Volcanic ash could aid carbon capture

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Scientists at the UK’s University of Southampton are investigating ways of removing carbon dioxide (CO) and other greenhouse gases from Earth’s atmosphere, and believe volcanic ash could play an important role in this process.

A team from the University’s School of Ocean and Earth Science has modeled the impact of spreading volcanic ash from a ship to an area of ocean floor to help amplify natural processes which lock away CO in the seabed. They found the technique has the potential to be cheaper, technologically simpler and less invasive than other techniques to remove harmful gases, with the findings published in the journal Anthropocene.

“As a result of overwhelming evidence, politicians have begun to take steps towards incorporating emissions reductions into policies, such as in the 2015 Paris Agreement with its long-term goal of ensuring that global average temperatures do not exceed 2°C above pre-industrial levels. However, it is becoming clear that to avoid the worst impacts of climate change, active greenhouse gas removal (GGR) will be required,” explained study co-author and University of Southampton professor of geochemistry Martin Palmer.

GGR techniques remove carbon dioxide and other gases from the atmosphere, thereby reducing the greenhouse effect, and in the longer term, slowing climate change. There are numerous potential approaches to GGR, from the simple, such as reforestation, to the complex, such as actively removing CO from the atmosphere.

The paper’s authors note that most volcanoes lie close to the oceans, and every year millions of tons of volcanic ash falls into them and settles to the seafloor.  Once there, it increases carbon storage in marine sediments and reduces atmospheric CO levels. This is important because the oceans are the greatest sink of manmade CO on Earth.

“One of the ways oceans lock away CO is by storing it in sediments on the seafloor as calcium carbonate and organic carbon. In our work, we discuss how this natural process may be augmented by artificially adding ash to oceans,” said Jack Longman, lead-author and former post-doctoral research assistant at the University of Southampton, who now holds a position at the Institute for Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg.

The scientists modeled the effect of distributing volcanic ash from a ship to an area of ocean. The results suggest that this method could sequester as much as 2,300 tons of CO per 50,000 tons of ash delivered for a cost of US$50 per ton of CO sequestered – much cheaper than most other GGR methods. In addition, the approach is simply an augmentation of a naturally occurring process, it does not involve expensive technology and it does not require repurposing valuable agricultural land.

The scientists note that further research is needed though to test the efficiency of enhanced ash deposition in the oceans and to make sure there are no unforeseen side effects, but initial indications suggest that it could be applied easily and cheaply in many areas of the world.

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Lawrence has been covering engineering subjects – with a focus on motorsport technology – since 2007 and has edited and contributed to a variety of international titles. Currently, he is responsible for content across UKI Media & Events' portfolio of websites while also writing for the company's print titles.

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