What is biodiesel?
Biodiesel is a type of fuel made from vegetable oil, animal fat or waste cooking oil. The fuel is created by a process called transesterification, where the glycerin is separated from the oil to create methyl ester. Methyl ester is the chemical compound name for biodiesel. The majority of suitable oil for biodiesel comes from rapeseed, palm or soybean crops. Because of its source, biodiesel is considered a renewable fuel alternative.
What is the “B factor”?
When people talk about biodiesel for cars, they are most likely talking about a type of blended fuel, where a certain percentage of biodiesel is combined with traditional fossil fuel diesel. This percentage is known as the B factor. A biodiesel with a B100 factor is 100% made from biodiesel, whereas a B20 factor means that the fuel contains 20% biodiesel and 80% petrodiesel. In the UK, standard diesel already includes up to 5% biodiesel, meaning that ‘regular diesel’ you get at the petrol station technically has a B5 factor.
What are the environmental benefits of biodiesel?
There is a lot of debate around the efficiency of biodiesel and its sustainable benefits but it can be a great medium-term solution as we transition to a more wide-spread adoption of electric vehicles. Pure biodiesel is often considered circular or carbon-neutral because the CO2 released while driving is removed from the atmosphere by the plant crops themselves. But that calculation isn’t so straightforward – when measuring the impact of biodiesel on the planet, scientists have to take into account the life cycle of the fuel, or in other words, the total emissions from its cultivation process: growing and transporting stock, the transesterification process, the change in land use for new crops and the CO2 quantities emitted while driving measured against the CO2 absorption rate of the crops themselves.
This is why biodiesel made from used cooking oil or waste animal fat is considered even more environmentally friendly – because it does not require a land use change and makes better use of waste products. According to a report by the UK Department for Transport, biodiesel produced from used cooking oil could reduce CO2 emissions by as much as 85%. This does not, however, mean that a vehicle emits fewer greenhouse gases if it runs on biodiesel – when biofuels are burned, they emit roughly the same amount as regular fuel – it’s just that the carbon emitted originally came from the plant’s absorption rather than coal or crude oil.
Governments are now funding extensive research into algal biofuel as an even more sustainable alternative. Algae can grow on land unsuitable for other forms of agriculture and can be produced using wastewater, so its carbon footprint is potentially reduced compared to rapeseed or soybean crops. Watch this space.
One other environmental benefit of pure biodiesel is that it is also rapidly biodegradable and non-toxic, so if an oil spillage with biodiesel occurred, it would do far less damage than fossil fuel spillages.
What are the benefits of biodiesel for drivers?
Aside from the environmental benefits of biodiesel, there are a few further advantages, like the fact that blended biodiesel is compatible with already existing engines. From Audis to BMWs to Porsches, almost all vehicles that run on diesel are capable of running on B5 to B20 biodiesel without having to perform any modifications to the engine.
From a chemical aspect, biodiesel also has a higher flash point than standard diesel making it safer in the event of a crash. It’s higher lubricity also means that biodiesel can reduce engine wear, extending car life.
It’s worth noting, though, that blends with higher B factors also have higher cold filter plugging points – in other words, the likelihood of the fuel freezing and clogging up the engine in cold climate is higher with biodiesel.
So... is biodiesel better for the environment? Well, yes and no. The source of biodiesel – namely vegetable oil – is renewable and contributes to CO2 absorptions, but longer-term consequences of deforestation and land use change can lead to excessive CO2 emissions and thus increase the carbon footprint of biodiesel. Biodiesel is not 100% clean – if you are looking for a more sustainable alternative altogether, we would recommend opting for an electric vehicle, joining a car sharing scheme or travelling by bike or public transport.