Clean Cargo Donau: A thought experiment with some practical tests

It has been known since the ancient Greeks that the best way to move something heavy is to float it on a barge. This can be experienced by holding a large boat in calm water with no wind; it is remarkable easy to move the boat around with some small, consistent force. This is not so easy to do when the boat is on the ground, as you can easily test as well.

The Danube Clean Cargo project has changed shape a few time but has come down to the form of a thought experiment with some practical experiments to settle a few details. The question that arose was that of regional supplies and deliveries, logistics and systems for food. Along the Danube river from Linz there is the Eferdinger basin, a flood plain that has excellent soil and is one of the mainstays for vegetables and other foods coming into the city. Currently this food is brought into the city with trucks and vans for distribution either to supermarkets or for direct delivery.

Map collage of our planned route

Our speculation was: how would this work if the artery for delivery was the Danube? How could this work? Would it make any sense at all, from energy, employment, timing and other points of view?

One way to investigate this speculation would be quantitative, to read a few numbers from certain websites about the energy requirements of certain vehicles, multiply these with weights of food and delivery lengths to come up with a few numbers about fuel use, electricity use, time use and any other easily measurable numerical quantities. Another course of action would be qualitative, to interview and work together with people in the industry to see how they do it, plan it, how it would interfere with their techniques, planning, processes and heuristics. Yet another would be experiential, to do the whole thing and find out how it works by embedding ones self in the process in an imagined future.

Being who we are, we chose all three. More is sometimes still more.

Previously and further, we investigated the possibilities of freight on the Danube from a legal and administrative perspective: what would we need to do in order to create a legal sail-electric delivery enterprise along the river. Interactions with legalities, such as the Tree Identity project from FoAM, can be a powerful and insightful way to look into the hegemonies of decision making in which we live. The legalities, policies, financial and other support for various enterprises creates ways of action for all participants, and are often created with the assistance of entrenched interests, lobby groups, friends’ advice and all the other aspects of political reality that have got us to where we are. It turned out to be neither particularly complicated or expensive to create a small, green cargo enterprise, and such a structure, once created, continues to exist without too much work or expense.

As part of this we had legally registered a small boat as a freighter capable of carrying up to 500kg of cargo. Not much compared to Tres Hombres or the Avontuur, much less compared to river barges such as Revolution and completely insignificant compared to a container ship or an ore train. But it was a thing, a stick in the sand, a position of reference. We looked at how to carry the standard vegetable boxes used throughout Europe, how to stack, secure, shade and cool them, moved cleats and deck equipment, planned movement and loading paths across the tiny deck.

Then we started talking to people doing this work already. Vegetable coops, vegetable box deliverers and solidarity farmers, e-trike deliveries in the city, bicycle trailer users, designers and builders. We spent time discussing storage areas for deliveries, as a community supported agriculture might not want to deliver each box to each customer directly. We spoke to people who deliver individual and individuated boxes of vegetables and other supplies to house doorsteps. We talked about trailer systems to allow various riders to deliver supplies, compared to using a customised trike with secure systems to avoid losing control in the wind, rain or snow. The use of boxes, evaporative cooling, ice bricks and other ways to avoid wilting the produce.

We learnt that it was not the distances or the routes that were the main blockage, but the handling between each stage, the logistical discontinuities. One development that was discussed at length for individuated boxes was the development of insulated minicontainers that would take around 20 individual boxes, stacked in the correct sequence for delivery and able to be easily loaded and locked onto a delivery bike. The rider would take the container, load and secure it, then ride to each address on the delivery list, always taking the next box without having to search for the right number. This led to looking at derrick cranes to load and unload minicontainers, each weighing up to 250kg, from the boat to a dock. All of a sudden those images of equipment on the Dutch Tjalk and English sailing barges made a lot more sense.

Lifting gear on a barge. A lot of people spent a lot of time designing simple, robust systems to move freight with minimum energy usage. No push buttons here. Photo fromClem Rutter on Wikimedia

It was clear that we had begun to slide into the experiential realm, where not only the anecdotal and qualitative understandings from interviews with people involved in today’s version of the industry played a role, but we were beginning to be part of the planning and development of ways forward. It was time to carry this onwards.

We visited the banks of the Danube around the areas that we would need to deliver to and looked at the places that could be used for landings. In a speculated future there would be a dedicated pontoon with access ramps wide enough for large bicycle trailers, for this we needed to rely upon existing infrastructure. We looked at ramps and pontoons and the back entrance to the Salonschiff Fräulein Florentine, a cultural barge with a bar on the banks of the Danube in Linz. We talked to bicycle transport people about the accessibility of each of these landings. We settled on a few possibilities.

