BIOGAS FUEL POTENTIAL IN MUNICIPAL WASTEWATER TREATMENT

Transcription

1 BIOGAS FUEL POTENTIAL IN MUNICIPAL WASTEWATER TREATMENT BANZ WORKSHOP, HAMILTON, SEPTEMBER 2017 EMANZ CONFERENCE, MAY 2016

2 BRIEF OVERVIEW OF THE OPPORTUNITY Municipal Wastewater Primary Treatment Primary Sludge Biogas/ Power Secondary Treatment (aerobic) Waste Activated Sludge Tertiary Treatment (aerobic/ anoxic) Waste Activated Sludge Dewatered Biosolids 2

3 MUNICIPAL TRADE WASTE CO-DIGESTION 1. Reduces costs of wastewater treatment services 2. Enables biosolids treatment cost reduction 3. Improves digester utilisation and efficiencies (2 fold) 4. Minimises energy costs (generates 100 % of site power) 5. Provides new sources of revenue (gate fee) 6. Maximises whole of life cost effectiveness 3

4 SUITABLE LIQUID TRADE WASTE Feedstock Material Dissolved Air (DAF) float (dairy factory, meat processing) % Dry Solids (DS) Range % (very high fat content) Cheese whey 5 % (high sugar content) Grease trap waste (municipal, commercial collection) Municipal biosolids (primary sludge) 5 10 % (high fat content) 3-4 % (medium fat content) 4

5 WWTP POWER PRODUCTION POTENTIAL TODAY Grease trap waste resource: Municipal sludge resource: Dairy factory WWTP DAF sludge resource: 0.15 MW el per 100,000 EP 0.15 MW el per 100,000 EP MW el per dairy factory Urban New Zealand (incl. dairy processing): about 18 MW el 5

6 REGIONAL CO-DIGESTION OPPORTUNITIES : Existing WWTP digesters with available capacity Total: 16 MWel 6

7 SNAPSHOP OF THE CURRENT SITUATION (BASED ON THE 2016 NZ MUNICIPAL WWTP INVENTORY WATER NZ) 7

8 KEY STATISTICS Current economic potential 53 % of current effective NZ population (EP) is connected to 15 WWTP s with anaerobic digesters (size from 16,000 EP to 1.2 million EP). This equals to 2.5 million EP (2016) and about 2.85 million EP (2030). The key economic drivers are reduced WWTP biosolids disposal costs. Current technical potential Up to 75 % of NZ population in 2030 could be connected to WWTP s with > 30,000 EP incl. sludge digestion (20 regional towns and all major cities). This equals to a total of 4 million EP with a power generation potential of 12 MWel in 2030, 100 % energy self sufficient WWTP s (about 30 plants). Power generation (> 90 KWel) is technically feasible in each site from WWTP biosolids and grease trap waste from the region in co-digestion. Future economic potential Ultimately this could be extended in 2030 to 78 % of NZ s population (WWTP s > 12,000 EP, total of 42 plants). Drivers for this are treatment costs, power price, carbon costs and biosolids disposal costs. 8

9 HOW TO GROW THE PIE RT-DIGESTERS 1. Low power consumption ( < 15 KW) 2. Fully automated 3. Low maintenance (weekly clean) 4. Low polymer consumption (4-5 kg polymer/t DS) Digester Feed Anaerobic Digester Sludge dewatering Polymer Dosing System Thickener Thickened Sludge Thickener Filtrate

10 HOW TO GROW THE PIE Infrastructure/OPEX paid by biosolids disposal cost savings Additional revenue earned from trade waste co-digestion Future 30,000 EP WWTP example, (2 x 450 m 3 digester): Liquid trade waste accepted at 60 $/m 3 gate fee: 1. Traditional feedstock blending (up to 20 % of sludge load). 10 m 3 trade waste /day, up to 600 $/day gate fees % increased gas production, full gas/power use at plant 2. High rate co-digestion/recuperative thickening, 20 m 3 trade waste /day, up to 1,200 $/day gate fees 100 % increased gas production, full gas use at plant 3. Ultimate capacity: 200 % increased gas production, power export Self-funded (with gate fees) WWTP digester possible 10

11 WWTP POWER PRODUCTION POTENTIAL (MUNICIPAL WWTP S > 30,000 EP, YEAR 2030 ) biogas from WWTP biosolids and grease trap waste, ICI waste: 7 x 10-4 GJ/EP/day, 0.25 GJ/EP/annum 4 million EP in 2030 in WWTP > 30,000 EP: 1 PJ/annum biogas/annum (incl. grease trap and ICI waste) WWTP gas production potential with trade waste co-digestion 2 PJ/annum biogas/annum (incl. dairy processing and ICI waste) Total WWTP gas production potential in 2030 at installed capacity: 3 PJ/annum (estimate incl. source segregated food waste) 3 PJ biogas/annum = GWh gas = 333,360 MWhel /annum = 39 Mwel power production capacity on WWTP in 2030 = equivalent to about two council owned geothermal power stations self funded by co-digestion gate fees with about 4 years payback 11

12 The end user energy potential from industrial, agricultural, commercial and municipal biosolids Co-digestion in New Zealand energy potential, 2016 about 110 % of MSW Scenario 1 (PJ/annum) R + ICI Sewerage Biosolids (PJ/annum) Paunch Processing (PJ/annum) Meat Processing (PJ/annum) 1 PJ methane/annum = 13 MW el generation Dairy Processing (PJ/annum) Dairy Farming (PJ/annum) Estimate of Nett National methane bioenergy potential from each sector (given in PJ methane biofuel/year) Note: The processing energy requirement (heat, power) is assumed to be covered from the produced methane and is already subtracted 12

13 COUNCIL BUSINESS OBJECTIVES 1. Reduced costs of wastewater treatment services 2. Improved asset utilisation and efficiencies 3. Reduced energy costs 4. Reduced environmental footprint 5. New sources of revenue 6. Maximised whole of life cost effectiveness 7. Unconstrained development 13

14 SIMILAR INITIATIVES 1. Queensland Urban Utilities (planning + pilot) 2. Sydney Water (pilots) 3. South Australia Water (Glenelg and Bolivar plants) 4. Other Australian Water Companies (planning + pilot) 5. Watercare, Auckland (planning) 6. Palmerston North City Council (since 2011) 7. Hamilton City Council (since 2014) 14

15 SUMMARY 1. The current infrastructure of municipal WWTP in our urban centres (with existing sludge digesters) could produce up to about 2 PJ biogas in 2030 when upgraded to industry best practice. 2. This can be achieved in stages and without new digester plants % of the 2 PJ biogas could be produced from efficient co-digestion of suitable trade and industrial waste. 4. Extending this technology to regional municipal WWTP > 30,000 EP (and Wellington) could produce additionally about 1 PJ biogas (with trade waste co-digestion). 5. Buy-in from local authorities (councils) is critical to achieve a vibrant biogas industry in NZ with active waste digester plants by The additional renewable power generation potential in 2030 could be up to about MWel from biogas powered municipal WWTPs. Contact: jurgen.thiele@calibregroup.com