kinetic energy of high

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14
Q

hwo do Reaction turbines work stating some examples

A

the pressure difference across the runners, or blades creates the desired torque

kaplan
Francis

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15
Q

How do impulse turbines work

A

impulse turbines are most appropriate in high-head, low-flow circumstances while the opposite is the case for reaction turbines

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16
Q

what are waterwheels and why can’t it be used to generate electrical power

A

slow-moving powerful turbines that convert potential energy into mechanical energy

the slow rotational rates of waterwheels are a poor march to the high speeds needed byu generators so they are not used for electric power

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17
Q

describe how the pelton wheel works in detail

A

water squirts out of nozzles onto ets of twin buckets attached to the rotating wheel
the bucketsa re carefully designed to extract as much of the kintetic energy as possible with an efficiency of 70-90%

Applications: high head, low flow

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18
Q

describe the turgo turbine in detail

A

Turgo turbine is siimlar to a pelton, but the runner has a different shape and the incoming jet of water hits the blades somewhat from one side, allowing exiting water to leave from the other, which greatly reduces the interference problem

it also allows the jet to spray several buckes at once, this spins the turbine at a hgiher speed than a pelton hwich makes it somewhat more compatible with generateor speeds

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19
Q

where are cros-flow turbines used

A

useful in low to medium head situations (5-10 meters)

simple to fabricate which makes them popular in developing countries where they can be built locally

20
Q

describe the kaplan turbine

A

most used for low head installations with large flow rates

runners are completely immersed in water and derive their power from teh mass of water moving through the rather than the velocity

used in micro hydro installations and have runners that look like outboard motor propeller

3-6 baldes which for small systems are usually fixed pitch

water is directed tangentially through the wicket gate and spiral on to a propeller shaped runner causing it to spin

21
Q

describe the francis turbine

A

the inlet is spiral shaped

guide vanes direct the water tangentially to the runner

this radial flow acts on the urnner vanes causing the runner to spin

the guide vanes or wicket gate may be adjustable to allow efficient turbine operation for a range of water flow conditions

best suited for sites with high flows and low to medium heads

efficiency of 90%

expensive to design, manufacture and isntall but operates for decades

22
Q

what are the factors that affect making decision about a site

A

quantity of water available

volume of water that can be economically stored

head

distance of site from load centes

accessibility of the siet

run. off due to seepage and impervious rocks

23
Q

list and describe the 3 studies conducted in the planning stage

A

reconnaissance study (is the side suitable or not?)
average annual flow
discharge available during low flow season
available head

feasibility study
should an investment commitment be made?
dam size and turbine generator size
penstock diameter/type
turbine diameter/type

definite plan study
water flow regulation (run of river, storage etc.)

24
Q

list the appropriate turbines according to head

High head
medium ehad
low head

A

impulse turbine
francis turbine
reaction turbine

25
Q

what are the energies associated with water

A

potential energy (hight from reference)
pressure energy (penstok)
kinetic energy (moving of water in turbine)

26
Q

what is a weir and what is it used for

A

for micro hydro systems, we can build a temporary plywood, concrete or metal wall called weir to measure flow of water

27
Q

what are the principal components of the electric power industry

A

generation
transformers step up the voltage to long distance transmission lines

transmission
voltages may be reduced for regional transmission using sub transmission lines

distribution
transformers located at load centers in the distribution substation step down the voltage to distribution level

28
Q

what is a distribution feeder

A

feeders carry power from the distribution substation to the final customer

they protect key components and allow different segments of the system to be isolated for maintenance or emergency fauts

29
Q

what are electrical grids

A

practical power systems that have multiple paths interconnected together

30
Q

what happens when demand exceeds supply

A

turbine generators slow down and the frequency drops for a few seconds to convert some of the kinetic energy into extra electrical power to meet the increased load (vice versa)

31
Q

what is load shedding

A

is the emergency measure used when frequency drops below the minimum threshold (high demand) and the generator turbines cannot response fast enough. this is to prevent damage to the generators

32
Q

what is the job of the following
SCC
ISO
RTO
ACE

A

managing the balance between supply and demand and operating the electric poewr grid is the job of the System Control Center (SCC) for isolated systems and independent system operator (ISO) and Regional transmission operator (RTO) for interconnected systems by controlling the Area control error (ACE)

33
Q

define the base load and give an example

A

some plants such as nuclear reactors are designed to run continuously to close to full power so they are referred to as must run or baseload

renewables are also considered must runs since they have almost zero marginal costs. the are usually curtailed depending on demand due to their fast ramp-up ramp-down and low marginal operating costs

34
Q

define load-following or intermediate plants and give an example

A

most fossil fueled plants and hydroelectric facilities can easily be slowly ramped up and down to track relatively smooth, predictable diurnal changes so they are referred to as load following

35
Q

what are peakers

A

small, cheap to build but expensive to run plants that re mostly used only a few tens of hours per year to meet the highest peak demands

36
Q

what are spinning reserves

A

plants connected to the grid but deliver no power until they are called upon such as when another plant suddenly trips offline

37
Q

what are regulation services , frequency regulation or automatic generation control (AGC)

A

small fast responding plants that may run at partial output to track the second by second changes in demand

AGC cna provide regulation up and down for a fixed monthly fee per MW regardless of whether the regulation service is rendered or not

38
Q

how to ISOs and RTOs contribute to balancing supply and demand

A

by exchanging power with neighboring utilities

39
Q

what is the demand response (DR) approach

A

changing the paradigm of energy on the grid by allowing customers to control their own power consumption

can be offered with financial incentives

40
Q

what is demand side management (DSM)

A

all methods of controlling load such as load shifting, valley filling and peak clipping

41
Q

compare primary and secondary energy

A

primary energy is embodied in sources where human induced extraction or capture with or without separation from contiguous material cleaning or grading (coal, oil …)

secondary energy should be used to designate all sources of energy that result from transformation of primary sources

42
Q

compare commercial and non commercial energy

A

commercial energy is available in teh market for a defnite price

non commercial energy are sources that are not available in the commercial market for a price (firewood, cattle dung)

43
Q

compare conventional and non conventional energy

A

conventional are anything before 1973 (fossil fuel, nuclear, hydro)

non conventional are anything after 1973 (solar, wind, biomass…)

44
Q

compare renewable and non renewable

A

energy obtained from the continuing or repetitive currents of energy occurring in the natural environment and is inexhaustible

nno renewable energy is the energy from fossil fuels and is finite

45
Q

what is distributed generation (DG)

A

small scale electric power generators that produce electricity close to customers. (micro turbines, reciprocating engines etc.)

46
Q

what are applications of DG

A

Peak shaving
emergency generation
green power source
reliability improvement

Renewable Energy (3 decks)

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