A new eco-friendly method for sustainable biodiesel synthesis using spent coffee grounds.
Coffee may become an increasingly crucial part of your morning routine as researchers develop a new approach to biodiesel production, using a reusable solvent to cut down on energy costs and increase maximum biodiesel yield.
‘DBU-assisted direct transesterification’ of wet spent coffee grounds is an eco-friendly and economically viable new approach for biodiesel synthesis.
The 2019 study uses the chemical ‘DBU’ as both the solvent and catalyst, streamlining what used to be a lengthy process into a highly efficient technique, delivering a maximum biodiesel yield of 97.18%. This is improved further by the ability to process wet coffee grounds (as opposed to dry), decreasing the required energy compared to conventional extraction.
Remarkably, DBU can also be reused at least 10 times without reducing efficiency, increasing the life-span of the chemical and reducing waste.
We, as an industry, waste a lot of coffee!
An astounding 9 million tonnes of coffee is brewed around the world every year, with an estimated 18 million tonnes of wet coffee grounds going in the bin. Usually these grounds end up in landfills, where they emit methane – a greenhouse gas 30 times more potent than carbon dioxide.
However, due to their high oil content and abundant supply, spent coffee grounds have received an increasing interest amongst biofuel researchers and small businesses, with one company powering a London bus for a year on coffee-derived biofuel blended with diesel.
Reusing coffee grounds is gaining popularity for good reason - by using this misused resource, we could be reducing waste, lowering biodiesel production costs, and facilitating sustainable energy production.
Moving away from purpose-grown biofuel crops (such as wheat, sugar cane and corn) has certainly been a step in the right direction, as they require a lot of land and water that is probably better spent growing actual food. Wheat crops take up almost half of the land used for biofuels in the UK, and it’s estimated that fuel based solely on this grain were actually worse for the environment than common petrol or diesel.
Previous research into direct transesterification have achieved very low efficiency rates, calling for either hazardous organic solvents or much higher reaction temperatures to increase efficiency, which raised environmental concerns and attributed large energy costs. Without these issues, the new process presents the most compelling case for commercially viable biodiesel synthesis on a large scale, using an untapped and hugely
available resource.
Although we may be a little way away from the circular-economy-coffee-powered-coffee-shops of our dreams, this is an exciting discovery for the industry, and should inspire us to find alternative functions for the waste we produce.
Read more about alternative uses for coffee grounds here!