Enhanced Weathering
Type
Carbon Dioxide Removal
Areas of deployment
Marine and coastal regions, Agricultural land, Industrial sites
Proposal
Crushing millions of tonnes of rocks and spreading them on land and in the oceans.
Featured project
Name: Vesta: Puerta Plata
Location: Dominican Republic
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Enhanced weathering techniques involve spreading large amounts of crushed rocks (particularly silicate minerals) onto farmland or beaches, or dumping them into the sea, in order to react with and fix atmospheric carbon dioxide into the oceans and soils.
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Description and purpose of the technology
Enhanced Weathering (EW) techniques are a set of theoretical proposals to remove carbon dioxide by spreading large quantities of finely-ground rock minerals onto extensive land areas, beaches or the sea surface. This hypothetical Carbon Dioxide Removal (CDR)
technology aims to mimic and accelerate the natural weathering processes of silicate and carbonate rocks, a slow carbonation process that is estimated to absorb about one billion tonnes of carbon dioxide from the atmosphere every year.
The acceleration of weathering processes could theoretically be achieved by mining and crushing large amounts of suitable rocks to increase their reactive surface. [1] This process would be hugely expensive, and the environmental harm, impacts on communities and energy and water consumption rates would be comparable to global coal mining at present scale. Suitable rocks, particularly silicate and carbonate minerals rich in calcium and magnesium such as olivine-rich ultramafic and mafic rocks or basaltic rocks, would need to be mined, crushed, transported and dispersed.
Other proposals involve the use of waste materials, such as mine tailings or industrial by- products from iron and steel production, for example steel slag or cement kiln dust, which may release pollutants with harmful effects. [2]
EW schemes are proposed in terrestrial, coastal and marine environments. On land, EW usually involves spreading crushed rocks onto farm land, based on the argument that the addition of stone meals may also increase soil fertility and therefore crop yields. [3] Although stone meals are regularly used as fertilisers and soil conditioners to correct deficiencies in soil nutrient levels or soil structure, it is unlikely that the amount required for an optimum supply of nutrients would be able to remove substantial amounts of carbon dioxide from the atmosphere—on average two tonnes of finely ground rock are needed to absorb one ton of carbon dioxide. [4]
Enhanced Weathering in marine environments is also referred to as Ocean Alkalinity Enhancement (OAE) and involves adding ground minerals directly to the ocean or dumping them on beaches where wave action disperses them into seawater. This theoretically increases seawater alkalinity, allowing the oceans to absorb more carbon dioxide from the atmosphere. The effects of OAE on biochemical processes or the marine food chain are poorly understood. [5]
Actors involved
Although some companies are attempting to commercialise EW approaches, most schemes are taking place within the scope of research projects in universities in the UK, the Netherlands and North America. In the UK, the Oxford Geoengineering Programme, an initiative led by Tim Kruger at Oxford University, leads and conducts research activities on EW. The project Greenhouse Gas Removal by Enhanced Weathering (GGREW) aims to explore the feasibility of EW in oceans, assess different ways to accelerate the weathering process artificially and plans to conduct open-ocean trials in the Great Barrier Reef, Australia, and in the Gulf of Aqaba, off the coast of Israel. Since 2008, Tim Kruger has been trying to market an OAE approach based on lime. His company Cquestrate has received early-stage funding from Shell.
The Leverhulme Centre for Climate Change Mitigation (LC3M), based at and led by the University of Sheffield, UK, was founded in 2016 to conduct research on EW on croplands as a potential strategy for increasing field yields while removing carbon dioxide from the atmosphere. The research activities also include field trials at farming sites, where 50 tonnes of mined and crushed basalt have been applied per hectare per year, to test EW in different agricultural environments. The trials are conducted on farms in Australia, Malaysia and the USA with various crops, among them oil palm, sugar cane and soy. The LC3M also studied EW in coastal environments and carried out laboratory tests with seawater in cooperation with the University of Brussels, in Belgium.
