8. Renewable Energy - Biomass

8/9/2019 8. Renewable Energy - Biomass

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Renewable energy – biomass

Prepared by

Wan, Man Pun

Assistant Professor

School of Mechanical & Aerospace Engineering

MA0100 – Environmental Sustainability


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Biomass

All non-fossil material of biological originSolar energy, converted to chemical energy by photosynthesis, is stored

in a variety of organic materials (biomass)World primary energy supply, 1971 - 2010

*Other includes wind, solar, geothermal, etc.

[IEA, 2012]

M i l l i o n t o n o i l e q u i v a l e n t ( M t o e )

10%

2


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Biomass

Global carbon cycle

[earthobservatory.nasa.gov]3

Global fast carbon cycle (in Gt/year)


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Biomass resources

4

Metabolic pathways for carbon fixation in photosynthesis

C3 system Produces

3-carbon organic acid (3-phosphoglyceric acid) from

carbon fixation

E.g., rice, wheat, potato,

etc.

represents 95% of Earth’s plant

biomass.Most common in temperate and cold

climate.

Utilizes 15 –30 mg CO2/dm2/h with

light saturation already at 0.8 –2.4

J/cm2/min

C4 system Produces 4-carbon organicacids (malate

and aspartate) from carbon

fixation

E.g., sugarcane, maize, etc.

represents 3% of Earth’s plant

biomass.

More common in warm climate.

Utilizes 70 –100 mg CO2/dm2/h with

light saturation around 4.2 –5.9

J/cm2/min

CAM

(Crasulacean

Acid

Metabolism)

system

Produces 4-carbon organic

acids (malate

and aspartate) from carbon

fixation

E.g., pineapple, sisal, etc.

Can capture light during the day and

later fix the CO2 during the night


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Biomass resources

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Wastes from crops used primarily for food

[http://www.wikipedia.com]


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Energy cropPlants that are low cost and low maintenance to grow and harvest, and

have high energy content.

Solid biomass

High-yield crop species burnt to generate power

Biomass resources

Poplar

Elephant grass


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Energy crop

Gas biomassEnergy crops used for production of biogas in anaerobic digesters.

E.g., maize, wheat, carrot, cabbage, cauliflower, etc.

Bio-diesel

E.g. copra, oilseed rape, sunflower, soya, peanut, mustard seed, etc.

Bio-ethanol

E.g. switchgrass, maize, sugarcane

Biomass resources

Copra (coconut kernel)

Sugarcane


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Animal wasteBiogas production from animal

waste

AlgaePhotosynthetic organisms that

span length scales from just a

few microns up to 50 m

Biomass resources

[http://international.bio-energie.de]

Kelp (macroalgae)Chlorella (single-cell microalgae)


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Biomass

Biomass composition

Can be > 50% Ultimate

analysisProximate

analysis


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Biomass energy technologies:

- Firing and co-firing

- Gasification/pyrolysis

- Fermentation

- Production of other fuels

Biomass energy utilization


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Biomass combustion

Firing and co-firing

Fuel Net Calorific

Value by mass(MJ/kg)

Adiabatic flame

temperature(oC)

Wood chips (30% MC) 12.5 530-840

Wood pellet (10% MC) 16.4 1,140

Grass (18% MC) 13.7 1,020

Straw (15% MC) 14.5 1,065

Anthracite 33.0 2,180

Heating oil 42.5 2,100

Propane gas 46.1 2,392

MC – moisture content


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Biomass as fuel for domestic cooking and heating


Wood as fuel for cooking and heating Dung as fuel for cooking

Yak dung being dried


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Common types of modern furnace


[http://www.rath-group.com]

[https://reader010.{domain}/reader010/html5/0603/5b141052861c1/5b14105ab106b.jpg]

[http://www.canadianbiomassmagazine.ca/images/

stories/2009/June-2009/WellonsCombustorCellProcess.jpg]

Fixed-bedfurnace

Fluidized-bed furnace

Cyclone furnace


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Common types of modern furnace


[http://www.sciencedirect.com]

Sloping-grate furnace


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Gasification processes1. Dehydration – removal of moisture content at about 100oC

2. Pyrolysis – release of volatile content and formation of char. 200 –

300oC

3. Combustion – combustion of volatile content and some of the char

with the addition of oxygen to provide energy for the subsequent

gasification process. Carbon dioxide (CO2) formed.

4. Gasification – char reacts with carbon and steam (from step 1) to

form carbon monoxide (CO) and hydrogen (H2)

5. Further reactions occur when the formed CO and residual waterfrom the organic material react to form methane (CH4) and excess

CO2

Gasification/pyrolysis


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Wood gas

Net calorific value: 5.7 MJ/kg

Gasification/pyrolysis

Element % by volume

Nitrogen 50.9

Carbon monoxide 27.0

Hydrogen 14.0

Methane 3.0

Carbon dioxide 4.5

Oxygen 0.6

Car ran on wood gas during WWII

Car with a wood gasifier in its trailer

[http://www.drboblog.com/wp-

content/uploads/2013/01/mr-fusion-back-to-the-future.jpg]

Remind you this?


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Fermentation of sugar Anaerobic (process conducted under the absence of oxygen)

degradation of sugars (glucose, sucrose and fructose) by yeast with

ethanol and carbon dioxide as by products.

FeedstockSugarcane, sugar beet

Starchy plants: potato, corn, cassava

Fermentation

Fermenting sugar[http://www.hitachizosen.co.jp]


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Commercialized ethanol fuel mixtures

Fermentation

Major bio-ethanol producers

[http://www.wikipedia.org]

[Asia Biomass Office]


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Biodiesel production process

Biodiesel

[http://teenbiotechchallenge.ucdavis.edu]

Crop Liter/Ha/yearPalm 5238

Jatropha 1684

Castor 1216

Canola 1076

Sunflower 842

Soybean 561

Crops for biodiesel production

and potential annual production

Palm treesJatropha


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Biodiesel net calorific values

Biodiesel

Diesel type Net calorific

value (MJ/kg)

No.2 diesel (petroleum diesel) 42.5

B2 blend biodiesel

(2% biodiesel, 98% petroleum diesel)

42.3

B20 blend biodiesel

(20% biodiesel, 80% petroleum diesel)

41.4

Biodiesel (B100) 37.5

Light-blend

No / minor

modification to

equipment

needed

Equipment

modifications using

biodiesel-

compatible

materials

Gas station providing ethanol fuel and biodiesel


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Major biodiesel producers

Biodiesel

[Asia Biomass Office]


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8. Renewable Energy - Biomass

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