1. Biodiesel and bio ethanol
Biofuels
Biodiesel and bio ethanol

2. Energy consumption and global warming

3. Exercise in groups For what purposes do we use energy?
Which energy sources do you know ?
Lad eleverne gå sammen to og to i 5-10 minutter og besvare spørgsmålene. Lav en fælles opsamling i klassen.
Transport, opvarmning, etc.

4. World energy consumption
Sours:
For updates, go to: – write ”statistics” in the search field
Here renewables refer to wind, geothermal, solar, biomass and waste.

5. Energy consumption in XX
To the teacher: Please add statistic showing energy consumption by source for your own country

6. Atmospheric CO2-levels are rising
Carbondioxide concentration from 1700 till now Carbondioxide concentration from 1958 till now

7. Greenhouse effect and global warming
The Greenhouse Effect (Youtube video)

8. 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 .
Discuss in class what the three points mean. Have students come up with examples.
You could add that there may be other for reducing reasons the use of fossil fuels than climate change. Fossil fuels are a limited resource and the supply of fossil fuels will in part from politically unstable countries.

9. Fossil fuels and biofuels

10. Fossil fuels
FOSSIL FUELS originate from organisms that lived millions of years ago. Examples of fossil fuels: coal, oil , natural gas,

11. Biofuels
BIOFUELS originate from organisms that lived recently. Examples of biofuels: wood, straw , biodiesel, bioethanol , biogas
Biodiesel

12. Energi, vand og CO2
Fossil fuels and biofuels both contain carbon (C) and hydrogen (H). The combustion will in either case result in the release of CO2 and water – as well as energy.
Energi, vand og CO2
CO2 is developed- whether you burn biofuels or fossil fuels . The difference is ...

13. Fossil fuels are not CO2-neutral
When you burn fossil fuels the atmospheric concentration of CO2 rises

14. Biofuels are CO2-neutral
When 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.

15. Some biofuels Fuel type Source Kan replace/supplement Biodiesel
Vegetable oils and animal fats
Diesel
Bio ethanol
Grain, corn, grasses, straw, can , willow, residual wood (carbohydrate part )
Gasoline
Biogas
Manure, straw, fat waste, grasses, whey (org . waste)
Natural gas

16. Biodiesel

17. Vegetable oil directly in your diesel engine? No…
Mineral diesel consists of long carbohydrate molecules which results in a liquid as “thin” as water. Vegetable oils consist of triglyceride molecules.
Due to their trident structure the vegetable oils are much “thicker”. Too thick for diesel engines with modern fuel injection nozzles which will get clogged.

18. Basic biodiesel chemistry
The triglycerides of a vegetable oil consist of a glycerol backbone and 3 fatty acids. When you mix the vegetable oil well with methanol and potassium hydroxide you get biodiesel and glycerol.
The potassium hydroxide is the catalyst (= makes the reaction happen but is not consumed).
Additional comments: The biodiesel molecules are long chains consisting of methanol and fatty acid, resulting in a liquid which is comparably “thin” as petroleum diesel. Both vegetable oil and biodiesel are molecules build from an alcohol and a fatty acid. Such molecules are called ester. That’s why the process of making biodiesel is called trans esterification (= conversion from one ester to another one).
When the oil is mixed well with methanol and potassium hydroxide, the bonds between the glycerol backbone and the fatty acids are broken and new molecules are formed: biodiesel and glycerol. Each molecule of vegetable oil needs 3 molecules of methanol in order to form 3 molecules of biodiesel and 1 molecule of glycerol.

19. Production of biodiesel – the short version
Fat
Methanol
Biodiesel

20. What kinds of fats can be used?
For instance
Animal fat (abattoir)
Used frying oil
Rapeseed oil
Discuss the use of these different types of fat

21. To the teacher: Here you might introduce the biodiesel experiment…

22. Bio ethanol

23. 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
(ethanol)
Alcohol
Ethanol or alcohol can be produced by fermentation of sugar. Basically it is the same process as in the production of wine : here, you add the sugar and yeast to the grape juice and let the yeast ferment the sugar into ethanol. The type of carbohydrate in the starting material determines how easily you can produce bioethanol. To understand why , let us take a look at the structure of carbohydrate.

