Sustainable Biosolids Management: Direct Energy Use Does Not Tell All

Transcription

1 Sustainable Biosolids Management: Direct Energy Use Does Not Tell All Ruth Borgmann, Hazen and Sawyer Erika Bailey, City of Raleigh TJ Lynch, City of Raleigh Stephanie Ishii, Hazen and Sawyer Amy Hanna, Hazen and Sawyer

2 Agenda for our time together Background GHG Evaluation Approach Results and Hotspot Analysis

3 Background

4 Neuse River Resource Recovery Facility Raleigh, NC Advanced BNR Process Current capacity 60/75 MGD Biosolids Management: Converting to THP and Advanced Anaerobic Digestion with conversion of biogas to RNG

5 Biosolids Outlets Current: Class B Liquid Onsite Offsite Composting Raleigh Plus Landfill Bioenergy: Class A Cake Land Application

6 Project Drivers Aging biosolids handling infrastructure Plan for future capacity needs Uncertainty of future Class B land application Sustainable solution for the future

7 Climate/Energy Action Plan City-wide interdepartmental effort Goals: Operational efficiency Energy reduction GHG reduction Cost savings Over 100 strategies were evaluated for implementation Bioenergy Recovery Project Completed in 2012; currently being updated Practical implementation of strategies to minimize carbon-related emissions, maximize energy efficiency of existing City facilities and provide renewable energy opportunities.

8 Greenhouse Gas Emissions

9 Why not just look at direct energy use? MW Current Bioenergy Direct energy use doesn t account for digester gas to beneficial use As a net energy producer the bioenergy project qualified for CWSRF Green Project Reserve Funding

10 GHG Evaluation Approach

11 GHG Evaluation: Alternatives Dewatering Lime Stabilization Class A Alkaline Raleigh Plus PS WAS Current Uncovered Aerobic Digesters Gravity Belt Thickening Covered Aerobic Digesters McGill Composting OR Landfill Class B Liquid Land App. - Onsite - Offsite Bioenergy FOG THP PS WAS Blend/ Screen Pre- Dewatering Final Dewatering Class A Land App. Thickening Anaerobic Digestion

12 GHG Evaluation: Approach Inventory Value GHG Equivalent GHG Footprint Operational Phase Functional Unit: 1 lb(dry) pre-processed biosolids CO 2 Equivalents

13 GHG Evaluation: Approach Functional Unit: 1 lb (dry) pre-processed biosolids Inventory Value GHG Equivalent GHG Footprint kwh Functional Unit OR lb. product Functional Unit lb. CO 2 e kwh OR lb. CO 2 e lb. product lb. CO 2 e Functional Unit

14 GHG Evaluation: Inventory Units: kwh/functional Unit or gal Alum/Functional Unit Inventory Value GHG Equivalent GHG Footprint Inventory Items Electricity Chemicals Biosolids transportation Offsets

15 Inventory Current Dewatering Lime Stabilization Class A Alkaline Raleigh Plus PS WAS Uncovered Aerobic Digesters Gravity Belt Thickening Covered Aerobic Digesters McGill Composting OR Landfill Class B Liquid Land App. - Onsite - Offsite Functional Unit: 1 lb (dry) pre-processed biosolids

16 Inventory Current Electricity Electricity Dewatering Lime Stabilization Class A Alkaline Raleigh Plus PS WAS Uncovered Aerobic Digesters Gravity Belt Thickening Covered Aerobic Digesters McGill Composting OR Landfill Class B Liquid Land App. - Onsite - Offsite Air Electricity CAD Mixing, Air & Odor Control Functional Unit: 1 lb (dry) pre-processed biosolids

17 Inventory Current Chemical Polymer Electricity LKD Dewatering Lime Stabilization Class A Alkaline Raleigh Plus PS WAS Uncovered Aerobic Digesters Gravity Belt Thickening Covered Aerobic Digesters McGill Composting OR Landfill Class B Liquid Land App. - Onsite - Offsite Air Electricity Polymer CAD Mixing, Air & Odor Control Functional Unit: 1 lb (dry) pre-processed biosolids

18 Inventory Current Offsets Polymer Electricity LKD N&P Offsets Dewatering Lime Stabilization Class A Alkaline Raleigh Plus PS WAS Uncovered Aerobic Digesters Gravity Belt Thickening Covered Aerobic Digesters McGill Composting OR Landfill Class B Liquid Land App. - Onsite - Offsite Air Electricity Polymer CAD Mixing, Air & Odor Control N&P Offsets Functional Unit: 1 lb (dry) pre-processed biosolids

