Integrated Systems + Principles Approach
Manufacturing Energy End-Use Breakdown
Source: California Energy Commission (2000)
Energy Systems
–
–
–
–
–
–
–
–
–
Lighting
Motor drive
Fluid flow
Compressed air
Steam and hot water
Process heating
Process cooling
Heating, ventilating and air conditioning
Cogeneration
Principles of Energy Efficiency
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Inside Out Analysis
Understand Control Efficiency
Think Counter-flow
Avoid Mixing
Match Source Energy to End Use
Whole-system, Whole-time Frame Analysis
Integrated Systems + Principles Approach
 Integrated systems + principles approach (ISPA) =
Systems approach + Principles of energy efficiency
Compress
Process Process
Electrical Lighting Motors Fluid Flow Air Steam Heating Cooling
Lean Energy Analysis Baseline
Inside Out Analysis
Minimum Theoretical Energy
Conversion and Control Efficiency
Match Source Energy to End Use
Maximize Counter-flow
Avoid Mixing
Whole-system, Whole-time Frame Analysis
 ISPA is both effective and thorough.
HVAC
CHP
1. Inside-out Approach
Energy
Supply
Conversion
Distribution
Inside-Out Analysis Approach
Use
Energy
Use
Inside-out Approach
Energy
Supply
Savings
Conversion
Distribution
Inside-Out Analysis Approach
Use
Energy
End–Use
Savings
Inside-out: Amplifies Savings
Reduce pipe friction: Savings =
Pump 70% eff: Savings =
Drive 95% eff: Savings =
Motor 90% eff: Savings =
T&D 91% eff: Savings =
Powerplant 33% eff: Savings =
1.00 kWh
1.43 kWh
1.50 kWh
1.67 kWh
1.83 kWh
5.55 kWh
Inside-out: Reduces Costs
 Original design: 95 hp in 14 pumps
 Re-design:
– Bigger pipes: Dp = c / d5
• (doubling d reduces Dp by 97%)
– Layout pipes then equipment
• shorter runs, fewer turns, valves, etc…
– 7 hp in 2 pumps
Avoid Outside-in Thinking
Plant Boundary
Ein
Primary
Energy
Conversion
Equipment
E
Energy
Distribution
System
E
Inside-out analysis sequence
for reducing energy
Traditional Analysis
Sequence for
Reducing Energy Use
Manufacturing
Process and
Equipment
W
Waste
Treatment
System
W
Waste
Disposal
Wout
Inside-out analysis sequence
for reducing waste streams
Traditional Analysis
Sequence for Reducing
Waste
Result: Incremental improvement at high cost
Think from Inside Out!
Plant Boundary
Ein
Primary
Energy
Conversion
Equipment
E
Energy
Distribution
System
E
Inside-out analysis sequence
for reducing energy
Inside-Out Analysis
Sequence for
Reducing Energy Use
Manufacturing
Process and
Equipment
W
Waste
Treatment
System
W
Waste
Disposal
Wout
Inside-out analysis sequence
for reducing waste streams
Inside-Out Analysis
Sequence for Reducing
Waste
Result: Significant improvement at minimal cost
2. Understand Control Efficiency
 Systems design for peak load, but operate at
part-load
 System efficiency generally changes at part load
 Recognize and modify systems with poor partload (control) efficiency
Control Efficiency
Poor
Energy
Excellent
Production
Air Compressor Control
1.00
Fraction Power (FP)
0.75
Blow Off
Modulation
0.50
Load/Unload
Variable Speed
On/Off
0.25
0.00
0.00
0.25
0.50
Fraction Capacity (FC)
FP = FP0 + FC (1 – FP0)
0.75
1.00
Power and Flow Control
100%
Power (%)
80%
60%
40%
20%
0%
0%
20%
40%
60%
80%
Volume Flow Rate (%)
By-pass
Outlet Damper
Variable Inlet Vane
Variable Frequency Drive
100%
Chiller Control
Boiler Control
Data Scatter Indicates Poor Control
2001 Gas Usage vs. Lime Production
Gas Consumption (mcf)
30,000
25,000
20,000
15,000
10,000
5,000
0
0
500
1,000
1,500
2,000
Lime Production (tons)
2,500
3,000
3. Think Counter Flow
 Heat transfer
 Fluid flow
Counter-flow Improves Heat Exchange
T
Q
Parallel Flow
T
x
Q
Counter Flow
x
Stack Furnace Pre-heats Charge
Reverb Furnace
Stack Furnace
Molten Glass Transport:
Each Exhaust Port Is A Zone
Counter-flow Within Zones
Contact length = 2 x (5 + 4 + 3 + 2 + 1) = 30 feet
Contact length = (10 + 9 + 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1) = 55 feet
Increases convection heat transfer by 83%
Tile Kiln (Counter flow?)
Tile
Exit
Tile
Entrance
Counter Flow Cooling Enables Cooling Tower
Cross-flow cooling of extruded plastic uses 50 F water from chiller
4. Avoid Mixing
 Availability analysis…
Useful work destroyed with mixing
 Examples
– CAV/VAV air handlers
– Separate hot and cold wells
– Material reuse/recycling
HVAC Applications
Cooling Energy Use
Heating Energy Use
Cooling Applications
Cooling Tower
Process
Load 1
Process
Load 2
Tp2
Chilled Water Tank
Tc1
Cooling Tower Pump
Tp1
Tc2
Process Pump
Separate hot and cold water tanks
Bypass
Valve
5. Match Source Energy to End Use
300
$/mmBtu cooling
250
200
150
100
50
0
Compressed air
Open loop
cooling
Chillers
Cooling towers
Match Source Energy to End Use
Utilize Current Daylighting
Wright Brothers Factory, Dayton Ohio
Replace Colored / Fiberglass Windows
with Corrugated Polycarbonate
Employ Skylighting
Skylights:
– Highest quality light
– Reduce lighting energy costs
– Increase heating/cooling costs
6. Whole System Whole Time Frame Design
Design heuristic derived from natural evolution
Nothing evolves in a vacuum, only as part of a system
No optimum tree, fan, …
Evolutionary perspective: ‘optimum’ synonymous with
‘perfectly integrated’
 Optimize whole system, not components
 Design for whole time frame, next generation
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Whole System “Lean” Manufacturing
400 ft/min
200 ft/min
200 ft/min
Whole System Energy Engineering
Optimum Pipe Diameter
 Dopt = 200 mm when Tot Cost = NPV(Energy)+Pipe
 Dopt = 250 mm when Cost= NPV(Energy)+Pipe+Pump
 Energy250 = Energy200 / 2
Whole System Accounting
 Budgeting and capital processes separate from
operational processes
 Organizational structures within companies
constrains optimum thinking
 Enlarge system boundary to include entire
company
Whole-Time Frame Accounting
“Efficiency Gap”
 “Numerous studies conclude 20% to 40% energy
savings could be implemented cost effectively, but
aren’t…..”
 Discrepancy between economic and actual savings
potential called “efficiency gap”.
 Puzzled economists for decades: “I can’t believe
they leave that much change lying on the table.”
Don’t Eat Your Seed Corn
 SP = 2 years
is
ROR = 50%
 SP = 10 years
is
ROR = 10%