II Training session:
Biogas and cogeneration
Ekodoma
Claudio Rochas
Alba Iulia 3.11.2011
3 November 2011
Ekodoma
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Introduction
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15 November 1991
Two professors of
Riga Technical
University
15 November 2011
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3 November 2011
20 years
18 employees
3 divisions
Ekodoma
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Content
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Definitions and technologies
CHP versus separate generation of heat and
power
Do you need a CHP unit? Examples:
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District heating system
Biogas production and use
Economical assessment of CHP projects.
Simple example
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Cogeneration - definitions
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Cogeneration is the simultaneous generation in one
process of thermal energy and electrical and/or
mechanical energy;
useful heat is heat produced in a cogeneration process
to satisfy an economically justifiable demand for heat
or cooling;
economically justifiable demand is a demand that
does not exceed the needs for heat or cooling and
which would otherwise be satisfied at market
conditions by energy generation processes other than
cogeneration.
DIRECTIVE 2004/8/EC
3 November 2011
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Cogeneration technologies
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Combined cycle gas turbine with heat recovery
Steam backpressure turbine
Steam condensing extraction turbine
Gas turbine with heat recovery
Internal combustion engine
Microturbines
Stirling engines
Steam engines
Fuel cells
ORC
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Cogeneration - definitions
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Cogeneration units:
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Micro-cogeneration means below 50 kWe;
Small-scale cogeneration means below 1 MWe.
Power to heat ratio ( ):
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the ratio between electricity from cogeneration and
useful heat when operating in full cogeneration
mode
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Default power to heat ratio
Type of unit
value
Combined cycle gas turbine with heat recovery
0.95
Steam backpressure turbine
0.45
Steam condensing extraction turbine
0.45
Gas turbine with heat recovery
0.55
Internal combustion engine
0.75
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CHP and separate generation
Losses - 5
Fuel input
100
Useful heat - 95
Losses - 57
Fuel input
100
Electricity - 43
Losses - 15
Fuel input
100
Electricity - 35
Useful heat - 50
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Efficiency coefficient for heat
generation only
Fuel type
Solid fuels
3 November 2011
Hard coal/coke
Peat
Wood fuels
Oil, LPG
Biofuels
Natural gas
Biogas
Overall efficiency
0.88
0.86
0.86
0.89
0.89
0.9
0.7
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Efficiency coefficient for
electricity generation only
Fuel type
Solid fuels
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Hard coal/coke
Peat
Wood fuels
Oil, LPG
Biofuels
Natural gas
Biogas
Overall efficiency
0.442
0.390
0.330
0.442
0.442
0.525
0.420
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Alternatives for heat and
electricity supply
Condensing power plant
Electricity
CHP
Electricity
Heat energy
Heat energy
Boiler house
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CHP and separate generation
Fuel input
Separate
generation
Power station
43%
81
53
Boiler house
95%
Total 134
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Fuel input
Output
CHP
Electricity
35
Heat
50
Electricity
35%
Useful heat
50%
100
134
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100 Total 100
Primary
energy
savings
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25%
134
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District heating - example
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Jelgava municipality:
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New biomass fired cogeneration station
23 MWe
44 MWt
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Current situation - 2010
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Fortum Jelgava
Heat energy generation
240GWh
Heat energy sales
200GWh
Heat energy losses
16.8%
District heating network 70.4 km
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Electricity generation
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3 November 2011
32GWh
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Energy sources in Jelgava
Kalciema
2.5MW
Ganibu I
113MW
Instituta
0.9MW
Skautu
0.3MW
Aviacijas
28MW
Ganibu II
5MWt/4MWel
Filozofu
0.8MW
New link
Neretas
1MW
New CHP
44MWt/23MWel
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Heat load profile
Load, MW
Heat only boilers
Natural gas
2.5MW
CHP
Gas fired
Time, days
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Heat curve
Load, MW
Heat only boilers
Natural gas
2.5MW
CHP
Gas fired
Time, days
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Heat load profile – with
Biomass CHP
Heat only boilers
Natural gas
Load, MW
2.5MW
CHP
Biomass
2.5MW
CHP
Gas fired
Time, days
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Heat load curve
Load, MW
Heat only boilers
Natural gas
2.5MW
CHP
Biomass
2.5MW
CHP
Gas fired
Time, days
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Investment
Boiler block and turbine
€32.1m
Engineering comm
€8.9m
Automatisation
€1.5m
Electrical installation
€3.4m
Civil engineering works and
frames
€8.1m
Other
€13.3m
Total
€67.4m
Cofinancing from ES
- €6.0m
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Time schedule
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Beginning of project
01.06.2011
Civil engineering works
01.10.2011
Plant erection (boiler block and turbine)
25.06.2012
Mounting
01.12.2012
Boiler testing with natural gas
12.04.2013
Boiler testing with biomass
18.05.2013
Synchronization
05.06.2013
CHP under testing regime
18.07.2013
CHP operation
09.09.2013
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Environmental benefits
CO2 emission from heat energy generation,
CO2/kWh
250
200
150
100
50
0
2005
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2006
2007
2008
2009
2010
2011
2013
2015
2018
2020
CO2 emissions reduced by 75%-90% (44-54 thous. T /year)
Overall efficiency in CHP mode – 89%
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Definition of biogas
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Biogas typically refers to a gas produced by the
biological breakdown of organic matter in the absence
of oxygen.
