Biofuels Biodiesel and bioethanol. Exercise in groups For what purposes do we use energy? Which...

BiofuelsBiodiesel and bioethanol

Exercise in groups

• For what purposes do we use energy?• Which energy sources do you know ?

World energy consumption

XXs energy consumption

(Please add statistic showing energy consumption by source for your own country)

Fossil fuels

FOSSIL FUELS originate from organisms that lived millions of years ago.

Examples of fossil fuels: coal, oil , natural gas,

Biofuels

BIOFUELS originate from organisms that lived recently.

Examples of biofuels: wood, straw , biodiesel, bioethanol , biogas

CO2 is developed- whether you burn biofuels or fossil fuels . The difference is ...

Energi, vand og

CO2

Energi, vand og

CO2

CO2

Fossil fuels are not CO2-neutral

When you burn fossil fuels the atmospheric concentration of CO2 rises

CO2

Biofuels are CO2-neutralWhen wood - or another biofuel – is burned, the CO2 concentration will not rise. CO2 is developed but only the same amount that the trees (plants) have used in photosynthesis while growing.

Political goals

The increased amount of CO2 in the atmosphere contribute to the greenhouse effect/global warming . EU climate policy has the following main objectives • reduction of greenhouse gases • use of renewable energy • increased energy efficiency .

In this context agriculture can play a part by growing crops that are wholly or partly used to produce energy .

Some biofuels

Fuel type Source Kan replace/supplementBiodiesel Vegetable oils and animal

fatsDiesel

Bio ethanol Grain, corn, grasses, straw, can , willow, residual wood (carbohydrate part )

Gasoline

Biogas Manure, straw, fat waste, grasses, whey (org . waste)

Natural gas

Production of biodiesel

Fat Ethanol Biodiesel

What kinds of fats can be used?

For instance• Animal fat (abattoir) • Used frying oil • Rapeseed

Discuss the use of these fats

Here you could introduce the biodiesel experiment…

How to make ethanol

• Alcohol/ethanol can be made by fermentation of sugar. • The starting material need not be pure sucrose, but may be biomass/plant

material which is rich in carbohydrate. • Before the fermentation can take place some preliminary steps are

necessary, however

Sugar Fermentation

Alcohol(ethanol)

Carbohydrates

The following slides give a brief overview of carbohydrate structure. In stead of showing the slides you could ask the students find information about mono-, di- and polysaccharides themselves. Types, structure, where do we find the different types etc.

CarbohydratesCarbohydrates are built up of carbon, oxygen and hydrogen.Carbohydrates are divided into monosaccharides , disaccharides and polysaccharides . An example of a simple carbohydrate is dextrose (glucose) , which is the sugar made in photosynthesis. In a dextrose molecule the atoms are organized in ring in the shape of a hexagon.

Monosaccharides

Other carbohydrates such as fruit sugar (fructose) has a structure like a pentagon.

Glucose and fructose are examples of monosaccharides. Mono means one and says they have only contains one “sugar ring”. A lot of different carbohydrates can be made of these simple building stones.

Sugar

Plain sugar (sucrose) and maltose is made of two sugar rings that are linked together. Therefore they are called disaccharides (“di” means two).

Starch – a polysaccharide

Polysaccharides er made by may ”sugar rings” (poly means many).

Starch is one example of a polysaccharide, that is made by long chains of dextrose.

. . . . . . .

Cellulose – another polysaccharideAnother example of a polysaccharide which is composed of glucose chains is cellulose, which is found in plant cell walls.

The bonds between the dextrose molecules in cellulose are not so easy to break as in starch. This difference also is important in the production of bioethanol.

. . . . . . .

Fremstilling af bioethanol

Sugar FermentationAlcohol

(ethanol)

During pre-treatment the polysaccharides are cut into monosaccharides before fermentation. The pre-treatment needed depends of the type of biomass used.

Biomass Sugar FermentationAlcohol

(ethanol)Pre-treatment

1. generation bioethanol

The raw material can be sugar cane and sugar beet (containing carbohydrate in the form of sugar), maize or cereal (containing carbohydrate in the form of starch).

This requires only a light pretreatment because starch can be broken down .

Biomass Sugar FermentationAlcohol

(ethanol)Light pre-treatment

2. generation bioethanol

The raw material can be• straw, corn stalks, wood (contains carbohydrates in the form of

lignocellulose ) These plants contain carbohydrates that are difficult to extract and convert into ethanol = energy intensive pretreatment.

Benefits: The method uses waste material, which is cheap and present in large amounts.

Biomass Sugar FermentationAlcohol

(ethanol)Energy intensiv pre-treatment

IBUS-plant – a second generation plant using straw

Pretreatment of straw : Chopping (1-5 cm long pieces ) Soaking in water Heating the " straw soup" at high pressure ( 190-200 ° C , 13-18 bar) for 10-15 minutes The carbohydrates in the heated " straw soup" are degraded by a number of enzymes added to the sugar

IBUS-plant – fermentation and waste

After pre-treatment , the sugar is ready to be converted to ethanol using yeast. After fermentation, filtration and distillation you have pure ethanol. The residual from the production is solid biofuel and liquid molasses: • The biofuel is used as an energy source for the pre-treatment and

distillation.• The molasses can be used as animal feed.