Green Project Elements Using Innovative, Energy Efficient, Sustainable Design. GMWEA Spring Conference May 30, 2013

Transcription

1 Green Project Elements Using Innovative, Energy Efficient, Sustainable Design GMWEA Spring Conference May 30, 2013

2 Overview 1. Process for Assessment and Decision Making 2. Opportunities and Solutions 2A. Site 2B. Buildings 2C. Process and Controls 2D. Mechanical 2E. Electrical 2F. Biogas Cogeneration 3. Take Aways

3 Process for Assessment and Decision Making

4 What do Green Project Elements Include? Green Infrastructure Stormwater solutions: Rain gardens, detention basins, buffers Site design: Porous pavement Energy Efficiency Gas use Electricity use I/I reductions Wet weather storage Water Efficiency Beneficial reuse of treated effluent Leak repair program Plumbing fixtures Repurposing Buildings Reducing impervious areas Tanks Treated effluent reuse Sustainability Choosing durable materials with longer useful life Waste reduction Stormwater BMPs

5 Matrix of Potential Objective: Identify items included and not included Identify all potential improvements Identify and document potential benefit

6 Industry Resources Identify Potential Improvements Industry resources Review age of equipment Review equipment operations and controls

7 Energy Efficiency - Where to Start? Establish an energy baseline Identify equipment with highest energy use Wastewater Example Blowers/Aeration Pumps Dewatering HVAC

8 Decision Making Process Determine Objectives Evaluation Criteria Economic Capital cost Annual O&M Cost Available funding sources ROI: Return on investment Social Feasibility Complexity Reliability/track record of emerging technologies Sustainable

9 Examples Town of Hartford White River Junction and Quechee WWTFs Worked with various participants and stakeholders Village of Essex Junction WWTF Green Project Elements Workshop 7 year return on investment (ROI) Champlain Water District Energy Savings Scoping Study

10 Town of Hartford Quechee & White River Junction WWTFs Participants/Stakeholders Town Staff Town Energy Committee Members State Facilities Engineering Wastewater Management Division EPA Efficiency Vermont

11 Green Project Elements Workshop Owner Staff Board Members Energy Committee Design Team State of Vermont EPA Efficiency Vermont VRWA Local Industry

12 Champlain Water District Funded by Efficiency Vermont Energy Saving Scoping Study Raw Water Intake Water Treatment Facility Four Pump Stations Transmission System Established baseline: Pumping accounted for 84% of overall electrical usage at CWD facilities

13 Champlain Water District - Recommendations Pump Control Efficiency Operational modifications Optimize VFD redundancy versus fixed speed operated pumps Using 1 VFD pump to trim flow to the desired amount rather than running multiple pumps at similar speeds Soft starts on fixed speed pumps to limit power spikes Pump replacement right sizing the pump to improve efficiency Pumps operating at significantly lower head than original design head Funding CWD allowed to reinvest energy fees into energy improvements

14 Opportunities & Solutions

15 Opportunities & Solutions Site Buildings Process and Controls Mechanical Electrical Biogas Cogeneration

16 Site

17 Site Porous Pavement Porous Pavement: Improves stormwater management by allowing passage of surface runoff to infiltrate into ground

18 Site Porous Pavement Examples: Hartford White River Junction WWTF Hartford Quechee WWTF Essex Junction WWTF

19 Site Porous Pavement Benefits: Reduces impervious area Eliminates need for additional stormwater treatment Lessons Learned: Requires sweeping and routine maintenance Need suitable permeable soil conditions Limited durability use in low traffic areas

20 Buildings

21 Buildings - Repurposing Examples: Hartford White River Junction WWTF Renovated existing Control Building Aeration tanks converted to SBR tanks Secondary clarifier converted to sludge storage Essex Junction WWTF Original filter building converted to chemical feed/storage building Benefits: Minimizes new construction Doesn t increase impervious area Lessons Learned: Not necessarily less expensive Creates more sequencing issues during construction

22 Buildings Solar Collector Walls Mounted a few inches from building s outer wall. Perforations in wall allow outside air to travel through wall and through the panel, then to the building s ventilation system. Summer bypass system

