Ohio Energy. Workshop G. Best Practices in Energy Efficiency to Help You Reduce Your Energy Spend. Tuesday, February 21, :45 a.m.

Transcription

1 Ohio Energy Workshop G Best Practices in Energy Efficiency to Help You Reduce Your Energy Spend Tuesday, February 21, :45 a.m. to Noon

2 Principles of Energy Efficiency Ohio Energy Management Conference February 21, 2017 Kelly Kissock Chair: Department of Mechanical and Aerospace Engineering / Renewable and Clean Energy kkissock@udayton.edu

3 Industrial Assessment Center Program Sponsored by U.S. Department of Energy (DOE) Began during 1970 s energy crisis 28 centers at universities throughout the U.S. 20 no-cost assessments per year for mid-sized manufacturers Goals Help industry be more resource-efficient and costcompetitive Train new energy engineers Advance practice and science of energy efficiency

4 University of Dayton Industrial Assessment Center Conducted 970+ assessments since 1981 Savings opportunities: 12 Simple payback: 2 years Identified savings: 12% Implemented savings: 6%

5 Qualifying for a Free Industrial Assessment To qualify you must Be a manufacturer with SIC code Have total annual energy costs between $100,000 - $2.5 million

6 Ohio Lean Buildings Program Sponsored by Ohio Development Services Agency 2016: 4 universities and 5 consulting partners Goals Make Ohio s buildings more energy-efficient and costcompetitive Train new energy engineers Advance practice and science of energy efficiency

7 Ohio Lean Buildings Program ASHRAE Level 2 assessments 5,682,695 ft 2 Average Savings Cost: 27% Normalized: $0.45 /ft 2 -yr ROI: 29%

8 Qualifying for a Free Building Assessment To qualify for a free building energy assessment, you must Be an Ohio building > 10,000 ft 2

9 Manufacturing: 12 Energy Systems

10 Buildings: 10 Energy Systems Electrical Lighting Zone temperature Outdoor air Fan system Pumping system Chillers Cooling towers Boilers Air heating and cooling

11 Four Principles Energy Efficiency

12 Systems + Principles Approach: Manufacturing Electrical Lighting Motors Fluid Flow Comp Air Steam Process Heat Process Cool HVAC 1) Think Inside Out 2) Maximize Control Efficiency 3) Maximize Energy Effectiveness 4) Analyze Wholesystems Over Whole-time Frames SPA: Effective, Reproducible, Teachable

13 Systems + Principles Approach: Buildings Zone Temp Outdoor Air Fan System Pumping System Chillers Cooling Towers Boilers 1) Think Inside Out 2) Maximize Control Efficiency 3) Maximize Energy Effectiveness 4) Analyze Whole-systems Over Whole-time Frames SPA: Effective, Reproducible, Teachable

14 Energy Efficiency Principle 1: Think Inside Out

15 Traditional Outside-In Approach Plant Boundary Ein Primary Energy Conversion Equipment E Energy Distribution System E Manufacturing Process and Equipment W Waste Waste Treatment Disposal Wout System Inside-out analysis sequence Traditional for reducing Analysis energy Sequence for Reducing Energy Use Inside-out analysis sequence Traditional for reducing waste Analysis streams Sequence for Reducing Waste Result: Incremental improvement at high cost

16 Inside-Out Approach Plant Boundary Ein Primary Energy Conversion Equipment E Energy Distribution System E Manufacturing Process and Equipment W Waste Waste Treatment Disposal Wout System Inside-out analysis sequence for reducing energy Inside-Out Analysis Sequence for Reducing Energy Use Inside-out analysis sequence for reducing waste streams Inside-Out Analysis Sequence for Reducing Waste Result: Significant improvement at minimal cost

17 Inside-Out Approach for Lighting Evaluate End-Use Quality and quantity of light Evaluate Distribution System Reposition blocked lights Improve efficiency of distribution Upgrade Primary Equipment Recommend higher-efficiency lights Recommend daylighting options

18 Inside-Out Approach for Compressed Air Evaluate End-Use Required quantity, pressure and timing of air Identify inappropriate uses Evaluate Distribution System Leaks, excessive pressure drop, storage capacity Upgrade Primary Equipment Generally recommend down-sizing with strategic control

19 Think Inside-Out Energy Supply Conversion Distribution Use Energy Use Inside-Out Analysis Approach Energy supply decreases as move from outside in

20 Think Inside-Out Energy savings increase as move from inside out

21 Think Inside-Out Inside-out Thinking Elements Efficiency Savings (kwh) Reduce pipe friction Pump 70% 1.43 Drive 95% 1.50 Motor 90% 1.67 Transmission and distribution 91% 1.83 Power plant 33% 5.55

22 Outside In Replace 4.2 scfm/hp compressor with 5.0 scfm/hp compressor Save 20% but cost $100,000

23 Reduce Blow-off with Solenoid Valves Flow from open tube (scfm) = 11.6 (scfm/lbf) x [Diameter (in)] 2 x Pressure (psia) Example Install solenoid to shut-off blowoff from 3/8-in pipe at 100 psig 80% of time Flow Savings = 11.6 (scfm/lbf) x [3/8 (in)] 2 x 115 psia x 80% = 150 scfm Cost Savings = 150 scfm / (4.2 scfm/hp x 0.90) x 0.75 kw/hp x (1-0.50) x 6,000 hr/yr x $0.10 /kwh = $8,933 /yr Cost of 3/8-inch solenoid valve = $100 Plant manager taking charge!

