Bioraff - Mer av trä

Bioraff-Mer av trä

Bioraff Mer av trä Project Final Report 2018

Content Bioraff - Mer av trä ........................................................................................ 1 Content .......................................................................................................... 1 Summary and general introduction ........................................................... 3 1 Mapping of intersectoral value chain tails from saw mill industry, pulpand paper industry and biorefineries in Jämtland, Västernorrland and Trøndelag ................................................................................................... 5

2

1.1

Introduction ........................................................................................................5

1.2

Background .........................................................................................................5

1.3

Method ................................................................................................................5

1.4

Results................................................................................................................ 6

1.4.1

Sawmills in Jämtland and Västernorrland .................................................... 6

1.4.2

The pulp mills in Jämtland and Västernorrland .........................................7

1.4.3

Raw materials in Trøndelag ....................................................................... 8

1.5

Conclusions .......................................................................................................10

1.6

References .........................................................................................................10

Fish feed.............................................................................................. 11 2.1

Introduction ...................................................................................................... 11

2.2

Background ....................................................................................................... 11

2.2.1

Pretreatment.............................................................................................. 11

2.2.2

Production of single cell protein ............................................................... 12

2.3

2.3.1

Raw materials ............................................................................................ 13

2.3.2

Pretreatment – reactor setup .................................................................... 13

2.3.3

Production of single cell protein ............................................................... 14

2.4

3

Methods ............................................................................................................ 13

Results and discussion ...................................................................................... 14

2.4.1

Pretreatment.............................................................................................. 14

2.4.2

Production of single cell protein ............................................................... 15

2.5

Conclusions ....................................................................................................... 18

2.6

Reference .......................................................................................................... 18

Green chemicals from pyrolysis oil ..................................................... 19 3.1

Introduction ...................................................................................................... 19

3.2

Background and aim ......................................................................................... 19

3.3

Methods ........................................................................................................... 20

3.3.1 (HTL)

Production of bio-oil via fast pyrolysis and hydrothermal liquefaction 20

3.3.2

Chemical modifications of bio-oil ............................................................ 20 1

4

3.4

Results and discussion ...................................................................................... 21

3.5

Conclusions ...................................................................................................... 23

3.6

Reference ......................................................................................................... 23

Black pellets ....................................................................................... 24 4.1

Introduction ..................................................................................................... 24

4.2

Background ...................................................................................................... 24

4.3

Method ............................................................................................................. 25

4.4

Results.............................................................................................................. 25

4.5

Conclusions ...................................................................................................... 26

4.6

References ........................................................................................................ 26

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Summary and general introduction The Nordic Green Belt is a region with significant forest resources and forest-based industries, both on the Swedish and Norwegian side. The project “Bioraff - Mer av Trä" was a three-year project owned by RISE PFI and RISE Processum. This project has contributed to further development and promotion of the region as a center of excellence in new conversion, biorefining, of forest-based biomass, thereby positioning Central Scandinavia as a key player in the development of the future bio-economic society. In close collaboration with existing forest-based industries and other industrial sectors in the region "Bioraff - Mer av Trä" have developed new green products and processes based on the region's forest resources.

The main purpose of “Bioraff Mer av Trä” was to produce and develop products that can be included in biorefineries, both integrated in the current production but also in new types of biorefineries. The development of these new products has strengthened existing companies and created new businesses based on forest resources.

“Bioraff Mer av Trä” built on the results achieved in “Bioraffinaderi Mitt-Skandinavien” and included four development projects. In the first, the focus was primarily on using existing forest industry waste streams for the realization of large-scale production of single cell protein, SCP, which is an interesting protein source in fish feed for the fish feed production industry. In addition, SCP can also be used as a feed source in other feed and food production industries. Production of SCP was the focus of the second project.

It included an advanced biotechnological approach to develop, evaluate and analyze a microorganism with high protein content.

The third project was based on the results of the solvolysis project conducted in “Bioraffinaderi Mitt-Skandinavien”. The aim of this project was to develop concepts which have better profitability through co-production of biofuels and biochemicals from pyrolysis oil.

The fourth project evaluated the use of torrefied material called "Black pellets". The purpose was to examine the environmental, technical and practical potential of torrefied materials in new markets. The results may help the replacement of fossil fuels in local heating stations and smelters with locally produced torrefied materials from locally/regionally available biomass and facilitate the establishment of "black pellets" in the small-scale market.

