3. 221129 Amsterdam CDR Report EN (1)

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Potential by 2030/2050: relates to the potential of the source to emit biogenic CO₂ in Amsterdam and the NSCA by 2030/2050: not promising; less promising; promising; very promising

Name Advanced Methanol Amsterdam (Gidara Energy)

Description Production of renewable fuel (methanol) from nonrecyclable waste, to be fully operational in 2025. Biogenic CO₂ stream is expected to be transported to greenhouses, but open to geological storage, depending on availability and potential of accessing SDE++ subsidies.

(Expected) scale of biogenic CO₂ emissions 116,000 t CO₂/year at operation

Potential for capture for CDR purposes by 2030

Potential for capture for CDR purposes by 2050

Less promising

Very promising

Operation will start in 2025, with initial biogenic CO₂ streams going to greenhouses (driven by summer demand), rather than storage.

Volumes of biogenic CO₂ are expected to increase, with the possibility of geological storage as more CCS projects come online thus increasing storage options.

Potential future hydrogen production would create additional biogenic CO₂ streams. AEB Amsterdam – bioenergy

Biomass power plant in the Port of Amsterdam, providing heat capacity for the city's district heating network. Fully biogenic carbon emissions, with preliminary studies for carbon capture.

~120,000 t CO₂/year

Less promising

Very promising

Potential capture capacity at operation: ~100,000 t CO₂/year

Still very early stages of development, with a quickscan being conducted for post-combustion carbon capture by 2030.

By 2050, fully biogenic carbon streams will be low-hanging fruits to capture and store; also as more storage options become operational.

AEB Amsterdam – waste-to-energy

Waste-to-energy plan processing approximately 1.3 million t of waste per annum and producing steam and electricity to be used in both district heating and the surrounding process industries. There is a planned CO₂ capture unit for mixed fossil and biogenic flue gas streams. While ~60% of AEB’s carbon emissions are biogenic, it is the largest source of biogenic CO₂ identified in the region.

~660,000 t CO₂/year currently

Promising

Very promising

Existing plans for CCS through the Aramis project could become operational by 2028–2029.

Geological storage could account for a greater part of the captured biogenic CO₂ share, as the business model is proved to be viable.

Cargill

Sunflower and rapeseed crusher and refinery for food products, with plans to use cocoa husks (24–25 kt/year) from existing processes to replace natural gas. This will generate a stream of biogenic CO₂, with no plans for capture currently.

~40,000 t CO₂/year by 2025

Less promising

Promising

With the cocoa husk project coming online by 2025 only, and no currently foreseen plans for capture, it is unlikely that this stream can be captured and stored by 2030 unless strongly incentivised

It is likely that by 2050, CCS will be more established, in terms of technology and regulations, so that Cargill will explore capturing its biogenic CO₂ to store it permanently.

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

Name Future Biogas

Waternet

Bio Energy Netherlands

Description

(Expected) scale of biogenic CO₂ emissions

Largest biomethane producer in the UK, with a new business model centred on anaerobic digesters, which produce biogenic CO₂ for storage in geological reservoirs. While this is not in the project’s geographical zone, similar technologies around Amsterdam could be targeted.

~5,000–15,000 t CO₂/year/plant

Public waste water treatment plant (largest in the Amsterdam harbour area, operating under the regional water authority and the municipality. There are currently no plans to capture and store CO₂ before 2030, but they are piloting green gas installations.

~85,000 t CO₂/year currently

Bio Energy Netherlands is not currently a source of biogenic CO₂, but is expected to develop into hydrogen production in the NL, including in the Amsterdam region, which would generate streams of biogenic CO₂.

TBC

Potential for capture for CDR purposes by 2030

Potential for capture for CDR purposes by 2050

N/a

N/a

Not operating in the project area, but similar companies in the area would be promising leads, with biogenic CO₂ streams being directly produced.

Not operating in the project area, but similar companies in the area would be very promising leads.

Less promising

Less promising

There are currently no plans to capture CO₂ before 2030. Capturing biogenic CO₂ would require a change in process, as Waternet highlights streams are currently too small and too diluted to capture.

With the development of capture technology, it could be expected that Waternet would be able to capture its biogenic CO₂ by 2050.

