Today Electric Power Lecture Carbon Trading Game Assignment 2 posted Thursday Electric Power Distribution and Storage Lecture Homework 3 (Conservation) due at start of class Group homework using eQUEST One homework/group Discuss Homework 3 Present an example problem to help with Homework 4 At 6 pm, reading quiz for Electric Power due
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Today Electric Power Lecture Carbon Trading Game Assignment 2 posted Thursday Electric Power Distribution and Storage Lecture Homework 3 (Conservation)
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Today
Electric Power LectureCarbon Trading Game Assignment 2 posted
Thursday
Electric Power Distribution and Storage LectureHomework 3 (Conservation) due at start of class
Group homework using eQUESTOne homework/group
Discuss Homework 3Present an example problem to help with Homework 4At 6 pm, reading quiz for Electric Power due
Week 4
ElectricityGeneration, Transmission, and Storage
World Energy Consumption by Service
electricity
transportation
heat
electricity, fossil
electricity, other
transportation, fossil
transportation, other
heat, fossil
heat, other
37 %
25 %
38 %
13 %
11 %
Why Care?
Electricity Consumption by Source
coal
oil
gas
biomass
waste
nuclear
hydro
geothermal
solar PV
solar thermal
otherInternational energy agency, 2003
Where is this electricity coming from?
39.9%
19.3%
16.3%
15.7%
6.9%
0.83%
0.37%
0.0033%
0.0033%
0.40% Includes wind
steam turbine
steam turbinegas and steam turbines
steam turbine
water turbine
How is it created?
So, what are we going to talk about most of the day?
Steam Trivia:
How much water do we (earthlings) change to steam every year in the name of electricity demands?
A. 10 km3
B. 55 km3
C. 6,000,000 m3
D. 190,000,000 m3
Salt Lake holds 16 km3 of water
1200 1500s 1603 1661 17001712
1776 1880 1900
1911 1920 1950 1967 1970
1306 1890
1973
19691940
1942 19481960
1963
19781976
19871988-92
1982 1996-97 20032002 2004
future2001
Britain producing 5x more coal than rest of the world.
Running out of accessible supply.Coal mines had to stop at the water table.
mine
coal
water table
1200 1500s 1603 1661 17001712
1776 1880 1900
1911 1920 1950 1967 1970
1306 1890
1973
19691940
1942 19481960
1963
19781976
19871988-92
1982 1996-97 20032002 2004
future2001
1st Newcomen engine (steam engine) was installed at a mine,to pump water out so they could dig deeper.
And, humans crossed the threshold.
control volume
1st Law of Thermodynamics:
Energyin – Energyout = ∆Energycv
chemical potential energy of coalelectrical energy
zero(on average)
& heat33% 67%
How do we analyze?
workin
boiler
turbine
pump
fuel
air
workout
heatout
heatin
no heatconstant s
no heatconstant s
no workconstant P
no workconstant P
Tboiler
External Combustion Engine
Closed Cycle Reversible Heat Engine
Most efficient type?
condenser
generator
electricity
Carnot
Steam Engine
Tpond
What is the Carnot efficiency?high
lowcarnot T
T1
%67600273
102731
carnot
%50300273
102731
carnot
For coal-fired power plants, maximum Tboiler = 600 °C
Ambient water (or air), Tpond = 10 °C
For nuclear power plants, maximum Tboiler = 300 °C
We keep reading that steam power plants are closer to 33 % efficient. Why the discrepancy?
Reversible closed cycle involving a two-phase substance cannot realize the Carnot efficiency.
T
s
boiler
turbine
pumpworkin
workout
heatout
heatin
condenser
1
2
3
4
What is this plot describing?
superheatedvaporsaturated
liquid & vapor
compressedliquid
Saturation Dome for Water/Steam
criticalpoint constant
pressurelines
Rankine Cycle
1
2
4
wpump,in
wturb,out
qcond,out
qboiler,in3
T
s
boiler
turbine
pumpworkin
workout
heatout
heatin
condenser
1
2
3
4
How do we improve efficiency?
1
2
4
3
Increase area of shape 1234
4’1’
2’
lower condenserpressure
Problems:Pmin
T
s
boiler
turbine
pumpworkin
workout
heatout
heatin
condenser
1
2
3
4
How do we improve efficiency?
1
2
4
3
Increase area of shape 1234
superheat steam tohigher T
4’
3’
Problems:Tmax
Qin limits
T
s
boiler
turbine
pumpworkin
workout
heatout
heatin
condenser
1
2
3
4
How do we improve efficiency?
1
2
4
3
Increase area of shape 1234
increase boiler
pressure
4’
2’
3’
Can we fix this?
Add Reheat
T
s
boiler
turbine
pumpworkin
workout
heatout
heatin
condenser
1
2
3
4
How do we improve efficiency?
1
2
5
Increase area of shape 1234
Preheat feedwater
7
3
4
Regeneration
6
boiler
turbine
pump
fuel
air
workin
workout
heatout
heatin
Tboiler
Tpond
generator
condenser
electricity
in
netcycle q
w
generatorturbinecycleboilercombustionpowerplant
+ air products + heatcoal
heating value of coal = 24 – 35 MJ/kg
CH0.67O0.043N0.010S0.003
(O2 + N2) CO2 + H2O + NO + SO2 + N2
+ air products + heatcoal
CO2 + 0.33 H2O + 0.010 NO + 0.003 SO2 + N2
+
Moles of O2 per mole of C = ½ (2 + 0.33 + 0.010 + 0.006 – 0.043) = 1.1515
1.152
4.261
CH0.67O0.043N0.010S0.003 (O2 + 3.7 N2)
Greenhouse gas
No worries
No worriesToxic & ozone friend
Toxic & PM friend
Toxic
More
Toxic
incompletecombustion
(1-x) CO2 + x CO + 0.33 H2O + (0.010+y) NO + 0.003 SO2 + (4.261-y) N2 + PM
completecombustion
+ mercury
Total = 3500 deaths/year (1200-6200 – 95% confidence)
If we were to use the numbers from that study, along with western air pollution values …
(310)
(1560)
(110)
(450)(860)
(100)
(200)
(50)
You tell me – how efficient can you make a heat exchanger?
How do you get this efficiency?
Heat Heat
You tell me – how efficient can you make a turbine?