how crushed stone could help fight climate change

Sugar plantations in Brazil in the tea fields in India, the crushed rock is sprinkled through large sections of agricultural land in the world in a new attempt to fight climate change.

The technique is called an alteration of improved rocks (ERW) and aims to accelerate natural capture and carbon dioxide storage – a greenhouse gas warming the planet.

These are potentially large companies with technological giants, airlines and fast fashion companies that queue to buy carbon credits from ERW projects to “compensate” or cancel their own emissions.

– What is Erw? –

Erw aims to kill a natural geological process called integrality.

Alteration is the degradation of rocks by carbonic acid, which forms when carbon dioxide in air or soil dissolves in water.

Alteration occurs naturally when the rain falls on rocks, and the process can lock carbon dioxide from air or soil in the form of bicarbonate, and ultimately limestone.

Erw accelerates the process using fast worn rocks such as basalt which are finely on the ground to increase their surface.

– What is ERW efficiency? –

Erw is always a fairly new technology and there are questions about the quantity of carbon it can delete.

An American study revealed that the application of 50 tonnes of basalt to one hectare of land each year could eliminate up to 10.5 tonnes of carbon dioxide per hectare over a period of four years.

But scientists applying basalt to oil palm fields in Malaysia and sugar cane fields in Australia have measured much lower elimination rates.

“Field tests show that there have been overestimation of the amount and the rate captured,” said Paul Nelson, soil scientist at James Cook University who studied Erw.

The rates depend on variables, in particular the type of rock and the size, how wet and warm climate is, the type of soil and land management.

And the measure of captured carbon is difficult.

The most popular technique measures “cations”, positively loaded ions which are released from the rock during the alteration.

But these cations are produced, whatever the acid with which the rock reacted.

“If there are stronger acids than carbon dioxide, it will react with them,” said Nelson, so measurable cations are produced even when carbon dioxide is not captured.

This does not mean that Erw is useless, said Wolfram Buss, a researcher on the elimination of carbon dioxide at the Australian National University, just that she must be carefully calibrated and measured.

“There is no doubt that this technique is working,” he said.

“However, to be sure of the quantity of carbon dioxide that we really delete, more funding is necessary to do fundamental studies.”

-Are there other advantages? –

The added rock increases soil alkalinity, which can stimulate the growth of crops, soil nutrients and soil formation.

The basalt is both naturally abundant and often available as a sub-product of the career, reducing the costs of the process.

Experts note that even if the rock reacts with other acids in the ground, not having locked carbon dioxide at this stage, it can always have planetary advantages.

Indeed, acids in the ground would end up washing the rivers and the sea, where acidification leads to the release of carbon dioxide.

If the rock neutralizes this acid in the ground, “you have prevented carbon dioxide from being released from water in the downstream atmosphere,” said Nelson.

However, the extent of these possible “prevented” emissions is not yet clear.

– What are the risks? –

Erw is widely considered safe because it simply accelerates an existing natural process. However, some rapid worn rocks have high levels of potentially toxic heavy metals.

The diffusion of finely ground rock also requires appropriate protective equipment for those involved.

But the main risk is that incorrect measures overestimate the captured carbon.

Some projects are already selling carbon credits to ERW. If a company buys an ERW credit to “compensate” its emissions but the process captures less than expected, it could cause higher carbon dioxide placed in the atmosphere.

– Where is Erw done? –

Projects occur in most regions of the world, including Europe, North America, Latin America and Asia.

Earlier this year, a project in Brazil announced that it had given the very first credits for the verified carbon of an ERW project.

The process is used or tested in agricultural environments tea plantations in the Darjeeling fields in India in soy and corn.

-What interest in investors is there? –

A startup ERW – Mati Carbon, working in India – won the price of $ 50 million for carbon elimination projects earlier this year.

In December, Google announced what was the largest ERW agreement in the world, for 200,000 tonnes of carbon elimination credits, to be handed over in the 2030s by Startup Terradot.

The cost of the agreement has not been disclosed, but a separate Terradot agreement with a company representing companies, including H&M, sold 90,000 tonnes for $ 27 million.

SAH / CWL / PST