Wind! The faster the train goes, the more power it generates. Free EnergyTM
I am not discounting the volatility and sheer power of the anal gasses of the standard Unicorn, only that they are perishable and so hard to come by.
You never met my Son.
They hang in the air like Joy Behar and he produces so many that hes in the Guinness Book of World Records.
Look it up.
The worst part is that hes proud of it.
Well, they are only hard to come by because they only allow virgins to have any contact with them ... and you can count the number of virgins in the Democrat Party on less than one hand ...