Case study of commercial grass silage digestion for power production & Digestion of solid agro-wastes

Transcription

1 Case study of commercial grass silage digestion for power production & Digestion of solid agro-wastes 1

2 INTRODUCTION Case study of commercial grass silage digestion for power production Tim Clarke 2

3 Biogas in Europe Over 8000 digesters have been installed in Europe since 2000, processing a very wide variety of biomass feedstocks and wastes. A large number of these are in Germany /Austria due to availability of high feed-in tariffs for renewable energy The most common biomass feedstock is maize (otherwise used as cattle fodder), which can produce between m3 of biogas per tonne fresh weight. These digesters generally perform best if there is a minimum 5% of animal manure or other appropriate feedstock Retention time is long (>100 days) at mesophilic temperatures 3

4 Use of grass as biomass feedstock In UK/Ireland, there is increasing interest in utilising grass Lower production costs (30-50% less) Utilises existing farm equipment and facilities (dairy farms) for production, harvesting, and storage Good ratio between input cost and gas yield Shorter retention time = smaller digester 4

5 Outline Process Summary 500kWe AD Plant Parameter Unit Value Actual Grass stored as silage (3-4 cuts/year) t/day 44.4 % DM Av % DM % DM t/day 10.2 % VS Av % of DS % VS t/day 9.2 Average methane yield m3ch4/kgvs Methane m3/d 3125 % CH4 in biogas % 55 Biogas m3/d 5682 Digester VSL kgvs/m3/d 3.0 Digester capacity m Digester biogas yield m3/m3/d 1.9 HRT days 69 LCV biogas MJ/m3 20 Biogas gross energy kw 1315 Electrical efficiency % 38 Gross electrical output kwe 500 5

6 High Solids Digestion of Grass Technical Demands - Mixing Grass particles tend to float to the digester surface Mixing options Usual = Propellor: High Electrical Requirements at High Solids Biogas Recirculation Advantages - more flexible - lower power input - no equipment inside tank - easily maintained 6

7 High Solids Digestion of Grass Feed System - Vogelsang Quickmix Fine chop to 5mm with moderate power input Increased biogas yield Automatic and flexible Easily operated and maintained 7

8 CASE STUDY FINANCIALS Case study of commercial grass silage digestion for power production 8

9 Energy production Electricity production, value and cost ULSTER N.I. R.o.I. IRL Gross electrical output kwe Plant total availability % Gross electrical production MWh/y Total value of electricity inc subsidy /kwh Annual value of electricity Eu/y Av parasitic electrical energy demand kwe Av parasitic electrical energy demand MWh/y Cost of electricity /kwh Cost of electricity /y Plant income/savings ULSTER N.I. R.o.I. IRL Electricity /y Value excess heat on farm/buildings /y Total value /y

10 Capital cost, operating and maintenance costs Capital, and o/m costs ULSTER N.I. R.o.I. IRL Total capital cost of AD plant Grass feedstock for AD plant t/a Cost of production (excl fertiliser) /t Annual cost of grass /y Repayment and finance cost /y Maintenance of CHP /y Maintenance of digester system /y Electricity cost /y Plant operator /y Recycling digestate to land /y Management and overheads /y Consultancy /y Insurance /y Sampling and testing /y Total costs /y Cost of producing grass varies widely depending on local conditions 10

11 Outline Project P/L Nominal P/L ULSTER N.I. R.o.I. IRL Gross annual income-savings /y Total costs /y Nett income-savings b/tax /y There are over 100 mainly grass silage digesters planned, under construction or in operation in Northern Ireland. There are none in the Republic of Ireland (except Dept Agriculture research project) 11

12 INTRODUCTION Digestion of solid agro-wastes - Anders Ek 12

13 WASTES FROM CASSAVA STARCH PRODUCTION BIOGAS AND ENERGY POTENTIAL 13

14 Cassava Starch Production Process Flow Process Water 18m m 3 Cassava Root 4.21 tons Root Rinse 5.3 m m 3 Chop / grind WASTEWATER 19 m 3 /ton Starch COD: 20,000 mg/l 7.3 m 3 Fibre and pulp separation 3.9 m m 3 Starch separation Starch dewatering Drying / Packing 6.6 m m 3 CASSAVA PULP RESIDUE 1.4 ton % TS 95 % VS Starch Product: 1 ton 14

