TRENDS AND PERSPECTIVES FOR ANAEROBIC DIGESTION: AN OVERVIEW

LUC DE BAERELUC DE BAEREORGANIC WASTE SYSTEMS

ISWA BEACON CONFERENCE: ‘THE GLOBAL CHALLENGE: OPTIMISING THE C-CYCLE’

PERUGIA, ITALY, MAY 22-23, 2008

ADVANTAGES OF ANAEROBIC DIGESTION OF SOLID WASTE

• PRODUCTION OF RENEWABLE ENERGY(60 TO 100 M³ OF METHANE/TON)

• RECOVERY OF ORGANIC MATTER AS COMPOST

• 200 TIMES LESS ODOURS THAN AEROBIC COMPOSTINGCOMPOSTING

• 20 TO 40% OF SURFACE AREA NEEDED FOR AEROBIC COMPOSTING: EASY TO INSERT

• HIGH PUBLIC ACCEPTANCE

WHAT IS THE STATE OF THE ARTOF ANAEROBIC DIGESTION

OF THE ORGANIC FRACTION OF MUNICIPAL SOLID WASTE

IN EUROPE?IN EUROPE?

DETERMINATION OF CAPACITY

CRITERIA

• HOUSEHOLD ORGANIC WASTE OR EQUIVALENT

• MORE THAN 10% HOUSEHOLD ORGANIC SOLID WASTE

• > 3000 T PER YEAR MINIMUM SIZE

• DESIGN CAPACITY USED UNLESS SPECIFIED • DESIGN CAPACITY USED UNLESS SPECIFIED OTHERWISE

• TOTAL CAPACITY FOR BIOWASTE, BUT ONLY DIGESTION CAPACITY FOR RESIDUAL WASTE

• PLANTS NOT ELIMINATED IF OPERATION STOPPED

• PLANTS AT LEAST UNDER CONSTRUCTION(ONLY PROGNOSIS FOR YEAR 2009-2010)

CAPACITY IN EUROPE

• 171 PLANTS IDENTIFIED IN 17 EUROPEAN COUNTRIES

• 5.204.000 T/YEAR CAPACITY IN 2010

• CAPACITY DEVELOPMENTPERIOD INCREASE AVERAGE SIZE PLANTS/YEARPERIOD INCREASE AVERAGE SIZE PLANTS/YEAR

91 - 95 39 KT/Y 13 KT/Y 3 96 - 00 224 KT/Y 25.4 KT/Y 8.8 01 - 05 415 KT/Y 38.5 KT/Y 10.806 - 10 346 KT/Y 31.4 KT/Y 11

CUMULATIVE CAPACITY

3.000

4.000

5.000

6.000

Inst

alle

d C

apac

ity (

kTO

N)/

y)

15

20

25

30

35

Average size plants (kTO

N/y)

Anual capacity

Cumulative Capacity

Cumulative AverageCapacity

0

1.000

2.000

till 19

90 91 92 93 94 95 96 97 98 9920

0020

0120

0220

0320

0420

0520

0620

0720

08>20

09

Inst

alle

d C

apac

ity (

kTO

N)/

y)

0

5

10

15

Average size plants (kTO

N/y)

FACTORS STIMULATING GROWTH IN CAPACITY

• LANDFILL DIRECTIVE AND RENEWABLE ELECTRICITY

• HIGH PRICE FOR OIL AND AGRICULTURAL CROPS MAY PLAY MORE OF A ROLE IN COMING YEARS

• IMPACT ENERGY PRICE LARGER FOR CLEAN • IMPACT ENERGY PRICE LARGER FOR CLEAN INDUSTRIAL ORGANICS THAN FOR HOUSEHOLD WASTE ORGANICS

• REVAMPING EXISTING COMPOSTING INSTALLATIONS (GROWTH FOR BIOWASTE DIGESTION, POSSIBLE GROWTH FOR RESIDUAL WASTE DIGESTION IN APPROXIMATELY 5 YEARS)

FACTORS HAMPERING GROWTH IN CAPACITY

• HYGIENIZATION REQUIREMENTS: NOT ONLY HIGH TEMPERATURE TREATMENT BUT ALSO SEPARATION NONHYGIENIZED/HYGIENIZED

• AIR EMISSION REQUIREMENTS: - RTO ON DIRTY AIR- RTO ON DIRTY AIR- LOW ODOR LEVELS

• STILL HIGHER COST THAN IN-VESSEL-COMPOSTING UNITS

CAPACITY PER COUNTRY

800.000

1.000.000

1.200.000

1.400.000

1.600.000

1.800.000

Inst

alle

d C

apac

ity (

t/y)