23 Buildings Solar Collector Walls Examples: Essex Junction WWTF Benefits: Reduced heating and cooling costs

24 Buildings Daylighting Maximize opportunities for daylighting building space Window, skylight placement considered in building design to maximize use of light and solar gain Benefits: Reduced electric lighting and heating usage

25 Buildings 2011 Vermont Commercial Building Energy Standards Building Envelope Higher R-values for building insulation required for roofs and walls Increased building material cost

26 Process & Controls

27 Grit Removal Systems - Vortex Non-mechanical grit removal Gravitational forces used to separate grit from water No external power source No internal moving parts Installed as free standing structure or in concrete structure

28 Grit Removal Systems - Vortex Examples Hartford Quechee Hartford White River Junction Middlebury Benefits Lower energy usage Smaller footprint Less concerns about odors Lessons Learned Provide screening upstream to reduce plugging of grit removal line

29 Biological Nutrient Removal Removal of BOD 5, phosphorus, and nitrogen through biological process

30 Anaerobic Selectors - Benefits Green Project Benefits Enhances biological phosphorus removal For lagoon systems increases BOD removal Reduces chemical usage and sludge generation Less sludge to dewater and dispose Decrease volume of RAS that needs to be pumped

31 Examples - Facilities with Biological Phosphorus Removal Phosphorus: Create conditions for phosphorus accumulating organisms (PAO) to thrive Anaerobic Selectors SBRs Conventional Activated Sludge Essex Jct WWTF Springfield WWTF Oxidation Ditch: Fair Haven Extended Aeration: Enosburg Falls Aerated Lagoon: Hardwick SBRs Hartford Quechee and White River Junction Shelburne Middlebury

32 Anaerobic Selectors Process Schematic Primary Effluent Metal Salt Addition (Alum) Anoxic Stage 1 Anaerobic Stage 2 Aerobic Secondary Clarifier Return Activated Sludge (RAS) Addition of anoxic zone for denitrification (nitrate removal)

33 Anaerobic Selectors Lessons Learned Lessons Learned Requires anoxic for denitrification to optimize biological phosphorus removal Mixing is required and consider type of mixer for reliability ORP automatic monitoring for process control Reduced RAS return rates

34 Hyperbolic Mixers More energy efficient option for mixing compared to submersible mixers Require ~40% less energy to achieve equal mixing

35 Examples Hyperbolic Mixers Essex Junction WWTF South Burlington Airport Parkway Benefits Lower Energy Required for Mixing Fewer units required Improved reliability over submersible mixers Motor accessible for maintenance

36 VFD Operation Pumps & Blowers Converting fixed speed motor operation to variable frequency drive (VFD) operation Equipment is designed for peak flows VFDs allow equipment motor to run at partial load to save energy at average flows at design year Automatic or manual Eliminate throttling valves Improved process flow control

37 VFD Operation Pumps & Blowers Benefits: Improves energy efficiency through range Provides better process control Lessons Learned: Locate VFD close to equipment Addition of VFD slightly reduces energy efficiency Use wall mounted units vs. cabinets Replace soft starts and can be used for phase converters Maintain minimum velocities in force main at low set speed

38 Right Equipment Sizing Inefficiency in oversized pumps & blowers for design Examples Champlain Water District Essex Junction WWTF Lessons Learned Multiple units sometimes 3 vs. 2 units

39 Turbo Blowers Turbo Blowers New blower technology available in US for ~5years Operate at a very high speed Manufacturers: Aerzen (formerly K-Turbo) Neuros APG Atlas Copco (HSI)

40 Turbo Blowers - Examples Essex Junction WWTF: HSI Hartford White River Junction: HSI Burlington WWTF: KTurbo South Burlington Airport Parkway: KTurbo

41 Turbo Blowers - Benefits Benefits Smaller footprint Includes internal variable frequency drive Greater capacity per BHP compared to other types of blowers Doesn t run hot Quieter

42 Turbo Blowers - Lessons Learned Lessons Learned Good incentives provided by Efficiency Vermont Doesn t have the wide turndown (operating range) claimed Better application in sizes > 100 HP Automatic control can be problematic in parallel operation with other types of blowers Long-term reliability still a concern

