My blog posts have focused mostly on the risks associated with running the Dragonpipe (the Mariner East 2 pipeline) through densely-populated Philadelphia suburbs, and rightly so. That is a reckless plan that puts hundreds of lives at risk and brings environmental destruction in its path. Its only benefit is to pipeline investors and the European plastics industry. The pipeline ends at Marcus Hook, PA, but the risk doesn’t end there.
In this post, I will outline the main risks associated with shipping the “natural gas liquids” (NGLs: ethane, propane, and butane gasses compressed into a liquid) to European markets. In the course of my web research, I have come to recognize that the fleet of eight “dragonships” that carry NGLs are also major risks, and no one is talking about them. (By the way: if you research this topic, don’t be confused by references to “LNG carriers”. These are ships that carry natural gas in liquefied form, and there is a fair amount of analysis on their safety. But it isn’t relevant to the safety of ships carrying NGLs, which have entirely different, and much more serious, safety issues).
The dragonship INEOS Insight. Photo source: Evergas.
NGL/ethane carriers. The ships that carry NGLs are often classed as “ethane carriers”. This seems to be in part because ethane is the most plentiful of the gases that make up NGLs, and in part because ethane is the hardest of the NGLs to deal with—if a ship is equipped to carry ethane, then it can carry propane and butane too. And ethane is a more common cargo that propane or butane for another reason: butane and propane have direct uses (butane mainly as a gasoline additive and propane as a fuel), but ethane is of little direct use. It generally needs to be processed by a “cracker” plant before it can be used (mostly as an ingredient in plastics manufacturing).
So ethane is useless except to a cracker plant, and these plants are few and far between. The ones in the US are almost all on the Gulf Coast, and they get ethane by pipeline, primarily from Texas. The plants in Europe need US ethane, however, because the supply from the North Sea gas fields has been declining. That’s the reason behind the construction of the Dragonpipe and the fleet of dragonships.
NGL and ethane carriers (including the dragonships that are transporting NGLs from Marcus Hook to Europe) are a relatively new category of ship. These ships use a combination of refrigeration and pressure to keep the NGLs in liquid form. Each of the eight dragonships can carry 27,500 cubic meters of liquified NGLs. That’s the equivalent of 172,000 barrels.
NGL explosion risks are enormous. If an NGL tank ruptured, the gases would escape as a colorless, odorless fog—the same thing that would happen with an NGL pipeline. They would stay low to the deck, the water surface, and any nearby land, until they reached a source of ignition, at which point there would be an explosion. Because the quantity of NGLs is so large, such an explosion would be far more powerful than the already catastrophic ones associated with a pipeline leak on land.
I have not found any analysis of the damage that would be done by such an explosion, but here are some numbers that provide a sense of the magnitude. The explosive power of each barrel of NGLs is roughly the equivalent of a ton of TNT. So one dragonship, when fully loaded, has the explosive power of roughly 170,000 tons (170 kilotons) of TNT. That is thousands of times more powerful than any conventional bomb, and well into the power range of nuclear weapons.
For comparison, the NGL explosion at Brenham, Texas, in 1992 involved the escape of just 5,000 barrels of NGLs. Yet it destroyed homes a mile away. Each dragonship carries over 30 times as much. It seems safe to say that an explosion involving a significant part of a dragonship’s cargo would have a blast radius of several miles.
What is at risk? If an explosion occurred out at sea, the ship and its crew would not survive, but there would be no harm on land. But suppose it happened near land, at one of the ports that the dragonships visit. If it happened at the dock, or in a channel such as the Delaware River (leading to Marcus Hook, where the NGLs are loaded), the Firth of Forth (leading to the cracker plant at Grangemouth, Scotland) or the Frierfjord (leading to the cracker plant at Rafnes, Norway), there would be the potential for massive casualties. In particular, the channel into Grangemouth passes within about a mile of Edinburgh, the Scottish capital, with a population of roughly half a million. On the US side, the Delaware River channel passes within a quarter of a mile of parts of Wilmington, Delaware; and the explosion of a ship moored at Marcus Hook would put tens of thousands of people in the Philadelphia suburbs at risk.
Whose job is it to protect us from this risk? Are any regulators even paying attention to it? These ships come and go freely, unprotected, unmonitored, and virtually unnoticed. They should not be permitted anywhere near centers of population like Edinburgh or Philadelphia. The risk is too great.