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

Energy transition panel discussion CEDA Dredging Days 2021 (Credit: CEDA)
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)
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)
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)
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
Transition schedule to convert to fossil fuel free dredging equipment

References

  1. CEDA Dredging Days 2021, CEDA
  2. Invitation to CEDA Commission on Decarbonisation (CCD), CEDA
  3. CEDA Working Group on Energy Efficiency (WGEE), CEDA
  4. Transitiepad Kustlijnzorg en Vaargeulonderhoud, Rijkswaterstaat
  5. Zero Emission Dredging Hub van start, EDB Drechtsteden
  6. Complete zandfabriek zo hoog als een flatgebouw dobbert ineens in de voorhaven van Deest, De Gelderlander
  7. Electrifying the world with offshore floating solar, SolarDuck

See also

We Choose To Adopt Energy Transition, But How Will We Succeed?

Comment

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

Book Review: Donald Duck A Muddy Fine Business; Artistic Equipment Design

Front page of Penny Pincher magazine with Donald Duck as dredge master (Credit: Disney)
Front page of Penny Pincher magazine with Donald Duck as dredge master (Credit: Disney)

Donald Duck is a Jack of all trades, that he eventually he would end up on a dredge was inevitable. The story was already published in 1977 in a Donald Duck comic magazine. It is written by Freddy Milton1 and drawn by Daan Jippes2. At that time, I read it and already liked it very much. Later, I had it in a comic album3, but lost it moving to a new house. I wanted to review this story here already for a long time. Eventually, I consulted ‘Bul Super’ in Delft4, he advised me to search for Daan Jippes. That helped to find the story back on the internet.5

Opening scene of ‘Muddy Fine Business’ or ‘Success Test’ (Credit: Disney)
Opening scene of ‘Muddy Fine Business’ or ‘Success Test’ (Credit: Disney)

The story revolves around the endless feud between Donald Duck and Gladstone Gander. This time they have to compete in a success test by operating two different vessels: a ferry, ‘Seagull’ and a dredge ‘Aristoteles’. They have varying degrees of success and the outcome is unexpected.

The best known illustrator of Donald Duck is Carl Barks6. But Daan grew into his footsteps and eventually his stories are at the same level as the original master. He was with the Disney studios in the USA, but was working mostly in the Netherlands. In this edition, Jippes drew one of the most Dutch professions: dredging. Jippes had a keen eye for the elements that make up a dredge, tough the execution lacks some reality. Here I want to highlight some shortcomings that will help to illustrate the tricks that should have made it work and explain how real life dredging equipment functions.

Various details of the ‘Aristoteles’ (Modified from Disney)
Various details of the ‘Aristoteles’ (Modified from Disney)

The ‘Aristoteles’ is a truly multi-functional dredging vessel. It features both a grab and a bucket chain and the sediment can be loaded unto the vessel itself like a hopper or into a barge in tow. It is also self-propelled, although there seems to be a magical power generation as there is no visible exhaust pipe. Maybe Donald is again ahead of his time and running fully electric already?

Than the dredging equipment; the grab is suspended from a gantry, but it does not seem to be able to swing. Loading the tow barge would be difficult, as he has to reposition either the dredge or the barge. Apparently Donald should know about the technology of a rotating crane, as the picture on the front page has such a crane. And how would the material end up in the hopper?

Discharging buckets with reception carriage on a bucket ladder dredge
Discharging buckets with reception carriage on a bucket ladder dredge

Maybe with the other dredging tool: the obvious bucket chain? Though it is not supported on a ladder. Maybe that makes sense, as the buckets seem to be positioned on port or starboard in various panels. The material falling from the buckets might end up in the hopper. The vertical orientation presents some difficulty, as the material will fall onto the previous bucket and eventually through the well. In a normal operation, this is controlled by moving a carriage receiving the load and bringing it to the chutes. With a real vertical orientation, this would not be helpful anymore.

I once saw a solution for working with a vertical bucket chain on an exhibit in the National Dredging Museum7. A manual operated drawer-like slide was moved between every passing bucket to catch the load. It seems very labour intensive and prone to accidents.

Even after breaking down these operational details in the design of the ‘Aristoteles’, the vessel serves its purpose in the story: it is a really useful dredge for dredge master Donald. Well done Daan.

