This is a summary of all lectures of the course Biorefinery (BCT-23306), which is given at Wageningen University. It is a complete overview of all material that needs to be mastered for this course. A better preparation for the exam of the course Biorefinery does not exist!
Summary Biorefinery (BCT-23306)
Lecture 1 – Introduction to biorefinery
Biobased economy (BBE): an economy based on technological developments that lead to a significant
replacement of fossil fuels by biomass in the production of pharmaceuticals, chemicals, materials,
transportation fuels, electricity and heat.
Many groups of people are interested in a biobased economy, since they are confident that a
biobased economy can contribute to their goals in some way. -> a biobased economy has the
following drivers:
- Avoiding being in trouble due to fluctuations of the oil prices.
- Getting more security of energy supply.
- Lowering the emission of greenhouse gasses and thereby tackling climate change.
- Stimulating rural development.
- Stimulating the development of developing countries.
- Being less dependent on geo-political conditions (e.g. countries which have no fossil fuels become
less dependent on countries which have fossil fuels and are therefore less affected by geo-political
conditions which could prevent getting fossil fuels from the countries which have fossil fuels).
Most important driver for a biobased economy = biobased economy is a step in trying to meet the
increasing energy consumption of the world population.
E.g. it is expected that in 2050 the energy consumption of the world population will be approximately
1000 EJ (1000 * 1018 J) instead of the 350 EJ (350 * 1018 J) it was in 2000 and in 2050 the energy
consumption of the world population is thus expected to be almost 3 times as high as it was in 2000:
The energy consumption of the
world population is thus expected to
increase due to:
- The increase of the world
population.
- The increase of the prosperity level
of the world population.
Biomass: organic material which is produced on a frequent basis.
a. The main sources of biomass to be used in the biobased economy are:
- Forestry residues (e.g. remains of felled trees)
- Aquacultures (e.g. macro-algae (e.g. seaweed), micro-algae)
- Animal residues (e.g. hair, hooves, intestines)
- Food industry residues (e.g. the ends of breads which are used for making packed sandwiches)
- Municipal waste (e.g. banana peels)
- Sewage (e.g. undigested biomass in feces)
- Agricultural residues (e.g. peels of potatoes)
b. The composition of biomass is as such that the major compounds in biomass are:
1. Carbohydrates
2. Proteins
3. Lipids (mostly triglycerides)
4. Lignin
5. Minerals
,Hugo Cloudt Biorefinery (BCT-23306)
European definition of a biorefinery = processing which has the following characteristics:
1. Is sustainable -> in the sense that it has not only optimal environmental performance, but is also
maximising economics and is socially acceptable.
2. Uses biomass
3. Produces a spectrum of products (food, feed, biobased chemicals and/or biobased materials) ->
not a single product is produced in the process but multiple different products are produced in the
process.
4. Produces marketable products -> people need the produced products and want to buy the
produced products.
5. Produces products which are biobased.
6. Produces bioenergy (biofuels, power and/or heat).
This is summarised in the following short definition of biorefinery:
Biorefinery: the sustainable processing of biomass into a spectrum of marketable biobased products
(food, feed, biobased chemicals and/or biobased materials) and bioenergy (biofuels, power and/or
heat).
Results of a biorefinery:
1. Products:
- Food
- Feed
- Biobased chemicals
- Biobased materials
2. Bioenergy:
- Biofuels
- Power
- Heat
Refinery: a process in which a certain raw material/feedstock is converted into products and energy.
-> 2 types of refineries:
1. Petrorefinery -> raw material/feedstock = fossil fuels (e.g. petroleum, crude oil, natural gas)
2. Biorefinery -> raw material/feedstock = biomass
Biorefinery = analogous to the
classical/traditional petrorefinery, only
biomass is used as raw material/feedstock
instead of fossil fuels.
Characteristics of a refinery:
1. Efficient use of raw materials/feedstocks.
2. High process efficiency
3. High process flexibility (e.g. a refinery has to be able to use various different starting
materials/feedstocks).
4. Process integration: coupling different processes to each other. -> a refinery is thus always coupled
to other processes.
