educompost, ks & jf energy from bio wastes energy from bio wastes: fundamental considerations,...
TRANSCRIPT
Educompost, ks & jf
Energy from bio wastes
Energy from bio wastes: Fundamental considerations,
data, comparison from products
Dr. Konrad Schleiss, UMWEKO
Dr. Jacques FuchsBiophyt SA
Educompost, ks & jf
Energy from bio wastes
Fondamentals The energy potential from wastes is considerable
Depending of their treatment, it cost or produce more or less energy
More dry the wastes are, more easy is the energy use by combustion
More wet the wastes are, more easy is the energy use by anaerobic digestion
Important for its energy efficiency is the use of the energy, not its global production
Educompost, ks & jf
Energy from bio wastes
Treatment by burning Burning use the complete energy capital of the
products; waste will be completely mineralized
Products are only mineral (ashes)
The energy content is describe by the highest calorific value (Gross Calorific Value GCV, without water) and the
lower calorific value (Net Calorific Value - NCV)
Wastes have a middle calorific value from NCV=3 kWh/kg
Bio wastes with a DM from 35 - 40% have a NCV = 0,1-0,5 kWh/kg
So the bio wastes bring not so much energy in the incineration plants
Educompost, ks & jf
Energy from bio wastes
Calorific value of wood and of bio wastes
Calorific value of bio waste is
similare to the calorific value of
wood if we consider only the
organic matter content
Valeur calorifique [kWh/kg]
Teneur en eau [%]
Relation entre la valeur calorifique et la teneur en eau (Jonas & Görtler, 1997)
Educompost, ks & jf
Energy from bio wastes
Treatment by composting
Generally, about 50% of the organic matter will be degradated by composting
In average, 0,03 kWh/kg of bio wastes are needed
According to Heller, compost contain still 2,6 kWh/kg MS = 1,3/kg MF = 0,78/lt MF = approx. 50% from input GCV
GCV from biowaste = 1,3 - 1,7 kWh/kg
Educompost, ks & jf
Energy from bio wastes
Treatment by anaerobic digestion
An average of 100 m3 biogas per ton of bio waste is produce
It correspond to approx. 600 kWh
If we produce fuel wit it, approx. 400 kWh can be used
If we produce electricity (without use of heat), we obtain approx. 140 kWh/t or 0,14 kWh/kg
Educompost, ks & jf
Energy from bio wastes
Comparison of the energey balances
CompostingAnaerobic
fermentation (solid material)
Incineration chips
Energy used 30140
25(40 electr. + 100 heat)
Production of usable energy
0 600 2000
Balance -30460
1975 (heat)(140 electr. + 280 heat)
Energy usual used
0 140 1975
Source: Kompost und Energie aus biogenen Siedlungsabfällen ATAL (Amt für technische Anlagen und Lufthygiene) und AGW (Amt für Gewässerschutz und Wasserbau, Kz ZH) Nov 1997
Educompost, ks & jf
Energy from bio wastes
Comparison (canton Zurich)
-0.5
0
0.5
1
1.5
2
2.5
incineration (6)
Anaerob. Dig.(6)
Composting(20)
En
erg
y u
sable
[kW
h/k
g Moyenne
Maximum
Minimum
Médiane
Educompost, ks & jf
Energy from bio wastes
Comparison
Incinerators burn normally waste with high energy content
New incinerators utilized very efficiently the energy
Also if the energy content of bio wastes is twice less important as the household wastes, the energy usable
by incineration is twice higher as by anaerobic digestion
The energy content in compost and digestate is here not consider
If we consider the organic matter, the comparison could be different...
Educompost, ks & jf
Energy from bio wastes
What are the products of the different treatments ?
Energie
Digestate solid
Digestate liquide
Anaerobic digestion:
Composts
(different qualities)
Composting:
Energie
Ashes
Incineration:
Educompost, ks & jf
Energy from bio wastes
Remark:
With an appropriate composting process, it is
possible to produce compost out of digestate.
Educompost, ks & jf
Energy from bio wastes
Which differences have the products out a agricultural
point of view.
Educompost, ks & jf
Energy from bio wastes
Chemical properties from composts, digestates and wood ashes
Source de données pour le compost, digestat et eau de pressage: Konrad Schleiss, Analysen des Kanton Zürich, 2004
Source de données cendres: Risikoanalyse zur Abfalldüngerverwertung in der Landwirtschaft, FAL, 2001
Compost Digestat Eau de pressage Cendres de boisMédiane (max./ min.) Médiane (max./ min.) Médiane (max./ min.) Médiane (max./ min.)