15 200 TPD Starch Factory 1,477,320 MJ per Day Starch 200 TPD WASTEWATER 3,820 m 3 /day COD: 20,000 mg/l PULP 280 ton/day 20 % TS 95 % VS of TS TOTAL COMBINED: Methane 25,200 m 3 /day Energy 904,500 MJ/d 10.5 MW-th Methane 15,960 m 3 /day Energy 572,836 MJ/day 6.63 MW-th Methane 41,160 m 3 /day Energy 1,477,336 MJ/day MW-th 15

16 Cassava Starch Production Process Flow Cassava Root: 842 tons ELECTRICITY REQUIREMENT 180 KWh / ton starch 648 MJ / ton starch Root Rinse Chop / grind Fibre and pulp separation ELECTRICITY 40% Eff. Daily Required Input: 324,000 MJ THERMAL REQUIREMENT 40 LitreHFO / ton starch Starch separation Starch dewatering Drying / Packing THERMAL REQUIREMENT 315,800 MJ Starch Product: 200 ton 16

17 200 TPD Starch Factory 1,477,330 MJ per Day Starch 200 TPD TOTAL BIOGAS PRODUCED Energy 1,477,330 MJ/day MW-th TOTAL ENERGY CONSUMED Energy 639,800 MJ/day 7.4 MW-th EXCESS AVAILABLE FOR GRID EXPORT Energy 837,530 MJ/day 9.73 MW-th Electrical: 3.9 MW-e 17

18 Starch Wastewater Biogas Plant, KWTE ,000 m3 WW/day 3 MW Power Plant and 22 MW(thermal) 1) Mixing Tank 3 2) Pump House 3) ABR 4) Control Room 5) Blower House 6) Power Plant

19 Cassava Pulp (garg) Biogas Plant, SWE 7 1,500 ton garg/day MW Power plant and MW(thermal) 1) Pulp Dilution 2) Mixing Tanks ) ABRs 4) Blower/Pump House 5) Control Room 6) Power House 7) Flares

20 Biogas plants at SWI, Thailand ) Starch Factory 2) Starch Wastewater Biogas Plant 3) Cassava Pulp (garg) Biogas Plant 11.4 MW Power Plant and 37 MW(thermal)

21 450 ton garg/day example 22

22 WASTES FROM PALM OIL PRODUCTION BIOGAS AND POWER POTENTIAL 23

23 Wastes from Palm Oil Production POME m3/ton FFB COD: ,000 mg/l EFB % of FFB 35 % TS 90 % VS of TS Decanter cake 4 % of FFB % TS % VS of TS 24

24 45 TPH POM Waste 5.3 (8.2) MW FFB 45 TPH POME 540 m3/day COD: 90,000 mg/l Methane 602 m3/h Power 2.46 MW EFB 248 ton/day 35 % TS 90 % VS of TS Methane 652(1304) m3/h Power 2.67(5.33) MW Decanter cake 43 ton/day 23 % TS 83 % VS of TS Methane 100 m3/h Power 0.4 MW 25

25 Energy production from EFB Biogas offers the only truly sustainable solution for Empty Fruit Bunches Energy Nutrients Structure material to soil Return to plantation No Yes Yes Composting No Yes Yes Incineration Yes No? No Pellet production Yes, indirect No No Biogas Yes Yes Yes 26

26 EFB Structure? (Doherty et al., 2010) (Mosier et al., 2004) 29

27 Pre-treatment breaking up fiber structure 5 mm 31

28 Biogas production from EFB PRETREATMENT (OPTIONAL) EFB PRESS (OPTIONAL) SIZE-REDUCTION OIL-RECOVERY POWER OIL GAS PROCESSING CBG SOLID FERTILIZER POME AFTER AD DIGESTION DIGESTATE DEWATERING LIQUID FOR IRRIGATION 32