,Hugo Cloudt Biorefinery (BCT-23306)
Usually, products of a biorefinery are intermediates which are in different processes (e.g. chemical
processes, microbiological processes, enzymological processes) converted to the end-products which
are actually used, therefore a biorefinery is positioned in the following way:
From the various constituents of the in biorefineries used biomass several different products can be
made, these products can be classified into the following categories:
1. Pharmaceuticals
2. Food & feed products
3. Bioplastics & other biopolymers
4. Bulk chemicals & fuels
5. Energy & heat
In general, the products belonging to a certain category have a different value than products
belonging to another category and from products belonging to a certain category a larger amount
can be made out of the biomass than from products belonging to another category, taking these
aspects into account results in the following pyramid scheme:
When utilising a certain type of biomass in a biorefinery you should always keep this pyramid in mind
for deciding into which products you are going to convert the biomass in the biorefinery and based
on that design the biorefinery, a good way to do this is by using biomass cascading: approach for
deciding into which product you are going to convert each constituent of the biomass used in a
biorefinery, in which you find out for each constituent into which products it can be converted and
based on that decide to convert the constituent which can be converted into the product with the
highest value into this product with the highest value, subsequently decide to convert the
constituent which can be converted into the product with the second highest value into this product
with the second highest value, then decide to convert the constituent which can be converted into
the product with the third highest value into this product with the third highest value and so on until
you have decided for each constituent of the biomass in which product it will be converted in the
biorefinery.
,Hugo Cloudt Biorefinery (BCT-23306)
A lot of different types of biomass can be used as raw material/feedstock for a biorefinery, these all
have different characteristics and therefore there are many aspects of the type of biomass which can
be taken into consideration when deciding which type of biomass to use for a biorefinery:
- Costs in amount of money (e.g. euros)/ton dry matter
- Yield in tonne dry weight ha-1 year-1 -> the higher the yield in tonne dry weight ha-1 year-1 of a certain
type of biomass, the better it is for a biorefinery.
- Composition
- Transport properties
- Storage properties
- Absence or presence of seasonality
- Possibilities for genetic improvement
- Geographic region where it can be produced
- Ability of processes for processing the type of biomass and thus the available options for processing
the biomass.
- Value of the products to be produced out of it
- Agronomic considerations related to the type of biomass (e.g. influence on soil quality, need for
water, whether it can be used in crop rotation etc.)
Obviously usually not all aspects of a certain type of biomass are as desired, fortunately there are
ways to cope with some negative aspects:
1. Bad composition -> genetics
2. Bad yield -> agronomy & genetics
3. Costs -> using genetics, fertiliser, chemicals, different harvesting techniques and/or producing the
type of biomass in a different region
4. Storage -> dewater, keep it in conditioned areas, add acids etc.
5. Transport -> dewater before transportation
Typical products of biorefineries:
a. Food ingredients:
- Starch
- Sugar
b. Feed:
- Soy meal
- DDGS (Distiller’s Dried Grain with Solubles): chunks which consist out of denatured proteins and are
fed to cattle.
c. Polymers:
- PLA (Poly Lactic Acid): polymer made by polymerising lactic acid.
d. Chemicals:
- Lactic acid
- Glycerol
e. Fibres:
- Board
- Paper
f. Fuels:
- Esters
- Bio-oils
- Ethanol
- Biogas
,Hugo Cloudt Biorefinery (BCT-23306)
When you are working on biorefineries in which fuels are produced you should always be aware of
the existence of the food-versus-fuel discussion: the discussion about if it is responsible to use land
which could be used for the production of food for the production of fuel instead. -> the existence of
this discussion proves that not all people are so fond of using land which could be used for food
production for the production of fuel and you thus should be aware that there will probably be a
significant number of people which will consider a biorefinery for producing fuels as something
negative.
