With the growing awareness of climate change and also of the finite nature of petroleum resources, there is growing interest in biofuels.
There is an issues with biofuels in general and biodiesel in particular , in that there have been quite a lot of instances of either agricultural land, or sometimes virgin rain forest, being turned over to the intensive production of palm oil as a feedstock for the process.
This is clearly unsatisfactory. There are, however, alternatives. Already, there is much use being made of used vegetable oils, waste from the catering industry, but there are other sources too.
One such is coffee grounds. Coffee contains about 9 – 20% of oily diterpenes, Cafestol and Kahweol. Much of this is extracted when the coffee is brewed but a significant amount remains. In 2013, the world consumed close to 9 billion kg of coffee. That is a lot of grounds and thus a lot of potential fuel.
This is a simple method using solvent extraction to obtain the remaining oils from used coffee grounds.