Not promising

Promising

Not currently producing biogenic CO₂ for use or storage.

By 2030, up to 20 gasifiers will be installed in the Netherlands for hydrogen production, which will generate biogenic CO₂ streams. Permanent storage is currently being considered as an option for these CO₂ streams.

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

Biogenic CO₂ source: combustion of biogenic wastes Waste-to-energy plants combust residual and municipal waste to generate heat and electricity. The share of waste input into a waste-energy system that comes from biogenic origins will produce biogenic carbon emissions upon combustion. AEB’s waste-to-energy plan processes municipal waste and sewage sludge and incinerates the residual (nonrecyclable) fraction to produce heat and electricity, which is supplied to the surrounding areas. AEB currently generates ~1.1 Mt CO₂ per year, of which ~60% is of biogenic origin. As the largest emitter of biogenic carbon in the area, AEB is well-placed to take a central role in demonstrating the potential for CDR in the NSCA. A CO₂ capture unit is already planned, with expected operation in 2028–2029, with a capture capacity of ~450 kt CO₂ per year. This represents ~9% of the City of Amsterdam’s entire emissions and is equivalent to the natural gas consumption of two thirds of all Amsterdam households. The captured CO₂ is intended for use in greenhouses, which would not result in CDR. However, this CO₂, or CO₂ from an expansion of capture capacity, could be redirected to permanent storage in the future, leading to CDR. AEB is also evaluating plans to capture up to ~100,000 t CO₂/year of biogenic carbon emissions from its biomass power plant in the Port of Amsterdam.

Carbon from low-quality prunings and wastewood would be captured using a post-combustion low energy-intensive process. It is envisaged that the carbon would be liquefied and transported by trucks.

although it can be expected that geological storage will account for a greater part of captured biogenic CO₂ as the business model is proved to be viable. Key considerations •

Waste incinerators and bioenergy plants often represent the largest source of biogenic CO₂ emissions in an urban area.

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Any considerations of CO₂ capture are largely driven by cost, including the cost of the input biowaste, which must be low enough to uphold the business model. Similarly, the choice of offtaker/storage for captured carbon is also financially driven, e.g. based on the availability and amounts of subsidies.

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Emissions from waste-to-energy plants have a ‘block’ profile, by which volumes cannot be ramped up or down. This must be considered when evaluating potential offtakers.

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As the largest source of biogenic carbon in the area, permanently storing AEB’s carbon emissions is an apparent opportunity and should be encouraged, in particular as it is already connected to the OCAP pipeline.

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Storing biogenic emissions (from all types of sources) requires deployment of dedicated infrastructure for capture and transport. Depending on the volume of emissions, this may take different modes of transport, for which any associated emissions also need to be taken into account.

Cargill operates a seed crush process and sunflower refinery plants in Amsterdam and Zaandam, which produces oil for food manufacturers and bottlers. As part of its energy transition plans, Cargill has plans to use waste cocoa husks to replace natural gas for its heat generation. This process will not only displace emissions from natural gas, but actually generate more biogenic CO₂ emissions – which could be captured – because of the lower energy density of cocoa husks. There are currently no plans to capture the carbon emissions from the biomass combustion process, with the lack of infrastructure and insufficient subsidies cited as a key factor. The expected scale of captured biogenic CO₂ is currently limited by the capture capacity of AEB’s CO₂ capture facility (~450 kt CO₂). It is still unclear how much will be dedicated to use rather than storage,

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

Biogenic CO₂ source: biofuel production plants Biogas is produced from the anaerobic digestion, or fermentation, of biomass and organic materials. The biogas can be upgraded to biomethane ('green gas') by separating CO₂ and removing other trace gases, typically resulting in a high-purity stream of CO₂. Biogas can be made from a variety of biogenic feedstocks, including waste wood and forest biomass, agricultural waste, or energy crops, such as cereals, maize and grass. Biomethane production plants are an example of obvious candidates for CDR, as CO₂ separation is a necessary part of the biogas upgrading process. For biomethane production, CO₂ emissions can be captured at much cheaper costs as they do not require separation from a flue gas stream (Future Biogas generates a stream of 98% ‘green’ CO₂ in its UK operations). Biogas plants can also emit fossil CO₂, e.g. from the use of natural gas or other fossil fuels for energy purposes. Approximately 200 million cubic metres of biogas were fed into the Dutch gas network in 2020.

