Sail Freight Thermodynamics

by Vermont Rice










Part of the rationale for this project is to demonstrate a less-wasteful way of moving goods. Hopefully both creating and operating the boat also prove to be economically and energetically viable in both the short and long term.  So let’s compare the moving of 8 tons of freight with our little T32x10 and by a conventional semi.  The semi is, after all, the likely alternative.  We could cloud the waters by comparing diesel-powered barge freight, or rail, but this will at least start the discussion.

Our boat costs about $10,000 in dollars for all its materials, and we expect it to last 15 years or so, with an annual maintenance cost of $1000 or less.  The semi costs around $100,000 and maybe lasts the same length of time, with an annual maintenance of maybe $10,000?  I am not that familiar with the economics of OTR trucking but I would guess that tires and mechanical repairs must be pretty high.  Of course this is hard to compare with the boat model since the boat can only make 12 or so 300-mile trips in a year whereas the semi can make hundreds.  If one semi can make, let’s say, two hundred and fifty trips per year at 300 miles each, we would need around twenty of our sailing barges in regular use to replace one semi.  Quite a fleet!  And this enterprise would employ about 40 sailors seasonally, instead of one truck driver year-round.  Let’s keep that in mind for later on.  For now it’s enough to say that this concept runs on people, and that it could possibly create a lot more jobs than the trucking status-quo does.

Next–let’s consider fuel.  The Freightliner Columbia equipped with a 12.7 liter Detroit Diesel and an aluminum flatbed trailer moves a ton of cargo 184 miles on one gallon of diesel.  To move eight 8 tons 300 miles (2400 ton-miles) would require about 13 gallons of diesel.  Of course this doesn’t include all the fuel it takes to make the roads and bridges the truck drives on.  The sailing barge might go through a gallon of fuel for backup maneuvering and cooking during a 300-mile trip, although this fossil fuel input isn’t strictly necessary as cooking can be done with a woodstove, and an engine is not really needed if the crew are good and handy with sails, oars, and poles.  But for argument’s sake,  let’s count the boat’s fuel consumption as 1 gallon for the trip.  That still leaves us at 13 times more fuel-efficiency than a semi.

The sail freight proposition is, however, much less labor-efficient than the semi.  This could be seen as a weakness or a strength depending on your perspective.  The semi driver will complete the trip in a single shift, but the boat crew will be on the water for 10 whole days.  I would personally prefer to be on a river for 10 days than driving  a rig a highway for one single hour, but that’s beside the point.  There does need to be adequate payout to financially reward the crew to the degree that they can continue to devote their lives to the project.  We expect this labor cost to be bearable because we can price it into the products the project carries.  But that’s just boring dollars-and-cents economics.  If that is all we are interested in then there is never really much incentive to do good work.

I am interested, however, in the energy inputs (i.e., food) the crew requires for the 10-day voyage.  But if we’re going to introduce food as an element of efficiency then we need to start using a new unit besides gallons of fuel.  Let’s go to Kilocalories, which most people just call calories.  There are about 35,000 Kcal in a gallon of diesel.  In total the semi proposition will burn up 2,000 Kcal of human food for the driver, and 455000 calories in diesel fuel, for a total of 457000 kilocalories.  The sailing barge will use 35,000 in fossil fuel and 20,000 in food (2 people at 2000 Kcal per day for 10 days), for a total of 55,000 Kcal.

Therefore, by this rough calculus, the sailing barge is roughly ten times more energy-efficient than the semi per ton-mile, even before taking into consideration that the food and auxiliary power that the boat uses can be easily derived from 100% renewable sources.  I would bet that when you tallied up the prorated ton-mile infrastructural costs of the semi and the generally cheap or free infrastructural costs of the boat, that the picture would be about twice as favorable, but I lack the chops to go after these numbers, being just your basic ignorant layman farmer.  Anyway, that’s how much energy it takes to move the freight from A to B.  Wonder how this stacks up in relation to the energy in the freight itself?  In other words, if it takes two people 10 days to deliver the food, how much food is being delivered and how far will it go?

Let’s say that the 8 tons of cargo is 100% rice.  That’s 16,000 lbs.  Uncooked rice has 1500 Kcal per lb, so that’s a total of 24 million calories, or enough to provide for half the caloric needs of 1000 people for 24 days.

Let’s imagine further, if we dare.  Some 15 thousand boats (with about 100 docked on any given day) plying this route could feed the entire NYC area about half their daily caloric needs, an estimated 1.2 million tons of rice per year.  Sounds like a lot but it would only take 60,000 or so small farms along the Hudson and Lake Champlain to devote 10 acres of rice paddy each to this trade to bring it about.  There is no physical reason that I can see why we as a region can’t do this, only economic ones.   The land is there, just not well-managed for this purpose at the moment.  And the water is there too, and it has been our highway in the past and could be again.