In the Netherlands, Olaf Schuiling conducted lab-based research on EW with olivine-rich rocks at Utrecht University. He founded the Smart Stones Foundation (formerly The Olivine Foundation) in 2009 to promote and commercialize olivine applications for carbon dioxide removal and conducted small-scale trials. Larger outdoor trials were proposed but have so far not taken place. Schuiling’s research contributed to the founding of Dutch companies greenSand and Green Minerals, which are both trying to commercialise EW using olivine-rich rocks. Green Minerals is also participating in the German research project CO2MIN, which explores using olivine-rich and basalt rocks to absorb carbon dioxide flue gas.
In North America, researchers at the University of Guelph, Ontario, proposed and tested EW with the calcium silicate rock wollastonite, in trials with beans and corn grown in pots. The suitability of using mine tailings from nickel, diamond and platinum production for EW is being tested in a research project financed by Natural Resources Canada and conducted by the University of British Columbia. UBC partnered with the FPX Nickel Corporation, an owner of several nickel mines, to conduct field trials at a mine in the Decar Nickel District in British Columbia, Canada. Oceankind, a philanthropic funding organisation, plans to form a knowledge hub on OAE with stakeholders from science, policy and the private sector and organised a kick-off event in California, in September 2019. [6]
California-based Vesta (formerly Project Vesta), founded by “biohacker” and brain drug entrepreneur Eric Matzner, is testing EW with olivine-rich rocks on beaches. In 2022, Vesta spread 650 tonnes of olivine over a 400 meter stretch of beach north of Southampton on Long Island in eastern New York, and the open-air experiment is expected to last two years, during which the amount of carbon dioxide absorbed will be measured. Vesta says it has also received approval from the Dominican Ministry of the Environment for the first phase of outdoor tests in two bays in the Dominican Republic, which was expected to begin in 2022. Vesta has applied for permission to conduct outdoor experiments in North Carolina and is seeking partners for additional experiments, including in the Great Lakes region of North America. It is also participating in a research project on OAE in tidal wetlands in a salt marsh ecosystem in Massachusetts, USA. [7]
Impacts of the technology
If EW were to be deployed on a large enough scale to remove significant amounts of carbon dioxide from the atmosphere, there would need to be an exponential increase in the scale of global mining operations, which would have devastating effects on communities and ecosystems around the world, and cause large amounts of greenhouse gas emissions. [8]
Furthermore, EW requires these big quantities of rocks to be milled, transported and dispersed, which further increases its carbon dioxide and environmental footprint. [9] Although ground rocks may add nutrients to agricultural land, they may also change soil properties and release substances with harmful effects even in small doses, such as nickel, chromium or cadmium. EW may also provoke hydrological changes and pollution in water bodies through leaching or erosion. [10] EW is often recommended for tropical regions with soils that are poor in nutrients such as oxisols and ultisols, but studies suggest that weathering is highly sensitive to temperature, with optimum results at temperatures between 10°C and 15°C, and with both low and high temperatures limiting weathering. [11]
If milled rocks are applied directly to the ocean and on a large scale, harmful substances, changes in silicon concentration or unintended biogeochemical processes may affect marine biota. OAE could therefore lead to changes in the composition of marine species and changes in the marine food web, and its effects on deep-sea life are also poorly-understood. [12] If mining and other industrial waste products are considered for EW or OAE, they are likely to contain substances such as heavy metals, which would also affect marine life and the ocean’s biogeochemistry. [13]
EW and OAE are cost and energy-intensive proposals for terrestrial, coastal and marine environments. They are associated with unforeseeable risks for ecosystems, large social impacts for communities in mining areas and a very doubtful overall emission balance. In addition, EW and OAE are impracticable due to the massive amounts of rock required and their potential to actually remove carbon dioxide on a larger scale is not proven.