Key considerations

Advanced Methanol Amsterdam, a project operated by Gidara Energy converts non-recyclable waste, such as certain types of wastewood and municipal waste, into renewable fuels, notably methanol. Due to be operational in early 2025, its 116,000 t CO₂ per year emissions (90% biogenic) will be captured and delivered to greenhouses using the OCAP pipeline, which will result in emission reductions rather than emission removals. The use of CO₂ by greenhouses is driven by summer demand and accessibility of SDE++ subsidies. Storing these emissions instead of using them in greenhouses could be an option, depending on how fast geological storage projects come online, the fossil/biogenic fraction of the waste input as well as commercial drivers. This is being actively considered by Advanced Methanol Amsterdam. However, carbon offtakers and transport providers can place restrictions on the fate of the CO₂.

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Biogas production plants are ‘low-hanging fruits’ for sourcing biogenic CO₂, as biogenic CO₂ is generated and purified as part of the production process; this means carbon capture technology does not have to be applied.

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The sustainability credentials of the biomass sources are critical for the assessment of removed carbon (when the biomass is not a waste), with any emissions related to biomass sourcing to be taken into account in full. The use of energy crops may entail additional sustainable development consideration, in case of competition with food crops or indirect land-use change effects.

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The fate of CO₂ between usage and storage is partly determined by demand from greenhouses, the origin (i.e. biogenic or fossil) of CO₂ as well as commercial factors (such as access to SDE++ subsidies).

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With likely greater demand for hydrogen in the future, further streams of biogenic CO₂ from hydrogen production will be generated.

Bio Energy Netherlands is expecting to construct 20 gasifiers in the country by 2030 including in Amsterdam, with the aim of producing hydrogen, which will also produce green CO₂ streams. The scale of these potential biogenic emissions is currently still unclear. It is also unclear how much of captured biogenic CO₂ from biofuel production will be earmarked for CCU rather than CDR.

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

Biogenic CO₂ source: wastewater treatment plants Wastewater treatment plants (WWTP) remove contaminants from sewage waters through physical, chemical and biological processes, so that cleaned water can be released into the environment. Biogenic carbon emissions are generated at various stages of this process, particularly in the water and sludge treatment processes, during which bacteria are fed oxygen in aeration tanks and emit CO₂.

Key considerations

Waternet is a public WWTP, operating under the regional authority and the municipality. Its Amsterdam plant is the largest wastewater treatment plant in the Amsterdam harbour area, serving approximately one million people. Biogenic carbon emissions are generated particularly during: i) the treatment process in which bacteria produce CO₂; ii) incineration of the sewage sludge at the AEB plant; and iii) biogas production. Insights into biogenic carbon emissions are a new topic within the water authority, with methane and nitrous oxide being priorities in the past. There are currently no plans to capture and store CO₂, in particular because the CO₂ streams are considered to be too small and diluted in the current process. It is likely that plans to capture and store CO₂ at Waternet will not occur before 2030. While the financial business case exists for capturing methane from WWTP processes, it does not for CO₂ under the national and EU incentives context.

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The potential scale of captured biogenic CO₂ for CDR purposes is still unclear.

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While there are a number of biogenic CO₂ streams in the wastewater treatment process, these are too small and diluted to consider carbon capture, which would be too costly for this process.

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More research is needed to fill the gaps in knowledge that remain, notably in terms of the technical and financial viability of fitting CCS infrastructure to existing WWTPs.

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Any potential sourcing or capture of biogenic CO₂ from WWTPs is likely to occur after 2030.

Rather than capturing carbon, it has been suggested that changes could be made to the water treatment processes to reduce emissions. In general, there remains knowledge and data gaps that need to be addressed for water treatment plants to consider CCS more comprehensively.