Examples of biorefineries in which fuels are produced:
1. A biorefinery of grain to bioethanol:
Which can be simplified to the following summary of the biorefinery:
Distillation column
Starch
This process is the process which was first used for producing bioethanol and is therefore the process
for producing first generation bioethanol. People realised that instead of only producing the low-
value product DDGS as side-product also or only other side-products could be produced by:
- Removing proteins before the distillation -> removed proteins do not denature in the distillation
column and therefore have a higher value than when they are denatured by the distillation.
- Removing some amino acids (preferably non-essential amino acids, while these have a lower
nutritional value than essential amino acids) to produce chemicals out of them.
E.g. removing glutamic acid, while it is a non-essential amino acid which is very useful for producing
numerous products.
In these ways the process became more profitable and was thus improved to become the process for
producing second generation bioethanol.
,Hugo Cloudt Biorefinery (BCT-23306)
2. A biorefinery of seeds to biodiesel = Jatropha seeds as oil source for biodiesel:
The protein-rich press cake is currently usually
used as fertiliser or burned to produce heat.
However currently it is investigated whether it can
be used for the production of glue or emulsifiers.
Charateristics of Jatropha:
1. Jatropha seeds are about 30-40% oil -> composition of Jatropha seeds:
2. Not suitable as food and feed, because it is toxic to humans and cattle since it contains compounds
which are toxic to humans and cattle.
3. Not yet domesticated.
Jatropha is by some considered to be a miracle crop, because it has the following advantages with
respect to other crops which are frequently used as oil source for producing biodiesel:
- It is not affected by the food-versus-fuel discussion, because:
a. It is not suitable as food and feed, because it is toxic to humans and cattle since it contains
compounds which are toxic to humans and cattle.
b. It can be grown in very dry soil/on barren land which is usually not suitable for food production.
- It increases the productivity of barren land and thereby helps increasing the development of rural
areas with a lot of barren land.
Jatropha could still be improved in the following ways to improve the sustainability of the biodiesel
production from Jatropha seeds and improve the welfare and well-being of local farmers:
- Decrease the genetic variability of Jatropha by domesticating it and/or by using genetics, to
decrease the fluctuations in yield and oil content which is the result of this high genetic variability.
- Detoxify Jatropha to be able to use the protein-rich press cake which is produced as side-product as
feed.
Since a biorefinery is a refinery and a refinery is characterised by process integration, a biorefinery is
always part of a chain of processes. Therefore, when designing a biorefinery you should always
design the biorefinery while taking the whole chain of processes into account. On the other hand,
new chains of processes in which new biorefineries can fit have to be developed.
Biorefinery -> NOT only replacing petrorefinery, but also complementing petrorefinery to be able to
result in a more efficient overall refinery process.
Biomass can best compete with fossil fuels when it is used as raw material/feedstock for the
production of chemicals, for the production of energy & heat it is way more difficult to compete with
fossil fuels since fossil fuels are way cheaper for the production of energy & heat than biomass for
the production of energy & heat.
Biorefinery guidelines (general rules to let processes with biomass as raw material/feedstock
compete with processes with fossil fuels as raw material/feedstock, under sustainable conditions):
1. Choose the right type of biomass as raw material/feedstock.
,Hugo Cloudt Biorefinery (BCT-23306)
2. Consider as many biomass components as possible.
3. Use each biomass component at its highest value (keep in mind that the (molecular) structure of a
biomass component is much more important than its calorific value/energy content.
4. Keep components as much as possible on the field where the biomass is produced to ensure soil
fertility.
Notes belonging to the guidelines:
1. Choose the right type of biomass as raw material/feedstock.
For biomass as raw material/feedstock in general the following applies:
The higher the protein content of the type of biomass, the higher the value of the type of biomass
and thus the higher the costs of buying the type of biomass to use it as raw material/feedstock for a
biorefinery.
2. Consider as many biomass components as possible.
Before designing a biorefinery for a certain type of biomass as raw material/feedstock the first thing
you should do is always comparing the value of this type of biomass which is used as raw
material/feedstock to the total value of all the products of the biorefinery (which is found by adding
up the values of all the products of the biorefinery) to see whether the biorefinery is actually
profitable and therefore economically feasible.
- Value of type of biomass used as raw material/feedstock -> biorefinery is NOT profitable and
therefore NOT economically feasible.