Reality check
EW and OAE are mainly based on modelling exercises and theoretical models, but a few field-scale trials are being conducted and further trials are anticipated or in preparation, among them experiments in reef environments in Israel and Australia (GGREW), on beaches in the Caribbean (Vesta), and in nickel mines in Canada (FPX Nickel Corporation and research partners).
Further reading
ETC Group and Heinrich Böll Foundation, Geoengineering Map. https://map.geoengineeringmonitor.org/
End notes
[1] Strefler, et al. (2018) Potential and costs of carbon dioxide removal by enhanced weathering of rocks, in Environmental Research Letters, Vol. 13:3, https://iopscience.iop.org/article/10.1088/1748-9326/aaa9c4; Bach, et al.
(2019) CO2 Removal With Enhanced Weathering and Ocean Alkalinity Enhancement: Potential Risks and Co-benefits for Marine Pelagic Ecosystems, in Front. Clim., Vol. 1, https://doi.org/10.3389/fclim.2019.00007
[2] Kelmen, et al. (2019) An Overview of the Status and Challenges of CO2 Storage in Minerals and Geological Formations, in Front. Clim., Vol. 1, https://doi.org/10.3389/fclim.2019.00009; Renforth (2019) The negative emission potential of alkaline materials, in Nature Communications, Vol. 10, https://doi.org/10.1038/s41467-019-09475-5; Köhler, et al. (2010) The geoengineering potential of artificially enhanced silicate weathering of olivine, in: Proceedings of the National Academy of Sciences of the United States of America, Vol. 107:20228-20233
[3] Strefler, et al. (2018); Hepburn, et al. (2019) The technological and economic prospects for CO2 utilization and removal, in Nature, Vol. 575:87-97, https://www.nature.com/articles/s41586-019-1681-6
[4] GESAMP (2019) High level review of a wide range of proposed marine geoengineering techniques, (Boyd, P.W. and Vivian, C.M.G., eds.). (IMO/FAO/UNESCO-IOC/UNIDO/WMO/IAEA/UN/UN Environment/UNDP/ISA Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection). Rep. Stud. GESAMP No. 98, 144 p.
[5] GESAMP (2019)
[6] ETC Group and Heinrich Böll Foundation (2020) Geoengineering Map, https://map.geoengineeringmonitor.org/
[7] Ibid.
[8] Kramer (2020) Negative carbon dioxide emissions, in Physics Today, Vol. 73(1):44, https://physicstoday.scitation.org/doi/10.1063/PT.3.4389; GESAMP (2019); Köhler, et al. (2010)
[9] Lefebvre, et al. (2019) Assessing the potential of soil carbonation and enhanced weathering through Life Cycle Assessment: A case study for Sao Paulo State, Brazil, in Journal of Cleaner Production, Vol. 223:468 – 481, https://doi.org/10.1016/j.jclepro.2019.06.099
[10] Hartmann, et al. (2013) Enhanced chemical weathering as a geoengineering strategy to reduce atmospheric carbon dioxide, supply nutrients, and mitigate ocean acidification, in Reviews of Geophysics,Vol. 51(2):112 – 149,
https://doi.org/10.1002/rog.20004; Strefler, et al. (2018)
[11] Zeng, et al. (2019) Sensitivity of the global carbonate weathering carbon-sink flux to climate and land-use changes, in Nature Communications, Vol. 10:5749, https://doi.org/10.1038/s41467-019-13772-4; Fuss, et al. (2018) Negative emissions-Part 2. Costs, potentials and side effects, in Environmental Research Letters, Vol. 13(6): 063002, https://doi.org/10.1088/1748-9326/aabf9f
[12] Bach, et al. (2019); Hartmann, et al. (2013); GESAMP (2019); Chisholm and Cullen (2001) Dis-Crediting Ocean Fertilization, in Science, Vol. 294(5541): 309 – 310, https://doi.org/10.1126/science.1065349
[13] Renforth (2019); GESAMP (2019)
Enhanced Weathering
TIPO
Carbon Dioxide Removal
Zonas de despliegue
Marine and coastal regions, Agricultural land, Industrial sites
Propuesta
Crushing millions of tonnes of rocks and spreading them on land and in the oceans.