40.000

50.000

60.000

70.000

80.000

Total Capacity

Average Capacity

0

200.000

400.000

600.000

800.000

GERMANY

SPAINFRANCE

ITALY NL UK

SWIT

ZERLA

NDBELGIU

MPORTUGAL

AUSTRIASW

EDENM

alta

Luxe

mbu

rgNorw

ayDenm

ark

POLAND

FINLA

ND

Inst

alle

d C

apac

ity (

t/y)

0

10.000

20.000

30.000

ANALYSIS OF INSTALLED CAPACITY

•••• MESOPHILIC (35 - 40 °C) VERSUS THERMOPHILIC (50 - 55°C)

•••• DRY (> 15 % DS) VERSUS WET (< 15 % DS)

•••• TWO PHASE (ACIDIFICATION + METHANIZATION)

VERSUS SINGLE PHASE (COMBINED)VERSUS SINGLE PHASE (COMBINED)

•••• CODIGESTION (SOLID WASTE + OTHER SUBSTRATE)

VERSUS SOLID WASTE DIGESTION (ONLY WASTE)

•••• MIXED OR RESIDUAL WASTE (NO SEPARATE

COLLECTION) VERSUS BIOWASTE

(SEPARATE COLLECTION OF ORGANICS)

MESOPHILIC VERSUS THERMOPHILIC

2.000

2.500

3.000

3.500

4.000

Cum

ulat

ive

(kT

ON

/y)

50%

60%

70%

80%

90%

100%

MESO

THERMO

%MESO

0

500

1.000

1.500

till 19

90 91 92 93 94 95 96 97 98 9920

0020

0120

0220

0320

0420

0520

0620

0720

08>20

09

Cum

ulat

ive

(kT

ON

/y)

0%

10%

20%

30%

40%%MESO

%THERMO

MESOPHILIC VERSUS THERMOPHILIC

• 69% MESOPHILIC VS 31% THERMOPHILIC IN 2010

• 95% OF THERMOPHILIC PLANTS ARE DRY FERMENTATION

• ONLY 1 DRY CONTINUOUS SYSTEM OPERATES MOSTLY MESOPHILICALLY

• DRY BATCH SYSTEMS ALSO OPERATE IN MESOPHILIC TEMPERATURE RANGE

MESOPHILIC VERSUS THERMOPHILIC

MESO VS THERMO 1991 – 1995 1996 – 2000 2001 – 2005 2006 - 2010

% MESOPHILIC 64 64 80 59

• FIVE YEAR DEVELOPMENT OF CAPACITY

% MESOPHILIC

% THERMOPHILIC

64

36

64

36

80

20

59

41

WET VERSUS DRY

2.000

2.500

3.000

3.500

Cum

ulat

ive

(kT

ON

/y)

40%

50%

60%

70%

0

500

1.000

1.500

till 1

990 91 92 93 94 95 96 97 98 9920

0020

0120

0220

0320

0420

0520

0620

0720

08>20

09

Cum

ulat

ive

(kT

ON

/y)

0%

10%

20%

30%WET

DRY

%WET

%DRY

WET VERSUS DRY

• DRY 57% , WET 43% IN 2010

WET VS DRY 1991 – 1995 1996 – 2000 2001 – 2005 2006 - 2010

• FIVE YEAR DEVELOPMENT OF CAPACITY

% WET

% DRY

37

63

38

62

59

41

29

71

ONE VERSUS TWO-PHASE

2.500.000

3.000.000

3.500.000

4.000.000

4.500.000

5.000.000

Cum

ulat

ive

(t/y)

50%

60%

70%

80%

90%

100%

ONE CUMULATIVE

TWO CUMULATIVE

%ONE

0

500.000

1.000.000

1.500.000

2.000.000

till 1

990 91 92 93 94 95 96 97 98 9920

0020

0120

0220

0320

0420

0520

0620

0720

11>20

09

Cum

ulat

ive

(t/y)

0%

10%

20%

30%

40%%TWO

ONE VERSUS TWO-PHASE

• 93% ONE-PHASE VS 7% TWO-PHASE BY 2010

• FULL-SCALE PERCOLATION SYSTEMS WERE CONSTRUCTED (CONSIDERED TWO-PHASE SYSTEMS) IN 2000-2005, BUT NO MORE IN 2006-2010 EXCEPT FOR BATCH SYSTEMS2010 EXCEPT FOR BATCH SYSTEMS

• SOME BATCH SYSTEMS HAVE TWO METHANOGENIC PHASES

ONE VERSUS TWO-PHASE

SINGLE VS TWO PHASE

1991 – 1995 1996 – 2000 2001 – 2005 2006 - 2010

% SINGLE 85 91 92 98

• FIVE YEAR DEVELOPMENT OF CAPACITY

% SINGLE

% TWO PHASE

85

15

91

9

92

8

98

2

SINGLE FEEDSTOCK VERSUS CODIGESTION

2.000

2.500

3.000

3.500

4.000

4.500

5.000

Cum

ulat

ive

(kT

ON

/y)