- Value of type of biomass used as raw material/feedstock < total value of produced products ->
biorefinery is profitable and therefore economically feasible.
So the total value of the products of the biorefinery should always be higher than the value of the
type of biomass used as raw material/feedstock, if not it makes no sense to start designing the
biorefinery since this process will never be profitable and therefore never be economically feasible!
E.g. comparison of value of the type of biomass used as raw material/feedstock and the products of a
biorefinery for the biorefinery of grass:
In the first instance, the biorefinery
of grass as raw material/feedstock
thus seems to be profitable and
therefore economically feasible.
3. Use each biomass component at its highest value (keep in mind that the (molecular) structure of a
biomass component is much more important than its calorific value/energy content.
Petrorefinery -> produced chemicals usually have a lower calorific value/energy content than the
compound out of which these are produced, so energy is released in the process.
Biorefinery -> produced chemicals usually have more or less the same calorific value/energy content
than the compound out of which these are produced, so energy no energy is released in the process.
In general the activation energy of the reactions to
produce chemicals in petrorefinery is way higher
than the activation energy of the reactions to
produce chemicals in biorefinery, therefore usually
a lot more energy has to be put in in petrorefinery
processes as opposed to biorefinery processes.
,Hugo Cloudt Biorefinery (BCT-23306)
4. Keep components as much as possible on the field where the biomass is produced to ensure soil
fertility.
Strategy to do this = setting-up small scale biorefineries on farms, for dewatering or drying and thus
removing water with the minerals dissolved in it:
a. Advantage = solves the problem of the low functional density of biomass (when not processed
biomass is very voluminous (e.g. due to a lot of water in it) and therefore the amount of useful
material per m3 of biomass is not so high), because it leads to:
- Less transportation necessary and therefore lower
transportation costs.
- Water and minerals staying on the field where the
biomass is produced. -> good idea because this ensure
soil fertility and it makes no sense to take something from
the field which you do not need!
- Less waste treatment (because the central processing
factory has to do less processing and therefore produces
a lot less waste).
- Increased storage times -> advantageous because it can
for instance ensure that central processing factories can keep processing the whole year instead of
just during a part of the year (e.g. sugar beet processing in the Netherlands can currently only take
place between September and December/January and therefore sugar beet processing factories are
currently only processing maximally 5 months of the whole year).
- More income for the farmers (because they are selling now a product which is already a bit
processed and therefore has a higher value). -> advantageous because it can lead to:
> More jobs in rural areas.
> Farmers becoming less dependent on other members of the production chain.
> Stimulates farmers to increase their productivity.
> Farmers starting to use other types of biorefineries on their farm as well, such as biorefineries for
biogas production.
- Faster innovation -> because:
> Since small scale production facilities always have lower absolute CAPEX (Capital Expenditures, the
investment costs necessary to let a business become reality) than large scale production facilities, it
is less risky to invest in an innovative small scale biorefinery for on a farm than in an innovative big
scale central processing factory and thus more innovations will become reality.
> Small scale biorefineries can be easier adjusted and thereby improved than large scale central
processing factories.
b. Disadvantage = no economy of scale -> economy of scale: the phenomenon that it is more
profitable and thus economically more attractive to produce on a large scale than to produce on a
small scale, since the larger the production scale the lower the costs per produced unit become due
to the fact that on a large scale compared to a small scale:
- The overhead costs per produced unit are lower.
- You can in general employ more people which are specialised in a certain aspect instead of people
with more general knowledge, which leads to a higher productivity.
- A company with a large scale is more powerful than a company with a small scale and can therefore
usually make better deals.
- For the technology, the investment costs per produced unit decrease when the scale of the
production process increases. -> expressed by the following equation:
,Hugo Cloudt Biorefinery (BCT-23306)
R = scaling factor: constant which has a value between 0 and 1 which differs for each type of
equipment and which shows for each type of equipment how strongly the investment costs per
produced unit decrease when the scale of the piece of equipment increases:
Lower R/R closer to 0? -> the investment costs per produced unit decrease more strongly when the
scale of the equipment increases.
