Why aren't we using vegetable oil engines instead of rock oil? The conversion process is possible. Why not convert more and more cars?

The scale of the problem entirely dwarfs that solution. It will never be enough; the demand is even increasing

If all of the used frying oil on earth was processed into biodiesel it would replace less than 1% of petrodiesel eing burned today. I make biodiesel and use it as heating oil in my furnace. It's only cost effective if I get used oil for free. Virgin vegetable oil is too expensive. Economies of scale would make large biodiesel refineries less costly but not enough to compete with petroleum diesel.

alcohol engines are already in use in places such as Argentina . derived from vegetation or nuts etc yes even nut oil can be. used to power an engine.

real answer will be battery and solar hybrids short term.long term probably gas ? solar/electric .

costs and supply .resources are Manu factors.rest is time and competition.

Bio fuels are a complete con, that is only possible because the standard of scientific knowledge amongst the general public and politicians in particular is woeful. They are promoted as green. Why? They still burn and produce carbon dioxide and could be used as food in a world where people are starving.

Because we need to eat.

The highways would smell like french fries and we would all be driving around hungry.

Source: It is 2 AM and I am sleep deprived

We are turning corn into ethanol and burning that. Which is one reason why food prices in the USA are so much higher than they are in Europe. Now you want to turn even more food crops into fuel? So what do we eat? Oil?

We cannot grow that many vegetables. There is much more energy in petroleum than there is in plant based energy. The future will be in increase battery efficiency and increased solar panel efficiency. In 20 or 40 years we will not need petroleum to run cars.

Plenty of vehicles are ‘flex fuel’ vehicles and can run on vegetable oil derived ethanol “E85”.

The issue is getting E85. It’s not widely distributed. And you get lower mileage on it so it’s as expensive or more expensice than gasoline.

It's too expensive. You can build a veggie-oil diesel but it's only a good deal because you can get old frying oil for nothing. (And I'm not sure you even can anymore).

ADM has a permanent $2 billion per year govt. subsidy to make fuel from corn. Even though studies have been done to show you use almost as much gas to grow the corn as you get alcohol from it. Corn-ohol might be a small part of energy reform but it will never replace rock oil.