40%

50%

60%

70%

80%

90%

100%

SOLID WASTE

CODIGESTION

% Solid Waste

% Codigestion

0

500

1.000

1.500

2.000

till 1

990 91 92 93 94 95 96 97 98 9920

0020

0120

0220

0320

0420

0520

0620

0720

08>20

09

Cum

ulat

ive

(kT

ON

/y)

0%

10%

20%

30%

40%% Codigestion

SINGLE FEEDSTOCK VERSUS CODIGESTION

• 92% ONLY SOLID WASTE VS 8% CODIGESTION BY

2010

• CODIGESTION WITH ENERGY CROPS (CORN) BUT LIMITED SO FAR

• MANY ENERGY CROP DIGESTION PLANTS ARE LOOKING FOR ORGANIC WASTE TO REPLACE EXPENSIVE CROPS, BUT ‘WASTE TREATMENT’ COMPLICATES THE PROJECTS SUBSTANTIALLY

SINGLE FEEDSTOCK VERSUS CODIGESTION

SOLID WASTE VS CODIGESTION

1991 – 1995 1996 – 2000 2001 – 2005 2006 - 2010

• FIVE YEAR DEVELOPMENT OF CAPACITY

% ONLY SOLID WASTE

% CODIGESTION

77

23

90

10

90

10

95

5

BIOWASTE VERSUS RESIDUAL WASTE

1.500

2.000

2.500

3.000

Cum

ulat

ive

(kT

:y)

50%

60%

70%

80%

90%

100%

BIOWASTE

RESIDUAL

%BIOWASTE

%RESIDUAL

0

500

1.000

1.500

till 1

990 91 92 93 94 95 96 97 98 9920

0020

0120

0220

0320

0420

0520

0620

0720

08>20

09

Cum

ulat

ive

(kT

:y)

0%

10%

20%

30%

40%

50%

BIOWASTE VERSUS RESIDUAL WASTE

• IN 1998: 87% BIOWASTE VS 13% RESIDUAL WASTE

• IN 2010: 52% BIOWASTE VS 48% RESIDUAL WASTE

• FIVE YEAR DEVELOPMENT OF CAPACITY

BIOWASTE VS 1991 – 1995 1996 – 2000 2001 – 2005 2006 - 2010BIOWASTE VS RESIDUAL

1991 – 1995 1996 – 2000 2001 – 2005 2006 - 2010

% BIOWASTE

% RESIDUAL

92

8

72

28

41

59

49

51

DIVERSITY IN APPLICATION

• MIXED WASTE + BIOWASTE + RESIDUAL WASTE

• RESTAURANT WASTE - CORN - INDUSTRIAL

ORGANICS AS ADDITIONAL FEEDSTOCKS

• MIXED/RESIDUAL WASTE: PARTIAL STREAM

DIGESTION (20 TO 70% OF ORGANICS) AND FULL

STREAM DIGESTION (100% OF ORGANICS)

DIGESTION CAN BE INSERTED INTO EXISTING COMPOSTING SITES

EXPANSION OF EXISTING COMPOSTING SITES

• MANY COMPOSTING SITES HAVE MORE WASTE BUT SITES HAVE NO ROOM FOR ADDITIONAL COMPOSTING AREA

• INSERTION OF PARTIAL STREAM ANAEROBIC DIGESTION CAN INCREASE EXISTING CAPACITY BY DIGESTION CAN INCREASE EXISTING CAPACITY BY UP TO 50% WITH MINIMAL SURFACE REQUIREMENT

• ECONOMICALLY VERY ATTRACTIVE

• WATER BALANCE IS CRUCIAL

CASE STUDY: INSERTION OF PARTIAL STREAM DIGESTION INTO EXISTING AEROBIC PLANT

• EXISTING AEROBIC COMPOSTING FACILITY

• CURRENT CAPACITY: 60.000 TPY OF BIOWASTE

• LOOKING FOR OPPORTUNITIES: COSTS, CAPACITY,…

• INSERTION OF AD PLANT FOR 40.000 TPY THROUGH PARTIAL STREAM DIGESTION

• USE OF EXISTING EQUIPMENT FOR AEROBIC TREATMENT

���� CONSEQUENCES?

