F&ES 86025
Energy Systems Analysis
86025_1
Introduction to Energy Systems
86025 Energy Systems Analysis
Arnulf Grubler
Energy Systems
Interaction between:
-- Society
-- Economy
-- Technology
-- Policy
that shape both
-- Demand
-- Supply
in terms of quantity, quality, costs, impacts.
86025 Energy Systems Analysis
Arnulf Grubler
Definitions & IS Units
• Energy: Capacity to do work
• Power: Rate of energy transfer
• Newton (N): 1 kg m/s (force)
• Joule (J): 1 N applied over 1 m (energy)
• Watt (W): 1 J/second (power)
• Example: 1 HP = 745 W (745 J/s)
for 1 hr = 0.745 kWh
Energy = Power x Time
Hence importance of load factors and load curves!
86025 Energy Systems Analysis
Arnulf Grubler
Examples of Power and Energy (both kill!)
Mercedes SLK 350
Power:
200,000 W (200 kW, 3.5L 6-cycl)
= 200,000 W/s
= 0.2 MJ/s
Lightning bolt
Power:
10,000,000 kW
(1 109 Volt x 1 104 Ampere)
for 1 second = 10,000 MJ/s
Energy:
max: 720 MJ/hr
0.2 MJ/s (x 3600 s/hr)
actual:
Fuel use: 10 l/100km
= 10 x 32 MJ/l
= 320 MJ/hr
(assuming 100 km/hr)
Energy:
max. equiv.: 2.8 MJ/hr
Fazit: Even if storable/useable
a lightning bolt’s energy
could fuel a SLK for
less than 1 km!
Power Examples
Human heart
~1 W
Light bulb
100 W
Horse
1000 W = 1 kW (kilo Watt)
Car
100,000 W = 100 kW
Yale PPL
20,000,000 W = 20 MW (Mega Watt)
Boeing 747
at max thrust
250,000,000 W 250 MW =
.25 GW
Niagara Falls
2,000,000,000 W 2 GW (Giga Watt)
All US PPL
885,000,000,000 W 885 GW
All World PPL
3,500,000,000,000 W 3500 GW
All US Automobiles
230 million with 23,000 GW
~ 100 kW each
Source: updated and modified after Tester et al., 2005.
Energy Units and Scales
(Source: IPCC Energy Primer)
zettajoule (ZJ)
Quick recap: exponentials to common basis are additive!
103 x 106 = 10(3+6) = 109 or 1000 MJ = 1 GJ
86025 Energy Systems Analysis
Arnulf Grubler
Energy Orders of Magnitude
(EJ = 1018 J)
5,500,000 EJ Annual solar influx
1,000,000 EJ Fossil occurrences
50,000 EJ Fossil reserves
440 EJ World energy use 2000
100 EJ USA primary energy supply
50 EJ OECD transport energy use
20 EJ Saudi Arabia oil prod.
4 EJ Italy oil reserves
1 EJ NY city or Singapore
energy use
Stocks; flows (yr-1)
86025 Energy Systems Analysis
Arnulf Grubler
Rough Equivalences
10 Gtoe
1 Gtoe
1 Quad
1 Mtoe
1 toe
1 boe
1 m3 gas
1 kWh
1 Btu
= 420 EJ
= 42 EJ
= 1 EJ
= 42 PJ
= 42 GJ
= 6 GJ
= 40 MJ
= 4 MJ
= 1 kJ
86025 Energy Systems Analysis
Arnulf Grubler
Converting Units
conv_fac.xls
v2 class server
“Resources/data”
86025 Energy Systems Analysis
Arnulf Grubler
Energy Flow Characteristics
• Physical: chemical, kinetic, electric,
radiant,…
• Processing depth:
primary→secondary→final
• Transaction levels:
producer→producer
producer→consumer
consumer→consumer (future?)
• System boundaries:
secondary→final→useful→service
86025 Energy Systems Analysis
Arnulf Grubler
Energy Conversions & Efficiencies
conversion
1st Law efficiency
Electric generator
m→e
~99%
Gas furnace
c→t
90-95%
Small electric drive
e→m
60-65%
Steam turbine
t→m
40-45%
Best PV cells
r→e
20-30%
Trad. Cook stove
c→t
10-15%
Beef production
c→c
5-10%
Fluorescent light
e→r
~10%
Incandescent light
e→r
2-5%
Paraffin candle
c→r
1-2%
Global
photosynthesis
r→c
0.3%
Adapted from Smil, 1998.
c = chemical, e = electrical, m = mechanical, r = radiant, t = thermal
Efficiency depends on form adequacy, technology, scale,…!!
Conversions are far from trivial:
Example of combustion (c → t)
• Fuel + oxidizer = Products ± energy
• In ideal conditions: energy is the net sum of
creation/destruction of chemical bonds
-- exothermic: producing energy
(e.g. CH4 as fuel)
-- endothermic: needing energy
(e.g. CH4 as chemical feedstock)
• But combustion is generally far away from ideal
leading to accounting complexities (HHV, LHV)
and most important of all: emissions beyond
ideal combustion conditions
86025 Energy Systems Analysis
Arnulf Grubler
Example of Methane
(ideal combustion)
• CH4 + O2 → CO2 + H2O (general reaction EQ)
• Balancing for C, H, and O:
1 C + 1 O2 → 1 CO2
4 H + 1 O 2 → 2 H2O
no oxygen in this fuel (but e.g. in wood!)