MS [% MF] 47,9 (30,7 / 75,8) 51,1 (41,8 / 68,5) 11,1 (2,5 / 19,6) 95MO [% MS] 44,7 (17,0 / 72,2) 44,9 (35,6 / 61,1) 49,0 (38,9 / 64,5) 0 Valeur pH 7,9 (7,0 / 8,6) 7,8 (7,5 / 8,6) 7,7 (7,5 / 8,1) Salinité [mS] 2,5 (0,9 / 6,6) 2,7 (1,7 / 5,3) 16,0 (7,3 / 22,9)NO3-N [g N/t TS] 284 (0 / 1506) 455 (0 / 968) 2554 (995 / 5458) 0NH4-N [g N/t TS] 28 (0 / 482) 913 (515 / 2001) 13057 (1288 / 38710) 0 NO3-N/NH4-N 6,6 (0,0 / 427,1) 0,4 (0,0 / 1,2) 0,25 (0,06 / 2,87) Ntot [kg N/t TS] 13,0 (6,9 / 26,1) 12,6 (8,8 / 26,0) 35,3 (19,1 / 69,7) 0 P2O5 [kg/t TS] 6,2 (3,7 / 12,9) 7,2 (5,8 / 10,1) 14,3 (9,9 / 24,3) 24K2O [kg/t TS] 10,5 (5,6 / 25,5) 10,3 (7,4 / 24,9) 35,1 (18,1 / 90,8) 70 Ca [kg/t TS] 53,9 (23,8 / 148,6) 62,9 (42,2 / 154,9) 36,5 (19,1 / 71,4) 300 Mg [kg/t TS] 6,5 ( 3,5 / 15,2) 6,3 ( 4,6 / 9,0) 9,5 ( 7,5 / 11,6) 25 SO4 [kg/t TS] 4,5 (2,0 / 7,5) 4,7 (3,3 / 7,0) 8,0 (5,0 / 10,2)
Cd [g/t TS] (GW: 1) 0,32 (0,12 / 0,49) 0,20 (0,12 / 0,62) 0,52 (0,14 / 0,66) 0,3-2,7Cu [g/t TS] (GW: 100) 40,7 (19,1 / 724,3) 38,7 (24,2 / 1504,0) 75,3 (38,0 / 106,8) 86-376 Ni [g/t TS] (GW: 30) 14,7 (5,9 / 29,7) 10,9 (4,3 / 19,1) 25,5 (9,8 / 38,5) 36-140 Pb [g/t TS] (GW: 120) 32,1 (8,2 / 66,9) 27,3 (17,4 / 55,2) 41,9 (15,1 / 90,4) 3,4-39,9 Zn [g/t TS] (GW: 400) 123,5 (71,9 / 316,9) 90,5 (42,4 / 189,6) 231,7 (153,6 / 355,4) 81-522 Zn [g/t TS] (GW: 400) 123,5 (71,9 / 316,9) 90,5 (42,4 / 189,6) 231,7 (153,6 / 355,4) 81-522
Educompost, ks & jf
Energy from bio wastes
Hygienic quality of the products:
Ashes: OK
Compost: OK
Digestates ?
Educompost, ks & jf
Energy from bio wastes
Hygienic quality of digestates:Influence of anaerobic digestion on survival from of clubroot
1 55 14
2 55 14
3 55 14
100
100
99
1
0
0
4 55 7
5 55 7
6 55 7
92
100
98
0
22
1
7 35 14
8 35 14
9 35 14
93
98
99
96
98
98
withoutanaerobic digestion
with
% diseased plantsTest
No.
Temp.
[ °C ]
Duration of anaerobic digestion
[days]anaerobic digestion
Educompost, ks & jf
Energy from bio wastes
Hygienic quality of digestates:
thermophile (55°C)
mesophile (35°C)
Temperatur assume not a hygienisation of the digestate. Other actions have to be done.
OK
Educompost, ks & jf
Energy from bio wastes
Hygienic quality of digestates:
thermophile (55°C)
mesophile (35°C)
Post-composting of solid digestate: OK
Post-treatement liquide digestate ?
Prée-treatement of input materials?
Educompost, ks & jf
Energy from bio wastes
Biological quality of the products
Ashes
● Biologically dead
● Availability of nitrogen: neutral (bring no nitrogen in soil, but immobilized also no nitrogen)
Educompost, ks & jf
Energy from bio wastes
Biological quality of the products
Liquid digestate ● Relatively similar to liquid manure
● Can be spread only when the plants can assimilate nitrogen (to be consider by the
calculation of the needed storage capacity)
● Concentrated N-fertilizer for the plants
Educompost, ks & jf
Energy from bio wastes
Biological quality of the products
Solid digestate● Qualitatively similar to manure
● Phytotoxic
● Problematic of nitrogen: depending of its storage and its post-treatment, the digestate can bring relatively important quantity of mineral nitrogen to the soil, but
can also immobilized the soil nitrogen.
● Biologically not stable
● Low disease suppressivity potential
Educompost, ks & jf
Energy from bio wastes
Biological quality of the products
Compost● Depending of its maturity stage: stabilized product,
good compatible with plants
● Influence positively the plant health(disease suppression)
● Problematic of nitrogen: depending of its maturity stage and of the process management, can blocked nitrogen in the soil, or give some nitrogen free in the
soil
● Influence positively the soil biology
Educompost, ks & jf
Energy from bio wastes
And the organic matter ?
Educompost, ks & jf
Energy from bio wastes
Importance of organic matter for the soil fertility
Influence the soil structure
Influence the water management
Protection against erosion
Amélioration of the soil biological activity
Influence the climat
Educompost, ks & jf
Energy from bio wastes
Quality of the organic matter of the different products
Every organic matter bring to the soil has not the same effect. Easy degradable
organic matter can also influence negatively the organic balance of a soil,
because it promote too much the microorganisms responsible for the mineralization of the organic matter.
Educompost, ks & jf
Energy from bio wastes
Quality of the organic matter of the different products
Ashes: no organic matter
Liquid digestate: organic matter very quickly degradable
Solid digestate: organic matter easily degradable
Compost: depending of its maturity stage, organic matter middle to high stable
Educompost, ks & jf
Energy from bio wastes
Middle or long term influence of the different products on the humus level
in soil
Ashes: neutral
Liquid digestate: neutral or negativ
Solid digestate: neutral or slightly positive
Compost: slightly to strong positive
Educompost, ks & jf
Energy from bio wastes
Conclusions:
There is more than only energy in bio wastes. These other aspects have to be consider when we choose a concept of
treatment for these products.
What do you mean ? How many kilowatts do we have in a
fertile soil ?