Over the past year or so there seems to have been far more train derailments of cars carrying crude oil that have resulted in huge, deadly explosions, and it is not a coincidence that the oil in these explosions originated from the Bakken shale formation in North Dakota.

One problem is that the light crude extracted from the Bakken is more flammable than heavy crude, but there are other factors at play here as well.

In order to extract oil in the Bakken the oil companies use fracking to split apart the shale rock and gain access to the tight light oil trapped there. A special mix of chemicals is used to split the rocks underground, and while companies refuse to disclose the exact composition of this cocktail of chemicals, claiming that it is a trade secret, there is a high possibility that they are extremely flammable. Some of these chemicals remain mixed up in the crude oil, thereby increasing its flammability.

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Recently the Wall Street Journal has also looked into the increase in explosions of rail tankers carrying fracked crude oil. “Crude is flammable, but before being refined into products such as gasoline it is rarely implicated in explosions,” wrote the WSJ. They suggested three possibilities for the explosions: irresponsible care during the transport of the crude; other, more flammable products such as propane naturally mixed into the crude; or the addition of flammable chemicals during the fracking process.

Back in August Bloomberg identified another problem caused by the fracking chemicals, which is much of the millions of gallons of chemicals injected into the ground during fracking is in the form of hydrochloric acid. This is a highly corrosive substance and the railway administration has begun to note an increasing number of tanker cars are suffering damage to their interior surfaces after transporting light crude, likely due to the presence of the acid, and that this is weakening the tanks and making them more prone to rupture.

An article on Grist reports that two government agencies, the Federal Railroad Administration and the Pipeline and Hazardous Materials Safety Administration, have launched a joint investigation into the impurities in the Bakken crude to try and determine whether new regulations are needed to ensure safe handling.

Some initial inspections have found that the oil includes chemicals that mean it is combustible at very low temperatures, meaning that it should be transported in special, secure rail cars reserved for extremely flammable products. Instead the crude is being loaded onto normal tankers that are designed with fewer safety precautions and intended for less flammable liquids.

By. James Burgess of Oilprice.com