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

4.2 Overview of sinks Table 3 below provides an overview of identified sinks (off-takers for transport and storage) of biogenic CO₂, based on the interviews conducted in the scope of this project. More detailed information on each source is presented in Annex 7.3. Table 3: Overview of interviewed sinks (including transport) of biogenic CO₂ Note on headers: •

Scale of storage: volume of biogenic CO₂ which can potentially be stored, under specified time indication

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Potential by 2030/2050: relates to the potential of the sink to store biogenic CO₂ from Amsterdam and the NSCA by 2030/2050, if implementation and scaling begins in the near-term: not promising; less promising; promising; very promising Name Air Liquide

Mitsubishi Corporation

OCAP

Description

(Expected) scale of CO₂ storage

Air Liquide processes CO₂ from emitters. It is only currently connected to large industrial plants, which generate fossil fuel-based emissions. In the future, Air Liquid will to some extent shift to biogenic carbon.

n/a – unclear

Mitsubishi Corporation is involved in multiple carbon mineralisation technologies, including: carbonates and aggregates from waste; readymix concrete from CO₂; and pre-cast concrete from CO₂. Although not currently operating in the NL, this technology is proven and can be rapidly deployed.

n/a – unclear

OCAP is a transporter and supplier of CO₂, especially to greenhouses in the south of the NL, via its own pipeline. Delivery for other applications often proves to be difficult, given the small purchase volumes and the high quality CO₂ that is required.

n/a – transport only (transports 600,000 t CO₂/year)

Potential to store biogenic CO₂ for CDR purposes by 2030

Potential to store biogenic CO₂ for CDR purposes by 2050

Not promising at present

Promising

Air Liquide is not currently focused on biogenic CO₂. While they have the technical expertise and network, it is unlikely that the shift to biogenic CO₂ will occur before 2030.

By 2050, it is expected that there will be stronger environmental and regulatory drivers, along with a better-established business case to focus operations on biogenic CO₂.

Less promising

Promising

Carbon mineralisation in building products can be implemented relatively quickly, if the biogenic CO₂ inputs can be sourced. In some cases, atmospheric CO₂ can also be used as inputs. However, the scale of CDR achieved is likely to be relatively small.

It is expected there will be more readily available sources of biogenic CO₂, though likely that only limited volumes would be used for mineralisation in building products in the project area.

Promising

Very promising

OCAP is the only existing pipeline network connecting Amsterdam to the CO₂ storage infrastructure in the Port of Rotterdam. As such, it is a central element of the CDR supply chain in the short-term. It is already connected to sources of biogenic CO₂, but currently for use rather than storage. Smaller volumes of biogenic carbon could be rerouted to permanent storage.

With developing and expanding legislation and regulation on CDR, it can be expected that OCAP will expand its capacity to accommodate a larger share of its CO₂ to geological storage projects in the Port of Rotterdam.

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

Name Porthos

Aramis

Sika

Description

(Expected) scale of CO₂ storage

Potential to store biogenic CO₂ for CDR purposes by 2030

Potential to store biogenic CO₂ for CDR purposes by 2050

CO₂ from industry is transported by onshore pipeline through the Port of Rotterdam, via a compressor station, and by an offshore pipeline to a platform in the North Sea, approximately 20 km off the coast. From this platform, the CO₂ will be pumped into empty gas fields, in a sealed reservoir of porous sandstone more than 3 km beneath the North Sea.

2,500,000 t CO₂/year for 15 years (exp. start in 2025)

Not promising (sold out)

Less promising

Porthos will be operational from 2025 and permanently store vast quantities of CO₂. However its current capacity is already fully sold out for storage of fossil emissions – additional storage options need to be developed.

Porthos is expected to be decommissioned by 2050, and the currently foreseen storage capacity is already sold out.

Similarly to Porthos, CO₂ from the Port of Rotterdam will be transported by pipeline to an offshore platform ~200 km off the coast. The CO₂ will then be injected into the gas field 3–4 km below the seabed.

5,000,000 t CO₂/year initially (exp. start in 2027–2028) Full capacity: 22,000,000 t CO₂/year

Very promising

Very promising – TBC

Aramis should be operational by 2030 and may include biogenic carbon.

Aramis will store millions of tonnes of CO₂ per year. It is likely that clients will include providers of biogenic CO₂, leading to carbon removals.

Technology to convert concrete demolition waste (CDW) into carbonated cement stone and aggregates for further construction. Pilot plant to prove concept; technology can then rapidly be deployed.

