In July 2007 my Toyota Hiace van was converted to be able to drive on 100% PPO (pure plant oil) because I was feeling more and more guilty of my dependancy on petrol (and therefor on big oil companies, the largest source of denial of climate change and resistance against sustainable energy). Since then I have driven more than 15.000 kilometres on PPO, including the whole Ember Summer Tour 2007 (7414 kilometres).

Any diesel engine can be converted! Although it’s not the definitive solution, it’s a hell of a lot better than regular fuels: carbon neutral and no harmful fumes. Instead of using food crops (which leads to rising food prices and therefor to problems in poor countries), more and more non-food crops are now being used for PPO and biodiesel like jathropa and algae.   
There are many websites devoted to PPO. Here are some important ones:

Elsbett are the German pioneers of the PPO technology in Europe. For more than 20 years they have been converting diesel engines for PPO use. They have branches in most European countries: garages that are trained to convert your diesel car/truck/bus into a much cleaner vehicle.  

Here’s a good forum for Dutch people who drive or want to drive on Pure Plant Oil.

Opgewekt is the website from the people who operate the PPO tankstation in Amsterdam North. You can find lots of interesting information, links, contacts and weekly newsitems.

With the help of Oliomap you can locate filling stations for PPO and biodiesel in different countries including Germany, France and the USA.