Integrated Systems + Principles Approach

Source: California Energy Commission (2000)

Manufacturing Energy End-Use Breakdown

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

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

Electrical Lighting Motors Fluid FlowCompress

Air SteamProcess Heating

Process Cooling HVAC CHP

Lean Energy Analysis BaselineInside Out AnalysisMinimum Theoretical EnergyConversion and Control EfficiencyMatch Source Energy to End UseMaximize Counter-flowAvoid MixingWhole-system, Whole-time Frame Analysis

ISPA is both effective and thorough.

1. Inside-out Approach

Conversion Distribution UseEnergySupply

Energy Use

Inside-Out Analysis Approach

Inside-out Approach

Conversion Distribution Use

EnergySupplySavings

Energy End–Use Savings

Inside-Out Analysis Approach

Inside-out: Amplifies Savings

Reduce pipe friction: Savings = 1.00 kWhPump 70% eff: Savings = 1.43 kWhDrive 95% eff: Savings = 1.50 kWhMotor 90% eff: Savings = 1.67 kWhT&D 91% eff: Savings = 1.83 kWhPowerplant 33% eff: Savings = 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

Ein PrimaryEnergy

Conv ers ion Equipment

EnergyDis tribution

Sy s tem

Manufac turing

Plant Boundary

Proc es s andEquipment

E E Was teTreatment

Sy s tem

Was teDis pos alW W Wout

Inside-out analysis sequence for reducing energy

Inside-out analysis sequence for reducing waste streams

Traditional Analysis Sequence

for Reducing Energy Use

Traditional Analysis Sequence for

Reducing Waste

Result: Incremental improvement at high cost

Think from Inside Out!

Ein PrimaryEnergy

Conv ers ion Equipment

EnergyDis tribution

Sy s tem

Manufac turing

Plant Boundary

Proc es s andEquipment

E E Was teTreatment

Sy s tem

Was teDis pos alW W Wout

Inside-out analysis sequence for reducing energy

Inside-out analysis sequence for reducing waste streams

Inside-Out Analysis Sequence for

Reducing Energy Use

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 part-

load (control) efficiency

Control Efficiency

Energy

Production

Poor

Excellent

Air Compressor Control

FP = FP0 + FC (1 – FP0)

0.00

0.25

0.50

0.75

1.00

0.00 0.25 0.50 0.75 1.00

Fraction Capacity (FC)

Frac

tion

Pow

er (F

P)

Blow Off

Modulation

Load/Unload

Variable Speed

On/Off

Power and Flow Control

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%0%

20%

40%

60%

80%

100%

By-pass Outlet Damper

Variable Inlet Vane Variable Frequency Drive

Volume Flow Rate (%)

Pow

er (%

)

Chiller Control

Boiler Control

Data Scatter Indicates Poor Control

2001 Gas Usage vs. Lime Production

0

5,000

10,000

15,000

20,000

25,000

30,000

0 500 1,000 1,500 2,000 2,500 3,000

Lime Production (tons)

Gas

Con

sum

ptio

n (m

cf)

3. Think Counter Flow

Heat transfer Fluid flow

Counter-flow Improves Heat Exchange

Q

T

T

x

x

Q

Parallel Flow

Counter Flow

Stack Furnace Pre-heats Charge

Reverb Furnace Stack Furnace

Molten Glass Transport:Each Exhaust Port Is A Zone

Counter-flow Within Zones

Increases convection heat transfer by 83%

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

Tile Kiln (Counter flow?)

TileExit 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

Separate hot and cold water tanks

ProcessLoad 1

ProcessLoad 2

Chilled Water Tank

Cooling Tower

BypassValve

Tp2

Tc2 Process Pump

Tp1

Cooling Tower Pump

Tc1

5. Match Source Energy to End Use

0

50

100

150

200

250

300

Compressed air Open loopcooling

Chillers Cooling towers

$/m

mBt

u co

olin

g

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

Whole System “Lean” Manufacturing

400 ft/min 200 ft/min

200 ft/min

Whole System Energy EngineeringOptimum 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%