20–60 kg CO₂/ t CDW; 100–200 t CDW/hour

Less promising

Promising

Although not implemented in the project area at the moment, this type of technology can be deployed relatively quickly, depending on availability of inputs (CDW).

If located near an input source (concrete/ demolition waste), there is high potential for this type of technology.

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

Biogenic CO₂ sink: geological storage Geological CO₂ storage – such as in depleted oil and gas fields – is one of the most durable forms of carbon storage, with limited risk of reversal. This process involves injecting captured and compressed CO₂ into existing geological reservoirs. It is particularly relevant for the Netherlands and for Amsterdam, which are in relatively close proximity to a number of such depleted reservoirs under the North Sea. The offshore storage capacity is expected to be in the range of 100s Mt CO₂ (conservatively), up to 1 Gt CO₂. This storage capacity has great potential to be used, considering existing oil and gas infrastructure and the location of industrial clusters along the coast. In fact, multiple initiatives are already underway to exploit this potential.

Porthos, which has been interviewed in the scope of this project, is one such example. Currently nearing final investment decision, Porthos is expected to become operational in 2025, and will inject 2.5 Mt CO₂ into permanent geologic storage every year for 15 years, in gas fields only 20 km from the coast of Rotterdam (Figure 12). However, this storage capacity is already sold out and committed to four large industrial clients. While the pipelines from the Port of Rotterdam have higher capacity, more storage sites need to be developed to store larger volumes of CO₂. The capital expenditure for Porthos was covered by state-owned entities, namely the Port of Rotterdam, Gasunie and EBN. The cost for transportation and storage, however, although dependent on the volumes of CO₂, is EUR ~50/tCO₂, not accounting for the cost of capture, which can reach upwards of EUR 100/tCO₂.

Figure 12: Map of CCS infrastructure in the Netherlands and beyond, including Porthos, Aramis and OCAP

Source: EBN whitepaper, 2022

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

A second geological storage initiative, Aramis, aims to increase the scale of CO₂ storage by 5 Mt CO₂/year initially – 22 Mt CO₂/year at full capacity – by accessing another depleted gas field approximately 200 km from the coast. It is currently still in a design and permit process phase, and not expected to become operational before 2027. Porthos and Aramis are essential to demonstrate the feasibility and viability of geological storage under the North Sea (Figure 13). Additional demand for geological CO₂ storage will undoubtedly lead to the preparation of additional

storage fields. Both Porthos and Aramis make use of CO₂ transport and storage infrastructure located in the Port of Rotterdam. This should still be of great interest to the City of Amsterdam, as the existing OCAP pipeline links the two areas, giving access to the Porthos and Aramis facilities. A third project – Athos – was planned to be implemented in Amsterdam, but was cancelled; however the development of CO₂ infrastructure in the North Sea Canal area remains an interesting opportunity for the future.

Figure 13: Illustration and description of Porthos and Aramis projects

Source: EBN, 2022

Key considerations •

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There is huge carbon storage potential under the North Sea, presenting the opportunity for CDR at scale for the Netherlands. Offshore storage capacity near Eindhoven is at least in the range of 100s Mt CO₂, but could be as large as 1 Gt CO₂ – this is as much as over 50 years of storage of the NSCA’s current annual emissions. Accessing these storage sites will require the development and extension of infrastructure (particularly pipeline) networks; currently, only the OCAP pipeline links the NSCA to the Port of Rotterdam.

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The first geological storage projects are due to come online in the next few years, offering proofof-concept and viability for development of additional decommissioned gas fields.

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Other storage sites, located beyond the Extended Economic Zone of the Netherlands such as in the UK or Norway, would likely have available storage capacity before 2030.

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

Biogenic CO₂ sink: carbon mineralisation in durable products Carbon mineralisation in durable products, such as construction materials, is another option for durably storing carbon. For example, Sika’s reCO₂ver technology, which uses concrete demolition waste (CDW) as an input, produces cleaned aggregates and carbonated cement stone, which can then be used in new constructions. CO₂ is sequestered in CDW in an accelerated chemo-mechanical process, producing carbonated limestone powder. Furthermore, the use of this output to replace conventionally-produced materials reduces the amount of cement or clinker required in concrete production. It should be noted that the CO₂ stored in aggregates is replacing the CO₂ emitted from the production of cement, which is made by removing CO₂ from limestone. Therefore, the origin and emission profile of the storage material must be carefully considered. Concrete and CDW will also naturally mineralize some atmospheric CO₂, without the need for additional energy input. However, this process is very slow for fresh concrete, as it is dependent on exposed surface area; over the lifetime of a building, no more than 10–20% of CO₂ emitted by limestone during cement production will be absorbed.