Proyecto destacado
Nombre: Vesta: Puerta Plata
Localización: Dominican Republic
Mostrar en el mapa
Enhanced weathering techniques involve spreading large amounts of crushed rocks (particularly silicate minerals) onto farmland or beaches, or dumping them into the sea, in order to react with and fix atmospheric carbon dioxide into the oceans and soils.
Última actualización de la tecnología
Mostrar actualización
Descripción y propósito de la tecnología
Enhanced Weathering (EW) techniques are a set of theoretical proposals to remove carbon dioxide by spreading large quantities of finely-ground rock minerals onto extensive land areas, beaches or the sea surface. This hypothetical Carbon Dioxide Removal (CDR)
technology aims to mimic and accelerate the natural weathering processes of silicate and carbonate rocks, a slow carbonation process that is estimated to absorb about one billion tonnes of carbon dioxide from the atmosphere every year.
The acceleration of weathering processes could theoretically be achieved by mining and crushing large amounts of suitable rocks to increase their reactive surface. [1] This process would be hugely expensive, and the environmental harm, impacts on communities and energy and water consumption rates would be comparable to global coal mining at present scale. Suitable rocks, particularly silicate and carbonate minerals rich in calcium and magnesium such as olivine-rich ultramafic and mafic rocks or basaltic rocks, would need to be mined, crushed, transported and dispersed.
Other proposals involve the use of waste materials, such as mine tailings or industrial by- products from iron and steel production, for example steel slag or cement kiln dust, which may release pollutants with harmful effects. [2]
EW schemes are proposed in terrestrial, coastal and marine environments. On land, EW usually involves spreading crushed rocks onto farm land, based on the argument that the addition of stone meals may also increase soil fertility and therefore crop yields. [3] Although stone meals are regularly used as fertilisers and soil conditioners to correct deficiencies in soil nutrient levels or soil structure, it is unlikely that the amount required for an optimum supply of nutrients would be able to remove substantial amounts of carbon dioxide from the atmosphere—on average two tonnes of finely ground rock are needed to absorb one ton of carbon dioxide. [4]
Enhanced Weathering in marine environments is also referred to as Ocean Alkalinity Enhancement (OAE) and involves adding ground minerals directly to the ocean or dumping them on beaches where wave action disperses them into seawater. This theoretically increases seawater alkalinity, allowing the oceans to absorb more carbon dioxide from the atmosphere. The effects of OAE on biochemical processes or the marine food chain are poorly understood. [5]
Actores involucrados
Although some companies are attempting to commercialise EW approaches, most schemes are taking place within the scope of research projects in universities in the UK, the Netherlands and North America. In the UK, the Oxford Geoengineering Programme, an initiative led by Tim Kruger at Oxford University, leads and conducts research activities on EW. The project Greenhouse Gas Removal by Enhanced Weathering (GGREW) aims to explore the feasibility of EW in oceans, assess different ways to accelerate the weathering process artificially and plans to conduct open-ocean trials in the Great Barrier Reef, Australia, and in the Gulf of Aqaba, off the coast of Israel. Since 2008, Tim Kruger has been trying to market an OAE approach based on lime. His company Cquestrate has received early-stage funding from Shell.
The Leverhulme Centre for Climate Change Mitigation (LC3M), based at and led by the University of Sheffield, UK, was founded in 2016 to conduct research on EW on croplands as a potential strategy for increasing field yields while removing carbon dioxide from the atmosphere. The research activities also include field trials at farming sites, where 50 tonnes of mined and crushed basalt have been applied per hectare per year, to test EW in different agricultural environments. The trials are conducted on farms in Australia, Malaysia and the USA with various crops, among them oil palm, sugar cane and soy. The LC3M also studied EW in coastal environments and carried out laboratory tests with seawater in cooperation with the University of Brussels, in Belgium.