The measurable goals of the project were: -

To map the forest industrial waste streams in the project region with respect to volume, type and quality.

Evaluate possible conversion routes for the different fractions based on the initial mapping of the waste streams.

Conduct at least two introductory laboratory studies for selected waste streams.

Develop an economically sound concept for SCP production from forest-based waste streams.

Conduct a market analysis of the value chain starting from the forest industry ending at the fish feed market within the Nordic green belt.

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-

Develop a technique for isolation of biochemicals from bio oils produced from wood and lignin.

Produce and characterize different bio oils from pyrolysis and fractionated condensation.

Market torrefied pellets from saw mill waste streams as an environmentally sustainable and user-friendly alternative to fossil fuels for small- and midsize usage and as top up for more energy demanding production processes.

Target groups: The project targeted biorefinery processes, forest valorisation industry, industry which utilize adhesives in their production, fish feed producers, energy companies and energy demanding industry.

Key words: RISE Processum AB, RISE PFI AS, Biorefinery, Single Cell Protein, SCP, forest industrial waste stream, bio-oil

Örnsköldsvik and Trondheim, 2018

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1 Mapping of intersectoral value chain tails from saw mill industry, pulpand paper industry and biorefineries in Jämtland, Västernorrland and Trøndelag 1.1

Introduction

The forest industry has a long history in Sweden and Norway and plays an important role in their economies. In the past, the forest raw material was used for production of wood products, paper, board, hygiene products and as a fuel in the form of charcoal, wood and chips. The increased usage of digital media as well as competition from fast growing forests have increased the competition regarding the production of selected paper types.

At the same time, the volumes of fellable forests have been predicted to increase thereby creating a space for establishing new bio-based products. Furthermore, the residual streams are expected to play an important role for the future facilities, e.g. biorefineries.

The aim of this work package was to evaluate the utilization of forest residual streams for production of single cell protein (SCP).

1.2

Background

Forest resources and forest management industries like saw mills, pulp- and paper industries and biorefineries are abundant within the regions of mid-Norway and midSweden. The pulp- and paper industries in Sweden are based along the coast line due to the huge production volumes. The sawmills on the other hand, are more evenly distributed in the region. Jämtland and Västernorrland have five pulp mills and 12 saw mills (with an annual production above 1000 m3 sawed products). This can be compared with a total amount of 32 pulp mills and 29 saw mills in the whole of Sweden. The 14 Norwegian companies are mostly situated in proximity to water. The raw material consumption and the production of side streams were evaluated in the region of the Swedish and Norwegian side of the Nordic Green Belt. The counties are Jämtland, Västernorrland and Trøndelag.

1.3

Method

An annual survey of the forest industries in Sweden is done by the forest industry data company SDC. The data of the raw material consumption of the saw- and pulp mills and the volumes of residual streams produced by the sawmills considered in this report is gathered from this survey. The data of the pulp mill side stream fractions are provided by the Forest Industries federation. A comprehensive survey of waste streams from the 5

mid-Norwegian forest- and wood industry was conducted within the Arena forest project ”Kartlegging av sidestrømmer fra Midt-Norsk skog- og treindustri” and was conducted in close collaboration with “Bioraff- mer av trä”.

As there are many saw mills which are operated in small scale, a delimitation was set in this survey to only include saw mills with a production above 1000 m3 sawed products per year for the Swedish side. For the Norwegian side, the cut-off was a yearly turnover 5 million NOK.

1.4

Results

1.4.1

Sawmills in Jämtland and Västernorrland

A total of 4 439 311 solid cubic meter under bark (sub) round wood was consumed by the sawmill industry in the region during 2017. No wood was imported to the region this year, but it is not possible to elucidate if the wood originated from the region or from other parts of Sweden. The distribution between pine and spruce is illustrated in Figure 1.4.1-1.

Figure 1.4.1-1. The consumption of roundwood by the sawmills. Solid cubic meter under bark (m3sub) is abbreviated in the figure above.