While neither of the two carbon mineralisation companies interviewed in the scope of this project currently operate in the NL, their solutions are technologically-ready and are able to be implemented relatively quickly, with new plants taking approximately one year to construct. The scale of removals that these opportunities could generate is, however, unclear, and very much dependent on the size and number of plants constructed. Sika’s pilot plant removes between 20–60 kg CO₂/t CDW (or 2–12 t CO₂ per hour) when in operation, depending on the input flow and age of the CDW; similar ranges could be expected if applied in the NL. Costs are similarly unclear; Sika’s pilot plant is complicated as it performs the whole process in one step, but could be operated with design changes for ease (and associated cost reduction) and scalability. While not interviewed for the purpose of this project, ENCI IJmuiden is one of the only two remaining

cement production sites in the Netherlands, and so a promising site to apply carbon mineralisation technologies. Depending on the specific technology, carbon mineralisation can make use of atmospheric CO₂, biogenic CO₂, or flue gas directly. The process would not be considered to be removing carbon if using flue gas, but interviewees have noted that it is difficult to secure biogenic CO₂. Transport of the captured carbon by truck, barge and rail are likely to be the dominant mode of transport. Pipelines could also be appropriate in industrial areas, although concrete production is often decentralised, making pipeline connections less likely. The potential for CO₂ storage through carbon mineralisation is still unclear, but is expected to be in the 10s kt CO₂ per year. Key considerations •

Carbon mineralisation technologies can easily be deployed, though location (e.g. nearby cement or concrete demolition plants) is key for access to inputs – available space to transport and store materials also needs to be considered.

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Regulations and standards for construction materials, which can be very conservative, may hinder the deployment of recycled concrete, even though it is a relatively low-cost solution, which could already generate CDR.

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The scale of removals achieved is directly related to: i) the number of plants made operational; ii) the amount of available materials, limited by the amount of local demolition wastes; and iii) the demand for materials such as recycled concrete.

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The increase in sales price of these products, compared to conventional concrete products can be up to two- or three-fold.

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Municipalities can play an important role in encouraging carbon mineralisation in construction products through public procurement, and e.g. mandating minimum thresholds for the use of recycled concrete in new constructions.

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

4.3 Overview of transport options Transport from biogenic CO₂ sources to permanent storage is an essential part of bioCCS. CO₂ transport options include trucks, rail and ships for liquified CO₂ and pipelines for gaseous CO₂. Pipelines are an efficient modality to transport CO₂ from its source to storage locations, particularly for larger sources of CO₂. Pipelines also offer the possibility of different sources to connect to the same CO₂ transport network, as long as certain quality requirements are met. However, their construction is expensive and the network is currently limited. OCAP is the most important CO₂ transport player in Amsterdam. OCAP makes use of the pipeline connecting Amsterdam to Rotterdam to provide ~600,000 t CO₂ per year to greenhouses. As such, it is currently the only connection between the Amsterdam area and the underground storage opportunities in the North Sea. The sales price to customers operating greenhouses is ~EUR 60/t CO₂ – this represents the cost per tonne for transport only, not accounting for capture or storage. OCAP’s supply capacity to greenhouses is expected to reach 2,000,000 t CO₂/year by 2030, but demand is highly seasonal. In situations where CO₂ sources are highly decentralised or smaller, pipelines will not be appropriate or economically-feasible.

The captured carbon therefore has to be processed and liquefied for transport by truck or ships or train. The CO₂ liquefaction process has high energy requirements and more expensive processing costs than that of gaseous CO₂. However, it offers the possibility of more distributed, higherquality and more efficient offtakes. These options were not explored in the scope of this project.

