The London-based Consultancy, LRS has suggested that London use biodiesel from used cooking oil (UCO) to fuel their bus fleet.
The goal of the project is for the Greater London Authority (GLA) to reduce the carbon footprint of their bus fleet using B30 - a 30% Biodiesel 70% diesel fuel mix. The use of UCO and other fats, oil, and grease (FOG) instead of virgin oil as a feed for biodiesel can increase sustainability, close production cycles, and avoid the food vs. fuel debate.
Hugh Smith, Principal LRS Consultant, stated that “Our research shows that London has the highest concentration of food businesses in the UK, producing between 32 and 44 million litres of used cooking oil every year.”
The Mayor of London, Boris Johnson added that, “by capturing used cooking oil right here in London and turning it into biodiesel we could provide 20% of the fuel needed to power London’s entire bus fleet, while saving more than 50,000 tonnes of CO2 and creating hundreds of new jobs.”
The project isn’t limited to cooking oil, “there is an opportunity for water companies to utilise the fats, oils and greases collected from the sewers … and use them to manufacture a low carbon fuel, in the form of biodiesel” said Hugh Smith.
Biodiesel is an environmentally benign substance, so spillage isn’t as scary as for fossil fuels. It also eliminates the odour and CO2 emissions associated with fossil fuels. Additionally, biodiesel can be used in standard diesel engines without modifications. Biodiesel is even associated with some engine improvements such as increased lubricity and engine knocking.
Biodiesel is produced when organic oils and fats (triglycerides) come into contact with an alcohol, usually methanol, and a catalyst. The bulky triglyceride bonds are broken releasing fatty acid methyl ester (FAME) or biodiesel. The glycerol and catalyst is then separated using gravity and water washing techniques.
The fastest catalysts are KOH and NaOH. However, H2SO4 is also used in a pre-processing reaction if the oil feedstock is contaminated with water as is often the case with UCO. Though slower, the acid catalyst will avoid the production of soap, thereby increasing the yield.
According to trials, there are no insurmountable technical barriers to the use of B30 in public transit fleets. This example demonstrates that we need to rethink what we consider to be waste to build a more sustainable future.