In the Netherlands, Olaf Schuiling conducted lab-based research on EW with olivine-rich rocks at Utrecht University. He founded the Smart Stones Foundation (formerly The Olivine Foundation) in 2009 to promote and commercialize olivine applications for carbon dioxide removal and conducted small-scale trials. Larger outdoor trials were proposed but have so far not taken place. Schuiling’s research contributed to the founding of Dutch companies greenSand and Green Minerals, which are both trying to commercialise EW using olivine-rich rocks. Green Minerals is also participating in the German research project CO2MIN, which explores using olivine-rich and basalt rocks to absorb carbon dioxide flue gas.
In North America, researchers at the University of Guelph, Ontario, proposed and tested EW with the calcium silicate rock wollastonite, in trials with beans and corn grown in pots. The suitability of using mine tailings from nickel, diamond and platinum production for EW is being tested in a research project financed by Natural Resources Canada and conducted by the University of British Columbia. UBC partnered with the FPX Nickel Corporation, an owner of several nickel mines, to conduct field trials at a mine in the Decar Nickel District in British Columbia, Canada. Oceankind, a philanthropic funding organisation, plans to form a knowledge hub on OAE with stakeholders from science, policy and the private sector and organised a kick-off event in California, in September 2019. [6]
California-based Vesta (formerly Project Vesta), founded by “biohacker” and brain drug entrepreneur Eric Matzner, is testing EW with olivine-rich rocks on beaches. In 2022, Vesta spread 650 tonnes of olivine over a 400 meter stretch of beach north of Southampton on Long Island in eastern New York, and the open-air experiment is expected to last two years, during which the amount of carbon dioxide absorbed will be measured. Vesta says it has also received approval from the Dominican Ministry of the Environment for the first phase of outdoor tests in two bays in the Dominican Republic, which was expected to begin in 2022. Vesta has applied for permission to conduct outdoor experiments in North Carolina and is seeking partners for additional experiments, including in the Great Lakes region of North America. It is also participating in a research project on OAE in tidal wetlands in a salt marsh ecosystem in Massachusetts, USA. [7]
Impactos de la tecnología
If EW were to be deployed on a large enough scale to remove significant amounts of carbon dioxide from the atmosphere, there would need to be an exponential increase in the scale of global mining operations, which would have devastating effects on communities and ecosystems around the world, and cause large amounts of greenhouse gas emissions. [8]
Furthermore, EW requires these big quantities of rocks to be milled, transported and dispersed, which further increases its carbon dioxide and environmental footprint. [9] Although ground rocks may add nutrients to agricultural land, they may also change soil properties and release substances with harmful effects even in small doses, such as nickel, chromium or cadmium. EW may also provoke hydrological changes and pollution in water bodies through leaching or erosion. [10] EW is often recommended for tropical regions with soils that are poor in nutrients such as oxisols and ultisols, but studies suggest that weathering is highly sensitive to temperature, with optimum results at temperatures between 10°C and 15°C, and with both low and high temperatures limiting weathering. [11]
If milled rocks are applied directly to the ocean and on a large scale, harmful substances, changes in silicon concentration or unintended biogeochemical processes may affect marine biota. OAE could therefore lead to changes in the composition of marine species and changes in the marine food web, and its effects on deep-sea life are also poorly-understood. [12] If mining and other industrial waste products are considered for EW or OAE, they are likely to contain substances such as heavy metals, which would also affect marine life and the ocean’s biogeochemistry. [13]
EW and OAE are cost and energy-intensive proposals for terrestrial, coastal and marine environments. They are associated with unforeseeable risks for ecosystems, large social impacts for communities in mining areas and a very doubtful overall emission balance. In addition, EW and OAE are impracticable due to the massive amounts of rock required and their potential to actually remove carbon dioxide on a larger scale is not proven.
