I agree. There are no comfortable or easy solutions it seems. There is an argument that says the CO2 released when the fuel burns is absorbed by the planted next crop of oil. Obviously I mean oil produced in this country only. I still think it's daft to give over masses of land to propelling our cars and boats.
Using recycled veg oil is a more environmentally friendly option but unlike the bio-diesel, needs some conversion to the engine as it's too viscous to use without pre-heating and involves burning normal diesel first. The glycerine content can damage the engine - or so I've read. I must research this more.
Meanwhile, we can reduce the amount of diesel we burn. Not using it to run lighting, fridge, etc is my old (sorry!) mantra - get a wind turbine or solar panels or both. If no-one else is about, I sometimes switch off when I get to a lock. It's surprisingly peaceful and more relaxing a process and as I tend to bow-haul out of locks (as I have the dog with me and also there's no-one else to go back and close the gates) I don't think I lose any time. I think I should get a horse!