The normal yield is about 96% and roughly 50% of this is sawed wood and 50% is residual streams. The residual streams produced from the saw mills in this region are either sold to the fiber industry, sold as external fuel or used internally at the site as fuel. The 6

distribution of the different residual streams from the 2017 survey is shown in Figure 1.4.1-2.

Figure 1.4.1-2. Side stream production from sawmills and todays end-use. m3sub is an abbreviation for solid cubic meter under bark.

1.4.2

The pulp mills in Jämtland and Västernorrland

A total of 8 668 512 m3sub of round wood and wood chips were used at the pulp mills in this region during 2017. Spruce and pine were the dominating raw materials used by the pulp mills, though birch comprised a significant fraction too. About 16% of the raw material was imported.

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The residual and waste streams from this industry are estimated to 1 100 000 ton dry matter per year in the whole country. In this region the amount is 150 000-200 000 ton estimated from the production of the mills. Currently, about 90% of these streams are recycled or reused in some way. In figure 1.4.2-1 the production of residual streams on a national level can be seen. The amount of waste from the forest industries that is sent to landfills is relatively small compared to their huge production volumes.

Ton dry matter/year

250 000 200 000 150 000 100 000 50 000 0

Figure 1.4.2-1. The waste and residual streams of the pulp and paper industry in Sweden.

1.4.3

Raw materials in Trøndelag

The yearly forest fell in the Trøndelag amounts ca: 840 000 m3 (Brodin et al. 2018).

Forest resource analysis have indicated a yearly felling potential around 1.1 million m3.

Most of the wood stem from the region, but approximately 30% is imported, see Figure 1.4.3-1. Spruce is the dominating biomass for the Trøndelag raw material (Figure 1.4.32).

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Figure 1.4.3-1. Overview of the origin of forest raw material in the Trøndelag region.

Figure 1.4.3-2. Overview of the type of forest raw material in the Trøndelag region.

The forest biomass is used for various high- and low value products. The waste streams mainly comprise of bark, saw chips and saw dust. Examples include fuels for incineration plants, biofuels, bio-oil, pellets, isolation material, fish food, biochemicals and paper and pulp. The yearly bark production from the 14 companies included in the study amounts 180 000 m3s, where s is an abbreviation for solid measure. 90% of that bark is incinerated in internal plants for energy and heat production. This is a low value product 9

and there is potential for increasing the values of biobased products in the region. This is true for bark, sludge, ash, wood chips and dust. Most of the bark is produced in the northern part of the Trøndelag, hence establishment of new bark-utilizing industry should be located in that region close to the current industry, e.g. the newspaper producer Norske Skog Skogn, CTMP-producer MMK FollaCell and the saw mill Moelven Van Severen. Industrial chips are utilized in the pulp- and paper production and in melting industry which gives higher value products. The saw dust production amounts to 75 000 m3s of which 55% is burnt. About one fourth of the saw dust is sold to the industry for production of particle boards. The remaining material is utilized by farms.

Most of the saw dust is produced in Namsos and in Selbu. Shavings comprise another large waste stream which amounts to 45 000 m3s per year. These ones are characterized by a lower moisture content compared with saw dust and saw mill chips. The shavings are used for burning (ca: 1/3), for farming and animal bedding (ca: ¼), about one fifth for particle board production and one fourth to briquettes.

1.5

Conclusions

Most of the waste and residual streams from the forest industries are currently mostly used for low value products, such as fuel, and there is a big potential for further processing of these streams to higher value products.

1.6

References

Brodin M., Øyaas K, Johansson L. 2018. Kartlegging av sidestrømmer fra Midt-Norsk tre- og treforedlingsindustri, RISE PFI-rapport 03/2018.

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2

Fish feed

2.1

Introduction

Fish farming delivers about half of the fish which is considered for human consumption.

The main protein source in fish feed is fishmeal or soy protein. The annual production of fishmeal in the world is in the range of 5-6 million ton, which is mostly used for fish feed production. However, there is concern that fishmeal will soon be a scarce commodity and it contributes to over-fishing in the seas. To address this problem parts of the fishmeal in fish feed, has been substituted with soy protein as the protein source during the last decade. However, soy is mainly produced in South America and its production is associated with environmental problems such as deforestation of rain forests. In addition, there are issues with food security if the food production of a country heavily relies on imported feed. Therefore, there is a need of finding alternative, sustainable, sources of protein which can replace the fishmeal and soy protein. One such alternative is protein rich microorganisms like filamentous fungi, i.e. single cell protein (SCP). It can be produced from industrial waste streams and could thus constitute a biorefinery sideproduct.