Higher R/R closer to 1? -> the investment costs per produced unit decrease less strongly when the
scale of the equipment increases.
R = 1? -> the investment costs per produced unit do NOT decrease when the scale of the equipment
increases.
Strategy to lower the investment costs of a biorefinery = minimise the heat exchange in the process.
-> the more heat exchange in a process, the higher the investment necessary to realise the process!
Highly exothermic or highly endothermic process in which a lot of heat exchange thus cannot be
prevented? -> split the process into 2 parts:
1. Part with a lot of heat exchange -> should occur on small scale on local level (e.g. densification of
biomass by dewatering or drying it on the farm).
2. Part with less heat exchange -> should occur on large scale (e.g. processing of the biomass coming
from the farmers in the central processing factory).
Lecture 2 – Biomass composition
The composition of biomass is as such that the major compounds in biomass are:
1. Carbohydrates
2. Proteins
3. Lipids (mostly triglycerides)
4. Lignin
5. Minerals
Next to the above mentioned major compounds in biomass there is another compound which is
usually the compound which is most abundantly present in biomass = water. -> the compounds listed
above are therefore only the major compounds in dry biomass, in the wet biomass which is found in
nature water should be added to the list of major compounds in biomass!
Water in biomass:
- Usually not considered as a product of a biorefinery.
- Usually removed from the biomass by dewatering or drying since when it remains in the biomass it
leads to:
a. Shorter storage times of the biomass (water in the biomass makes the biomass more perishable).
b. More difficult transport of the biomass.
- In general a higher amount of water in biomass makes the biomass less attractive for biorefinery,
since then more water has to be removed from the biomass by dewatering or drying, which increases
the costs of the process because:
a. For dewatering as well as for drying equipment is necessary.
b. Dewatering can take out other components than water out of the biomass as well (components
which are dissolved in the removed water).
c. For drying a lot of energy is needed.
Types of biomass have:
- Varying carbohydrate content
- Varying protein content
, Hugo Cloudt Biorefinery (BCT-23306)
- Varying lipid content
- Varying lignin content
- Varying mineral content
- Usually a high water content
Carbohydrates: compounds which consist out of one or multiple to each other coupled units which
consist out of C atoms, O atoms and H atoms which have formed a ring structure (usually with 6 C
atoms).
- Although the chemical structure of a unit of a carbohydrate is in nature a ring structure it is
sometimes shown as a linear structure:
Left = chemical structure of the carbohydrate glucose
when it is displayed as a linear structure.
Right = chemical structure of the carbohydrate glucose
when it is displayed as the ring structure it actually has
in nature.
- Carbohydrates are usually classified into different categories by the number of units they have,
when this is done the following categories of carbohydrates are distinguished:
a. Monosaccharides: carbohydrates which exist out of 1 unit.
E.g. glucose:
b. Disaccharides: carbohydrates which exist out of 2 via a glycosidic bond/glycosidic linkage to each
other coupled units/monosaccharides.
E.g. sucrose = the monosaccharides glucose & fructose which are coupled to each other via an α-D-
glycosidic bond/α-D-glycosidic linkage.
c. Polysaccharides: carbohydrates which are long chain polymers of via glycosidic bonds/glycosidic
linkages to each other coupled units/monosaccharides. -> most important polysaccharides for
biorefinery are:
1. Starch
2. Cellulose
1. Starch: polysaccharide which is present in plants (usually in the tubers, bulbs or seeds) as a storage
component (component which is formed in an organism to store energy).
- Consists out of units/monosaccharides (all glucose) which are linked to each other via α-D-glycosidic
bonds/α-D-glycosidic linkages.
α-D-glycosidic bond/α-D-glycosidic linkage = glycosidic bond in which 2
carbohydrate units/monosaccharides are linked via an O atom which is
for both carbohydrate units/monosaccharides in an axial position.
- Easy to digest/degrade, can be done with all kinds of acids and all kinds of enzymes.
- Examples of plants with a lot of starch:
> Potatoes (1/5 starch)
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