A Solution in Plain Sight

Enhanced Rock Weathering (ERW) is another pathway to CDR and is slowly gaining popularity. The best part of ERW is that it is really simple, with the science having been around for a long time. As the name suggests, ERW is nothing but weathering of rocks at an accelerated and enhanced pace and is a nature-based solution to lock away carbon dioxide. Rock weathering, as we know, is a natural process that takes place over hundreds of years, which not only neutralises the carbon dioxide in the air but also wears down massive mountains. This process that takes hundreds of years is sought to be accelerated in ERW, so that large amounts of carbon dioxide are removed from the air in a far shorter time period. Let us discuss this in more detail.

ERW: A Workable and Easy to Access Solution

Weathering of rocks is a phenomenon that takes place over hundreds of years as a result of the interaction between rainwater, carbon dioxide and the silicate rocks that form a bulk of the Earth’s crust. Carbon dioxide dissolves in rainwater, forming carbonic acid, which reacts with the silicates when it rains. Carbonate ions and Sand (Silicon Dioxide) are formed as a result of this chemical reaction, which enter the river streams and ultimately the oceans. This locks up carbon dioxide at the ocean floor for good. The added advantage is that the powdered basalt or olivine adds many minerals and nutrients to the soil raising its fertility and productivity. What if this weathering of rocks is scaled up exponentially?

This proposal to scale up rock weathering or ERW was put forward by Olaf Schuilling in 2007, when he suggested that truckloads of powdered olivine rock (which is a silicate rock composed of forsterite or Mg2SiO4) could be procured from mines in Norway and spread over miles and miles of North Sea beaches. This proposal could not be implemented for a variety of reasons such as the costs of hauling large amounts of olivine, the cold temperature of the North Sea etc. However, the science was sound and an idea had been planted.

Today, there are a number of startups across the world who have blazed a trail in the promising and upcoming area of ERW. Some of these companies are: Terradot and InPlanet from Brazil (working on Agricultural lands in Brazil), Project Vesta from the US (working on Schuilling’s original idea of spreading Olivine on coastal beaches, with pilots in North Carolina, the USA and North Sea, the UK), UNDO Carbon from the UK (working on agricultural lands in the USA and the UK), Mati Carbon and Alt Carbon (working on spreading basalt powder on Agricultural lands in India), Lithos Carbon and Eion Carbon (US-based company working on Agricultural Lands in the US).

ERW offers a number of advantages such as improved soil productivity in addition to locking up carbon dioxide, which has been discussed above. Another advantage is the attractive economics of this CDR technique. For example, the cost of putting away a tonne of carbon dioxide ranges from USD 160 to USD 180 in the USA. While numbers from India are not available, it is likely that the costs will be lower than in the USA. This is far lower than the cost of USD 1,000 per tonne of carbon dioxide in the Swiss company Climeworks’ Direct Air Capture (DAC) plants in Iceland.

While ERW has been touted as a win-win solution for all, because of its evident positive externalities (the farmers benefit from the improved soil and people benefit from reduced carbon dioxide), many scientists have also urged caution. Some of the concerns raised are the availability of large amounts of powdered silica rocks and the costs of trucking them over long distances. The other concern is that of accurately measuring the amount of carbon dioxide captured and the need for standards as well as world class laboratories for the purpose.

Conclusion

While ERW offers a lot of promise and is a disarmingly simple way to capture carbon dioxide, these are early days. A lot of promising work is being done in this area and it is necessary that there are standards developed to measure the carbon dioxide captured. Further, laboratories that work according to these standards are developed across the world.

The writer is Additional Chief Secretary, Department of Cooperation, Government of West Bengal.
Views expressed are personal