It is said that an average plate of food in North America crosses 2400 km (1,500 miles) on fossil fuels before it is served, which naturally made me wonder – what are the biggest gas guzzlers in the world of moving supplies from point A to point B?
I had an idea to compare the biggest cargo-hauling fuel suckers on the planet with their four-wheeled counterparts. At least in terms of their fuel economy, that is. But after the idea to write this article had set, it took me some time to decide what vehicle I should use as a yardstick. Do I simply pick out a truck since it is closest to being a cargo vehicle, and which one? Or would I be OK to pick out something more efficient, like a mini? After all, I know at least one person who uses her mini to buy groceries – meaning her mini hauls cargo (a part of same cargo that semis hauled on the way to the supermarket… or would that be considered cheating?).
After much deliberation, I realized that, for all intents and purposes, comparing the miles-per-gallon economy of any vehicle to a cargo vessel is pointless since the economics of shipping are expressed in miles per gallon per ton of freight (whereas consumer vehicle economy is simply rated in miles per gallon).
So in the end it didn’t matter what I picked – I would be comparing apples to oranges anyway. But since the whole idea behind this exercise was to provide some interesting trivia (and have fun along the way), I abandoned the truck idea, and focused on cars instead. And since car manufacturers today utilize cutting edge technology to create more fuel efficient vehicles to meet the demands of the market, I figured I would simply use the bottom-line fuel efficiency as my determining factor.
An average fuel efficiency in new vehicles in Canada and United States has gone up to 25.5 miles per gallon (that’s a US gallon, folks). That seemed like a good starting point until I discovered that a diesel edition of a smart car boasts an impressive 71.3 mpg (3.3 L/100 Km). Even an average motorcycle gets poorer mileage than that, so I made a final decision to stick with that.
There are over 5.6 million semi-trucks registered in the US. A large 68% of goods in the US are delivered by these kings of the highway – that’s where a large chunk of the 2400 km per plate of food comes from, after all.
But how many smart cars could you drive on the amount of fuel that a semi-truck consumes over the same distance? Although there are still a lot of old trucks on the road that get meager 5.1 miles per gallon, recent fuel economy standards have pushed the fuel consumption of newer semi-trucks to 6.5 mpg, which translates into just 11 smart cars.
Not bad – with all the talk of poor mileage and high emissions, these behemoths are actually at the top of the list being the most efficient cargo vehicle… Uh, what gives?
Remember – we’re comparing bare-bones mileage here. If we measured miles per gallon per ton of freight, and used a fleet of smart cars to transport the same amount of cargo as a semi, we’d barely make the first pit stop.
Cargo planes have a huge range of fuel economy. The worst offender, a military C-5 Galaxy, uses up about 18.5 (wait for it) gallons per mile! You, you read it right – gallons per mile, not the other way around. That’s basically as much fuel consumption as 1,319 smart cars.
Luckily, that’s far from the average. A civilian cargo planes use about 1 gallon of fuel every second, which works out to be about 5 gallons per mile. That might sound like a bad deal, but consider that an old-but-still-in-use-today fully-loaded DC 10 uses 6.3 gpm, so it’s clearly an improvement. All in all, air seems to be a good way to ship cargo at an efficiency of only 403 smart cars per distance traveled.
Again, averaging the amount of goods being shipped brings down the cost per item significantly, of course, which is why you won’t see fleets of AEN Logistics SmartCars on the road any time soon.
It may be surprising to learn that trains are the least expensive way to move freight, given a fully loaded train uses up as much fuel per mile as 3,008 smart cars.
Trains are actually real good at squeezing mileage out of fuel – through a combination of low wind resistance, minimal friction with the track and high-efficiency engines, a diesel-powered electric train engine pulls each ton of freight at a whopping 452 miles per gallon.
Despite best efforts, the US uses 136 billion gallons of fuel per year (2014 stats). However, substantially more fuel is used for shipping when compared to other forms of cargo transport.
The fuel used by cargo ships varies largely on the size of the ship and the speed at which they cut through the ocean. Water is dense, and every time you double the speed, you quadruple the drag. So a cargo ship traveling at 24 knots uses about 225 tons of fuel each day, while the same cargo ship traveling just 3 knots slower uses only about 150 tons of fuel each day.
During times of financial crisis of 2008-2009, when demand for cargo shipments was lower, many companies reduced traveling speeds to save money – a practice that largely remains in effect today. It makes more sense for a cargo ship to travel at a speed that optimizes fuel usage, commonly called slow steaming. However, due to the public’s demand for shorter shipping times, slow steaming is not always possible.
Clearly, pinning down a number that would be considered average is difficult, but even at the slow speed, an average cargo ship will use up as much fuel per mile as 3,770 smart cars.
Given the above stats, you might wonder why it is that we don’t use trains as much as we use cargo ships (or at least why not use them more than we do). The simple answer is engineering – that big body of salty and frothing wet that separates continents doesn’t provide good support for train tracks. To boot, trains are not known for their ability to travel long distances under water. So for as long as the need for overseas goods and materials exists, we’ll have to rely on ships.
Hey, cargo is hauled to the International Space Station all the time, so why not look at the economy of the space program vessels while we’re on the roll?
Needless to say, space rockets don’t burn diesel. A combo of solid fuel, liquid hydrogen and oxygen that the space program uses is hard to translate into diesel economy. The amount of energy per unit of volume in rocket fuels is much greater than that in traditional fossil fuels, so to keep things simple, I did a conversion by fuel weight only.
Also, I used a retired Space Shuttle rather than any current space program delivery system because reliable Russian rocket fuel consumption numbers are notoriously difficult to come by and verify.
During launch, the Space Shuttle and its solid rocket boosters would propel the vehicle upward at the equivalent consumption of 0.0009 mpg. More specifically, the whole assembly would lift 4.758 feet for each gallon of fuel burned – not bad considering the apparent size and weight of space vehicles.
In terms of smart cars, if you drove a fleet of 79,134 vehicles to cover the same distance, you would get the exact same fuel consumption.
So there you have it – despite the method of transportation, all of these gas guzzlers have a purpose that can’t be denied. Cargo ships, trains, planes, and semi-trucks all provide us with a lifeline to invaluable goods that we couldn’t live without.
And while using these large vehicles does come at a cost to our environment, just remember that the rock-bottom mileage isn’t the determining factor of a vehicle’s efficiency. It’s the mpg per ton of freight that dictates the economics of cargo transport. If that wasn’t the case, fleets of smart cars would have replaced the world’s shipping infrastructure years ago.