Columbia Boulevard Wastewater Treatment Plant Biogas Utilization - - PowerPoint PPT Presentation

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Columbia Boulevard Wastewater Treatment Plant Biogas Utilization - - PowerPoint PPT Presentation

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Columbia Boulevard Wastewater Treatment Plant Biogas Utilization Technology Experiences September 22, 2017 Jim Brown, PE, Senior Engineer Environmental Services l CBWTP Biogas Utilization 1 Acknowledgements City of Portland o Vu Han,

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Environmental Services l CBWTP Biogas Utilization 1

Columbia Boulevard Wastewater Treatment Plant Biogas Utilization Technology Experiences

September 22, 2017

Jim Brown, PE, Senior Engineer

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Environmental Services l CBWTP Biogas Utilization 2

Acknowledgements

  • City of Portland
  • Vu Han, PE
  • Paul Suto, PE
  • Muriel Gueissaz-Teufel, PE, BCEE
  • Sarah Covington
  • Karen Martinek
  • Cliff Meier, PE (Retired)
  • Danny Grady
  • David Tooze (Retired)
  • HDR Inc
  • Jeremy Holland, PE
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Environmental Services l CBWTP Biogas Utilization 3

Columbia Blvd WTP

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Anaerobic Digestion

  • Treatment process for solids removed from

wastewater

  • Heated and mixed process
  • Generates biosolids and anaerobic digester gas
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Environmental Services l CBWTP Biogas Utilization 6

“Traditional” Biogas Usage At CBWTP

  • Boilers
  • Digester heat
  • Facility heat
  • Malarkey Roofing
  • $180K to >300K per year!
  • Flares….
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Environmental Services l CBWTP Biogas Utilization 7

Biogas Technologies Evaluated

  • Fuel Cell
  • Micro-Turbines
  • Internal Combustion Engine-Generators
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Environmental Services l CBWTP Biogas Utilization 8

200 kW Phosphoric Acid Fuel Cell - 1999

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Clean Exhaust Useful Heat Heat & Water

Fuel Cell Power System

Fuel

Fuel Processor

Hydrogen Rich Gas

Power Section DC Power Power Conditioner AC Power

Air

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Environmental Services l CBWTP Biogas Utilization 10

Fuel Cell Cost Funding Pie Chart:

OR Bus. Energy Tax Credit $126K OR Office of Energy $14K U.S. DOD/DOE $200K Portland's Cost $790K PGE Renewable Energy $247K

Outside Funding Total Cost: $1.3 Million $6,500 /kW

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Design and Installation Issues

  • Waste Heat (low temperature)
  • Scrubber Carbon
  • Sulfur Content/Gas

Contamination

  • Moisture Trap
  • Supply Pressure
  • Water Treatment
  • Fuel Piping Size
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Estimated Annual Operation

  • Produces 1.4 MWh/year
  • Revenue $60,000/year
  • Maintenance cost $10,000
  • Annual Stack Replacement Cost
  • $22,000 x 6 years = $ 132,000
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Operational History

Year Operating Time (hrs)

Operational Uptime (%)

Grid MWh Delivered Energy Savings ($)

Maintenance Cost ($) Fuel Consumed (MSCF)

1999- 2000 6,166 70 901 58,565 18,069 16.2 2000- 2001 6,858 97 872 56,654 34,575 16.1 2001- 2002 6,474 74 824 53,586 40,861 15.3

2002-

2004

(Avg)

6,031 69 737 47,873 37,066 13.8

Fuel Stack Replacement after 5 years = $250K to $300K!

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Decommissioned January 2005

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Fuel Cell Project Benefits

  • Better understanding of Cogen

technology

  • Learned how to benefit from

Oregon Business Energy Tax Credit

  • Ratepayers and general public

feel good about the project

  • Made way for Micro-Turbine

technology

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Booster Compressor Refrigerated Dryer Micro-Turbine Carbon Vessels Desiccant Compressor Heat Recovery Heat Exchanger

Micro-Turbines - 2003

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Environmental Services l CBWTP Biogas Utilization 17

Micro-Turbines Cost Data

  • Purchased 4 units @ 30kW each = 120kW
  • Purchase cost = $300,000
  • Turbines, compressors, heat recovery, gas

processing, and electrical

  • Estimated installation cost $46,000
  • Total cost: $346,000 or $2,883 per kW
  • Cost after BETC pass through = $309,000 or $2,575

per kW

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Expected Performance

  • Electric Output
  • 30 kW @ 480VAC, 60 Hz
  • Efficiency
  • Electrical :

27%

  • Thermal:

53%

  • CHP:

80%

  • Noise Levels
  • 65 dBA @ 33 feet
  • 83 dBA @ 2 feet
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Operational History

  • Installation and startup completed April 2003
  • One month later, system shutdown due to excessive water,

stayed down for 1-1/2 years

  • Intermittent uptime – Dec 2004 to June 2007
  • Decommissioned following startup of COGEN in 2009
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Pencil It

Proposal Basis (Annual) Actual

  • Dec. 2004 to

June 2007 Run Time Hours 21,900 (30 months) 16,000

(not all running)

Production 890 MWh 480 MWh Electric Bill Reduction $40,000 $22,000 Maintenance Cost $4,000 $17,000 5 yr rebuild costs $10,000 ???

