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– Theoretical Minimum Energy Use– Whole-system, Whole-time Frame Analysis

Integrated Systems + Principles Approach

Integrated systems + principles approach (ISPA) = Systems approach + Principles of energy efficiency

ISPA is both effective and thorough.

Electrical Lighting Motors Fluid Flow Comp Air Steam Proc Heat Proc Cool HVAC CHPInside OutControl EfficiencyCounter-flowAvoid MixingMatch Source Energy to End UseTheoretical Minimum Energy UseWhole-system, Whole-time Frame Analysis

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 First 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

Inside-Out: Example

Aluminum die-cast machines Use 100 psig air to force aluminum to mold Need 40 psig air Purchase low-pressure blower and avoid

compressor upgrade Estimated savings = $11,000 /yr Estimated implementation cost = -$47,000

Inside-Out SummaryOutside-In

Small savings at high first costs

Focuses on support equip

Fosters extraneous and periodic efficiency efforts

Inside-Out Big savings at low first

costs Focuses on core

products and processes Internalizes and sustains

efficiency efforts

2. Understand Control Efficiency

Systems designed 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

3. Think Counter-flow

Q

T

T

x

x

Q

Parallel Flow

Counter Flow

Counter-flow Stack Furnace Pre-heats Charge

Reverb Furnace Efficiency = 25% Stack Furnace Efficiency = 44% (Eppich and Nuranjo, 2007)

Counter-Flow Heat Treat

Extending hood saves $40,000 /yr

BurnersStack

Current Design

Recommended Design

Counter-Flow Heat Recovery

Vinegar Pasteurization and Cooling

Cool vinegar in steam in

steam outPasteurizedvinegar out

Heat exchanger Atransfers heat from hotvinegar to coolincoming vinegar.

Heat exchanger Ctransfers remainingheat from hot vinegarto city water.

Citywater

in

Citywaterout

Heat exchangerB transfers heatfrom steam toincomingvinegar.

135deg. F

70 deg.F

Counter-Flow Heat Recovery

Counter-flow heat exchanger saves $17,000 /yr

Cool vinegar in steam in

steam outPasteurizedvinegar out

Heat exchanger Atransfers heat from hotvinegar to coolincoming vinegar.

Heat exchanger Ctransfers remainingheat from hot vinegarto city water.

Citywater

in

Citywaterout

Heat exchangerB transfers heatfrom steam toincomingvinegar.

135deg. F

70 deg.F

Counter-flow Glass Heating

Counter flow 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

Counter-flow Tile Kiln

TileExit

TileEntrance

Counter-flow tile kiln saves 33%

Counter-Flow Cooling

Counter flow enables 50 F to 70 F water saves 10x

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 tank into hot and

cold sides

5. Match Source to End Use

0

50

100

150

200

250

300

Compressed air Open loopcooling

Chillers Cooling towers

$/m

mBt

u co

olin

g

Pumping

Air Pumps Use 7x More Electricity

Lighting

Eyes See Best in Sunlight

6. Theoretical Minimum Energy Use

Always ask “how much energy is really required ?”

Not much.

2.5% of primary energy used to provide energy services Ayers (1989)

TME of Industrial Processes

Choate and Green (2003), Fruehan, et al. (2000), and Worrell, et al. (2000)

Parts on UV Curing Oven

Slowed belt, shut of excess lamps, saved 50%

7. 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 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 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.”

Whole System Accounting:“Don’t Separate Capital and Operational Budgets”

Separate capital and operational budgets

Organizational sub-systems constrain optimums

Enlarge budgeting to consider entire company

Whole Time Frame Accounting:“Don’t Eat Your Seed Corn”

SP = 2 years (10 year life) is ROI = 49%

SP = 5 years (10 year life) is ROI = 15%

SP = 10 years (20 year life) is ROI = 8%