renewable energy materials qxu7027

Dr Zhe Li

Senior Lecturer in Materials Science

[email protected]

Renewable Energy MaterialsQXU7027

mailto:[email protected]

A world of possibilities…

Palm oil waste

15.8 Mt/yUnripe coconut

husks 5 Mt/yCassava starch

228 Mt/y

1 Mt/y of

food wasteAgro-residues

46 Mt/y

Spent coffee

grounds 3 Mt/y

Orange peels

12 Mt/y30 Mt/y of Agro-

residues 382 t/y

coffee husks

What do we do with our waste?

What a waste!!

Waste is tomorrows resource

We need to encourage the greater use of chemically rich waste as a resource

Biowaste/Biomass-can you think of any?


What is biomass?

Sugars

Phenols

Natural Dyes

Chitosan

Chitin

Starch

Alginic Acid

Lipids

Pectin Proteins

HemicelluloseCellulose

Lignin Waxes Tannin

What´s in biowaste?

Lignocellulosic Biomass (Agricultural wastes) as an example…

1. Most abundant renewable biomass resource on the planet ( 1.9 trillion tons/year)

2. We can not eat it…so no competition between fuels and food

Confidential

What’s in Lignocellulosic Biomass

Cellulose (纤维素)

Lignin (木质素)

Hemicellulose(半纤维素)

Cellulose (纤维素)Lignin (木质素)

50‐70% 10‐40%10‐30%

Hemicellulose(半纤维素)

How we can separate cellulose and hemicellulose from lignin?

• 3D amorphous polymer

• cross-linked phenolic polymers

• Forms cell walls of woods and bark

• an organic compound with the formula (C6H10O5)n

• primary cell wall of green plants

• Both crystalline and amorphous parts

• Random, amorphous structure with little strength.

• often coexisits with cellulose but with very different structure

Cellulose (%) Hemicellulose (%) Lignin (%)

Hardwood stems 40–55 20–40 18–25

Softwood stems 45–50 25–35 25–35

Rice straw 35–45 18–25 10–25

Wheat straw 38–45 20–32 7–10

Tobacco chops 22–30 15–20 15–25

Arundo donax 30–38 18–22 8–20

Miscanthus 35–40 16–20 20–25

Newspaper 40–55 25–40 15–30

Composition of some common used lignocellulosic biomasses

Separate them into individual component is the first step


➢ Can not hydrolyse cellulose to glucose(葡萄糖) because of the high degree of crystalinity

➢ Cellulose, hemicellulose and lignin are naturally packed and protected against chemical breakdown

➢ Neither cellulose and lignin are soluble in any conventional solvents

How we can separate cellulose and hemicellulose from lignin?

Challenges:

Separation Method 1: Kraft Process

• A process for conversion of wood into wood pulp, which consists of almost pure cellulose fibres, the main component for e.g. paper and other chemicals.

• The kraft process entails treatment of wood chips with a hot mixture of water, sodium hydroxide (NaOH), and sodium sulfide (Na2S), known as white liquor, that breaks the bonds that link lignin, hemicellulose, and cellulose.

• Controversial as Kraft plants can release odorous products and in some situations produce substantial liquid wastes.

Separation Method 2: Organosolvation

• Organosolv is a very promising approach

• Organic or aqueous organic solvent mixture with inorganic acid catalysts (HCl or H2SO4) is used to break the internal lignin and hemicellulose bonds.

• The solvents more frequently used in organosolv processes are acetone, methanol, ethanol, phenols, ethylene glycol and tetrahydrofurfuryl alcohol.

• After precipitation, the recovered lignin (organosolv lignin) is a is a sulfur‐ free lignin, with high purity and low molecular weight, to be used for many purposes.

Separation Method 3: Ionic Liquids (ILs)

ILs are salts generally formed by large organic cations and small inorganic anions, which are liquid at low temperature and can be used as non–aqueous alternatives to traditional organic solvents.

