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Personal Announcement: Going Back To School To Cut Some Clay

Learning early or later in life, studying is always a joy when you make it practical

‘Never too old to learn’ is my motto. Everyday I look around me and I wonder how this beautiful world fits together. Whether it be the stars in the sky, the waves at sea or life as we know it, there is always something to be learned about it. At school, I was not a great pupil, but I was always curious to learn more. For my master thesis at the Delft University of Technology, I investigated the performance of a dredge and made recommendations to improve its operation1. As the project was more focussed on mixture forming (and turbidity) and the redesign of the auger head, there was no attention for the soil mechanics involved in the cutting process.

Fully covered cutter head in sticky clay

Now is the time to get that straight. In my daily business, I came across several projects where the clay cutting was a real problem. This was one of the triggers that sparked my interest in sticky clay and made me pursue a more detailed investigation into this nasty stuff. I am very grateful my management was willing to grant me time to go back to the university and start a PhD project with professor Cees van Rhee to learn more about clay.

Synthesis of clay and the relevant properties for dredging

Clay is a completely different material than sand or rock. Those are either plastic and non-cohesive or elastic and cohesive. Clay is the worst of both worlds: plastic and cohesive. It can be described with certain soil parameters as e.g. undrained shear strength and internal friction angle. The failure model is based on Mohr’s circle etc. But those are all continuum approaches2. When you zoom in to the particle level of clay, a whole new world opens up. I already wrote about the interesting particle interaction in a previous post3.

Boltzmann strain rate function in clay cutting

It appears, that the consistency, deformation and failure of clay is related to the tiny electric charges distributed over the platelet crystals. The movement along the charges needs energy. The model to describe dislocation energies along electric charges has been studied by Ludwig Boltzmann4,5. His model governs a wide range of applications, ranging from cosmology to particle physics. I really plunged into the deep end of science with just simple clay. It already took some time to get my head around the concepts involved. Slowly it dawns on my what possibilities there are to improve our understanding of the cutting of clay and possibly to improve our products eventually.

Gallery of my dredging professors (l) prof. de Koning, (m) prof. Vlasblom, (r) prof. van Rhee

My ‘old professor’ de Koning was a proponent of ‘thinking with your hands’6. Professor Vlasbom encouraged me to graduate on a practical problem and also my current professor van Rhee suggested to do some preliminary experiments with sticky stuff to get some feeling about what I am going to study. Of course I took some clay home to play with it. But the best suggestion was by my colleagues, who thoughtfully gave me stroopwafels7. The ultimate representation of sticky non-Newtonian stuff between layers of latticed disks.

Fresh supply of stroopwafels for practice and celebration

References

Second Thoughts On The Energy Transition Panel At the Latest CEDA Dredging Days

Energy transition panel discussion CEDA Dredging Days 2021 (Credit: CEDA)

The CEDA Dredging Days are long gone1. Maybe some of you still have a faint memory of the innovative online event. After this event I was quite occupied and not able to do a proper review. I did even miss the opportunity for the traditional new years welcome post. My apologies, more to that another time. Concerning the Dredging Days. I still kept some nagging thoughts about the Energy transition panel discussion that I want to share with you. And the recent invitation for participating in the CEDA Commission on Decarbonisation is another good motivation2.

On the second day of the conference there was a session with a panel discussion on the ‘Energy transition in the dredging industry’. Several experts in the dredging community were invited to present their perspective on the energy transition. From the legislation side (Dagmar Nelissen, CE Delft), clients (Joris Vijverberg, Rijkswaterstaat), suppliers (Benny Mestemaker, Royal IHC) and contractors (Sven Kramer, Van Oord). The panel was moderated by Paul Vercruijsse from the CEDA Working Group on Energy Efficiency3.

The take-aways of the panellists were amongst others: ‘No single solution for all, Transitional fuels should be flexible, Transition should be facilitated by regulation, There might be a financial objection to change.’ Along these lines, there were polls on the perspective of the audience. The response to two of the polls surprised the panellists.

Results on the polls for rate of transition (l) and preferred energy carrier (r) (Credit:CEDA)

As I was present there, I have my own perspective on the discussion. First the rate of transition. The panel was surprised that the audience was expecting a transition ahead of the IMO planning. I was responding to our own national situation. Currently I see so some initiatives to convert dredges and projects to electric drives, that it could be possible4,5,6. But I expect to see a next generation of newbuilds soon that will be virtually or completely decarbonized.

Well to propeller emissions (Credit: CEDA)

The other surprise is was the preference for hydrogen as the final fuel of the future. Although all the alternatives do have better performance, are easier to store or downright cheaper according to the experts in the panel. That might be very well, but I think the answer is in the presentation by Benny Mestemaker. It will simply be the fuel with the lowest emission to supply and use. In the end we will have to go to that dot on the horizon. And I do see other advantages where my opinion differs from the experts. The complaints of the panel was the complete lack of infrastructure for hydrogen at both the project sites and the vessels themselves.