Key considerations •

An extensive CO₂ transport network is essential to unlocking decentralised carbon removals, but plant operators may not have the finances to invest in such a network.

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There is a public role in facilitating the construction of such a CO₂ collection infrastructure in the same way as other public infrastructures such as water and electricity are financed or deployed through regulated assets.

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OCAP remains the only available pipeline to access the CO₂ hub in the Port of Rotterdam and geological storage in the North Sea.

•

It is unclear how much of OCAP’s transport capacity will be dedicated to carbon storage rather than use.

•

Each transport modality is associated with its own emissions, which must be taken into account when measuring net removals.

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CO₂ transport as a service is being deployed on inland waterways and the seas, offering potential opportunities for biogenic point source emissions at facilities along the NSCA.

•

Additional research must be undertaken to evaluate the potential of transport of liquefied CO₂ by truck, rail and ship.

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Transport by e.g. truck may lead to increased congestion.

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

4.4 Summary of bioCCS pathways The bioCCS pathway to achieve CDR is unachievable without three essential components: i) a source of biogenic CO₂; ii) a mode of transport for the CO₂ to go from source to sink; and iii) a storage solution to durably store the CO₂. Figure 14 provides a summary of the main options identified at this stage for each of these components.

Figure 14: BioCCS requires a chain of technologies that capture, transport, and permanently store biogenic CO₂.

Step 1: Biogenic CO2 source Waste-to-energy Biogas production Wastewater treatment

Step 2: CO2 transport Pipeline Trucks Ships Rail

+

+

Step 3: Permanent CO2 storage Geological reservoirs Mineralisation

Waste-to-energy plants, notably AEB, provide the most appropriate source of biogenic CO₂ to date: large streams of CO₂ are produced, a high proportion of which are biogenic, at a predictable and consistent rate. The scale of AEB’s emissions – the largest in the area – make its capture, transport and offtake cheaper and easier to implement. Biomethane production is also an appropriate source of carbon for bioCCS pathways, as it involves the generation of a high-purity CO₂ as a by-product. While these are much more distributed, and their scale much smaller, biogas producers could provide CDR ‘quick

wins’. Green hydrogen production is expected to be a significant source of biogenic CO₂ in the future, whereas WWTPs are unlikely to provide a usable source of biogenic carbon before 2030. Carbon mineralisation in building products is limited by the scale of concrete production and demolition in the NSCA, as well as the type of concrete used. Regional data were unavailable, but the remineralisation potential for concrete wastes in the Netherlands as a whole, is unlikely to exceed 1 MtCO₂/ year. Given the relative ease with which this technology can be deployed and the co-benefits of reducing demand for CO₂-intensive fresh concrete production, remineralisation is still an important technology of interest to both accelerate the deployment of CDR and reduce construction-sector emissions. Additional data are needed to more comprehensively assess the potential of mineralisation in products. Geological storage remains the most appropriate storage option for bioCCS, providing largescale permanent storage, just off the coast of the Netherlands. The Netherlands is indeed well placed to access empty gas fields, with a storage capacity which can increase with demand for the foreseeable future, and existing oil and gas infrastructure which can be repurposed.

The infrastructure for geological storage is still limited, but the success of projects such as Porthos and Aramis will be a considerable signal for industrial actors to move in the same direction – both in terms of better valuing the capture of (biogenic) CO₂, and in exploring and commissioning additional storage sites. Linking these biogenic CO₂ sources and sinks will require the development of an extensive infrastructure network, both for processing and transporting CO₂. Pipelines have been identified as the most appropriate mode of transport for large scale bioCCS, particularly because this is the main modality linking Amsterdam to the CCS infrastructure and geological storage opportunities in the Port of Rotterdam. While it is very expensive to extend the existing network, the system is in principle scalable as demand increases. As decentralised bioCCS requires additional widespread pipeline connections, it is likely that – to a lesser extent – transport of liquefied CO₂ by truck or ship will also increase.