24 Reduce Blow off with Air-Saver Nozzles Nozzles maximize entrained air and generate same flow and force with ~50% less compressed air Example Add nozzle to 1/8-in tube at 100 psig Flow Savings = 11.6 (scfm/lbf) x [1/8 (in)] 2 x 115 psia x 50% = 10.4 scfm Cost Savings = 10.4 scfm / (4.2 scfm/hp x 0.90) x 0.75 kw/hp x (1-0.50) x 6,000 hr/yr x $0.10 /kwh = $620 /yr Nozzles cost about $10 each

25 Identify Leaks Using Ultrasonic Sensor

26 Measure Savings By Logging Flow or Power

27 Think Inside-Out During Design Needed new air compressor 60% of air used at 20 psig Buy low-pressure blower New compressor not needed Needed chiller replacement with new refrigerants Lighting retrofit saves 50% on lighting energy VFD retrofit saves 30% on fan energy and New chiller 25% smaller

28 Summary: Outside-In Approach Focuses on support equip and wastes that are not core business Fosters periodic and extraneous view of resource minimization that relies on outside experts Incremental improvement at high costs

29 Summary: Inside-Out Approach Focuses on products and processes Internalizes and sustains efficiency efforts Savings amplified through system Significant savings at low costs

30 Energy Efficiency Principle 2: Maximize Control Efficiency

31 Inefficient Flow Control By-pass Valve By-pass loop (No savings) By-pass damper (No savings) Valve/damper/vanes (Small savings) Intermittent Flow (Small savings)

32 Identifying Flow Control Savings Opportunities Bypass (all the lights on, all the time) Throttling (pedaling bike hard with brakes on) Intermittent pump/fan operation (tortoise and hare)

33 Efficient Flow Control Close By-pass Valve dp VFD Trim impellor for constant-volume pumps Slow fan for constant-volume fans VFD for variable-volume pumps or fans

34 Pump/Fan and System Curves DP Pump/Fan Curve System Curve P 1 Operating Point W f = V DP V 1 V

35 Bypass Flow: Zero Energy Savings DP Pump/Fan Curve System Curve Wf at low flow requirement Wf at peak flow requirement V 2 = V 1 V When bypassing, V through pump is constant Thus, pump work is constant and no savings

36 Throttle/Vane Flow: Small Energy Savings Throttled System Curve DP Design System Curve Wf at low flow requirement Wf at peak flow requirement V 2 = V 1 / 2 V 1 V With throttling and inlet vanes, V decreases but P increases Thus, net decrease in W (area under curves) is small

37 Reduce Pump/Fan Flow: Big Energy Savings DP Pump/Fan Curve Close Bypass Valve dp System Curve VFD Wf at peak flow requirement Wf at low flow requirement V 2 = V 1 / 2 V 1 V Reducing flow generated by pump/fan by 50% reduces work to overcome friction by: Frac Sav = 1- (V 2 /V 1 ) 3 = 1- (1/2) 3 = 88%

38 Maximize Control Efficiency

39 Air Compressor Control Maximize Control Efficiency

40 Savings from Modulation to Load/Unload Control Reduced power 35% and saved $17,000 /yr

41 Chiller Efficiency Varies with Load Constant-speed: efficiency decreases as load decreases Variable-speed: efficiency increases as load decreases

42 Stage Constant-Speed Chillers to Run Fewest Possible Chillers Running 1 chiller at (60% load and 0.30 kw/ton) instead of 2 chillers at (30% load and 0.37 kw/ton) saves 19%.

43 Stage Variable-Speed Chillers to Run Maximum Possible Chillers Running 2 chillers at (40% load and 0.22 kw/ton) instead of 1 chiller at (80% load and 0.27 kw/ton) saves 20%.

44 Energy Efficiency Principle 3: Maximize Energy Effectiveness

45 Energy Analysis E waste E in E useful E useful = E in E waste

46 Energy Analysis The First Law states that energy can be converted, but not created or destroyed But is first law consistent with our intuition? Isn t something irretrievably lost when a tank of gas is consumed while driving a car or a log is burned to heat a house?