43 Solar Aerators Solar aerators supplement or replace the mixing/aeration in lagoons & ponds Lagoon Aeration Swanton WWTF Item Description Original Proposed Average Daily Flow 0.9 mgd 0.9 mgd Peak Hour Flow 2.2 mgd 2.2 mgd Aerators Type Grid Powered Solar Number x 80 watt 5 HP Power Requirements each unit photovoltaic panels

44 Solar Aerators Lessons Learned Good incentive through Efficiency Vermont Lease arrangements available Shouldn t be used to replace original aeration system, but operated to supplement Haven t been in operation long enough to determine longterm reliability

45 Instrumentation Monitoring DO Pacing blowers to meeting DO concentration set point ORP Process control for biological nutrient removal Flow pacing chemicals Benefits Optimizes energy usage Improves process control

46 Non-potable Reuse Optimizing use of plant water in lieu of potable water Benefits Reduces municipal potable water use Lessons Learned Filtering may be required Covering of tank may be needed to minimize algae growth

47 Mechanical

48 Mechanical Heat Recovery System Example Hartford White River Junction Transfer excess heat generated in blower room to other spaces Essex Junction WWTF Solar collector walls pre-heat air for ventilation Benefit Reduced heating energy and energy costs

49 Buildings Heat Recovery New Code requirements NFPA 820 Fire Protection Class I, Div 1, Group D Spaces - NFPA 820 requires 12 air changes per hour for continuous ventilation and 30 air changes per hour if intermittently ventilated Headworks Primary Sludge Pumping Influent Pumping Challenge in winter to heat buildings when drawing in cold air to meet ventilation requirements Opportunity for heat recovery to reduce heating energy use

50 Mechanical Heat Pump Systems Use of treated effluent for heating/cooling

51 Mechanical Heat Pump Systems Hartford White River Junction WWTF Essex Junction WWTF

52 Mechanical Heat Pump Systems Benefits Beneficial reuse of effluent Reduces energy usage for heating and cooling Lessons Learned Maintain storage in chlorine contact tank May want to cover chlorine contact tank to minimize algae growth Filter or straining is needed

53 Mechanical Geothermal Wells Used to supply building heating and cooling Two Types: Open Loop: Water from well(s) as conductor Closed Loop: Earth/ground as conductor

54 Mechanical Geothermal Wells Example: Essex Junction WWTF Open loop system Benefits: Delivers 3-5 times more heat than the electrical energy Lessons Learned: Open loop systems are more efficient System needs to be compatible with building heating system Well pump needs to be sized appropriately

55 Electrical

56 Solar Electric Solar panels are used to generate electricity for on-site use or net metering Example Hinesburg WWTF Montpelier WWTF Benefits Reduces energy usage Reduces greenhouse gases Lessons Learned Funding challenges Public/Private Partnership Payback

57 Lighting Lighting Occupancy Sensors Daylighting Lessons Learned Incentives available from Efficiency Vermont

58 Biogas Cogeneration

59 Biogas Cogeneration Methane gas from the anaerobic digestion process is used to generate electricity. Requires pre-treatment with gas conditioning for siloxanes and/or hydrogen sulfide and moisture removal Power is generated by either microturbines or internal combustion engines

60 Biogas Cogeneration Essex Junction WWTF Gas production ~37,000 cfd System Components Biogas Treatment Moisture Removal Siloxane Removal Combined Heat and Power (CHP) Module 120 kw Engine Generator

61 Biogas Cogeneration - Benefits Benefits Use of methane gas for electrical generation reduces electrical costs Plug & Play - Engines are available in container module Engine vs. microturbines Higher electric and thermal efficiencies Better turndown Gas compression system is not required

62 Biogas Cogeneration Lessons Learned Lessons Learned Good incentives from Efficiency Vermont Need to determine if sufficient gas production is available Gas treatment is necessary for siloxanes and hydrogen sulfide plus moisture removal Microturbines are not available or supported in smaller sizes Be aware of space classifications - some equipment may need to be exterior

63 Take Aways

64 Take Aways Many of these opportunities should be standard for most large upgrade projects Communicate and share experiences with other facilities and stakeholders Public education and outreach for customers on green project elements Solutions need to provide reasonable Return on Investment (ROI) of 7 to 10 years Explore and leverage all public/private funding opportunities Understand the complexity, reliability, and O&M costs of newer technologies

65 Questions?

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