We then readied the boat and took off for some experiments on the water. How accessible are these positions from the water? Are there hidden hazards below the silty waters? Can we moor up safely? Are there good attachments points, delivery access, flat surfaces to roll a stack of boxes? We travelled the route to investigate the effect of curves in the river on water speed, to see how close we could be to each bank, when it made sense to cross over. We slipped into quantitative research: what was the necessary speed on the electric motor, what was the charge in the batteries, how long and how much charge did each kilometer take? As we motored along we looked at different regimes of power to the motor: too high and the batteries drained quickly, too low and we made no headway against the current. There is probably some sweet spot that could be ascertained and we had begun talks with colleagues in the energy analysis sector to work out what these might be. Experiential factors re-emerged: is this a one-person show, or does it require crew? Transport is an essentially meditative task, hours on the helm or at the steering wheel are repetitive but require constant awareness. So what happens if the freight from the streets end up on the water? What if this was the reality?

While we were in a position to run some test deliveries in order to best ascertain whether the process would make sense, it was decided that the necessity of a stable and documented uninterrupted cold chain was paramount and that actual freight could not be safely transported within the financial and organisational bounds of the project. For while it is somehow a lot of hours of work to pedal the bike, drive the van or helm the boat, so much more work goes into the logistical organising of all the boxes that are moved by these various transporters. Whether it is the heavy coloured steel boxes of the trans oceanic freighters or the small plastic boxes of organic fruit and vegetables, so much effort goes into organising them, securing them and making sure the right one gets delivered to the right place in the right condition. If you didn’t want zucchini in your vege box, you are not happy when you get the wrong delivery, a whole box of them. A container filled with plastic toy ducks does not replace the family furniture being shipped across the world.

So we arrive once again at the qualitative. And partially the speculative. We journeyed from the harbour in Linz to the loading pontoon in near Eferding at Bradtstatt. That return journey required 7.3 kilowatt-hours (kWh) of energy, measured by the amount of electricity consumed to recharge the batteries. Note that this was a worse (but not worst) case scenario in many ways: the river was slightly above average depth and thus flowing strongly and we did not use sails at all for the journey. This is the equivalent of 26.3 megajoules (MJ), the proper SI unit of energy. The road delivery to Linz and back from the same place is a roundtrip of 53km. The best case road version of this journey would be done with a high efficiency “Neighbourhood Electric vehicle” (NEV) which can transport up to a tonne effectively. Based upon standard figures (e.g. Wikipedia) this would require 20 MJ, so it would be slightly more efficient in terms of energy than the boat. However these vehicles are probably not road legal outside the city.

A more valid comparison would be with one of the new generation of electric delivery vans. Based upon claims rather than experience, the Chanje V8100 (link) with 1000 kg of load would has a range of 240km from its 100kWh capacity, which without being too exact would indicate that 53km would take 22.1 kWh which is about 80MJ. Even if this is out by a factor of 2 because the range is based on using only half the battery capacity, we are still at around 40MJ for a delivery van to do this journey. Comparing it to contemporary systems: a delivery van would need about 8 liters of fuel for the journey, 18kg of CO2. So over a year, the CO2 footprint of about 1.4 people as a global average. Given that overnight charging would use hydroelectric power from the turbines on the Danube, so with zero CO2 emissions, this is a significant but not huge change from this perspective.

The times required begin to play a role here too. The van would be finished with this journey in a bit more than half an hour each way. The NEV has a much lower speed and would require (if legally possible) about an hour each way. The boat requires around 4.5 hours upstream, 1.5 hours downstream. Plus the time to get through the lock at Ottensheim, which can be (and has been) anywhere from 15 minutes to over 2 hours. In terms of paying an employee to drive the boat, this probably makes a significant difference.

There are also questions of scale. What if this was a real thing? Someone would be having to deliver this every day, leaving at dawn to get the freight to Linz for delivery in the colder hours of the morning. The romance of boat living raises its head – is this attractive? The boat we are using would not be appropriate or particularly effective, as it is neither rain proof nor having proper sun cover. However in order to deliver the 300 vege boxes that would be around the daily deliveries to Linz, a speculative small boat using the minicontainer system described above would not need to be significantly longer or larger and could be designed to have a much better underwater shape for efficient movement. It is arguable that a vessel for the 1000kg transport would have a similar wetted surface as the test boat and would thus require essentially the same energy. The weight of the batteries acts as ballast in order to balance the small but helpful sail plan.

Speculative images of river freighter electric-sail shipping communities arise unbidden. After a night on the leash, re-charging their batteries, the wind rises just before dawn and the small crews take in their lines to head off to the next harbour with silent electric motors turning, sails being raised to use the wind to their advantage, bidding another a good trip as they head off. Cargo bicycles await them at the next harbour where appropriately sized minicontainers are unloaded for local delivery. At times the solar surfaces and sails recharge the batteries almost as fast as they are being emptied by transport, the good skippers balance speed, reliability and resources to the river, the cargo and their minimal crews.

Perhaps there are connections back to a past that is barely remembered. There is an old paragraph, relating a simple story of some barges waiting out a storm or adverse winds. The dawn breaks, the winds and tide are favourable, the barges begin to move off. With a cup of tea in hand, the author notices in passing, that several thousand tons of cargo are on the move, with barely a sound.


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