19 Inventory Current Transport Polymer Electricity LKD N&P Offsets Dewatering Lime Stabilization Class A Alkaline Raleigh Plus PS WAS Uncovered Aerobic Digesters Gravity Belt Thickening Covered Aerobic Digesters McGill Composting OR Landfill Class B Liquid Land App. - Onsite - Offsite Air Electricity Polymer CAD Mixing, Air & Odor Control N&P Offsets Transport Functional Unit: 1 lb (dry) pre-processed biosolids

20 Inventory Bioenergy WAS Thickening Steam Boiler CNG Buses Gas Cleaning PS Blend/ Screen Pre- Dewatering THP Anaerobic Digestion Flare Final Dewatering Class A Land App. FOG Alum Sidestream Functional Unit: 1 lb (dry) pre-processed biosolids

21 Inventory Bioenergy CNG Buses Electricity WAS Thickening Steam Boiler Gas Cleaning Flare PS Blend/ Screen Pre- Dewatering THP Anaerobic Digestion Final Dewatering Class A Land App. FOG Alum Sidestream Functional Unit: 1 lb (dry) pre-processed biosolids

22 Inventory Bioenergy CNG Buses Natural Gas WAS Thickening Steam Boiler Gas Cleaning Flare PS Blend/ Screen Pre- Dewatering THP Anaerobic Digestion Final Dewatering Class A Land App. FOG Alum Sidestream Building Heat Functional Unit: 1 lb (dry) pre-processed biosolids

23 Inventory Bioenergy CNG Buses Chemical WAS Thickening Steam Boiler Gas Cleaning Flare PS Blend/ Screen Pre- Dewatering THP Anaerobic Digestion Final Dewatering Class A Land App. FOG Alum Sidestream Building Heat Functional Unit: 1 lb (dry) pre-processed biosolids

24 Inventory Bioenergy CNG Buses Offsets WAS Thickening Steam Boiler Gas Cleaning Flare PS Blend/ Screen Pre- Dewatering THP Anaerobic Digestion Final Dewatering Class A Land App. FOG Alum Sidestream Building Heat Functional Unit: 1 lb (dry) pre-processed biosolids

25 Inventory Bioenergy CNG Buses Transport WAS Thickening Steam Boiler Gas Cleaning Flare PS Blend/ Screen Pre- Dewatering THP Anaerobic Digestion Final Dewatering Class A Land App. FOG Alum Sidestream Building Heat Functional Unit: 1 lb (dry) pre-processed biosolids

26 Inventory Bioenergy CNG Buses CNG WAS Thickening Steam Boiler Gas Cleaning Flare PS Blend/ Screen Pre- Dewatering THP Anaerobic Digestion Final Dewatering Class A Land App. FOG Alum Sidestream Building Heat Functional Unit: 1 lb (dry) pre-processed biosolids

27 GHG Evaluation: Equivalent Units: lb. CO 2 e / kwh or lb. CO 2 e / gal Alum Inventory Value GHG Equivalent GHG Footprint Electricity City of Raleigh GHG Inventory Report approach (EPA references) Biosolids transportation City of Raleigh GHG Inventory Report approach (EPA tools, MOVES2014a) Chemicals Literature review Offsets Literature review

28 GHG Evaluation: Footprint Units: lb. CO 2 e / Functional Unit Inventory Value GHG Equivalent GHG Footprint Editable Excel Workbook Option for default and/or user defined values for inventory items and GHG equivalents References / explanations for default values Dynamic figures Total GHG comparison across alternatives GHG hotspot analysis within alternatives

29 Results and Hotspot Analysis

30 GHG Footprint 0.10 lb. CO 2 e / lb (dry) pre-processed biosolids Current Bioenergy

31 GHG Footprint Without Offsets lb. CO 2 e / lb (dry) pre-processed biosolids Current Bioenergy

32 GHG Footprint With Offsets 0.60 lb. CO 2 e / lb (dry) pre-processed biosolids Current Bioenergy

33 Current vs. Bioenergy GHG Production Annual GHG Production Cumulative GHG Production tons CO 2 e/year 5, ,000-10,000-15,000-20,000-25,000-30, Current Bioenergy ,000 50, , , , , , , , , Current Bioenergy Bioenergy is able to convert digester gas to RNG which allows for GHG Footprint to decrease with increasing flow to Neuse River RRF Typical Passenger Car is estimated to emit 5.5 tons CO 2 e per year

34 Hotspot Analysis Current Transport Chemical Electricity Phosphorus fertilizer offset Nitrogen fertilizer offset Landfill Transport Offsite Class B (GFI) Transport Offsite Class B (COR) Transport Onsite Class B Transport Class A McGill Transport Class A Raleigh Plus Transport LKD Current Polymer - BFP and DCEN Polymer - GBT Offsets Electricity - Dewatering, DCEN Electricity - Dewatering, BFP Electricity - CAD Odor Control Electricity - CAD Air Electricity - CAD Mixing Electricity - GBT Electricity - UCAD Air