Concerning the infrastructure near the project site. Yes, there are no installations yet. However, the thing is. You can find renewably generated hydrogen everywhere. As long as you have access to sun, wind and water. And that is exactly where most dredging projects are happening. Off course, there is no factory yet, but that is outdated philosophy. There will be movable plants available that will create a new market. e.g. I am very hopeful of initiatives like ‘Solar Duck’7. They can roam the projects delivering tailor made hydrogen production, right where you need it.

Floating solar power plant (Credit: SolarDuck)

Concerning the vessels. Yes, the installation to sail the vessel on hydrogen will take up a lot of valuable cargo space. But, that is no technical problem. We’ve had technologies that required an even bigger chunk of the vessel deadweight: coal burning steam ships. The big equalizer is: there was no other solution. Everybody was using it. And that is the same here. I think there will be no other solution than to use hydrogen, as it is completely emission free. One of my perspectives on design choices: select the solution that you know will solve the problem!
Transition schedule to convert to fossil fuel free dredging equipment

Transition schedule to convert to fossil fuel free dredging equipment

References

Comment

CEDA will provide access to the panel discussion shortly. Dredging Days attendees can still (re-) watch it on the conference platform.

CEDA Dredging Days 2021: Sustainable Dredging And Innovation

Promotional banner of the CEDA Dredging Days 2021 (Credit: CEDA)

Tomorrow, another event with a long tradition will start: the CEDA Dredging Days1. Due to the Covid issues, this time, it will be a virtual event, just as a lot of other regular happenings. Hopefully, it will be the last days of this dreadful period. I can’t wait to meet people again in real life. Back at the office, we are slowly starting to get back. But meetings with people far outside the regular circle were difficult. For instance, I was a member of the Technical Paper & Program Committee and the preparation was completely digital.

Home page of your CEDA Dredging Days on the Swapcard platform (Credit: CEDA)

Now, the event itself is also digital. Of course, this is still not the real thing. Having a coffee and a chat in the lobby is a much more enjoyable experience than sitting in front of your screen. I have to say that with the Sawpcard platform2 selected by the organising committee, it is much easier to arrange your own program, adapted to your personal interests. Moreover, it will also facilitate meeting people with the same interest. In a sense, this might be an opportunity to approach those. In the real world, people will not get seated next to you when they have the same interest. And certainly don’t have them captioned on their chest.

Pump design workflow (inspired by Suman Sapkota)

As member of the TPPC, I had the opportunity of a sneak preview of the articles and presentations and I can guarantee there are a lot of interesting sessions. For starters, there are three presentations by my colleagues. Suman Sapkota will have presentation on his research in various novel methods to apply numerical research into the design of dredge pumps3. We are happy to share with you some experiences and insights on the Dredging Days.

Testing the non-radioactive density sensor

Another presentation will be by Frank Bosman4. He has been active in the development of an instrument that will measure the mixture density, without using a radio-active source. This intelligent solution is not only more sustainable, but will also provide easier access to this information. If you don’t know the density, you are very likely to underperform with your dredge. He will present some experiences and data gathered on the performance of this system.

Example of recent electric DOP dredge family

Our last presentation will be by René Sens3. Less technical, but surely an interesting perspective on the future of dredging equipment. Everyone in the dredging community is aware of the necessity to change and adapt to a more sustainable approach of our dredging business. There is an urgency to reach the goals set by the UN to leave the world behind as a better place than we received it. Although usually an increase in size also increases the efficiency of a dredge, the UN goals look beyond that single parameter. With that in mind, small and medium size dredges will be far more interesting than at first sight.

Session 7: Young CEDA ask a CEO (Credit: CEDA)

There will be a lot more going on and I could produce a long list of other interesting presentations. I think you should also check out: Edwin de Hoog and Joep Goeree, Basel Yousef and Jeroen van Stappen, and if you really want to get academic: Janek Gundlach, Ebi Shahmirzadi and Arno Talmon. You can just add to your own list and see who also joins in in the audience. Other interesting sessions will be the student ‘Flash Talks’5 and the ‘Young CEDA ask a CEO’ session6 with Peter Berdovski and Kees van de Graaf. And I am very curious what the other working groups and commissions of CEDA have to present about their work.

Personal Announcement: Going Back To School To Cut Some Clay

References

See also

Second Thoughts On The Energy Transition Panel At the Latest CEDA Dredging Days

References

See also

Comment

CEDA Dredging Days 2021: Sustainable Dredging And Innovation

References

See also