Advantages

●tunable properties (e.g., viscosity, melting point, polarity, and hydrogen bond basicity) depending on the selection of the anion and cathion.● high chemical and thermal stability● non–flammability● low vapour pressures (they remain liquid in a wide range of T)●good (selective) solvation properties due to the swelling of the plant cell wall, with disruption of inter– and intra–molecular hydrogen bonding between lignin and cellulose, and also to the possible electronic interaction of the organic cathions and the aromatic rings of lignin

Drawbacks

● high viscosity (a serious limit to mass and phase transfer)

● Expensive and only Kg scale production

Separation Method 3: Ionic Liquids (ILs)

After separation, what can we do next?


Petroleum

feedstock

Fuels

Solvent

Bulk chemicals

Plastics

Fibres

Fine chemicals

Oils

Petroleum Refinery

Bulk chemicals

Solvent

Plastics

Fine chemicals

Fibres

Oils

Biowaste

An analogous to Petroleum Refinery-Biorefinery

Fuels

What can we do with biomass?

Biofuels

• Bioethanol• Biodiesel• Hydrogen• Methane• Hydrocarbons

Chemicals

• Glycerol• Acids• Aldehydes• Furanes• Heterocycles

Materials

• Carbon• Polymers• Carbon Fibrers• Composites• Inorganics

• “Proalcool “program: Brazil’s National Fuel Alcohol Program promoted by the oil crisis in the ´70s

• SUGARCANE TO ETHANOL

• USA followed in the 90s with a massive production of ethanol (CORN TOETHANOL)

• EU is moving towards a mandatory biofuel usage of 10% of the energy used by 2020

• Japan has set a goal of replacing 20% of its oil demand with biofuels or gas to liquid fuels by 2030

Bioethanol

• Sugar Cane• Sugar Beet• Sweet Sorghum

ADVANTAGES

• High yield of sugar/acre• Low conversion costs• Ethanol from sugarcane in Brazil

costs 0.81$/gallon

DISADVANTAGES

• Natural seasonal and local availability• Compete with food

Bioethanol from Sugar

• 10% of the cultivated land (13.8 million acres)

• Over 50% of Brazil’s sugar cane production for ethanol production

• The leftovers (leaves, fibers‐called BAGASSE) isused to generate steam and then electricity forthe biorefinery

• The liquid effluent (waste-water vinasse) isused as fertilizer and irrigation supply of thecane fields

• Brazil´s ethanol is the cheapest in the world

• Today the effort are directed towards expanding sugar cane refineries through the processing of bagasse for cellulosic ethanol

• This will improve the economics and allow ethanol production during winter

Sugarcane in Brazil

• Major source of sugar in Europe and North America• Used for Bioethanol production in France• Can generate 20‐50 tones of sugar beet per acre• Ethanol yield is 25 gallons/ tone of sugar beet• Requires a greater energy input and therefore is more expensive

Sugar Beet

1gallon= 4.5L

Sweet Sorghum

• Not widely grown

• The sugar is contained in the main stalk

• Sugar is recovered by pressing the stalks with rollers

• Yields are around 20 gallons ethanol / t of stalks

• China wants to switch from corn to sweetsorghum for the regions where corn doesnot grow well

• The best economical option would be to engineer a station where one could switch between ethanol as a fuel and sugar production

Sugar Cane BiorefinerySugarcane

Sugarcane crush rollers

First lime addition and filtration

Juice heating

Sugar crystal centrifugation

Syrup A Molasses

2‐nd lime addition and filtration

Sugar Crystal Centrifugation

Syrup B Molasses

Enzymatic Saccharification

Yeast Fermentation

Distillation

SUGARCANE SUGAR BEETS SWEET SORGHUM

LIME Ca(OH)2

LIME

SUGAR

B MOLASSES

CONDENSED MOLASSESSOLUBLES FOR ANIMALFEED

HYDROUS ETHANOL

INVERTASE, DEXTRANASE

SACCHAROMYCES CEREVISIAE

• Corn is the second largest feedstock source for ethanol production worldwide

• Most important starch feedstock

• 11 billion gallons of ethanol were produced from 2 bilion tones of starch worldwide