In “Bioraff- Mer av Trä” one of the key goals was to develop a microorganism with a high protein content. That microorganism had to be able to grow efficiently and utilize the sugar components in the wood feedstocks. The wood feedstocks need pretreatment for selective conversion of wood polysaccharides into fermentable sugars without forming compounds which inhibit the fermentation. In theory, the microorganisms should be able to utilize sugars derived from both cellulose and hemicellulose. The aims of this work package were to develop pretreatment methods for production of fermentable sugars and optimization of single cell production from these sugars. In the first part of this study, the hydrolysate after pretreatment of wood feedstock have been used as substrate for single cell production. Furthermore, in the second part of this study, the pretreated wood material was converted to sugars through enzymatic hydrolysis and the sugar rich hydrolysate was further converted to SCP through fermentation. These results will be published in a scientific journal. Therefore, in order to avoid self-plagiarism, only the results from the first part of this study are presented here.

2.2

Background

2.2.1

Pretreatment

Pretreatment of forest biomass in this concept is conducted in order to make the sugars in the biomass available for further treatment. The selection of suitable pretreatment method(s) depends on several factors: the biomass structure and properties, the subsequent conversion process which may be biochemical or thermochemical and 11

finally, what kind of product mixture there is; high or low value products. Three different pretreatment methods, hot water extraction, low temperature sulfonation and organosolv, have been investigated in this project to produce high yield of fermentable sugars and good lignin separation for the wood biomass.

The “Low temperature sulfonation” pretreatment is a methodology developed at RISE PFI which aims at obtaining sulfonation lignin at mild conditions, i.e. low temperature.

In this process most of the lignin is dissolved as lignosulfonates and a quite cellulose rich solid material remains. The advantage with this method is that the lignin dissolution gives the enzyme good access to the cellulose chains favoring a high enzymatic hydrolysis yield. In addition, the process allows isolation of lignin sulfonates which can be sold as a byproduct. In the “Low temperature sulfonation” pretreatment most of the hemicelluloses will be hydrolyzed into oligomer and monomer sugars which dissolves together with the lignin.

The “hot water” pretreatment is a process which give efficient dissolution of hemicelluloses as oligomer and monomer sugars, whereas a solid fiber/wood chips material of cellulose and lignin remains. Xylan is hydrolyzed slightly faster than glucomannans. Therefore, the hydrolysate typically contains mostly xylose from xylan and a mixture of monomers and oligomers from glucomannans. A mild post hydrolysis treatment can be done to further convert dissolved hemicellulose oligomers into monomers.

The acetone based organosolv pretreatment method is based on the ACOS process. This process gives a good fractionation of biomass into its pure fractions: lignin, hemicellulose and cellulose. Theoretically, cellulose remains in the solid fractions while hemicellulose and lignin are released into the liquid fraction. Furthermore, the lignin is easily separated from the liquid fraction by precipitation, e.g. via addition of an antisolvent like water.

This process increases the enzyme accessibility to cellulose and a high-quality lignin byproduct is produced.

2.2.2

Production of single cell protein

Processum has conducted a successful up-scaling experiment where a protein-rich filamentous fungus was produced from an industrial waste stream from the cellulose manufacturer Domsjö fabriker. The fungi were evaluated as an alternative for fishmeal in fish feed and it was shown that the fish (Tilapia) fed with the fungi grew equally well or better than fish fed with fishmeal-based reference feed (Alriksson et al. 2014).

However, the current value of the fungi was a bit low to motivate the investment of a large production unit. Hence, there was a need to increase the value of the product and one way of doing that is by increasing the protein levels in the fungi. The aim of the current work package was to optimize (improve) the protein levels in the fungi in order to improve the financial calculation of the production of SCP from forest raw material.

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2.3

Methods

2.3.1

Raw materials

Norway spruce (softwood) and birch (hardwood) were debarked, dried and chipped at RISE PFI with a hammer mill and fractionated in different sizes, see example in Figure 2.3.1-1. A -8/+7 mm fraction was stored at room temperature until further use. Both softwood and hardwood were used in the study since their carbohydrate composition is different. Softwood has a higher availability and is therefore the preferred feedstock.