Biogas is a mixture of gases produced by the
fermentation of waste by microorganisms under
anaerobic conditions. The gases present in the mixture
are methane (CH4), carbon dioxide (CO2) and traces
of odorigenic sulphates.
The methane contained in the biogas may be used as
fuel.
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Composition of biogas
Component
Methane, CH4
Carbon dioxide, CO2
Water vapour, H2O
Carbon oxide, CO
Nitrogen, N2
Hydrogen, H2
Hydrogen sulphide, H2S
Oxigen, O2
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
Fate clic per
%
modificare
il
50-75
formato 25-45
del testo
della struttura
1-2

0-0.3livello
Secondo
1-5
struttura

0-3
Terzo
livello
0.1-0.5
struttura
<2
 Quarto
Ekodoma
livello
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Biogas in terms of livestock
units
670 = 250 = 7 = 3 = 1
1 lu = 500 kg
lu = livestock unit
1 lu = 1,3 m3 biogas/day
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Biogas in terms of energy crops
Energy crops
(e.g., maize silage)
1 ha:
= 60 t (fresh matter)
= 22 t (dry matter)
= 9 900 m3 biogas
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Formation of biogas
Biomass
Dry matter
Water
Organic
Lignin
Fats
Inorganic
Sugars
Proteins
Minerals
Methane and Carbon dioxide
Biogas (CH4 and CO2)
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Feedstock for biogas production
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As a feedstock for anaerobic digestion can be
used several kind of organic matter, e.g.:
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Manure
Food waste and waste from food processing
industry
Cropping, forest and wood processing waste
Peat
Organic fraction of municipal waste
Sewage sludge
Greens from plants
...
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Biogas feedstock
Manure
Food waste
Agricultural waste
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Gas yield from different substrates
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Biogas yield (outcome) depends from:
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Feedstock used for anaerobic fermentation
(substrate),
Conditions during the anaerobic digestion process
(temperature, pH, retention time),
Content of micro-organisms,
Other factors like components and composition of
organic matter.
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Gas yields from different substrates
Biogas yields (rel. to fresh
DM
oDM
m3 Biogas
substance and cult. area)
(in %)
(% of DM)
40-75
45-70
40
83
Grain straw (diverse)
85-90
85-89
Poultry manure
50-70
60-70
Vegetable waste
5-20
60-90
Canteen waste
9-18
90-95
Chicken manure
21
75
12-15
90
Grass
20
80
Maize silage (dow stage)
30
95
Maize silage (wax ripeness stage)
33
96
Horse manure
28
75
Rape cake
91
93
12-25
65-85
Bio waste
Grass silage
Potato waste
Cattle manure
Wheat grain
90
Sugar beets leaf silage
18
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per kg oDM
Fate
clic per
m3/t FM
m3/ha
0,45
120il
-modificare
0,455
220
5720
0,3-0,6
217-481testo1084-2403
formato
del
0,55-0,65
300-490
-della
0,45 struttura
80
-0,55-0,78
80-170
--
160
-Secondo
livello
0,25-0,35
27-47
-0,48
160
4480
struttura
0,6
151
5600

0,5
0,63
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196
7385
Terzo82 livello -0,72
612
1224
struttura
0,2-0,3
650
3250
 Quarto
90
3590
Ekodoma
livello
0,45
Source: GERBIO
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Main components of the farmscale biogas plant
Source: BiG>East Biogas Handbook
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Main components of the farmscale biogas plant
Loading of solid and liquid
feedstock
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Main components of the farmscale biogas plant
Bioreactor
Digestate storage tanks
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Gas holder
CHP unit
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Biogas has many utilisations
Source: FITEC
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Efficient biogas pathways (bold
arrows)
R
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b
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ly
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a
sb
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a
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Source: AEBIOM
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CHP unit
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Standard utilisation for biogas
Most common is in internal
combustion engines
Efficiency up to 90%
Power to heat ratio up to 70%
Typically:
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35% Electricity
65% Heat
Alternatives: Stirling-Motors,
micro gas turbines and fuel cells
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Cost for biogas plant
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3000- 4000 €/kWe for average size biogas
plant (250-500 kWe)
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Cheap and low standard plant is 2800 €/kWe
Medium standard plant is 3500 €/kWe
High standard plant is 4000 €/kWe
Waste treatment plants (more complex
feedstock preparation and treatment process)
are about 5600 €/kWe.
