midterm exam review-2016-ljm

7/25/2019 Midterm Exam Review-2016-LJM

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Midterm Exam Review

Prof. L. Muzio

Spring Quarter 2016

EfficienciesCostsFuelsSolar Energy


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The following slides summarize the key points ofthe lectures that I gave this quarter; at least as Isee them.

A lot of information is discussed in this class,while it all is important in one way or the other,there are some key points that you should takeaway from each discussion.

Review all of your lecture notes and the slides.

If you have any questions, or feel that you needsome help, between now and the midterm pleasecontact The TAs or me:

Tel: 949- 677- 0107

E-mail: [email protected]


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U.S. Electricity by Source (AEO2014 EarlyRelease Outlook)(US Energy Information Administration)

2013 Current

EIA Short Term Forecast 2016NG-33%

Coal-32%

Major shift coal to Nat.Gas


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Projected New Natural Gas Resources(Power Engineering March 2012)

New sources of natural gas. Recall thedifference between Shale and Tight gas


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History: U. S. New Electric CapacityAdditions

For both economic and environmentalreasons natural gas is displacing coal


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Heat Engine Concept


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Rankine Cycle

Wet steamleaves the turbineTurbine Erosion

Superheat intendedto protect turbineSecondary benefithigher eff.

Heat added at higheraverage temperatureHigher eff.

Simple Rankine Cycle Superheat/Reheat Cycle Supercritical Cycle(*)

P=const.

P=const. P=const.

Water~3200 psia, 705F (217 atm, 374 C)

(*) also utilizes Reheat


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Combined Cycle Thermodynamics

Using the waste heat from the Gas TurbineBrayton Cycle in a steam Rankine cyclemarkedly increases the efficiency( decreasesthe Heat Rate)


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ASME PTC 4.1 Heat Loss Efficiency Method

There is more than just the Thermodynamic efficiency to consider. In the case of asteam cycle you need to consider how much of the chemical energy in the fuelcan actually be used to make steam; what are the main losses?


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Cost Of Electricity EstimatesCost Elements

Capital Cost ( what it cost to build)

Variable O&M ( primarily fuel); depends on the use

Fixed O&M ( routine maintenance, repairs, staff)-Sometimes called Other than Fuel

TermsOvernite Costs ( capital costs assuming plant builtovernight, not over 3-10 yrs)

Cost of Money (or interest rate paid on a loan)

Inflation rate ( decrease in the value of $)

Present Value ( current value of a series of paymentsmade in the future)

Discount Rate ( definition can vary, can include,interest, inflation, expected profit; simplistically =Interest-inflation)


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Capacity Factors

0

20

40

60

80

100

CapacityFactor,%

Lower capacity factor means less KW-hrmeans higher cost per KW-hr


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ExampleCapital Cost Coal Unit Nat. Gas Combined Cycle Wind

Cost C $/kw 1800 1000 2000

Interest Rate I % 10 10 10

Inflation Rate IFR % 3 3 3

Unit Life T yrs 30 20 20 Excel Functions

Capital Payment Pi $/yr $191 $117 $235 PMT(I/100,T,C,0)

Total Payments $/kw $5,728 $2,349 $4,698

Present Value $/kw $3,964 $1,850 $3,700 XNPV(IFR/100,P1:pf,Y1:Yf)

Fixed Operations and Maintenance

($/kw)/yr 30 12 30

Variable Operations and Maintenance (Fuel)

Plant Heat Rate Btu/Kwhr 9200 6700

Heat Input MMB/Kwhr 0.0092 0.0067 0

Capacity Factor % 85 85 32

Unit Fuel Cost( Present Value) $/MMBtu 2 4 0

Fuel Cost(Variable O&M) $/Mwhr 18.4 26.8 0

Unit Size MW 500 500 500

Capital Cost $/MW $3,963,805 $1,850,101 $3,700,202

$/MWhr 17.74 12.42 66.00

Fixed O&M $/MWhr 4.03 1.61 10.70

COE $/MWhr 40 41 77

In the spreadsheet I used in class I did Not Calculate XNPV for Fixed O&Mor Fuel Why?

