At the end of 2007, the BioTruck team, led by Andy Pag, completed the first ever carbon-negative driving expedition across the Sahara Desert to Timbuktu in Mali, West Africa. The Expedition set off from the UK on the 26th of November and arrived in Timbuktu on the 26th of December 2007. The Expedition helped to raise awareness of the value of different carbon reducing measures, and was powered entirely on a unique biodiesel fuel made from waste chocolate! Needless to say, the four-week trip was eventful - filled with run-ins with customs agents, a near shoot-out with Al-Qaeda, daily repairs and unexpected sandstorms. Below, Andy recounts his motivation for the trip and shares his insights on using biofuel as an alternative fuel:

Over the last 12 years I've run expeditions all over the world and the I've always felt there's a hypocrisy about traveling to see the world's most beautiful landscapes in a car burning fossil fuels. In the back of my mind, I always wanted to do an expedition that was carbon neutral and in the end what we achieved was carbon negative. I think it's a great example of how people's behavior changes. Even though there was a will to do something, I only managed to change my behavior when I found a solution that was practical and didn't mean sacrificing doing what I love.

To make biodiesel from chocolate you first have to extract the cocoa butter, then you are left with the sugar which you distill to make alcohol and then you mix it with the liquid cocoa butter using caustic soda as a catalyst. It's not really practical to do it with chocolate in your garden shed, but making biodiesel with waste cooking oil is perfectly possible. You can buy machines that will do it and produce biodiesel that is so good, you don't have to convert your car to run on it. Here in the UK, a gallon of Diesel costs about US$9 so there's a big movement of diesel home-brewers.

I was surprised how positive people's response was to the Biofuel Pledge on our site, and how international. It's really great to see. It comes back to what I said before about how people get to a point where they will change their behavior when they see there is another way that is practical for them. The problem with biofuels is that the stuff that's made on an industrial scale tends to have a poor environmental impact. There are farmers in Indonesia cutting down rainforests to grow biodiesel crops, and that makes fuel which has a worse carbon footprint than fossil diesel. So, understandably, people have been put off. Biofuels only work when they are made from waste materials (like the surreal example of chocolate in our case) but in practice there isn't enough waste material to supply our globe's fuel thirst. Nonetheless, there are some really exciting new technologies emerging that allow us to use all sorts of weird waste projects, and also new "second generation" crops that can produce 1000 times the oil yields of the palm oil they are growing in South East Asia.

During our expedition, we hit this amazing sandstorm. I've been in a few before, but this went on for days and overnight there was the most amazing lightning storm in the pitch black of the desert. Really eerie, it was like the air was electric. We had loads of grief at all the borders, so the day we crossed the last one into Mali was a good day too. While we waited at the border, I managed to get the stereo in the truck working and we bought a load of Malian music tapes from a local guy. Thundering down the road to Ali Farka Toure's mellow blues and waving at the kids in the villages was a great feeling.

Our next trip is going to be the first-ever biofuel flying expedition to Outer Mongolia. It's going to be brilliant, I can't wait. We're using a fuel with is made by reconfiguring the molecular structure of garbage into fuel molecules. It can even be used to make aviation fuel, so we are also taking powered Paragliders (like a motorized parachute) with us on the drive to Outer Mongolia. It's early days but this technology could be the dawn on low-carbon passenger flights. Can you imagine how earth shattering that would be if we can make a fuel that cuts emissions from aircraft by 90%! The truck we are taking will be loaded with eco-gadgets too -- solar panels, a wood stove, tires that cut fuel consumption, even a composting toilet, so our life on the road is going to be low carbon as well as the fuel. We are looking for a title sponsor at the moment and companies can get in touch via the website, especially if they have some wacky gadgets that might help us cut our emissions in the biotruck.

As far as role models, I don't think it's a very healthy idea to put people on a pedestal, there's greatness in everyone of us, even the guy that spilled coffee over me this morning on the way into work, and equally even our heroes are fallible. I admire anyone that has the courage to instigate positive change, without compromising their goal, whether it's on the scale that Mandela achieved or the kid that puts his hand up in class to tell the teacher they made a mistake.

At the moment I'm reading about Marco Polo, who arguably set us on the road to globalization, and also Lindbergh who flew the first the trans-Atlantic flight and again leapfrogged us towards the globalized world we now live in. I wonder how they felt as they took the first steps on their epic journeys, before they'd made the transition from dreamers to iconic achievers who changed our world.