29 Biogas from POME & EFB Conclusions? Energy + Nutrients + Structure material to soil Power output POME & EFB to 90,000 mg COD/L Mill size Different pre-treatment tonffb/hour Min Max MW 8.2 MW MW 11 MW MW 16 MW MW 22 MW 33

30 UPGRADING OF BIOGAS TO CBG/bioCNG FOR USE AS VEHICLE FUEL 39

31 Biogas Produced from anaerobic digestion of organic material. Methane (CH 4 ) 50 80% Carbon dioxide (CO 2 ) 20 50% Hydrogen Sulfide (H 2 S) x00 x000 ppm Water (H 2 O) Saturated Siloxanes, Ammonia (NH 3 ), Nitrogen (N 2 )

32 Biomethane/CBG/bioCNG Upgraded biogas suitable for CNG/NGV vehicles or for gas grid injection. Methane (CH 4 ) % Carbon dioxide (CO 2 ) 1 5 % Hydrogen Sulfide (H 2 S) Water (H 2 O) Siloxanes, Ammonia (NH 3 ), Nitrogen (N 2 )

33 CBG Pricing Thailand: CBG90 Power baht/kwh 14.8 baht/nm3 CH Nm3 CH4 CBG kg 12.5 baht/kg 11.6 baht/nm3 CH baht/kg 13.4 baht/nm3 CH4 16 baht/kg 14.8 baht/nm3 CH4 (???)

34 Upgrading Technology Ad/absorption media Regeneration method Working pressure (bar) PressureSwing Adsorption (PSA) Dry medium,e.g. Activated Carbon Depressurisation 4 7 Water Scrubber Water Depressurisation + air stripping, or None Amine Scrubber Amine solvent, e.g. Mono Ethanol Amine (MEA) Heat 5 10 Ambient Organic solvents Ethers of polyethylene glycol, e.g. Selexol, Genosorb Depressurisation + air stripping 7 8

35 Water Scrubber Source: ISET, 2009

36 Case studies Example from Sweden Local biomethane grid Local raw gas grid NG grid injection Biogas train Example from South Korea

37 Local Biomethane Grid, Linköping, Sweden Water scrubber Amine scrubber 4 bar biomethane grid 5 public filling stations 1 bus depot > 12 million L petroleq/year Sources: Svensk Biogas AB

38 Local raw gas grid with grid injection in Sweden Sources: New networks for raw biogas (SGC 264, 2012)

39 Biogas Train in Sweden Sources: Svensk Biogas AB

40 Biomethane filling station Seoul, South Korea Water scrubber 1 million L petroleq/year Sources: EcoEnergy Holdings Ltd

41 New proposed FIT Thailand FiT rate of purchasing power in the form adopted in 2558: the investment in the energy sector VSPP natural power. (Baht/kWh) Premium Production capacity (MW) FiT Support Period For projects in South 1) Water Power 200 kw years ) Wind Power All Size years ) Solar Power Roof 0-10 kw years 0.50 Roof > kw years 0.50 Roof >250-1,000 kw years 0.50 On the ground all sizes years

42 New proposed FIT Thailand FiT rate of purchasing power in the form adopted in 2558: the investment in the energy sector VSPP biopower. FiT (Baht/ kwh) Support FiT Premium (Baht/ kwh). Production capacity (MW) Period (years) FiTF FiTv,2560 FiT(1) Bonus 8 years For projects in South 1) Garbage (waste management, hybrid). 1 MW MW MW ) Garbage (landfill waste). All size ) Biomass 1 MW MW MW ) Biogas (Waste water/waste) All size ) Biogas (Energy crop) All size

43 Biogas Design Engineering Services EPC and Turnkey Project Construction Project Financing Solutions Biogas solutions for: Cassava Starch Palm Oil Manure Energy Crops (Grass) Agro-industrial Wastes Food/Beverage Ethanol asiabiogas Bangkok Singapore Jakarta 53