CASE STUDY: LAYOUT SITE

190 m

90 m

35 mANAEROBIC DIGESTION0,2 ha

AEROBIC

125 mCOMPOSTING

2,4 ha

CASE STUDY: NEW PROCESS SCHEME

Biogas

GAS STORAGEDRANCO-

DIGESTER

2.600 m³

BiowasteFLARE

(<40 mm)

SIEVE

ENGINES Electricty (1.150 kW)

Heat (>40 mm)

(1.150 kW)

41

1 2 3

Tons/year 90.000 40.000 800

SteamDOSING UNIT

MIXING UNIT/ FEEDING PUMP

(<40 mm)

Existing aerobic composting

Heat

MIXER

(1.150 kW)

2

3

5

6

4 5 6

6.575 34.225 50.000

7

7

84.225

CASE STUDY: RESULTS

• NEW SITE CAPACITY = ca. 90.000 TON PER YEAR (DEPENDING ON TOTAL SOLIDS CONTENT OF THE SUBSTRATE)

• AD ON ONLY 10% OF THE SURFACE AREA OF THE AEROBIC COMPOSTING INCREASES SITE CAPACITY WITH ABOUT 50%

• AD PLANT PRODUCES ENOUGH ENERGY FOR THE WHOLE SITE

• DESPITE HIGHER CAPACITY, ODOR EMISSIONS ARE LOWER

• NET PROFIT OF AD PLANT POSSIBLE, DEPENDING ON LOCAL REVENUES FOR GREEN POWER OR ENERGY PRICES.

DIGESTION CAN BE COMBINED WITH DRYING USING WASTE HEAT OF ENGINES

SHREDDER

ROTATING

GAS STORAGEDRANCO

DIGESTER

Biowaste BiogasFLARE

> 60ElectricityGAS ENGINES

-Treatment of biowaste without wastewater productio n -

FLOW SCHEME DRANCO PLANT LEONBERG (GERMANY)

ROTATINGSIEVE

MAGNET

MAGNET

SHREDDER

DOSING UNIT FEEDINGPUMP

DRYERAEROBIC

COMPOSTING

2.440 m³

Residue

< 60

Overflow

ElectricityGAS ENGINES

Heat

Heat

Compost

DRANCO PLANT LEONBERG

750

1,000

1,250

1,500T

ON

S

150

200

250

300

Nm

³ BIO

GA

S/T

ON

INP

UT

0

250

500

50 1 5 9 13 17 21 25 29 33 37 41 45 49 4 8 12 16 20 24 28 32 36 40 44 48 52 3 7 11 15 19 23 27 31 35 39 43 47 51 2

WEEK (end 2004 - start 2008)

TO

NS

0

50

100

Nm

³ BIO

GA

S/T

ON

INP

UT

INPUT IN REACTOR BIOGAS PRODUCTION AVERAGE BIOGAS PRODUCTION PER YEAR

DRANCO INSTALLATION IN LEONBERG

DRYER

SOLID WASTE DIGESTION TECHNIQUES ARE BEING UTILIZED FOR ENERGY CROPS

WITH WASTE HEAT RECOVERY

HORIZONTAL WASTE DIGESTER: BIOWASTE+CROPS

HORIZONTAL DIGESTER WITH HEAT RECOVERY

VERTICAL WASTE DIGESTER WASTE FOR CROPS

SOLID WASTE DIGESTION APPLIED TO ENERGY CROPS WITH HEAT RECOVERY

TOTAL DIGESTER INPUT & ELECTRICITY PRODUCTION- DRANCO-FARM PLANT NÜSTEDT -

200

240

280

320

360

400

Ton

s

50,000

60,000

70,000

80,000

90,000

100,000

kWh electricity

0

40

80

120

160

200

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51

Week

Ton

s

0

10,000

20,000

30,000

40,000

50,000

kWh electricity

TOTAL INPUT IN DIGESTER kWh PRODUCED MAX kWh (PERMIT)

• INCREASE IN 2006-2008

(NO INCREASE SINCE 1996)

• SO FAR LIMITED TO BIOWASTE

BATCH DIGESTION SYSTEMS

• SINGLE PHASE AND TWO-PHASE SYSTEMS

• LESS INVESTMENT AND MAINTENANCE

(BUT ALSO LESS RECOVERY)

• MORE WET ORGANIC INDUSTRIAL FEEDSTOCKS

• MORE EASY TO INTEGRATE WITH

WET ENERGY CROP PLANTS

WET DIGESTION

• GROWTH CONTINUES AT THE SAME PACE AS BEFORE

(ABOUT 11 PLANTS PER YEAR WITH AVERAGE SIZE OF 3500 0 T/Y)

• BATCH DIGESTION SYSTEMS REACTIVATED IN 2006-2008

• INSERTION OF BIOWASTE DIGESTION PLANTS

IN EXISTING COMPOSTING PLANTS

CONCLUSIONS

IN EXISTING COMPOSTING PLANTS

• CONTINUED GROWTH IN FRANCE AND UK FOR MIXED WASTE

• FURTHER EXTENSION INTO OTHER COUNTRIES

HOW ABOUT ITALY?