However, it is easier to make a selective conversion of hardwood than of softwood.

Figure 2.3.1-1. Wood chips for pretreatment experiments. Photo RISE PFI.

2.3.2

Pretreatment – reactor setup

Two pretreatment strategies were applied for the low temperature sulfonation and hot water extraction. These treatments were carried out under “mild“ and “extensive” conditions. Here, “mild conditions” meant that the pretreatment was done at milder conditions (lower temperature etc.) to obtain most of the pretreatment effect but at the same time avoid formation of toxic inhibitors. “Extensive conditions” meant that the pretreatment was done in a way to make most of the wood carbohydrates available for enzymatic hydrolysis but, as rather tough conditions were applied, there was risk for formation of inhibitors.

The hot water extraction and low temperature sulfonation were carried out in a circulation reactor equipped with four autoclaves of 1000 ml each, a circulation pump, a temperature control and a pressure device. The organosolv pretreatment process was carried out using a new reactor design at RISE PFI called “High Pressure rapid heating displacement pretreatment reactor” (Toven et al. 2017). The extraction yield and the chemical composition were analysed after the pretreatments.

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2.3.3

Production of single cell protein

The single cell protein was produced via a multi-step procedure using the extraction liquids obtained from the pretreatment as starting material. Three different studies were conducted in this part of the project.

1) A screening experiment where the starting material constituted the extraction liquids from the pretreatment step (methods described in section 2.3.2 and examples shown in Figure 2.3.3-1). Biomass and protein content after fermentation were analysed for all the different cultivations.

2) The second study was an up-scaling experiment in a 50L reactor aiming at testing the possibility to obtain the same results of single cell production in a smaller scale.

3) The third and final study aimed to optimize the protein concentration in the SCP. The optimization was conducted by varying parameters such as pH, temperature, size of starting culture, nutrient boost and fed-batch. The protein concentration was analysed as a function of time.

2.4

Results and discussion

2.4.1

Pretreatment

The chemical composition of both Norway spruce and birch is given in Figure 2.4.1-1. It is well known that xylan is the predominant hemicellulose compound in hardwood (birch) while galactoglucomannan is the predominant hemicellulose compound in softwood (spruce). The lower lignin content in hardwood makes it easier to disrupt the lignocellulose structure.

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Figure 2.4.1-1. Chemical composition in the raw material, Norway spruce and birch.

Increasing the cellulose accessibility favors a high sugar yield from the enzymatic hydrolysis. However, carbohydrate degradation is undesired during pretreatment, as the degradation products may inhibit further biological processing of the pretreated material.

2.4.2

Production of single cell protein

The results from the first study to produce SCP showed that cell growth was observed in only 3 of the 8 pretreatment liquids. Best growth was in the media containing mild hot water liquid extraction of birch (11.8g/L), the second best grew on extensive hot water liquid extraction solution from spruce (7.8g/L) and the third pretreatment liquid which resulted in biomass growth stemmed from the mild hot water extraction of spruce (4.0g/L, see Fig. 2.4.2-1A). The protein concentration in the dry biomass were similar to the biomass concentration, with the exception that extensive hot water liquid extraction solution of spruce resulted in slightly higher protein concentration than birch treated by mild hot water liquid extraction (Fig. 2.4.2-1B).

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Fig. 2.4.2-1. Production of single cell protein using the pretreatment liquid as starting material. (A) Cell growth and (B) Protein concentrations. HWE is an abbreviation for the hot water extraction, Ext means extensive or severe and Mild refers to the milder extraction conditions.

The second study showed that it was possible to scale up the protein production to 50L. For the protein optimization study (Study 3), it was found that the protein concentration increased with decreased cultivation time (Fig. 2.4.2-5). The protein concentration also increased with decreasing pH and decreasing biomass concentration (Fig. 2.4.2-6). A protein content of 62% was achieved for the best cultivation experiment at lab scale which proves that it is possible to reach protein concentrations over 60%. Nevertheless, repeating it at larger scale and in combination with high yield and biomass concentration remains to be proven.

