Transcript Life Cycle Assessment - University of Dayton

Energy in Context
Overview
• Magnitude of Energy Use
- Implications to human living
- Implications to global climate change
• Technological Cycles
– Impact of human practices on energy use
Magnitude of Energy Use
Energy Required to raise 100 kg a
distance of 1 m.
~1000 Joules
Energy required for 60 Watt light
bulb operating 1 hours
~216,000 Joules
Energy required to heat 5 kg pan of
water to boiling temperature
~1,670,000 Joules
Energy required to process 1 kg
wood products
~2,000,000 Joules
Energy required to process 1 kg of
plastic products
~100,000,000
Energy required to mine/smelt 1 kg
aluminum
~220,000,000 Joules
Energy required to drive an SUV 25 ~200,000,000 Joules
miles
Implications for how we live?
Connection to ‘Global Climate
Change’
(gCO2 per 3,600,000 Joules)
Energy Source
Coal
Oil
Gas
Hydro
Nuclear
Solar
PV
Current technology
972
684
684
18
21.6
126
Next generation
technology
288
504
504
18
10.8
28.8
Energy Efficiency of Industrialized
Economy
• Est. 1-3%
• Why so low?
Product Life Cycle
Consider life cycle energy impact of a 1 kg of aluminum being
used in an aluminum wheel of a Ford Excursion over a 150,000
mile life.
Case A – No Recycling
coal
nat. gas
nat. gas
Oildiesel
Smelting
process
Casting
process
product
aluminum ore
materials stage
manuf. stage
use stage
landfill
Life Cycle
Stage
Total Energy Input
from Fuel (typical)
Energy efficiency
(typical), %,
Minumum energy
required if 100%
efficient
Mining
10 MJ/kg
30
3.33 MJ/kg
Materials
Processing
220 MJ/kg
60
132 MJ/kg
Manufacturing
- Casting
20 MJ/kg
60
12 MJ/kg
375 MJ/kg-al
15
56.75 MJ/kg
625 MJ/kg
32.6
204
Use[1]
Total
[1] Ford Excursion = 3000 kg, 15 mpg, 150,000 miles/life…Useful energy from I.C. engine overcomes rolling resistance, inertia, drag.
75% of this is dependent upon weight. Therefore the mass consumed in the burning of gasoline over life due to the 1 kg mass on the
vehicle is:
(150,000 miles/life)/(15 miles/gallon) x (3 kg-fuel/gallon) / 3000 kg-al x 0.75 = 7.5 kg – fuel/kg-al
Energy consumed = 7.5 kg-fuel/kg-al x ( 50 MJ/kg-fuel) = 375 MJ/kg-al
Material
Aluminum
Recycle
d MJ/kg
Cost[1]
220
20
$1.50/kg
Polyethylene
98
56
$0.80/kg
PVC
65
29
$1.20/kg
Steel
40
18
$0.45/kg
Glass
30
13
$0.20/kg
Nylon
120.2
32.1
$2.50/kg
200
10
$5.00/kg
Copper
[1] Source: American Metals, amm.com
Virgin MJ/kg
Case B – Recycling r% of the aluminum
coal
Eprocessing
nat. gas
nat. gas, Eng
Oildiesel
Smelting
process
Casting
process
product
aluminum ore
materials stage
use stage
manuf. stage
separate
r
1-r
landfill
Same energy use as in Case A except that
the mining energy and material
processing energy are reduced by:
r(Emining + Ematerials)
where r is the fraction of recycled
aluminum going into the making of a new
wheel
Life
Stage
Total Energy Input
from Fuel (typical)
MJ/kg-al
Energy efficiency
(typical), %,
Minumum energy
required if 100%
efficient MJ/kg-al
Mining
(1-r) 10
30
(1-r) 3.33
Materials
Processing
(1-r) 220
60
(1-r) 132
Manufacturing
20
60
12
Use[1]
375
15
56.75
395+(1-r)230
….
68.75 +(1-r)135.33
Total
Cycle
[1] Ford Excursion = 3000 kg, 15 mpg, 150,000 miles/life…Useful exergy from I.C. engine overcomes rolling resistance, inertia, drag.
75% of this is dependent upon weight. Therefore the mass consumed in the burning of gasoline over life due to the 1 kg mass on the
vehicle is:
(150,000 miles/life)/(15 miles/gallon) x (3 kg/gallon) x 0.75 / 3000 = 7.5 kg – fuel
Exergy consumed = 7.5 kg-fuel x ( 50 MJ/kg-fuel) = 375 MJ/kg-al
Comparison
600
400
200
0
0
0.5
recycle fraction
1
overall efficiency (% )
NRG/kg-al
800
40
30
20
10
0
0
0.5
recycle fraction
1
Cost Comparision
If 100% recycle and given a cost of
$0.10 / (3.6 MJ), a 230 MJ reduction in energy yields
a
$6.30 savings per kg
Note: This is 4 times more expensive than it would
seem because aluminum companies have been
given cheap access to hydroelectric energy!!!!!
Energy Generation Efficiency
Process
Efficiency
CoalElectricity
 transmission
20%
Natural gas 
electricity 
transmission
25%
Fuel Cell
40% (70-80%) if
heat used
Solar PV
20% typical
Wind
30%