Concerns mount that shale oil and gas debt could trigger mass bankruptcies in the sector

There are fears renewable energy projects could be among the casualties of the falling oil price - but it's investors in shale gas debt who may also get their fingers burnt.

Much of the shale gas exploration in the US has been funded by borrowing vast sums of money - a lot of that debt is sold as so called junk bonds to investors - with a high yield - because its so risky..

And now they are finding out just how risky it might be. A few analysts are predicting that if oil dips lower than 60 dollars a barrel, much more energy debt could be labelled 'distressed' - that's even lower than junk bond status, and there could be mass defaults to the extent that another financial crisis could be triggered.

So is this all a bit of hot air or is could a big gas bubble really forming under the wall street funded scramble for shale?

Oleg Melentyev is head of US Credit Strategy at Deutsche Bank, and told us why he's concerned.