Bugs in key role of CO2 storage method

Tiny microbes are at the heart of a novel agricultural technique to manage harmful greenhouse gas emissions.

Scientists have discovered how microbes can be used to turn carbon dioxide emissions into soil-enriching limestone.

Their technique uses help from a type of tree that thrives in tropical areas, such as West Africa.

Locking away carbon

Researchers studied what takes place when the Iroko tree is grown in dry, acidic soil and treated with a combination of natural fungus and bacteria.

They saw that not only does the tree flourish, it also produces the mineral limestone in the soil around its roots - a way of locking up carbon.

The tree makes a mineral by combining calcium from the earth with CO2 from the atmosphere. The bacteria then create the conditions under which this mineral turns into limestone.

The discovery offers a novel way to lock carbon into the soil, keeping it out of the atmosphere.

Developing world

In addition to storing carbon in the trees’ leaves and in the form of limestone, the mineral in the soil makes it more suitable for agriculture.

The discovery could lead to reforestation projects in tropical countries, and help reduce carbon dioxide emissions in the developing world.

It has already been used in West Africa and is being tested in Bolivia, Haiti and India.

Collaborative study

The findings were made in a three-year project involving researchers from the Universities of Edinburgh, Granada, Lausanne and Neuchatel, Delft University of Technology, and commercial partner Biomim-Greenloop.

The project examined several microbiological methods for locking up CO2 as limestone, and the Iroko-bacteria pathway showed best results.

Work was funded by the European Commission under the Future & Emerging Technologies (FET) scheme.

By taking advantage of this natural limestone-producing process, we have a low-tech, safe, readily employed and easily maintained way to lock carbon out of the atmosphere, while enriching farming conditions in tropical countries.

Bryne Ngwenya

School of GeoSciences