As has been covered in the media, Greta Thunberg (GT) is sailed across the Atlantic ocean in a £4 million racing yacht, in order to “demonstrate” low carbon transport, and avoid air travel. The boat has been especially chartered for this trip and has already been shown to be a controversial decision. To recover the boat for its existing schedule, a crew of five are reported to have to fly out to New York with the two current sailors, also said to be returning by air. Not only that but GT’s destination is Chile. So more emissions will have to be expended to get GT to Chile.
However one startling fact that is overlooked, is the boat itself. GT’s team have gone to unlimited lengths to describe this as a zero carbon mode of transport. Yet this can only be claimed for the fuel cost of the trip. Certainly the boat itself and its manufacture, are carbon intensive. While exact data cannot be ascertained, we do have the following (all figures obtained from various resources at Team Malizia – Team Malizia):
- The material for the boat is carbon fiber (virgin).
- The boat weighs ~8 tonnes (this includes diesel engine and ancillaries).
- A crew of 5 is typical but single manning is possible.
- The boat to this date (21/09/2019) has traveled approximately 40,000 km.
- The boat was launched in 2015.
I have made very large, conservative assumptions
- 7 flights confirmed for the crew. Not accounted in the calculation below but these emissions would amount to 4.2-9 TCO2e
- I have given the boat a very generous lifetime.
- I have counted 75% the boat as carbon fiber. It is likely more.
- I have not counted the carbon cost of the other half of the boat (i.e. keel) or the ancillaries such as the diesel engine they are carrying (mass 372 kg = 0.66 T CO2 in raw steel)
- I have not counted the manufacturing process for the boat, which not doubt, will have emissions of its own.
- I have not counted the disposal emissions of the boat.
- I have not counted the infrastructure or maintenance emissions associated with the boat.
The carbon footprint for carbon fiber is circa 29 TCO2e/T material (European research project MultiHemp, FP7/2007-2013, grant agreement n° 311849). The keel and ancillaries come to about 2T. Thus the carbon cost of the boat is 8*29*0.75 = 174 TCO2e. There will of course be some uncertainty of this number.
The ongoing lifetime of the boat will clearly lower this, as more kilometers are traveled. Given the boats current mileage is approximately 10,000 km per year and a lifetime of 20 (maintenance free) years (Malizia expect the boat to be competitive for 10 years), we could guesstimate a final CO2 emissions figure.
CO2 emissions = 87 g/km.
The estimated distance for GT’s trip is circa 5337 (update 13/11/19). The boat must go back so this is doubled as it would not be making the return otherwise. Thus the trip will emit an equivalent of 87*10,674/100,000, assuming the boat makes it the full 20 years
CO2 cost of trip = 9.3 tonnes CO2.Per passenger (2) = 4.6 tonnes CO2
The air trip from Stockholm to New York, is estimated at 1-2 tonnes passenger. But how can that be? Well the issue lies with the low occupancy of the boat. While the Boeing 737 weights 8 times heavier, it carries far more people per trip. Further the fuel cost is also spread out among the many people, whereas the cost of manufacture for the boat is only spread to a small number of passengers.
This is turning into a very carbon intensive trip.