35 Hotspot Analysis Current Phosphorus fertilizer offset Lime Transport Chemical Nitrogen fertilizer offset Landfill Transport Offsite Class B (GFI) Transport Offsite Class B (COR) Transport Onsite Class B Transport Class A McGill Transport CAD Air & Mix Electricity Class A Raleigh Plus Transport LKD Current Polymer - BFP and DCEN Polymer - GBT N Offset Offsets Electricity - Dewatering, DCEN Electricity - Dewatering, BFP P Offset Electricity - CAD Odor Control Electricity - CAD Air Electricity - CAD Mixing Electricity - GBT Electricity - UCAD Air

36 Hotspot Analysis Bioenergy Bioenergy Transport Chemical Electricity Offsets Phosphorus fertilizer offset Nitrogen fertilizer offset Diesel Offset (buses) Class A Disposal Transport Alum Siloxane Media Polymer - Dewatering, BFP, DCEN Polymer - Pre-Dewatering Polymer - GBT CNG (buses) Flare (NG) Boiler Heat (NG) Building Heat (NG) Electricity - Boiler, flare, gas holder Electricity - Alum Electricity - Sidestream Electricity - Gas Cleaning Electricity - FOG Electricity - Dewatering, DCEN Electricity - Dewatering, BFP Electricity - Anaerobic Digestion Electricity - THP Electricity - Pre-Dewatering Electricity - Blending Electricity - Sludge Screening Electricity - GBT

37 Hotspot Analysis Bioenergy Gas Cleaning Anaerobic Dig. Bioenergy Transport Chemical Electricity Phosphorus fertilizer offset Nitrogen fertilizer offset Diesel Offset (buses) Class A Disposal Transport Alum Siloxane Media Polymer - Dewatering, BFP, DCEN Polymer - Pre-Dewatering Polymer - GBT CNG (buses) Flare (NG) Boiler Heat (NG) Diesel Offset (Buses) Offsets Building Heat (NG) Electricity - Boiler, flare, gas holder Electricity - Alum Electricity - Sidestream Electricity - Gas Cleaning Electricity - FOG N Offset P Offset Electricity - Dewatering, DCEN Electricity - Dewatering, BFP Electricity - Anaerobic Digestion Electricity - THP Electricity - Pre-Dewatering Electricity - Blending Electricity - Sludge Screening Electricity - GBT

38 Effect of Varying FOG Quantities - Bioenergy Gas Cleaning Anaerobic Dig Gas Cleaning Diesel Offset (Buses) Diesel Offset (Buses) N Offset P Offset Footprint: lb CO 2 e/functional Unit FOG Receiving 30,000 gpd Footprint: lb CO 2 e/ Functional Unit FOG Receiving 0 gpd

39 How does this help CORPUD? Internal decision making Further operational adjustments for hotspot reduction Communication with stakeholders and public about environmental stewardship

40 Thank you from the team for your attention Contact Information: Ruth Borgmann, PE

41 BULLPEN

42 Effect of Varying Biosolids Outlets Current Original Scenario Raleigh Plus: 20% Composting: 20% Onsite Class B: 4% Offsite Class B: 9% Landfill: 47% Updated Scenario Raleigh Plus: 0% Composting: 50% Onsite Class B: 0% Offsite Class B: 0% Landfill: 50%

43 Effect of Varying Biosolids Outlets Current LKD Electricity - UCAD Air Electricity - GBT Electricity - CAD Mixing Electricity - Dewatering, DCEN Polymer - BFP and DCEN Class A McGill Transport Onsite Class B Transport CAD Air & Mix Current Current N Offset P Offset Footprint: 0.06 lb CO 2 e/functional Unit Footprint: lb CO 2 e/ Functional Unit

44 Sustainability and efficiency is a core focus of the City of Raleigh s strategic plan Objective 3: Optimize public infrastructure projects to address community resiliency, sustainability and efficiency. Development of a bioenergy recovery program for the Neuse River Resource Recovery Facility is a key deliverable under this initiative.

45 GHG Footprint - Current Functional Unit: 1 lb (dry) biosolids lb CO 2 e / Functional Unit Offsets: Nitrogen Fertilizer Phosphorus Fertilizer Biosolids Outlets: Raleigh Plus Composting Class B Onsite Class B Offsite Landfill

46 GHG Footprint - Bioenergy 0.45 Functional Unit: 1 lb (dry) biosolids + FOG blend lb CO 2 e / Functional Unit Offsets: Diesel Nitrogen Fertilizer Phosphorus Fertilizer

47 EPA GHG Analysis Approaches