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Biochar: A sustainable game-changer in the Norwegian metallurgical industry

Lorenzo Riva of the Faculty of Engineering and Science  at the University of Agder has submitted his thesis entitled “Production and Application of Sustainable Metallurgical Biochar Pellets”, and will defend the thesis for the PhD-degree Monday 7 September 2020. (Photo: Private)

Compared to the long-studied and optimized production chain related to fossil coal and coke, the specific production of biochar pellets pollutes more. However, once the emissions associated to the application in a metallurgical context are considered, due to the carbon neutrality, the use of biochar pellets might bring a reduction of about 31%.

Lorenzo Riva

PhD Candidate

The disputation will be held digitally, because of the Corona covid-19-situation.

Lorenzo Riva of the Faculty of Engineering and Science  at the University of Agder has submitted his thesis entitled “Production and Application of Sustainable Metallurgical Biochar Pellets”, and will defend the thesis for the PhD-degree Monday 7 September 2020.

He has followed the PhD Programme at the Faculty of Engineering and Science with Specialization in Renewable Energy at the University of Agder.

Summary of the Thesis by Lorenzo Riva:

Biochar: A sustainable game-changer in the Norwegian metallurgical industry

Figure 1 Forest total area in Norway (in millions of hectares) in the interval 2014-2018. Data elaborated after SSB.

Figure 1 Forest total area in Norway (in millions of hectares) in the interval 2014-2018. Data elaborated after SSB.

Certain industrial branches are dependent on fossil fuels for their physio-chemical characteristics and less as fuel. For instance, the metallurgical industry (e.g. steel, silicon and manganese production) traditionally requires fossil coal and coke (thermally treated coal) as reducing agent in the reactions required to purify the metal ores.

Unless going through a dramatic change in the technological process, the carbon neutrality of these systems must be reached finding a similar but renewable material. In Norway, where the metallurgical industry is estimated to produce about 8% of the overall national CO2 emissions, such solution might therefore help the country to significantly reduce its carbon footprint.

In this regard, biochar has been targeted as a promising solution. Biochar is a coal-like material generally produced by the thermal conversion of woody biomass in absence of oxygen. This treatment is called pyrolysis. The emissions released when biochar is used are considered as neutral, since absorbed during the lifetime of the processed biomass.

Unfortunately, there are several barriers, which obstructs the utilization. Among them, the market price and the mechanical weakness are worth to be mentioned. However, as Figure 1 shows, the forest potential in Norway is extremely high and, if managed wisely and exploiting the traditional local wood industry, its conversion in biochar might enable a new internal market.

Pelletization to address mechanical weakness and make biochar industrially more appealing

In the following thesis, a method to improve the mechanical properties of biochar was developed and investigated.

The method is shown in Figure 2 and is based on the combination of pyrolysis with a consequent densification, with recovery of pyrolysis oil as binder.

Pyrolysis oil is a liquid material, which is also produced during pyrolysis. When the biochar pellets blended with pyrolysis oil undergo a further heating treatment similar to pyrolysis, their mechanical properties increase dramatically and reach values which compete with the ones generally characterizing fossil fuels.

Besides, to limit the market price, the economy of the process was addressed. This was done by trying to minimize the cost through a smart recovery of the byproducts and wastes.

Figure 2 The process investigated in the thesis.

Figure 2 The process investigated in the thesis.

The process investigated in the thesis

Throughout the thesis, the novel method was deeply investigated and optimized both in terms of quality of the final product and feasibility of the process. An example of biochar pellets is shown in Figure 3.

It was found out that it possible to produce superior quality pellets when the thermal processes are performed at temperatures higher than 600 °C. This is due to the change of physio-chemical properties biochar experiences at these temperatures, which optimizes the pelletization process guaranteeing a proper binding of biochar and pyrolysis oil.

Figure 3 Example of biochar pellets.

Figure 3 Example of biochar pellets.

Example of biochar pellets

Some post-production related issues, which may limit the industrial diffusion, were pointed out.

In particular, it was addressed the self-heating behavior biochar pellets might have when produced and stored industrially. The process was analyzed, and a solution was found in performing the second heat treatment at sufficient high temperatures.

Sustainability

Finally, the sustainability of the process was studied.

Compared to the long-studied and optimized production chain related to fossil coal and coke, the specific production of biochar pellets pollutes more.

However, once the emissions associated to the application in a metallurgical context are considered, due to the carbon neutrality, the use of biochar pellets might bring a reduction of about 31%.

The results provided useful information about the suggested process and the related key-parameters.

The novel knowledge may be used to produce fossil fuels-competitive and sustainable biochar materials and, hence, foster the renewable transition in the metallurgical industry.

Disputation facts:

The Candidate: Lorenzo Riva (Parma, Italia 1992) Masters degree in Energy Engineering (energy for development track) at Polytechnic of Milan. Present position:Power Market Analyst at Statkraft.

The trial lecture and the public defence will take place online, via the Zoom conferencing app (link below)

Head of Department of Engineering Sciences, UiA,Professor Geir Grasmo, will chair the disputation.

The trial lecture at 10:15 hours
Public defence at 12:15 hours

Given topic for trial lecture“Comparison of technologies for agglomeration of raw materials to metallurgical industry with a main focus on pelletization of iron ores”

Thesis TitleProduction and Application of Sustainable Metallurgical Biochar Pellets

Search for the thesis in AURA - Agder University Research Archive, a digital archive of scientific papers, theses and dissertations from the academic staff and students at the University of Agder.

Opponents:

First opponent: Professor David Chiaramonti, Polytecnico di Torino, Italy

Second opponent: Senior research scientist Eli Ringdalen, SINTEF

Associate Professor Zhiyu Jiang, Department of Engineering Sciences, University of Agder, is appointed as the administrator for the assessment commitee.

Supervisors were Professor Henrik Kofoed Nielsen, Department of Engineering Sciences, University of Agder (main supervisor) and researcher Therese Videm Buø, Elkem AS (co-supervisor)

What to do as an audience member:

The disputation is open to the public, but to follow the trial lecture and the public defence you have to log in as an audience member.

We ask audience members to join the virtual trial lecture at 10:05 at the earliest and the public defense at 12:05 at the earliest. After these times, you can leave and rejoin the meeting at any time. Further, we ask audience members to turn off their microphone and camera and keep them turned off throughout the event. You do this at the bottom left of the image when in Zoom. We recommend you use ‘Speaker view’. You select that at the top right corner of the video window when in Zoom.

Opponent ex auditorio:

The chair invites members of the public to pose questions ex auditorio in the introduction to the public defense, with deadlines. Questions can be submitted to the chair, Head of the Department og Engineering and Sciences, Professor Geir Grasmo, on e-mail geir.grasmo@uia.no

The thesis is available i AURA: https://hdl.handle.net/11250/2675537