spent

Fuel From Coffee Grounds | Earth Wise

December 8, 2022 By EarthWise Leave a Comment

The world drinks a lot of coffee. Americans alone consume 400 million cups a day. Each cup of coffee results in about half an ounce of coffee grounds. Adding that up, this country produces over 6,000 tons of coffee grounds each day. While coffee grounds are not particularly harmful, that is an awful lot of waste that mostly ends up in landfills or is incinerated.

Researchers at Aston University in the UK have developed a method of producing high-quality biodiesel fuel from coffee grounds. Their study was published in the journal Renewable and Sustainable Energy Reviews.

The technique consists of growing a particular species of microalgae (Chlorella vulgaris) directly on spent coffee grounds. The coffee grounds provide both the nutrients for the microalgae and a structure upon which it can grow. Exposing the algae to light for 20 hours a day and dark for just four hours a day produced the best quality biodiesel.

Microalgae is well-known as a feedstock for biodiesel production. Previously, it has been grown on materials like polyurethane foam or nylon which don’t provide any nutrients. Using the coffee grounds as the substrate for growth means that no external nutrients are needed.

The resultant enhanced biodiesel produces minimal emissions and good engine performance and meets both US and European specifications. This feedstock for producing biodiesel is ideal since it doesn’t require any competition with food crops and instead makes use of a widely available waste product. The hope is that it may reduce the cutting down of palm trees to extract oil for biofuel. In southeast Asia, this has been a major source of deforestation and increased greenhouse gas emissions.

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Aston University researchers ‘feed’ leftover coffee grounds to microalgae to produce low emission biodiesel

Photo, posted October 13, 2007, courtesy of David Joyce via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A Pesticide From Beer | Earth Wise

July 23, 2021 By EarthWise Leave a Comment

Researchers from the Neiker Basque Institute for Agricultural Research and Development in Spain have demonstrated that a combination of rapeseed cake and beer bagasse can be used to reduce populations of soil parasites and increase crop yields.

Beer bagasse is spent brewers’ grain – the stuff that is left over after the beer is made. Beer brewing generates substantial amounts of by-products, including large amounts of spent grain. It already has some practical uses, including as a feedstock for biofuel, as a food additive, and it even has some medical uses. But the new research has shown that the bagasse can be the basis for a biodisinfestation treatment to be used in agriculture. The aim is to disinfect soils, protect soil microorganisms, and increase crop yields.

The actual material studied was a mixture of beer bagasse, rapeseed cake, and a generous amount of fresh cow manure. The high nitrogen content of the mixture promotes the activity of beneficial microorganisms in the soil, which helps to break down organic matter and kill off nematodes and other parasites that damage crops.

Nematodes are common parasites that can penetrate plant roots to lay their eggs, which damages the root and prevents the plants from absorbing nutrients effectively. Application of the bagasse-based mixture over 12 months increased crop yields by 15% and boosted healthy soil microbes.

The study demonstrated that agricultural byproducts can be an effective treatment for root-knot nematodes and other soil parasites, increase crop yields, and help promote sustainable food systems to reduce waste from the agricultural industry. The researchers hope to identify other potential organic treatments for tackling soil parasite problems.

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Beer byproduct mixed with manure proves an excellent organic pesticide

Photo, posted July 1, 2011, courtesy of Quinn Dombrowski via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.