Scientists harness cow dung to fight climate change

Image copyright Sophy Annis

Scientists have demonstrated that a potentially harmful but useful way of checking for methane from cow dung can be used to fight climate change.

A team at MIT in the US carried out experiments on lightning and patties, one of which used cow dung to generate kinetic energy.

The electricity was used to power a 500m runner.

Researchers hoped that, once outside in the real world, the technology would improve.

But the results of the testing – published in Nature on Tuesday – show that the device used at MIT is effective against methane and other trace gases that produce heat-trapping methane in the atmosphere.

How it works

The device is made of a plastic tube with a connector at the end to which scientists attached a 300m runner with a thin film of film.

The aim is to attach lightning to the surface of the fluid on the end of the liner to create electrical force and voltage.

When the runner is tapped at the other end, the science data is sent from an external computer. It computes the amount of power the device generates and compares it to a traditional “earth anchor” – a piece of metal that is stuck to a rock as a marker for energy output.

When this is compared to a metal object, it shows the device generates far more energy than a traditional attachment or tether.

‘Risk reduction’

“This experiment … was also designed to evaluate the throughput of a system that could function in a practical way,” said Sophy Annis, who has built and tested the device in an MIT lab since 2015.

“This work also included the development of a technology with the potential to mitigate greenhouse gases. The system has serious potential as a risk reduction strategy – with the goal of mitigating greenhouse gases and conserving energy.”

Methane is emitted in ever-increasing quantities into the atmosphere. Some estimates suggest up to 20% of the gases produced in the EU are caused by this gas.

Scientists estimate emissions from livestock are more than 100 times larger than that from other industrial sources, such as the UK coal-fired power plant.

Prof Anneke on water in the M48

“To further investigate the possibility of automating one of the most challenging areas of climate change research – environmental methane detection – the scientists took advantage of the perceived anonymity of lightning, which is also found in wastewater and other source gases,” said lead author Dr Greg Froude of MIT.

“The consequence was that the perception of wildfire may drive microbial communities to produce methane.”

Prof Jenny Saville from University College London’s European School of Water and Environment said: “At present the human ability to generate electricity using atmospheric methane is based on reactive emissions generated from the furnaces and paints, chemicals and heavy metals that humans leave around our homes and workplaces.

“On the other hand, electrical power generated from field measurements comes from generation of reactive particles within clouds, wherein, as the authors note, a bacterial community is simultaneously activated and methane produced.

“The devil would appear to be in the details, and so what we are seeing in these results could all be down to best practices.

“The ‘nature anchor’ technology is a natural step in the effort to find effective methods of feeding energy and therefore energy-generation capability into this realm.

“A technology akin to this would be very cost-effective in its application to sensors to measure aviation emissions.”

Prof Peter Wolff from the University of Cambridge’s Centre for the Environment and Society said: “This experimental machine mimics both the microbial and free-charging conditions that natural methane exchangeators thrive in.

“What’s not in the paper, however, is that the microbial pattern generator produces methane only when the surface is heated to a threshold temperature, which means that despite its apparent efficiency, the electricity it generates is delivered only at temperatures of up to 12 degrees Celsius, which is the ideal range for lightning.

“Having said that, I hope that this future device, if built, will have the benefit of much deeper processing: through chemical and quantitative modelling, it will be possible to estimate current energy from cellular processes and to develop a model of the availability of energy across the forest floor.”

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