47 Exergy Analysis The Second Law of Thermodynamics states that the disorder of a closed system always increases. Thus some order is always lost. The Second Law acts as a one-way sign: the arrow of time Combining First and Second laws creates new property called exergy Exergy is maximum useful work that a system can produce as it comes into equilibrium with the environment. In contrast to energy, some exergy is always destroyed. Thus, exergy analysis is consistent with our intuition that something is irretrievably lost when a tank of gas is consumed while driving a car or a log is burned to heat a house.

48 Exergy Analysis and the Inside-Out Approach X waste X in X destroyed X useful X useful = X in X waste X destroyed X destroyed = (X in X useful) - X waste

49 Exergy Analysis: Look for internal exergy destruction as well as external exergy loss So when is exergy destroyed? Heat transfer from high to low temperature. Mixing Turbulence or friction So when is exergy destruction minimized (i.e. energy effectiveness maximized)? Minimize heat transfer from high to low temperature. Minimize mixing Minimize turbulence or friction

50 Employ Counter-Flow

51 Employ Counter-Flow Counter-Flow Stack Furnace Preheats Charge Reverb Furnace Efficiency = 25% Stack Furnace Efficiency = 44% (Eppich and Nuranjo, 2007)

52 Employ Counter-Flow Counter-Flow Heat Treat Current Design Stack Burners Recommended Design Extending hood saves $40,000 /yr

53 Employ Counter-Flow Counter-Flow Glass Heating Contact length = 2 x ( ) = 30 feet Contact length = ( ) = 55 feet Counter flow increases convection heat transfer by 83%

54 Employ Counter-Flow Counter-Flow Cooling Counter flow enables 50 F to 70 F water saves 10x

55 Minimize Heat Loss: Insulate Pipes and Tanks Insulate Steam pipes Condensate return pipes Condensate return tanks Deaerator tank Valves

56 Combined Heat and Power (CHP) Exergy analysis is foundation of CHP CHP systems generate power AND use low temperature heat Increases energy utilization / efficiency

57 Steam to Power With High/Low Pressure Steam

58 Coal fired boilers generate high-pressure steam for turbine. Turbine powers electrical generator to generate electricity Lower pressure steam to plant Lowest pressure steam condensed and returned to boiler Appvion Paper CHP

59 Power to Heat: Gas Turbines

60 University of Cincinnati CHP 46 MW natural gas-fired CHP system powered by two Solar combustion turbines Satisfies 50% of campus electricity demand During winter: steam used for space heating During summer: steam produces additional electricity that makes chilled water. At night, when less cooling is needed, chilled water stored in a 13,200 m 3 underground storage tank. Saves university $4 million/year Operating efficiency of 73% Prevents 95,000 tonnes of CO 2 emissions per year.

61 Avoid Mixing: CAV to VAV Fan Energy Use

62 Avoid Mixing Cooling Applications Separating tank into hot and cold sides reduces cooling tower fan energy by 22%

63 Avoid Mixing Eliminating mixing of supply and return hot water increases boiler efficiency by 2%

64 Avoid Turbulence (Throttling): Process Pumps

65 For Constant Liquid Flow: Trim Pump Impellor A: Flow throttled by partially closed valve B: Flow with valve open Wsav = A C = 11.2 kw 5.6 kw = 5.6 kw C: Valve open and impellor trimmed Frac Sav = 5.6 kw / 11.2 kw = 50%

66 For Constant Air Flow: Slow Fan with Larger Pulley

67 For Constant Air Flow: Slow Fan with Larger Pulley A: Flow throttled by partially closed damper B: Max flow with damper open C: Damper open and fan speed (RPM) reduced Wsav = A C = 20 hp 5 hp = 15 hp Frac Sav = 15 hp / 20 hp = 75%

68 For Variable Flow: Install VFD

69 For Variable Flow: Install VFD A C A B A: Flow throttled by partially closed valve B: Max flow with valve open C: Valve open and pump slowed by VFD Wsav = A C = 18 hp 6 hp = 12 hp Frac Sav = 12 hp / 18 hp = 66%

70 Eliminate Intermittent Fan Operation: Vary Cooling Tower Fan Speed with VFD

71 Energy Efficiency Principle 4: Analyze Whole Systems over Whole Time Frames

72 Optimize System Not Components 400 ft/min 200 ft/min 200 ft/min

73 Optimum Pipe Diameter D opt = 200 mm when Tot Cost = NPV(Energy)+Pipe D opt = 250 mm when Cost= NPV(Energy)+Pipe+Pump Energy 250 = Energy 200 / 2

74 Consider Whole System Over Whole Time Frame 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.

75 Consider Whole System Over Whole Time Frame 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%

76 Conclusions Systems + Principles Approach (SPA) for energy assessments is: Effective Reproducible Teachable Systems + Principles Approach incorporated into the Energy Efficiency Guidebook (EEG) public domain software

77 Interested? Kelly Kissock: