Transcript Energy

BUDAPEST UNIVERSITY OF TECHNOLOGY AND ECONOMICS
FACULTY OF CHEMICAL AND
BIOCHEMICAL ENGINEERING
DEPARTMENT OF CHEMICAL AND
ENVIRONMENTAL PROCESS
ENGINEERING
Future and energy
BIOENERGY
What about me 40 years later ?
Dr. Bajnóczy Gábor
Tonkó Csilla
The pictures and drawings of
this presentation are used and
can be used only for education !
Any commercial use is
prohibited !
Perhaps this will be my car ?
Or these vehicles ?
Fuel shortage !
Is it me at home in winter ?
Or she is my wife waiting for me at home
Energy from bio-energy plant
Adequate technology is applied to convert the biomass to
- energy (direct conversion)
● combustion
- fuel (indirect conversion)
● thermal gasification
● bio-oil by pyrolysis
● gasification by biomethods
● bioethanol production
● biodiesel production
The most important questions are the
- ENERGY CONTENT OF THE BIOMASS
- Availability of Biomass
- Costs
ENERGY CONTENT OF BIOMASS

Unit:

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
solid, liquid fuels kJ/kg, MJ/kg
gas fuels: kJ/Ndm3, MJ/ Nm3
N refers to normal state (0°C ≈ 273,15 K and 1 atm = 101325 MPa)
Low heat value (LHV) and high heat value (HHV)
complete
combustion
PRODUCTS
CO2, SO2, H2O
+ HEAT (LHV)
REACTANTS
fuel + oxygen
T=298 K
P= 1 bar
T= 298 K
P= 1 bar
PRODUCTS
CO2, SO2,H2O
+ HEAT (HHV)
complete
combustion
liquid
T= 298 K
P= 1 bar
LHV and HHV of fuels
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
Measuring by calorimeter
Calculation by
not typical in biomass
available hydrogen
33829 C% + 144277 (H% - 1/8 O2%) + 10467 S%
HHV = ------------------------------------------------------------------ [kJ/kg]
100
2500 (9H% + water%)
LHV = HHV - ---------------------------- [kJ/kg]
100
LHV values of fuels
Natural gas
CH4
48 MJ/kg
the highest hydrogen content
Liquid gas
CH3-CH2-CH2-CH3
46 MJ/kg
less hydrogen content
42 MJ/kg
even less hydrogen content
38 MJ/kg
even less hydrogen content
Oil
CH3-CH2-….-CH2-CH3
Biodiesel
CH3-(CH2)n-C-OH
II
O
Coal
Coke
32 - 22 MJ/kg
mainly carbon
Biogas
28 MJ/kg
CH4 : CO2 ≈50-50%
≈24 MJ/kg
CH3-CH2-OH
27 MJ/kg
Bioethanol
Wood, straw
14 - 16 MJ/kg
oxygen, water is present
lack of hydrogen !
CO2 does not burn
increased oxygen content
high oxygen content and water
Direct Thermal Conversion of Biomass
Combustion
Some row materials for biomass combustion
Forestry product
Agriculture product
Agriculture residue
wood
wheat
Straw
branch
maize
oilcake
bark
rape seed
Wood for biomass combustion
firewood
wood chips
Wood pellets
The prime cost is
significant
Energy input:
- decreased water content
- grinding to powder
- high pressure must be
applied
BIOMASS CONVERSION TO ENERGY
COMBUSTION ON MOVING GRATES
BIOMASS CONVERSION TO ENERGY
Combustion in Fluidized Bed Combustion (FBC) boiler
The air stream through the grate is strong
enough to keep fluid or bubbling state the
wood particles
Secondary air
(over fire air)
Primary air
(under fire air)
The fuel must be uniform in size !
BIOMASS CONVERSION TO ENERGY
COMBUSTION III.
GILLES pellet heater
Household: 10 – 160 kW
Industrial: 140 kW – 5 MW
The pellet heating is getting
more and more popular in
western countries
What can we do at home ? (η = efficiency)
Tile stove only
for wood
η = 60 – 70 %
Open fire place
η= 10 – 15 %
Tile stove for
wood and coal
η = 60 – 70 %
Central heating
by pellet
η ≈ 90 %
Closed fire place
η = 20 - 30 %
Biomass transformation to fuel
Thermal gasification
THERMAL GASIFICATION OF BIOMASS
Conversion of biomass into carbon- and hydrogen-rich fuel gases
(carbon monoxide, hydrogen, methane)
Fuel gas
better utilization
efficiency of energy conversion ≈ 90 %
perfect combustion due to
perfect mixing of fuel gas
and air
less environmental polluting materials
due to perfect mixing of fuel gas
and air less carbon monoxide,
hydrocarbons and shoot particles
will be formed.
THERMAL GASIFICATION OF BIOMASS
GASIFIER
Downdraft gasifier
atmospheric
Syngas or producer gas
CH1.4O0,6 → CO + C + (CH)x + H2O
Wood (12-20w%
moisture)
300 - 400 °C
C + CO2 → CO
C + H2O → CO + H2
> 200 °C
CO + H2O → CO2 + H2
300 - 700 °C
800 - 1000 °C
CH1.4O0,6 + O2 → CO2 + H2O
The methan concentration can be increased
by pressure increase
CO + 3 H2  CH4 + H2O
2 C + 2 H2  CH4
1450 °C
CO 17-22 v%
H2 16-20 v%
CO2 10-15 v%
CH4 2-3 v%
N2 55-60 v%
LHV : 5-5,86 MJ/Nm3
THERMAL GASIFICATION OF BIOMASS
in circulating fluidized (CFB) boiler
Environtherm.de
THERMAL GASIFICATION OF BIOMASS
Direct heat system
Condensation
▼
Bio-oil
Direct heat system
Synthesis gas for
methanol, ethanol
production
Synthesis gas for
Fischer-Troops
plant
petrol
diesel oil
lubricating oil
GASIFICATION BY BIOMETHODS
BIOGAS
Produced by biological breakdown of wet organic matters
- biomass
- manure
- sewage
- municipal waste
- green waste
- energy crops
in the absence of oxygen (anaerobic digestion)
PRODUCT
COMBUSTIBLE BIOGAS ~ 25 - 10 MJ/Nm3
Natural gas
32 MJ/Nm3
Technology of biogas production
ENERGY FROM BIOGAS
row material
Biogas
yield
[Nm3/t]
cattle, pig manure
Energy*
content
[kJ]
Wood
eq.**
[kg]
Oil
eq.***
[kg]
60
1080
77
27
500
9000
643
225
1300
23400
1671
585
fat grease trap
250
4500
321
113
slaughterhouse
waste
300
5400
386
135
techn. glycerin
500
9000
643
225
brewer grains
180
3240
231
81
grain
560
10080
720
252
fresh grass
fat
* Methane content 50 v%
** 16 MJ/kg
*** 40 MJ/kg
LANDFILL GAS
15-30 Nm3 / ton. year from the second year
flaring
heating
Electric energy
Greenhouse effect: CH4 >> CO2
The landfill gas is a very polluted gas !!
Mercury, chlorinated hydrocarbons,
non methane organic compounds
Jenbacher gasmotor
Energy from biomass
bioethanol → motor fuel
Maize corn
BIOPLANTS FOR LIQUID BIOFUELS
BIOETHANOL
Photosynthesis of glucose:
6 CO2 + 6 H2O + light = C6H12O6 + 6 O2
Fermentation by yeast:
C6H12O6 = 2 C2H6O + 2 CO2 + heat
Combustion of ethanol:
2 C2H6O + 6 O2 = 4 CO2 + 6 H2O + heat
The carbon dioxide balance is zero → No greenhouse effect
BIOPLANTS FOR LIQUID BIOFUELS
BIOETHANOL
Row materials:
- sugar containing biomass (sugarcane, sugar beet)
● direct fermentation
- starch containing biomass (maize, wheat, potato)
● hydrolysis
● fermentation
- cellulose containing biomass (wood)
☻long chain cellulose (40-60%) is resistant to
hydrolysis
☻ hemi cellulose (20-40%): easy to hydrolyze but the
five ring sugars can not be fermented
☻lignin: it is not sugar (10-24%)
BIOPLANTS FOR LIQUID BIOFUELS
BIOETHANOL
TECHNOLOGY
1. Hydrolysis in case of starch containing row materials
2. Fermentation of glucose
- significant water claim, strict pH and temperature control,
- additives for the yeast wellness
3. Ethanol separation by distillation
- significant energy claim
4. Dewatering of ethanol, by molecular sieves
5. Biofuel mixing
- E100 pure ethanol
- E90 90v% ethanol 10 v% petrol
BIOPLANTS FOR LIQUID BIOFUELS
BIOETHANOL
Which is the best row material ?
1. Sugar beet 7140 dm3/ hectare
2. Sugar-cane 6620 dm3/ hectare
3. Cassava 4100 dm3 / hectare
Sugar beet
4. Maize corn 3540 dm3/ hectare
5. Wheat
Maize corn
2770 dm3/ hectare
Sugar cane
wheat
1 hectare = 10 000 m2
cassava
BIOPLANTS FOR LIQUID BIOFUELS
BIOETHANOL
ADVANTAGES

No contribution to the greenhouse effect. The carbon dioxide
balance is neutral.
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No sulfur dioxide emission

Decrease in carbon monoxide CO, hydrocarbon (CH)x, soot
emission due to the oxygen content of bioethanol.
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No need to change the distribution system.
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Octane numbers: RON: 121 MON: 97
real RON : 106 - 108

Well known technology can be applied

Miscibility with petrol
BIOPLANTS FOR LIQUID BIOFUELS
BIOETHANOL
DRAWBACKS

Lower energy content
petrol: 43,5 MJ/kg

Starting problems in winter (max: E75)

Danger of corrosion
ethanol: 26,8 MJ/kg
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Week electrolyte itself
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Water and acetic acid formation during storage (electrochemical corrosion)
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Peroxy acetic acid formation inside the chamber (chemical corrosion of metal
alloy)
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Immiscibility with lubricating oil.
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New environmental pollutants (aldehyde and acetic acid)
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The row material might be food. (rival in food supply)

The energy balance is not outspokenly positive (debates)
Energy from biomass
rape
rape from rape seed
Biodiesel from rape → motor fuel
Rape-straw, rape-cake: burning → by-products: energy sources
BIOPLANTS FOR LIQUID BIOFUELS
BIODIESEL
BIOPLANTS FOR LIQUID BIOFUELS
BIODIESEL
Row material:
- plant product containing any vegetable oil
- animal fat (ONLY IN WASTE FORM !)
- waste vegetable oil
TECHNOLOGY
1. Pretreatment of oil seeds
2. Oil gain by pressing → oil and oilcake
3. Rest oil extraction by organic solvents
4. Transesterification
5. Separation of methylester
6. Purification
BIOPLANTS FOR LIQUID BIOFUELS
BIODIESEL
Which is the best row material ?

palm oil tree : 5000 - 7000 dm3/hectare

coco palm: 2300 dm3/hectare

yathropa : 1900 dm3/hectare

soya : 760-1610 dm3/hectare

rape seed: 1000 dm3/hectare
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hazelnut: 900 dm3/hectare

sunflower: 820 dm3/hectare

algae: 2700 dm3/hectare
Row materials for biodiesel
Oil palm
Oil palm
yathropha
algae farm
BIOPLANTS FOR LIQUID BIOFUELS
BIODIESEL
ADVANTAGES

No contribution to the greenhouse effect. The carbon dioxide
balance is neutral.

The energy content is 9 % less than that of biodiesel.
Higher cetane number.
Due to the oxygen content less CO and (CH)x. Debates on soot
emission.
Sulfur content is low. biodiesel : < 0,01mass% diesel : 0,2 mass%
Biodegradable
Miscibility with diesel oil
Excellent lubricating effect.
Smaller power loss on roads at higher altitudes from see level (the
fuel contains oxygen)
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BIOPLANTS FOR LIQUID BIOFUELS
BIODIESEL
DRAWBACKS

The row material might be food. (rival in food supply)

The energy balance is not outspokenly positive (debates)

The exhaust gas has a definite oily smell.
Bacterial attack.

IS THE BIOMASS
A REAL ENERGY SOURCE ?
Let see Hungary !
93 000 km2
Let’s substitute the petrol consumption by bioethanol !
Petrol consumption = 1 600 000 ton/year
petrol: 43,5 MJ/kg
ethanol: 26,8 MJ/kg
Alcohol claim : 1 600 000 * 43.5/26.8 ≈ 2 600 000 ton/year
Maize 2,8 ton alcohol/hectare/year
Area claim: 2 600 000/2,8 ≈ 930 000 hectare = 9 300 km2
The growing can not be repeated on the same site :
Area claim ≈ 3 * 9 300 = 27 900 km2
Let’s substitute the diesel oil consumption by biodiesel !
Diesel oil consumption = 2 500 000 ton/year
Biodiesel claim : 2 500 000 * 1,1 = 2 750 000 ton/year
Rape: 1000 dm3 biodiesel /hectare/year ≈ 880 kg/hectare/year = 0,88 ton/hectare/year
Area claim : 2750000/0,88 = 3 125 000 hectare = 31 250 km2
The growing can not be repeated on the same site :
Area claim ≈ 3 * 31 250 = 93 750 km2
Bioethanol vs. Biodiesel II.
The rate of energy output and energy input
By Monica Gottfried 2006 thesis
Energy rate
Wheat
bioethanol
Maize
bioethanol
Sunflower
biodiesel
Rape
biodiesel
Energy
grass
only
combustion
1,19
1,42
2,35
2,13
4,95
Energy distribution in the future
Conclusions

The biomass is only one possibility to reduce
the consumption of fossil fuels and decrease
the greenhouse effect carbon dioxide
emission.

From the point of ‘sustainable development’,
the total substitution is impossible.

From the point of ‘sustainable survival’, it
has an outstanding significance.