Week 8: Optimization and Efficiency

Themes

We can strive for efficient processes or for overall efficiency (considering all components, energy, etc.)

Investment strategies for systems with multiple sub-processes needs to focus on the slowest rates.

Optimization for multiple criteria can be challenging.

Efficiency is related to the processes, it's not the goal for society.

 

Schedule for this lecture

1. Two types of efficiency
2. Process efficiency
3. Overall efficiency - requires LCA
4. Examples of seeking efficiency - houses
5. The problem of multiple objectives
   1. conversion factors
   2. graphing optimal outcomes
   3. example
6. Optimal management - efficiency isn't the goal

 

Know-ledge	Control	Values Match	Approach (Chapter)
L	L	L	Scenarios (18)
L	L	H
L	H	L	Environ-Entrepreneur (20)
L	H	H	Sci. Adapt. Manage. (19)
H	L	L	Multi-Criteria (17)
H	L	H	Hedging/Diversification (17)
H	H	L	CPR institutions (16)
H	H	H	Optimal Proj. Man. (17)

 

1. Efficiency

Two definitions:

all of these are same units - efficiency is dimensionless or maybe 1/time

process efficiency

output / input

examples:

 

overall efficiency that includes machinery

output / (input materials and energy + machinery + other costs)

examples:

 

 

2. Simple process Efficiency

input

output

waste

3. Overall efficiency

process A

process B

formation requires 2 As for each B

overall efficiency = (rate of product formation) / (machinery A + machinery B)

example

process A = 10 * 0.5 = 5

process B = 10 * 0.5 = 5

formation of product 5 of A + 2.5 of B

total efficiency is 2.5 / 20 = 0.125

increase efficiency by

machinery A up to 20 --> efficiency goes to 5/30 = 0.167

or decrease B down to 5 --> 2.5 / 15 = 0.167

 

 

4. Examples

houses.html

Houses
2 construction methods in Japan

5. Multiple objectives

Using conversion factors:

Some we might agree on

• 1 gallon of gas = $4 = 6.3 lbs of liquid = 20 lbs of CO2 = 33.41 kWh
• 2.08 lbs CO2 per kWh for coal
• 1.22 lbs CO2 per kWh for natural gas

 

Some we might have to think about all the assumptions

• salmon per forgone revenue
• CO2 avoided if we stopped buring wood inefficiently

 

Some are pure speculation -

 

 

 

 

tradeoffs

• red - linear tradeoff
• blue - interference
• green - synergism

possible land uses

• Agriculture
• Managed forestry
• UGB
• Rural residential
• Conserved wild areas

possible outcomes

• upper left
• lower right
• point I -- below the surface

6. Efficiency and optimizations are ways to solve problems

not the goal of society

you often hear - "if all other factors are the same" we should do things efficiently

need to study those other factors using multiple perspectives

 

Example of waste - it's not all the same

waste in the production and use of lumber

• trees that fall to the forest floor
• sawdust on the mill floor
• defective wood product that has already shipped to the consumer

Streamlined and highly efficient process

maybe overly sensitive to variability

may not be resilient to shocks - good or bad

As with other environmental problems

knowledge, control, values

 

7. Conclusions

During finals week - i.e. week 11
"Extra credit" assigment
create an example that links to course learning objectives and has a graphic, reading assignment, video or simulation

tell me which lecture it should be used in and what it might replace

tell me which assignment you want this score to replace (already get 2 throw outs)