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

25. Carbohydrates
Carbohydrates are built up of carbon, hydrogen and oxygen.
Carbohydrates contain energy.
Carbohydrates are divided into
Monosaccharides
Disaccharides
Polysaccharides
Find evt. mere detaljerede figurer af kulhydrater på nettet…

26. Monosakkarider er simple kulhydrater
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.
Another example is fruit sugar (fructose) which has the shape of a pentagon.
Mono means one and implies that they only have one “sugar ring”.
Find evt. mere detaljerede figurer af kulhydrater på nettet…

27. Disakkarider Maltose – is made of two glucose molecules.
The simple monosaccharides can serve as building blocks.
By putting together two monosaccharides you get a disaccharide (“di” means two).
Maltose – is made of two glucose molecules.
Sucrose (plain sugar) is made of one glucose and one fructose molecule.

28. Starch – a polysaccharide
Polysaccharides er made by many monosaccharides put together (”poly” means many).
Starch is one example of a polysaccharide, that is made by long chains of dextrose.

29. Cellulose – another polysaccharide
Another 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.
Also we can digest the starch, but not cellulose. Ruminants ...

30. Structural formulas…
On this website you can find more structural formulas for monosaccharides, disaccharides and polysaccarides (including the difference between starch and cellulosis)

31. Production of bio ethanol
Sugar
(ethanol)
Alcohol
Ethanol or alcohol can be formed by fermentation of sugar (top figure). The preparation of bioethanol also occurs by fermentation. The starting point here is not pure sugar, but biomass / plant material rich in carbohydrates.
Biomass
Sugar
Fermentation
Alcohol
(ethanol)
Pre-treatment
During pre-treatment the polysaccharides are cut into monosaccharides before fermentation.
The pre-treatment needed depends of the type of biomass used.

32. 1. generation bio ethanol
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 .
Today grain, corn and sugar cane are used in several places in the world for the production of bioethanol, e.g. Brazil and the United States . These biomass sources are characterized by containing available carbohydrates, which can be relatively easily extracted and converted by microorganisms into ethanol by fermentation. Plants using substrates of this type , are called first generation bio-ethanol plants. In these plants only the sugar and starch part of the plants are used for ethanol production. The rest is waste .
Discuss with students the disadvantages of the method (using edible crops to generate energy , not using everything. )
Biomass
Sugar
Fermentation
Alcohol
(ethanol)
Light pre-treatment

33. 2. generation bio ethanol
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.
A second-generation bioethanol plant can utilize biomass where carbohydrates are not readily available as in corn and sugar cane. The carbohydrates are in for instance wood are bound in a compact chemical structure called lignocellulose. On the other hand, these substrates represent a very cheap and abundant biomass, typically residues or so-called energy crops from agriculture. It could be willow tree, stems from maize plants, straw and different grasses. Lignocellulose constitutes 75-98% of all green plants. (Lignocellulose comprises the three macromolecules of cellulose, hemicellulose and lignin, which make the plant cell walls rigid. Cellulose constitutes 35-40% of straw and is resistant to microbial and chemical attack. The hemicellulose constitutes 20-30% of the straw. Lignin is the last approximately 20-25% of straw, lignin are not soluble in water. Unlike cellulose and hemicellulose, lignin is not made up of carbohydrates.)
Biomass
Sugar
Fermentation
Alcohol
(ethanol)
Energy intensiv pre-treatment

34. 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 ( ° C , bar) for minutes The carbohydrates in the heated " straw soup" are degraded by a number of enzymes added to the sugar
In a second generation plant the inaccessible carbohydrates (lignocellulose ) must be broken down into sugars before fermentation can occur . This step is the most complex of all of the processes and has been the focus of intensive research . How can you break the strong chemical structure of lignocellulose, freeing the valuable monosaccharides without using a huge amount of energy? The slides explains the process used in the Danish IBUS demonstration plant (

35. 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.
A figure above the plant can be seen here (not so good unfortunately)