For fixed O&M mainly salaries , unless you have other informationlike history of union negotiations will likely increase close toinflation. So, if I escalated the costs by the inflation rate then did thenet present value calculation I end up with the current costFor Fuel, similar argument, unless you have information on futurefuel prices( perhaps a mine mouth plant where you have hadnegotiations on future fuel costs that can be projected into future),these are difficult to forecast so it is common to just use todays fuel

cost


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Capital Cost vs. Size

Capital Cost Usually expressed as $/KW

$/KW will vary with the size of the plant

Typically $/KW decreases with increasing size-Why?Engineering costs dont scale linearlyEquipment purchases might not scale linearly

400MW Coal- uses 4 pulverizers ( 3-in service, 1-spare)800MW Coal-8 pulverizers? No probably 7 (6-in sevice, 1-spare)The cost of a continuous emissions monitor in the stackdoes not vary much with size

C1/C2~(S1/S2)^n

C=Cost, S=Sizen= scaling factor, typically n=2/3


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Coal

What is it?-basically plant matter that hasbeen under pressure and temperature for along time

Progression: CoalificationPlant Matter Peat Lignite Subbituminous Bituminous Anthracite

HeatPressure

Time

Hydrogen and Oxygen Decrease


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Effect of Coal Rank (Why?)

PA

=1.00

PA (Plan Area)

W

D

1.08W 1.16W1.26W 1.29W

1.06D 1.08D 1.24D 1.26D

PA

=1.15

PA

=1.25

PA

=1.56

PA

=1.63

Medium-Volatile

Bituminous

High-Volatile

Bituminous or

Subbituminous

Low-Sodium

Lignite

Medium-Sodium

Lignite

High-Sodium

Lignite


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Solar


17/24

Radiation Review

Black Body Radiation ( Perfect Radiator)

Pl=Power per m area per m wavelengthh = Planck's constant (6.626 x 10-34Js)

c = Speed of Light (3 x 108m/s)l = Wavelength (m)k = Boltzmann Constant (1.38 x 10-23J/K)T = Temperature (K)s= Stefan's-Boltzmann Constant= 5.67 x10-8W m-2K-4

p= 2898/T


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Flat Plate Solar Collector ( Solar Hot Water)

Pi

Pi

Pi)

Pi

Pi

Single Pane T increases from 93Cto 144 C for one pane of glass

Pi= s/(n+1) (T4T4a)N=# of glass panes

Pi

The panes of glassmake the collectorhave an effectiveemissivity


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Absorption of a Photon

E=hn>EG

E=hn=EG

P

N N

N

P

P


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Silicon Absorption of Solar Radiation

Energy of aPhoton of

wavelength -


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Solar BehaviorIf Fixed Make Tilt=Latitude

Simple Calculator at

(http://solarelectricityhandbook.com/solar-angle-calculator.html)


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Operating CharacteristicsSolarCollectors

CSPTechnology

Concentra-tion Ratio

TrackingRequirements

OperatingTemp (oC)

Averagesolar toelectricityefficiency

Unit Sizerange

Status

PowerTowers

500-1000 2 axisheliostat

400-600 12-18% 30-400MWe

Currentlargest:

392MW(Ivanpah,CA)

ParabolicTroughs

10-100 1-axisreflector

100-400+ 8-12% 30-100MWe

20 yearsoperating inCA

DishEngines

600-3,000 2-axis 600-1,500 15-31% 5-50 MWe Prototypestested at25kWe


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Power Plant CoolingOnce ThroughClosed Look

Dry


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Combined Heat and Power(CHP)

CO2 (lb/MW-HR)-Uses the energy of the steam in the denominatorAvoids burning fuel just for the process steam

midterm exam review-2016-ljm

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