• Ethanol production from corn is concentrated inUS

• Spain, Germany, France and UK uses wheat to produce ethanol

• Rye and barley are also used in Spain and Germany

• Corn has a longer lifespan than sugar crops

• The use of corn adds another step to ethanolproduction as starch must be first broken into itsconstituents sugars

ETHANOL FROM STARCH

ETHANOL FROM STARCH

Dry Mill/Grind

Corn Milling

Liquefaction

Cooking

Yeast Fermentation

Beer Well

Distillation

Drum Dryer

CORN

CARBON DIOXIDE

DRY DISTILERS GRAIN SOLUBLES

AMYLASE/GLUCOAMYLASE

SACCHAROMYCES CEREVISIAE

Food Grade Ground Corn

Enzymatic Saccharification

HYDROUS ETHANOL

Dehydration

Centrifugation

ETHANOL

Wet Distillers Grain

Wet Cake Processing

Thin Stillage Processing

Dehydration Evaporation

ADVANTAGES:➢ No competition with food➢ 50‐80% estimated reduction in the emissions compared with gasoline

DISADVANTAGES:➢ Needs additional substances and processes to break down plant fibbers into fermentable

sugars➢ Not the same bacteria that convert glucose ( 6C) can also convert pentose ( 5C)➢ Costs are high

ETHANOL FROM LIGNOCELLULOSIC BIOMASS

ETHANOL FROM LIGNOCELLULOSIC BIOMASS

Lignocellulose

Biomass Densifying Chopping

Fine Grinding

Heated Biomass Hydrolysate Production

Neutralization

Cellulose Hemicellulose Enzymatic Treatment

Lignin Separation

Liquid Hydrolysate

Enzymatic Scarification

Yeast Fermentation

Distillation

SWITCHGRASS SWITCHGRASS ENZYMES OIL PLANTS WITH LIGNOCELLULOSE

Cellobiase, dextrinase, amylase, pectinase, exoglucanase, peroxidase, xylanase, etc

Saccharomyces Cerevisiae

Lignin

Ethanol

Plant Oil Removal

• 94% less carcinogenic particle matter• Lower sulfur content• Less volatile• Easier to handle• Degrades more rapidly‐lower environmental impact

BIODISEL is the most widely used biofuel in Europe

Fatty acid alkyl esters

Others:• Palm oil• Soybeans

BIODIESEL FROM VEGETABLE OIL

Rudolf Diesel, 1912

“…the fact that fat oils from vegetable sources can be uses as many seem insignificant today,but such oils may perhaps become in course of time of the same importance as some naturalmineral oils and the tar products are now”

• from the 70‐90´s there were many problems using vegetable fats directly in Diesel engines because of the high viscosity

• emulsions with diesel oil, vegetable oil and water were similar to the original fuels, however with lower NOx emissions than original diesel oil or original vegetable fasts.

• emulsions have never been implemented because of fear of phase separations as well as water corroding the engine


• All the problems with deposits in the engine due to the high viscosity of pure vegetable fats was solved by converting the triglycerides (甘油三酯) in the oil to alkyl esters

• These alkyl esters become known as biodiesel

• This was first demonstrated by Knothe in Belgium

• Several Biodiesel plants were buit in Europe in the late 80´s

• US formed the “ National Soydiesel Development Board” in 1992


BIODIESEL PRODUCTIONTRANSESTERIFICATION

• Reacting the feedstock with an alcohol in the presence of a catalyst

A COMPLETE BIODIESEL PLANT

Reactor

OIL

Methanol

Catalyst

SeparatorMethyl Esters Neutralization

and methanolremoval

Water washing

DryerBIODIESEL

Gray water

Water

Acid

Methanol/water rectification

Wet methanol

WaterMethanol Storage

Glycerin (50%)

Acidulation and separation

Methanol Removal

Acid

Free fatty acids

Crude glycerin (85%)

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