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Operational Lessons Learned

  • Gas Treatment is Critically Important
  • Carbon Bed
  • Gas Drying
  • Siloxane Removal
  • Equipment Requires Attention – not “Set and Forget”
  • Filter Cleaning
  • Carbon Media Replacement
  • Design Issues
  • Hot Water Usage
  • Grid Independent Operation?
  • Integration into System; SCADA
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Internal Combustion Engine-Generators

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Engine Generators Cost Data

  • Two Units @ 850kW Each = 1.7 MW
  • Purchase Cost, Engines and Electrical:

$1.4M

  • 5 Yr Engine/Electrical Maintenance:

$ 1.1M

  • Total Cost:

$ 7.9 Million or $ 4,650 per kW

  • Cost After Oregon Energy Trust/BETC Pass-Through

@ 25% (~$2.0 M): $ 6 Million or $ 3,500 per kW

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Expected Performance

  • Electric: 850 kW Each @ 4160 VAC, 60 Hz
  • Thermal: 3.6 MBTU /hr/ Unit
  • Efficiency
  • Electrical:

37%

  • Thermal:

47%

  • CHP:

84%

  • Noise Levels
  • 117 dBA @ 3 feet
  • Emissions – Lean-Burn

Combustion

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Digester Gas Treatment

  • Skid Mounted, Vendor Design and Fabricate
  • H2S Scrubber
  • Iron Sponge
  • Pressure Boost
  • 2.5 PSIG
  • Moisture Removal
  • 40 degree F

Dew Point

  • Siloxane Scrubber
  • Activated Carbon
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CBWTP Purchased Power

500,000 1,000,000 1,500,000 2,000,000 2,500,000 3,000,000 Jun-05 Oct-05 Feb-06 Jun-06 Oct-06 Feb-07 Jun-07 Oct-07 Feb-08 Jun-08 Oct-08 Feb-09 Jun-09 KWHrs

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CBWTP Electrical Power FY13-17 Average

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CBWTP Gas Utilization FY15-17 Average

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COGEN Performance History FY15-17

  • Uptime: 90%
  • Power Generation: 15,300,000 kWh/yr
  • Approximately $1M/year utility bill reduction
  • $211K/year O&M Costs
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Lessons Learned

  • Biogas Treatment
  • Heat Balance – Use and Waste
  • Power Company Coordination (PGE)
  • Grid Synchronization
  • Grid Independent Operation (no, in our case)
  • Buy Back Power or Trip?
  • Engine
  • Housing
  • Load Follow, Fuel Follow?
  • Auxiliary Motor Control and Interlocks
  • Communications and Monitoring
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Operational Lessons Learned

  • Performance is not NPDES

permit related

  • Waste heat system

inadequate

  • Iron Sponge Media life

shorter than expected

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Current Biogas Utilization

Heat Reservoir System Gas Clean Up Malarkey Roofing Products Anaerobic Digesters Waste Gas Burner Engine Generators Power Wastewater Solids Biogas Thermal Energy Electrical Energy Plant Heating Boilers

24% 19% 36% 21%

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Environmental Services l CBWTP Biogas Utilization 36

Biogas Utilization (Encore)

Find the most beneficial use for the digester gas that is being flared.

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Project Goals

  • 100% methane recovery

and most beneficial use for remaining biogas

  • Maximize value to

ratepayers

  • Optimize return on

investment with best balance of risk and reward

  • Align with City’s goals,

policies, and Climate Action Plan

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Future CBWTP Gas Utilization Technology Alternatives Analyzed

Cogeneration Expansion without Biogas Storage

AL TE RNATIVE

1

Cogeneration Expansion with Biogas Storage

AL TE RNATIVE

2

Biogas Treatment for Vehicle Use

AL TE RNATIVE

3

Biogas Treatment for Sale to Industry/ Pipeline Injection

AL TE RNATIVE

4

Biogas Used in Biosolids Drying

AL TE RNATIVE

5

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Pipeline Injection for Transporting RNG

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Map of CNG Fueling Stations in the U.S.

Source: NGVAmerica

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Biogas (Methane) to Renewable Natural Gas Facilities

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RNG Production Technology (Water Wash)

Source: Greenlane Biogas

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On-Site RCNG Fueling Station

  • Consists of

compressor, storage tanks and fuel dispensers

  • Use for City Fleet or

contractor vehicles with operation on site

  • Enter Schedule H

agreement with NWN to design, build and maintain

  • ODOE AVFI Tax credit

available Source: GE CNG-IN-A-BOX

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  • Located on CBWTP site for monitoring RNG quality before the pipeline

injection

  • NW Natural to design, build, operate and maintain during the term of the

agreement, with BES to pay the costs over time

NWN Monitoring Facility

Source: Fortis BC

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Triple Win Solution

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Questions?

Presenter eMail Addresses: James.Brown@portlandoregon.gov

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End of Presentation