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Figure 2.4.2-5. Protein concentration over time. Samples were collected daily and the protein concentration was measured. The protein concentration is reported as % g/g dry weight.

Figure 2.4.2-6. Protein concentration versus biomass at different pH. The dashed lines are for visual guidance.

In summary, these materials are easy to work with to produce single cell protein and many of them give a high cell biomass and also a high protein content. A next step with these starting materials might be to use low pH and fast-growing cells, for example in a continuous mode (where new growth media is continuously being added and cells 17

removed at identical speed). A high protein content (>55%) with a remaining high biomass concentration might be possible using this method (>10g/L).

2.5

Conclusions

Several of the pretreatment methods resulted in an improved enzymatic hydrolysis.

There is a big potential for further improvements with respect to sugar yield. Several of the hydrolysates resulted in good SCP production, whereas some contained too much inhibitory substances.

2.6

Reference

Alriksson B., Hörnberg A., Gudnason A.E., Knobloch S., Arnason J., Johansson J. (2014) Fish feed from wood, Cellulose Chem. Technol., 48 (9-10), 843-848

Toven K., Øyaas K., Tanase-Opedal M., Eriksen Ø., 2017 – High PressureRapid Heating Displacement Pretreatment reactor – A unique tool for developing new pretreatment technologies, poster NWBC 2017.

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3

Green chemicals from pyrolysis oil

3.1

Introduction

Technologies for upgrading fast pyrolysis oils is an area of active research. However, there are still many routes to explore when it comes to fast pyrolysis of lignin and production of bio-oil via fractionated condensation which is the focus of the current project. Modern pulp facilities typically have a net production of energy, which can be used for converting the lignin in the black liquor to a high-value product. Lignin comprise about one third of the raw material and often ends up as a waste stream which is burnt.

Therefore, valorisation of that lignin can increase the profitability of many current and future biorefineries.

3.2

Background and aim

Pyrolysis is a thermal treatment where a carbon-based material is decomposed in an inert atmosphere at elevated temperature. Charcoal has been produced via pyrolysis for thousands of years, whereas fast pyrolysis of liquids has only been known for about 40 years (Bridgwater). Fast pyrolysis is an upcoming technique for the conversion of biomass to bio-oils that can be upgraded e.g. to biofuels. Pyrolysis oil contain many different chemicals with varying properties. It is possible to separate, i.e. fractionate, those compounds via addition of water to the oil. The water phase will then contain chemicals such as alcohols, acids and aldehydes. The oil phase will contain phenolic compounds which are good starting materials for making chemicals. Phenol formaldehyde resins comprise one of the most common glues for industrial purposes.

Since pyrolysis oil from wood contains a phenolic structure it is believed that the pyrolysis oil may be used as the phenolic source in glues or adhesives.

The aims of this work package were to produce and characterize different bio-oils produced via pyrolysis and fractionated condensation. Furthermore, we aimed at producing bioadhesives, i.e. materials composed of chains or networks of a repeating unit (a polymer) which has glue-like properties. Potential uses for those bioadhesives comprise production of fibre boards, plywood or post-it notes.

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3.3

Methods

3.3.1 Production of bio-oil via fast pyrolysis and hydrothermal liquefaction (HTL) To get a raw material with a high concentration of phenol like compounds, pyrolysis oil was produced via fast pyrolysis of pinewood at PFIs facilities in Trondheim. The pyrolysis oil also contained a lot of water after the thermal process, which lowers the phenol concentration. To increase the phenolic content a forced phase separation was made by adding water to the pyrolysis oil while stirring vigorously and then cooling the liquids.

The oil phase was collected, cooled and then separated again. The water content and viscosity were analyzed. The remaining oil product was used as raw material for further chemical modifications at Processum. This final oil is referred to as “bio-oil”. The bio-oil was extracted with various solvents at different pH to obtain an oil with an increased phenolic content.

Figure 3.3.1.1 Pyrolysis facilities at PFI (to left). Photo RISE PFI. HTL at RISE Processum (to right). Photo RISE Processum.

Another route of producing bio-oil was also investigated. Lignin from pre-treated (steam explosion) and enzymatically hydrolysed wood chips from spruce and pine was heated in an aqueous slurry to 340°C in a closed container resulting in a high pressure (ca: 150 bar). This converted the lignin into 4 fractions; a solid fraction (biochar), a liquid fraction (HTL-oil or bio-oil), a gaseous fraction and a water-soluble fraction. These bio-oils were fractioned by extraction.