Exhibit with vertical ladder at the national dredging museum
Exhibit with vertical ladder at the national dredging museum

Call to the audience

The exhibit is still there, but unfortunately, it is broken. The mechanism has to be repaired, any model building fanatics are invited to help the museum restore it. There is a special event for new volunteers, now!

References

  1. Freddy Milton, Wikipedia
  2. Daan Jippes, Wikipedia
  3. Oom Dagobert En De Ondergrondse Kluis, nr34, Disney
  4. Stripboekhandel Bul Super
  5. Read online Walt Disney’s Comics Penny Pincher comic – Issue #4, ZipComic
  6. Carl Barks, Wikipedia
  7. Nationaal Baggermuesum

See also

Sniffing Out The Details Of Dredge System Fittings

Sniffer valve on the discharge line
Sniffer valve on the discharge line

The mixture carrying system of a cutter suction dredge, is more than just a cutter and a pump in a pontoon. In the dredge system, there are many valves and fittings, that make the system work. One question I was asked, what these extra valves do. Actually, there are several valves, that are worth mentioning. The sniffer valve, the vacuum relief valve and the non-return valve. For working in the designed operating point, you don’t need them. But, to get there and back, they can be quite useful.

Dredge system layout and fitting locations
Dredge system layout and fitting locations

The first valve is affectionally called a sniffer valve. A more descriptive name would be ‘discharge line de aerator valve’. Usually, it consists of a floating ball in a cage with a seat at the top, that can be closed by the ball. Provided the ladder is already under water and starting up the dredge pump from a fresh situation, probably air is in the high onboard discharge pipe sections on deck. Behind the dredge, the line goes down again and the air is basically trapped, preventing the dredge pump from properly priming. The sniffer valve allows the air to escape and the water to enter the floating discharge pipe at the water line. Problem solved.

Arrangement and operation of a sniffer valve
Arrangement and operation of a sniffer valve

On the other hand, when the discharge pressure falls, the ball floats down with the receding water level. This opens the top and allows air to enter the pipe again. Which is no problem as it can be expelled again through the same sniffer valve. When the water can flow away from the high section on board, this will break the water volume in the system. When opening the pump, only the small section between pump outlet and bulk head passage will fall in the pump well. Or, if properly executed: need to be drained and discharged.

A last function of the sniffer valve is in case there is a blockage of the suction pipe. There will be no new mixture flowing in, but the mixture in the discharge line still has a lot of momentum. For a 1 km, 500ø mm pipe, the mixture has the equivalent momentum of a 75 ton truck barrelling down the pipe at 80 km/h. You don’t stop that in an instant either. The mixture keeps flowing and draws a vacuum. The sniffer ball drops and allows air to enter the pipe.

A better way to prevent the vacuum, is to install a vacuum valve in the suction line. That will allow water in and enable you to clean the discharge line without a cavitating pump. Once the suction block is removed, the relief valve opens again and mixture can be inserted in the dredge line system.

Suction pipe vacuum relief valve
Suction pipe vacuum relief valve

In case there is a high discharge height, the mixture mass will not be broken by the sniffer valve. The geodetic pressure will close the sniffer and all of the mixture volume wants to return through the system out of the suction mouth; or open pump, swamping the dredge. To prevent this from happening, a non-return valve can be mounted in the onboard discharge line.

On board discharge non-return valve
On board discharge non-return valve

These fittings will cover most operational situations. There might be even more for exceptional situations, depending on the design choices by the manufacturer1 and to the taste of the owner.2 e.g. We provide a suction deaerating valve. Any ideas about such a provision?

Suction deaerating valve
Suction deaerating valve

References

  1. Cutter Suction Dredger, Damen
  2. Product Finder Dredging, Damen

See also

Sunken Treasures From ¡VAMOS! At Silvermines

Comment

04/03/2020, Mark:

I did receive the right comment about to the purpose of the suction deaerator valve. It is indeed for letting out the air trapped in the suction pipe when the ladder is being lowered. It could be argued that the air will also leave through the sniffer valve at the back of the dredge. If somehow, the air would have trouble escaping all the way to the back, the pump will be very slow in priming itself. Providing a deaerator on the local high at the bulkhead passage, the suction line can purge the air there and the pump starts quicker.