Silicate, an Irish company that uses crushed concrete to help farmers sequester carbon, has been selected as one of eleven finalists in the THRIVE Shell Climate-smart agriculture challenge.
The company, which was founded by Maurice Bryson in 2021, has developed a method of sequestering high rates of carbon dioxide (CO2) by spreading concrete over fields to optimise the soil’s pH, which then acts as a medium for a specific reaction to occur.
Speaking to Agriland, Bryson outlined how the process works.
Carbonic acid – which is simply water containing CO2 – is present in soils, and when the company’s concrete mix is spread on the field, it reacts with this acid and creates bicarbonate.
During this reaction, CO2 gets trapped in the bicarbonate, which is then washed away by the water in the soil, ultimately ending up in the ocean.
“The carbonic acid is weathering our minerals, creating bicarbonate and those molecules are then leaving the soil and flowing into the ocean. The reaction is happening in the water in the soil,” he said.
This wash away is helpful, allowing farmers to continue ploughing their fields without releasing the carbon back into the atmosphere, as is the case in other types of organic carbon farming.
Although the concept is a relatively new one, Bryson reiterates that it’s safe as well as effective.
“It’s just like ground limestone, farmers will leave it a couple of weeks before putting animals back out to graze.
“You can still grow crops, you can still graze animals, there’s no difference apart from the material that’s spraying out,” he stated.
Furthermore, Bryson outlined that the question of machinery needn’t be a cause for concern either, as the material can be spread using “the exact same machinery as you would use to spread ground limestone”.
Concrete mix
Globally, up to 40 billion tonnes of concrete are produced each year, although the practice of over-ordering leaves much of this unused, Bryson told Agriland.
“Roughly between 2% and 5% of all concrete produced is sent back, and that’s the stuff that we work with primarily, so there are millions of tonnes globally that we can use to capture CO2 with.
Silicate crushes this concrete down to the EU’s liming specifications – 70% less than 1mm in diameter – before it’s brought to farms and spread on pre-selected fields, to bring the soil’s pH to the level that the farmer has requested.
“It’s all driven by what the farmer wants, we add enough to make that happen and then we measure to see how much carbon has been removed.
“Sometimes we add catalysts to speed up the process, but the really important bit is the measuring afterwards to see how much carbon has been sequestered,” Bryson added.
Benefits of the method?
There are three main positives to implementing this system on farms, according to Bryson. These are: Sequestering carbon dioxide and reducing your emissions, stronger crop health, and better nitrogen efficiency.
“Eventually, Teagasc will be launching a sort of ‘on-farm carbon calculator’ and farms will have to measure their emissions and see how they’re being reduced over time.
“If that comes, then farmers will need all the different solutions that they can get to lower the emissions from the farm,” he said.
According to Bryson, spreading concrete instead of lime can be an effective way to do this, with the company’s tests demonstrating a carbon removal potential of 0.55t per 1t of crushed concrete spread.
The company can also add silica to its mixture, which strengthens crop stems and can result in a decreased need for pesticides, Bryson explained.
“The third benefit is that by having optimal soil pH, we can reduce the nitrous oxide emissions from your farm, which means you’re getting better use of your fertiliser.
“So there’s numerous benefits and we are working now on proving scientifically that our material can deliver that,” he concluded.
As the EU carves out a plan to become carbon neutral by 2050, the Irish agricultural sector has also been tasked with reducing its greenhouse gas emissions by 25% by 2030 against 2018’s levels.
New technologies and scientific methods are set to play a major part in achieving this, and Bryson hopes that Silicate can be involved, as it rolls out its method and moves to sell the carbon credits collected to third parties.
Speaking about making the shortlist in the THRIVE Shell competition, he said:
“The recognition is great; for us it’s a chance to speak about enhanced weathering and the potential of it on a global stage. It’s nice to raise awareness and let people know what we can do.”
Silicate, along with the other 10 finalists from around the globe, will pitch to the competition’s judging panel, with the winners gaining the opportunity to showcase their solutions at the South by South West tech conference in Texas in March 2023.