3.3.2

Chemical modifications of bio-oil

The bio-oil was chemically modified aiming at producing an adhesive like material.

Different chemicals were added, to either elongate the structures or to make them denser by creating more connections between the molecules. The glue properties were evaluated via two routes: via lamination of copy paper and via gluing of two pieces of wood. One copy paper was laminated with each product and another copy paper was added on top and then left to dry while pressurized. The adhesive properties of the products were 20

investigated via the paper testing methods, Scott bond and Z-strength. About 1g product/55 cm2 of wood was applied and left to dry under pressure. Since there are no available certified analysis for evaluating the strength of the glue, attempts to separate the wooden pieces by hand were conducted. A total of four persons tried to separate each of the pieces.

3.4

Results and discussion

The bio-oil obtained via fast pyrolysis contained less water and more phenolic/aromatic compounds than its starting material. The analysis also indicated that the bio-oil had a higher content of high molecular weight (HMW) components. HMW components are desirable for further processing. The extraction schemes purified the concentrated liquid bio-oil to a soft mouldable solid which liquifies upon heating, see Figure 3.4-1. Bio-oil obtained via the high temperature and pressure procedure had a much lower oxygen content than its starting material. Therefore, it was less hydrophilic and thus spontaneously separated from the aqueous phase.

Figure 3.4-1. Left: bio-oil, middle: separation after acidification of aqueous phase, right: product after extraction with organic solvents. Photo RISE Processum.

The bio-oils were chemically modified. More than 20 different experiments were conducted, examples shown in Figure 3.4-2. All modifications resulted in a visual change in the physical properties of the bio-oils. Some bio-oils got higher or lower viscosity and some of the samples became very sticky and some less sticky. They also varied in consistence, some were liquid, others had a waxy consistence, and some were solid. Biooil mixed with Fenton’s reagent (hydrogen peroxide and iron) is an example of a successful modification resulting in a soft workable product that solidify over time.

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Figure 3.4-2. Products after chemical modifications of bio-oils. Photo RISE Processum.

All bio-oils and bio-oil mixtures with hydrogen peroxide or formaldehyde were weaker than regular copy paper, examples shown in Figure 3.4-3. The strongest glues, evaluated via gluing of two wood pieces, were those based on bio-oil, bio-oil mixed with formaldehyde and bio-oil mixed with hydrogen peroxide, respectively. All other glued wood-pieces were possible to separate by hand. However, the other glues (bio-oil mixed with Fenton’s reagent and extract mixed with formaldehyde) were strong enough for not being separated by hand force by 3 of 4 persons who examined them. Examples of glued wood pieces are shown in Figure 3.4-4.

Figure 3.4-3. Left: Successful lamination of copy paper, right: laminated papers after testing. Photo RISE Procesum.

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Figure 3.4-4. Wood pieces glued with bio-oils and/or extract mixtures.

Photo RISE Procesum.

3.5

Conclusions

It is possible to chemically modify pyrolysis oil, but it has been challenging to evaluate the products. For example, there were no major differences in the molecular weight distribution after the chemical modification despite clear visual changes. The adhesion of the glue to the paper was not very good, but based on the tests with the wood pieces, it can be concluded that the products might be suitable adhesives for fibrous materials like wood.

It was also shown that it is possible to replace formaldehyde, a volatile chemical subject to limitations, with more environmentally friendly chemicals such as Fenton’s reagent consisting of hydrogen peroxide and iron. Future work should focus on optimizing this and other chemical modification aiming at replacing formaldehyde in applications where the use of formaldehyde is problematic.

3.6

Reference

Bridgewater T. (2018) Challenges and Opportunities in Fast Pyrolysis of Biomass.

Johnson Matthey Technology Review, 62, 118-130.