• Therefore:
CH4 + 2O2 → CO2 + 2H2O
• Net energy:
- 2628 kJ from bonds broken
+3438 kJ from bonds created
+ 810 kJ net energy
86025 Energy Systems Analysis
Arnulf Grubler
Moving beyond ideal combustion:
Example of CH4 Cont’d
• Ideal combustion:
810 kJ/mole = Lower Heating Value
• Incl. energy from condensation of water vapor:
890 kJ/mole = Higher Heating Value
• Emissions:
CO2 only in ideal case
1 mole* CO2 = 12gC = (12+[2x16]) = 44 gCO2
• Emission factors:
12gC/890 kJ = 0.0135 gC/kJ = 13.5 gC/MJ HHV
12gC/810 kJ = 0.0150 gC/kJ = 15.0 kgC/GJ LHV
Σ : Fuel-specific energy conversion and emission factors
that don’t specify basis (LHV or HHV) are useless!!
*mole: mass in g equals molecular weight
a mole contains 6.023 1023 molecules (Avogadro’s number)
The Real World
• Emissions under real conditions:
-- combustion in air and not pure oxygen
→N emissions (air: 21% O, 78% N, 1% other)
-- fuel impurities (S, N, ash, heavy metals..)
-- incomplete combustion (e.g. hydrocarbons,
CO, soot, etc…)
• Important tradeoffs:
higher efficiency → higher combustion
temperature (cf. second law of
thermodynamics) → higher N emissions
• Scale dependency (emissions, and control
possibilities): preference for large, centralized
combustion
86025 Energy Systems Analysis
Arnulf Grubler
Characteristics of Some Fuels
Source: D. Castorph et al., 1999, GRI, 2005.
C
%
H
%
S
%
O
%
N
%
Ash
%
H 2O
%
LHV
kJ/g
HHV
kJ/g
HHV/
LHV
Wood
50
6
0
44
0
<.5
1020
14.616.8
15.918.0
1.071.09
Coal
88
5
1
4.5
1.5
3-12
0-10
27.324.1
29.335.2
1.051.07
Diesel
86
13
.3
-
-
-
-
43.0
45.9
1.07
Natural
Gas*
CH4
7498
CH
s
020
H 2S
0-5
CO2,
O2
N2
0-5
-
-
(hard coal)
(Range)
H 2*
100
38-48
0-8
-
-
120
42-56 1.101.17
142
1.18
* Note difference to LHV on volume basis: gas: 40 MJ/m3 H2: 10.8 MJ/m3
More info:
v2 class server:
Resources/data/doe_fueltable.pdf (useful
even if non-metric)
NREL (liquids):
http://www.nrel.gov/vehiclesandfuels/apbf/p
rogs/search1.cgi
Engineering Toolbox (tons of info), e.g.:
http://www.engineeringtoolbox.com/combus
tion-boiler-fuels-t_9.html
86025 Energy Systems Analysis
Arnulf Grubler
Non-physical Definition of Energy
• System boundaries, processing depth,
upstream/downstream:
primary→secondary→final →
→useful→service
• Transaction levels/actors involved:
producer→producer
producer→consumer
consumer→consumer (future?)
86025 Energy Systems Analysis
Arnulf Grubler
What means….
• Primary energy: Resources as extracted from
nature (crude oil, solar heat)
• Secondary energy: Processed/converted
energy (gasoline from crude oil, electricity
from coal or hydropower)
• Final energy (as delivered to consumer)
• Useful energy (converted by final appliances
(heat from radiator, light from bulb)
• Services = actual demand: comfort,
illumination, mobility,… (units ephemeral!)
86025 Energy Systems Analysis
Arnulf Grubler
System Boundaries
• Energy sector: Primary→ Final
(domain of supply bias)
• Energy end-use: Final→Useful
(domain of consumer bias)
• Energy Integration (IRM, LC):
Primary→Useful/Services
• Full Integration (IA): Whole environment
(incl. “externalities”)
86025 Energy Systems Analysis
Arnulf Grubler
Global Energy Flows (EJ in 1990)
Source: modified after Nakicenovic/Gilli/Kurz, 1996. Update: IEA, 2006.
In 2005:
(#’s rounded)
TPC: 380.8
Coal
91.1
ALS*
8.0
International
bunkers
5.0
14.3
ALS*
1.3
ALS*
4.7
TFC: 270.0
14.1 0.1 1.2
Useful energy:
137.5
59.1
0.8 0.3 0.8
1.6
25.5
21.6
15.4
Useful:
160 EJ
20.5 20.4 18.82.0
17.8 9.8 17.7
21.8
41.9
108.9
84.9
Loss
29.9
18.3
Transportation
50.3
Conversion loss
74.7
Central electricity & heat generation51.5
20.1 2.6
Loss
42.6
Feedstocks
Renewables**
TPC: 380.8
46.6
Oil:133.2
Coal: 91.1
ALS*
Gas: 70.5
0.1
Renewables:20.5
Hydro: 18.8
Nuclear: 46.6
7.6
Transmission
loss
60.9
losses:
- 160 EJ
Nuclearpower
18.8
ALS*
9.3
losses:
-180 EJ
Final:
320 EJ
Hydropower
20.5
Natural gas
70.6
** Includes traditional fuels
Primary:
500 EJ
Crude oil
133.2
55.0
Industry
Loss
60.0
48.9
Conversion
losses
ALS: 110.8
TFC: 270.0
Oil:106.0
Renewables:44.5
Gas: 40.8
Coal: 36.1
Electricity:34.8
Heat: 7.8
Residential & commercial
*ALS = Autoconsumption, losses, stock changes
2005: Total losses: 340 EJ for 160 EJ useful energy delivered
86025 Energy Systems Analysis
Arnulf Grubler