Greenhouse Gas Removal via Enhanced Rock Weathering

Project summary

The Plynlimon Research Catchments host a demonstrator site to test the hypothesis that application of basalt rock dust onto upland grassland will enhance the long-term capture of carbon in the soil and water.

The Enhanced Rock Weathering (ERW) demonstrator project is part of the UKRI BBSRC funded GGR CO2RE programme, a multi-disciplinary, multi-centre national research hub on Greenhouse Gas Removal (GGR).

The Plynlimon site is led by UKCEH, being the first larger scale test to see if rock dust application can be an effective GGR programme in upland grasslands. Based at the long-term Plynlimon Research Catchments, we will annually apply two years of rock dust (May 2023 and 2024) in a paired catchment experiment, monitoring the impacts through high resolution water, soil, vegetation and GHG measurements.

The project has several key collaborators in the wider GGR via ERW demonstrator, including the Leverhulme Centre for Climate Change Mitigation, Rothamsted Research and NOC.

Plynlimon Research Catchments

The Plynlimon Research Catchments are two, almost identical, adjacent uplands catchments, with the exception that one is used for grazing sheep while the other is mostly under plantation conifer forestry. Intensive and long-term monitoring within the catchments underpins a wealth of environmental research, with over 500 publications in peer-revewed journals.

Plynlimon Research Catchments

Testing the hypothesis

The weathering of rock is a natural process - so the idea is to speed up (or 'enhance') this by crushing the rock to a fine dust, making more surface area for the weathering process to happen quicker.

The theory of Enhanced Rock Weathering is rainwater will react with crushed silicate rock that has been spread across a field to form new chemical bonds that hold on tight to their carbon. These strong bonds are then washed through the river system to the sea, where they will sink and be stored in the deep ocean for a very long time (~100,000 years!).

Some of the new chemical bonds will stay in the soil, this about half as effective at storing carbon, but can still be stored for a very long time (~10,000 years).

We are testing this theory in the real world to see if it really is as effective as the hypothesis and smaller scale tests suggest. On an upland grassland catchment in mid-Wales, we will apply rockdust to 3.5ha of land to see what impact it has on carbon storage in the soil and carbon export through the water course.

Other potential benefits

Carbon drawdown is the primary goal of ERW.

But there are other potential benefits too. Improved soil health, better crop production and reduced N₂O emissions being some of them.

As part of this study we will monitor all the anticipated impacts rckdust application could provide to be able to assess the overall cost and benefits of future possible uptake as a GGR technology. Our findings will feed into the wider project feasibility and scalability assessments.

What are we monitoring?

The Plynlimon site is a paired catchment wide monitoring programme, one catchment for rockdust application and a neighbouring catchment as a control.

To robustly assess the impact rockdust application is having we are undertaking a wide range of analysis including; Water chemistry and flow, Greenhouse Gas emissions, soil cores, biodiversity surveys, grass production and forage quality, freshwater biology and we are even tracking sheep grazing patterns to see if there is a change in grazing pressure (i.e. do they prefer rockdust grass or not?).

This study is situated within the wider context of the Plynlimon Research Catchments that will also provide a long-history of metreorological, hydrological and soil data from nearby monitoring stations.

Wider GGR via ERW project

The Plynlimon demonstration site is one of three sites assessing the impact of rockdust application as part of the wider ERW progect. Led by LC³M, the £4.7M collaborative GGR grant funding through UKRI aims to assist the UK Government in getting to Net Zero by 2050. The programme involves social scientists, earth system modellers and geochemists from a number of institutions including; University of Sheffield, Rothamsted Research, University of Southampton, National Oceanography Centre, University of Oxford, University of Cardiff, University of Aberdeen, Heriot-Watt University and University of Leeds.

The Enhanced Rock Weathering demonstrator is one of five innovative methods of large scale GGR from the atmosphere funded by the UK Government as part of the CO₂RE hub. CO₂RE is a multi-disciplinary, multi-centre national research hub on Greenhouse Gas Removal.

UK Enhanced Rock Weathering twitter