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4

Black pellets

4.1

Introduction

Black pellets comprise thermally treated biomass which has been pelletized and have a dark color as a result of the thermal treatment, see Figure 4-1. The thermal treatment is called torrefaction and it is a thermochemcial process which dries and decomposes structures in the biomass resulting in a product with significantly different physical and chemical properties than the starting material (Bioendev). The main differences between black pellets and regular white pellets are that the torrefied material has a higher energy density, is more brittle, is less sensitive to biological decomposition, has a reduced of risk biological contamination because of the high temperature treatment and is hydrophobic, i.e. it repels water. These factors lower the cost of transportation, prolongs the shelf-life, results in lower grinding costs and facilitates outdoor storage of the pellets. The torrefied biomass resembles fossil coal more than its starting biomass raw material or white pellets and can e.g. be used for co-combustion in coal power plants or replace charcoal in powder burners. Hence, locally produced biomass can be used to replace fossil-based fuels in order to mitigate greenhouse gas emissions.

Figure 4-1. Black pellets. Photo: Bioendev.se

4.2

Background

The concept of utilizing local sawmill waste streams for small scale plant usage in sparsely populated areas have not been evaluated before (Uhlir and Wernersson Brodin, 2018). Verification of technical and environmental aspects of use of torrefied material is lacking within these markets. Neither have largescale utilization of torrefied material been evaluated. Fuels in the form of torrefied pellets based on local sawmill waste streams could potentially comprise a new, big market which would benefit the stakeholders in all parts of the value chain from forest owner to sawmills and end energy users (Uhlir and Wernersson Brodin, 2018).

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There are several sawmills in the Norwegian project area with a significant production of sawmill waste streams which might be suitable for torrefication, e.g. Moelven van Severen, InnTre and Kjelstad-konsernet. There are also several district heating plants, e.g. run by Statkraft. These are currently utilizing waste and biofuels. Torrefied, energy dense, material might be interesting to utilize. The torrefied pellets might also be used for top-up in energy demanding industry.

The aim of this work package was to examine the environmental, technical and practical potential for torrefied, sawmill waste stream, material, i.e. black pellets, within new market areas with small and mid-sized plants.

4.3

Method

Raw material was collected from different suppliers, i.e. sawmills. The raw materials were analysed and compared with those currently utilized in Bioendev’s facility in Holmsund, Sweden. Black pellets were produced from sawmill waste streams. Results from a market analysis performed by PFI within the Arena-forest project ”Kartlegging av sidestrømmer fra Midt-Norsk skog- og treindustri” focusing on forest and wood industry wastes streams in terms of quantities and current use were utilised in the WP. Pellets were analysed with respect to fuel properties, elemental composition, size distribution, mechanical durability and compression strength. Burning experiments with 10 tonnes of black pellets were conducted in the Nord Energies 700 kW incineration plant in Vikhammer which is normally operated using standard white pellets. The results were evaluated, reported and disseminated.

Figure 4.3.1. Nord Energis incineration plant at Malvik’s upper secondary school in Vikhammer municipality (to left) and burner with moving grate (to right). Photo RISE PFI.

4.4

Results

The waste streams from Norwegian forest and wood industry were recently evaluated within the Arena forest-project ”Kartlegging av sidestrømmer fra Midt-Norsk skog- og 25

treindustri”, which was conducted in close collaboration with this project (“Bioraff – mer av trä”). Bark, saw chips and saw dust comprise the waste streams which might be suitable as starting materials for black pellet production.

The analysis of the saw dust starting material confirmed that the Swedish and Norwegian material had similar elemental content as well as heating values and energy density. As expected, the black pellets had higher calorimetric heat value and effective heating value than the white standard pellets. The demonstration of burning black pellets in the midsized incineration plant in Vikhammar showed that it was possible to change the fuel from standard white pellets to black pellets without manual adjustments. The black pellets were easy to handle and displayed good burning properties.

4.5

Conclusions

The analysis of the raw material, saw dust from Swedish and Norwegian saw mills, were equal, as expected. The analysis of the pelleted material confirmed that the black, torrefied, pellets had a higher energy density and lower mechanical durability compared with white standard pellets. The burning trials confirmed that it is possible to replace white standard pellets with black torrefied pellets in the plant and that the handling and transportation of the black pellets works very well.

4.6

References

Bioendev. http://www.bioendev.se/technology/torrefaction/ Last visited 2018-12-19 Uhlir L., Wernersson Brodin F. 2018 WP4 Svart Pellets. Slutrapport i Bioraff – Mer av trä.

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