Deer Island Treatment Plant

Transcription

1 Massachusetts Water Resources Authority Deer Island Treatment Plant Heat First-Power Second CHP Daniel O Brien, PE Deputy Director, Operations NBP Webcast September 22,

2 Massachusetts Water Resources Authority Presentation Outline MWRA Background Overview of Deer Island Energy Use Profile Self-Generation & Energy Savings Initiatives Current CHP Scheme Future CHP Modifications Questions 2

3 Massachusetts Water Resources Authority MWRA Background Independent Public Authority created in 1985 Wholesale Provider of Water and Sewer Services Service Population 2.2 million (42% of State) 61 Communities receive some form of service Centralized wastewater treatment at Deer Island 3

4 Massachusetts Water Resources Authority 4

5 Massachusetts Water Resources Authority Deer Island Treatment t Plant 2 nd Largest Wastewater Treatment Plant in the United States Built on 150 Acres Treatment Capacity: Maximum 1.27 Billion Gal/Day Avg. Daily Flow 365 Million Gal/Day 5

6 MWRA Leading by Example As a leading environmental agency, MWRA has been striving to meet the goals established in Governor Patrick s Executive Order 484 (April 2007) Goals include: Overall Reduction of Energy Consumption Increase Renewable On-site Energy Production (30% by 2020) Purchase of Renewable Energy Original 1988 design already had similar goals 6

7 Self-Generated Renewable Energy MWRA self-generated over 40% of it s energy demand in FY10 from Deer Island Renewable Energy assets Digester gas heat supply Digester gas STG electricity Hydro electricity Wind Solar Deer Island Renewable Energy assets generated over 16% (35M kwh/yr) of MWRA s total electricity demand (215M kwh/yr) in FY10 Or 22% of Deer Island total electricity demand (164M kwh/yr) 7

8 Self-Generation & Energy Savings Initiatives 8

9 Deer Island Electricity ELECTRICITY USAGE BY PROCESS AREA Pumping 30% Secondary 30% Residuals 14% Primary 12% Thermal 8% Support Facilities 6% 9

10 Massachusetts Water Resources Authority Overview of DI Facilities Deer Island 365 mgd (avg); 1270 mgd (peak) Pure Oxygen Secondary Plant Primary:Secondary Sludge Ratio 65:35 Thickening Gravity Thickeners & Centrifuges Egg-shaped Digesters 12 units at 3 mg each Detention days; VS Destruction 65% (avg) Gas Utilization 98-99%; Production 185,000 scfh Sludge Production 105 dry tons per day 10

11 Deer Island Aerial View 11

12 Deer Island Site-Specific Factors Site-Specific Factors Impacting Decisions Remote Site Limited Access Constrained Site Little Open Space Power Plant Complex Tight Interior Layout No Supply of Natural Gas (Public Opposition) Sale of power to grid prohibited by supplier contract Air Emissions Permit Noise Restrictions 12

13 Residuals Complex Egg-Shaped Digesters DIGESTER GAS Current Utilization 98-99% Thermal Value 5 MG ($10-15M/yr) Electricity it Production 28M kwh/yr ($2.8M/yr) MA RPS - Renewable Energy Certificates > $500k/yr 13

14 Digester Gas Utilization Digas Beneficially Utilized at the Deer Island Thermal Power Plant 100% 90% 80% 70% lized % Util 60% 50% 40% 30% 20% 10% 0% Jul-03 Nov-04 Mar-06 Aug-07 Dec-08 May-10 14

15 Digester Gas Utilization Digas Beneficially Utilized at the Deer Island Thermal Power Plant 100% 90% 80% 70% ized % Utili 60% 50% 40% 30% 20% 10% 0% Jul-08 Oct-08 Jan-09 Apr-09 Aug-09 Nov-09 Feb-10 Jun-10 15

16 CHP Original Design Concept Original Design Concept Dedicated power cable to local supplier base power On-site availability of digas to fire dual-fuel boilers High-pressure boilers to meet thermal load STG to generate electricity CTGs (Pratt-Whitney) to provide backup power STG sized to provide add l power if needed 16

17 Boilers Existing Installation Installed Model - Zurn (2) Rated Capacity 150,000 #/HR each Average Output t 70,000#/HR000#/HR 17

18 STG Existing Installation Installed Model - Demag Deval Rated Capacity 18 MW Average Output 3.2 MW 18

19 BP STG New Installation Installed 2011(planned) Model - Siemens Rated Capacity 1.2 MW Expected Output.5 MW Cost - $2.2M2M 19

20 STG Production STG Production at the Deer Island Thermal Power Plant , ,000 STG Genera ation, MW ,000 3,000 2,000 Gas Utiliz zed, KSCFH , Jul-03 Nov-04 Mar-06 Aug-07 Dec-08 May-10 0 Steam Generator Output Gas Used at Thermal Power Plant* 20

21 STG Production STG Production at the Deer Island Thermal Power Plant STG Genera ation, MW Gas Utiliz zed, KSCFH Jul-08 Oct-08 Jan-09 Apr-09 Aug-09 Nov-09 Feb-10 Jun-10 0 Steam Generator Output Gas Used at Thermal Power Plant* 21

22 Existing CHP Issues Actual conditions differed from design projections Sludge (and therefore digas) production much less Both power and thermal demand less Treatment Plant full build-out was reduced STG full output requires lots of supplemental fuel Some ancillary support equipment undersized 22

23 BP STG Planned Modifications (winter mode) 23

24 BP STG Planned Modifications (summer mode) 24

25 Dump & Vacuum Condenser Existing & Future Original Installation 1998 (tube bundle replaced 2004) Model - Katema Heat Transfer New Installation 2011 Model TBD Cost - $2.8M 25

26 Expected Benefits of Modifications Overall STG Output Increased Expected Increase 5.4M KWH/YR (20%) Estimated Annual Savings - $540,000 Boiler efficiency increased (hotter feedwater) Less wasted steam More flexibility for seasonal heat load swings Payback Period 6-8 years 26

27 Self-Generation Current & Future (Annual) Deer Island Total Power Demand 166M kwh Purchased Power 127M kwh (76%) Existing STG 28.5M kwh Future BP STG 5.4M kwh Existing CTG 52MkWh 5.2M Existing Hydro 6.0M kwh Existing Wind & Solar 2.3M kwh Future Wind & Solar 3.5M kwh 27

28 Massachusetts Water Resources Authority Thank You Contact Information - Daniel O Brien, P.E. Dan.Obrien@mwra.state.ma.us (Questions will be taken once all presentations have been completed) 28