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Maintaining the CHP plant
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0.3 – 2.5 €c/kWhel.
Maintenance costs for all other components
of a biogas plant are about 1 – 3% of the
total investment sum (Steiner, 2009).
In Germany, the transport of each m3 of
biomass costs about 2 – 2.9 € per kilometer
(Theissing, 2006).
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Planning:
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CHP plant
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Costs for planning the biogas plant generally at be
estimated 10% of the total investment.
Costs for the CHP about 20% of the total
investment (Steiner, 2009).
Fermenter:
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Costs for the fermenter can reach 40 – 50% of the
total investment sum (Steiner, 2009)
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Biogas upgrading
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Biogas can be used for the same
purposes as natural gas
Upgrading to biomethane
Methane content > 95%
Common methods use the
absorbtion with solvent. Water
solvent scrubbing, organic solvent
scrubbing, pressure swing
absorption
Costs are not linear to the plant
size
Biogas input > 500 m³/h
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Biogas as vehicle fuel
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Utilisation of biomethane in the
transport sector is a technology
with great potential
Biomethane is used in the same
way like natural gas
There are specially built biogas
vehicles
Biomethane has the highest
potential as vehicle fuel of all
biofuels
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Biomethane for grid
injection
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Upgraded biogas (biomethane)
can be injected and distributed
through the natural gas grid
Connect rural production areas
with high populatet areas
The gas can be used on a higher
efficiency level
The Biomethane has to fit the
national standards for natural
gas
The costs are the same as for
upgrading plus the grid
connection
3 November 2011
Source: FITEC
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Biogas and greenhouse gas
emissions
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The combustion of biogas releases CO2. However, the main
difference, when compared to fossil fuels, is that the carbon in
biogas was recently up taken from the atmosphere, by
photosynthetic activity of the plants.
The carbon cycle of biogas is thus closed within a very short
time (between one and several years).
Biogas production by anaerobic digestion reduces also
emissions of methane (CH4) and nitrous oxide (N2O) from
storage and utilization of untreated animal manure as fertilizer.
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Biogas production – a tool for
manure management
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Positive changes of liquid manure properties
through fermentation:
 Decomposition of organic substance
•
•
Decomposition rates oDM: of up to 40%
The fermented liquid manure can be pumped and
sprayed better compared to the raw liquid manure
 Odor reduction
 Reduction of the odor causing substances (humid acids,
Phenols, Phenol derivate)
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Use of biogas digestate
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Digestate can be spread on the fields - no hygiene restrictions
with animal slurry and plant material
Improved Fertilizer
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avoids nutrient losses
reduces burning effect on plants
improves flowing properties
improves plant compatibility
improves plant health
reduces germination ability of weed seeds
Environmentally sound
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reduces the intensity of odor
reduces air pollution through methane and ammonia
reduces the wash out of nitrate
sanitizes liquid manure
recycles organic residues (co-fermentation)
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Economical assessment
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Example: CHP Unit- internal combustion engine – natural gas
Electrical nominal capacity, EJ
= EJ/Qs
4,0 MWe
0,75 (power to heat ration)
Heat nominal capacity, Qs = EJ/
5,33 MWt
Overall efficiency,
0,90
Operational hours
4000 Hours/year
=(E+Q)/F
Generated electricity, E
16000 MWhe/year
Generated heat energy, Q
21333 MWht/year
Fuel consumption F=(E+Q)/
41481 MWhf/year
Fuel lower calorific value, Qzd
9,3 MWh/t.nm3
Fuel consumption, F = F/Qz
4460 t.nm3/year
Fuel tariff, Tg
325,5 €/t.nm3
Unit fuel costs, CF=Tg/Qz
Fuel (variable) cost, VC=CF x F
3 November 2011
35 €/MWhf
1 451 835 €
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Investment costs
Specific investment costs, IP
Total investment costs, K=IP x EJ x 1000
Discount rate, r
Economical life time, n
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940 €/kWe
3 760 000 €
10%
10 years
Note:
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Operation and maintenance costs are not
included
40 € /kWe x 4000kWe = 160 000 €/year
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Project cash flow analysis
6000
5000
4000
3000
k Euro
2000
1000
0
-1000
1
2
3
4
5
6
7
8
9
10
-2000
-3000
-4000
-5000
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References
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CHP Goes Green
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BiogasIN
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http://www.chp-goes-green.info/
http://www.biogasin.org/
Urbanbiogas
Big-East
COGEN
DIRECTIVE 2004/8/EC
3 November 2011
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Thank you!
Ekodoma
3-3 Noliktavas Street, Riga
LV1010, Latvia
Tel: +371 7323212
Fax: +371 7323210
Mob: +371 26745700
email: claudio@ekodoma.lv
Web side Ekodoma:
www.ekodoma.lv
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