Visión realista
EW and OAE are mainly based on modelling exercises and theoretical models, but a few field-scale trials are being conducted and further trials are anticipated or in preparation, among them experiments in reef environments in Israel and Australia (GGREW), on beaches in the Caribbean (Vesta), and in nickel mines in Canada (FPX Nickel Corporation and research partners).
Lectura complementaria
ETC Group and Heinrich Böll Foundation, Geoengineering Map. https://map.geoengineeringmonitor.org/
Notas finales
[1] Strefler, et al. (2018) Potential and costs of carbon dioxide removal by enhanced weathering of rocks, in Environmental Research Letters, Vol. 13:3, https://iopscience.iop.org/article/10.1088/1748-9326/aaa9c4; Bach, et al.
(2019) CO2 Removal With Enhanced Weathering and Ocean Alkalinity Enhancement: Potential Risks and Co-benefits for Marine Pelagic Ecosystems, in Front. Clim., Vol. 1, https://doi.org/10.3389/fclim.2019.00007
[2] Kelmen, et al. (2019) An Overview of the Status and Challenges of CO2 Storage in Minerals and Geological Formations, in Front. Clim., Vol. 1, https://doi.org/10.3389/fclim.2019.00009; Renforth (2019) The negative emission potential of alkaline materials, in Nature Communications, Vol. 10, https://doi.org/10.1038/s41467-019-09475-5; Köhler, et al. (2010) The geoengineering potential of artificially enhanced silicate weathering of olivine, in: Proceedings of the National Academy of Sciences of the United States of America, Vol. 107:20228-20233
[3] Strefler, et al. (2018); Hepburn, et al. (2019) The technological and economic prospects for CO2 utilization and removal, in Nature, Vol. 575:87-97, https://www.nature.com/articles/s41586-019-1681-6
[4] GESAMP (2019) High level review of a wide range of proposed marine geoengineering techniques, (Boyd, P.W. and Vivian, C.M.G., eds.). (IMO/FAO/UNESCO-IOC/UNIDO/WMO/IAEA/UN/UN Environment/UNDP/ISA Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection). Rep. Stud. GESAMP No. 98, 144 p.
[5] GESAMP (2019)
[6] ETC Group and Heinrich Böll Foundation (2020) Geoengineering Map, https://map.geoengineeringmonitor.org/
[7] Ibid.
[8] Kramer (2020) Negative carbon dioxide emissions, in Physics Today, Vol. 73(1):44, https://physicstoday.scitation.org/doi/10.1063/PT.3.4389; GESAMP (2019); Köhler, et al. (2010)
[9] Lefebvre, et al. (2019) Assessing the potential of soil carbonation and enhanced weathering through Life Cycle Assessment: A case study for Sao Paulo State, Brazil, in Journal of Cleaner Production, Vol. 223:468 – 481, https://doi.org/10.1016/j.jclepro.2019.06.099
[10] Hartmann, et al. (2013) Enhanced chemical weathering as a geoengineering strategy to reduce atmospheric carbon dioxide, supply nutrients, and mitigate ocean acidification, in Reviews of Geophysics,Vol. 51(2):112 – 149,
https://doi.org/10.1002/rog.20004; Strefler, et al. (2018)
[11] Zeng, et al. (2019) Sensitivity of the global carbonate weathering carbon-sink flux to climate and land-use changes, in Nature Communications, Vol. 10:5749, https://doi.org/10.1038/s41467-019-13772-4; Fuss, et al. (2018) Negative emissions-Part 2. Costs, potentials and side effects, in Environmental Research Letters, Vol. 13(6): 063002, https://doi.org/10.1088/1748-9326/aabf9f
[12] Bach, et al. (2019); Hartmann, et al. (2013); GESAMP (2019); Chisholm and Cullen (2001) Dis-Crediting Ocean Fertilization, in Science, Vol. 294(5541): 309 – 310, https://doi.org/10.1126/science.1065349
[13] Renforth (2019); GESAMP (2019)
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