digest

Electricity From Bacteria | Earth Wise

June 3, 2022 By EarthWise Leave a Comment

Microbiologists at Radboud University in the Netherlands have demonstrated in the laboratory that methane-consuming bacteria can generate electrical power. Their study was recently published in the journal Frontiers in Microbiology.

The bacteria studied is called Candidatus Methanoperedens and in the natural environment it consumes methane in water sources that are contaminated with nitrogen including places like water-filled ditches and some lakes. The bacteria in the study make use of the nitrates in the water to break down and digest the methane. Methanogens, which are bacteria that reduce carbon dioxide to form methane, are the source of the methane in these places.

The researchers exploited these complex interactions of bacteria to create a source of electrical power that is essentially a kind of battery with two terminals. One of the terminals is a chemical terminal and one is a biological terminal. They grew the bacteria on one of the electrodes where the bacteria donate electrons that result from its conversion of methane. (Other microbiologists at the same institution had previously demonstrated electrical generation from a similar battery containing anammox bacteria that use ammonium rather than methane in their metabolic processing).

In the study, the Radboud scientists managed to convert 31% of the methane in the water into electricity but they are aiming at higher efficiencies.

This approach represents a potential alternative to conventional biogas electricity generation. In those installations, methane is produced by microorganisms digesting plant materials and the methane is subsequently burned to drive a turbine to generate power. Those systems in fact have an efficiency of less than 50%. The researchers want to determine whether microorganisms can do a better job of generating electricity from biological sources than combustion and turbines can do.

**********

Web Links

Bacteria generate electricity from methane

Photo, posted December 3, 2008, courtesy of Martin Sutherland via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Australian Plastic Bag Ban

December 31, 2018 By EarthWise Leave a Comment

Last summer, the two largest supermarket chains in Australia – Coles and Woolworth’s – decided to stop offering single-use disposable plastic bags to customers. The initial public reaction was decidedly negative. However, within just three months after the radical change, the country’s National Retail Association reported an 80% drop in the consumption of plastic bags nationwide.

In that three-month period, it is estimated that 1.5 billion bags have been prevented from use. Some retailers are reporting reduction rates as high as 90% in the use of the bags. The move by the big supermarkets has paved the way for smaller businesses to follow suit. The smaller businesses typically can’t afford to risk the wrath of their customers with a major change like this. Customers have to learn to bring their own bags or buy reusable bags at the store.

In much of Australia, the phase-out of plastic bags has been legislated, but the state of New South Wales, home to Sydney, the country’s largest city, has not enacted such legislation. So, supermarkets themselves are doing the work of getting rid of the bags.

The change has not been without hiccups. For the first couple of months after the plastic bag ban was put in place, Woolworth’s saw poor sales in its stores. However, customers eventually got used to the new way of doing things and sales levels returned.

Disposable plastic bags often find their way into the oceans where they break down into microparticles. Studies have shown that these plastic bits are ingested by a wide variety of marine life. For example, a UK study found that 100% of sea turtles in the Pacific and Atlantic oceans as well as the Mediterranean Sea had plastic in their digestive systems.

**********

Web Links

Australia-wide ban leads to ’80 per cent drop’ in plastic bag consumption

Photo, posted September 18, 2018, courtesy of Matthew Paul Argall via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Fighting Methane With Bacteria

June 14, 2018 By EarthWise Leave a Comment

Bacteria may have an important role to play in the effort to reduce greenhouse gas emissions. A group of researchers at the University of Alberta are genetically engineering non-hazardous bacteria that consume methane and turn it into fuel.