Coffee grounds to low emission biodiesel

Categorie(s): Climate, Sustainable Energy

High quality biodiesel from leftover coffee grounds could decrease reliance on palm oil to produce biofuel.
Two Aston University researchers have produced high-quality biodiesel after  ‘feeding’ and growing microalgae on leftover coffee grounds.

In just the UK, approximately 98 million cups of coffee are drunk each day, contributing to a massive amount of spent coffee grounds which are processed as general waste, often ending up in landfill or incineration.

The researchers found that spent coffee grounds provide both nutrients to feed, and a structure on which the microalgae (Chlorella vulgaris sp. photo)) can grow.  As a result, they were able to extract enhanced biodiesel that produces minimal emissions and good engine performance, and meets US and European specifications.

Up till now, algae have been grown on materials such as polyurethane foam and nylon that don’t provide any nutrients. However, the researchers found that microalgal cells can grow on the leftover coffee without needing other external nutrients.

They also found that exposing the algae to light for 20 hours a day, and dark for just four hours a day created the best quality biodiesel. This is a breakthrough in the microalgal cultivation system.

Biodiesel from microalgae attached to spent coffee grounds could be an ideal choice for new feedstock commercialisation, avoiding competition with food crops.
Furthermore, using this new feedstock could decrease the use of palm trees to extract oil to produce biofuel. In southeast Asia this has led to continuous deforestation and increased greenhouse gas emissions.

The research was developed in collaboration with colleagues from Malaysia, Thailand, Egypt, South Africa and India.

Source: Aston University 01/11/2022

N.B. Algae are already used for producing biodiesel. Chlorella’s are green algae, producing organic material with water, CO2 and sunlight, like plants. What are they using the coffee grounds for?

N.B. 2 Other microbes can also ben used for producinge biodiesel: cyanobacteria, also called blue-green algae. Read: blue-green algae produce oil 

N.B.3. Coffee grounds are already being used for making biodiesel by extracting the oil from the coffee grounds  

but the new method produces much more than just the oil contained in the coffee… (explain why!)