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

4.4.1 Barrier analysis Based on the interviews conducted with biogenic CO₂ emitters and offtakers, a range of barriers were highlighted that hinder the development and deployment of bioCCS, in the region and beyond. The below subsections contain details on each barrier, directly informed by the responses provided by interviewees. •

Regulatory barriers: lengthy processes permitting and end-of-waste status

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Policy barriers: absence of CDR-specific targets and legislation

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Financial barriers: insufficient incentives to deploy bioCCS at scale

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Infrastructure barriers: lack of accessible transport networks and long lead time

•

Public perception barriers: public awareness and acceptance, e.g. on mitigation deterrence and sustainability credentials of non-waste biomass

Regulatory: lengthy processes for permitting and end-of waste status A key barrier to capturing biogenic CO₂ in the Netherlands concerns the attainment of necessary permitting and the so-called end-of-waste status. When a waste stream receives the end-of-waste status, it is no longer considered waste and no longer has to comply with waste regulations. In order to capture biogenic CO₂ from an industrial process for CDR purposes, the emission must be given the end-of-waste status. This barrier was identified by a number of emitters, including Air Liquide, Advanced Methanol Amsterdam, AEB, Waternet and Bio Energy Netherlands – the latter even highlighted this as the most important barrier to bioCCS development. Companies are issued permits based on their specific activities; to expand activities to CO₂ capture, additional permits are required, the process for which can take up to a year. Furthermore, these permits may have associated caps or maximum ceilings on CO₂ volumes. Regional authorities (e.g. NSCA Environmental Service) have the right to make rulings on decisions to provide permits, e.g. for endof-waste status or CCS activities. However, with no comprehensive CCS national legislation, these entities do not have a clear indication of what position to take on the subject. Specific licences are provided based on intended use, which may vary widely. The recognition

of collected CO₂ as a waste stream is a particular issue, as it entails additional permitting requirements. Policy: absence of CDR-specific targets and legislation n the Netherlands climate agreement, there are no regulatory targets for CDR. Moreover, there is no differentiation between CCS and CDR. Both are considered under regional and national industrial decarbonisation strategies and are described as a potential solution, though a maximum cap of 8.7 Mt CO₂ has been placed on CCS – the full capacity of the Aramis project already exceeds this cap. Geological storage options, such as the Porthos and Aramis projects, are also hindered by issues relating to permitting procedure, for example on the nitrogen deposition issue in Natura 2000 areas. A supreme court ruling is expected on whether government exceptions are in line with the European Habitats Directive. An unfavourable ruling would translate into additional permitting requirements and time before commissioning. The Netherlands would benefit from establishing an additional and separate target to remove carbon from the atmosphere with bioCCS and DAC and storage both in the short- to medium-term and as a clear component of net-zero targets. This would send a clear signal to the market as well as assuage potential concerns of mitigation deterrence expressed by civil society regarding BioCCS and DACCS.

Furthermore, emissions of biogenic CO₂ are currently not accounted for and are not subject to emission caps or taxes. The absence of valuation of biogenic CO₂ (both in liability for emission or compensation for storage) is a barrier to bioCCS. Financial and market: insufficient incentives and limited demand Financial and market barriers also hinder the deployment of CDR in the region and in the Netherlands more generally. Particularly, emitters of biogenic CO₂ are discouraged to capture their emissions for CCS and CDR because of insufficient incentives for such activities, leading to poor business cases and projects not being initiated. This was notably highlighted by AEB. Although the SDE++ subsidy is in place, it is

37

Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

not attractive for many players whose activities fall within gaps in the subsidy. SDE++ targets existing infrastructure rather than new infrastructure, and for specific uses. For example, waste-to-energy processes are not eligible under the subsidy, although SDE++ now covers certain low-carbon processes with CCUS. In the case of CCS, the production limit for 2022 is 5.3 Mt CO₂ per year over 15 years. This adjustment was made as CCS is described as ‘sufficiently stimulated’. Regarding EU incentives, the historically low carbon price of the EU ETS has been a major barrier for fossilbased CCS; biogenic CO₂ is not covered by the EU ETS at all. As well as subsidies, the market for CO₂ is, to date, relatively small. In the NL, it is dominated by demand from greenhouses. Without credible incentives, the case for storing biogenic emissions rather than using them may not be strong enough. Infrastructure: lack of accessible networks and long lead time Limited infrastructure – particularly transport infrastructure – impedes faster deployment of capture and storage of (biogenic and other) CO₂. Large-scale sources of biogenic carbon are most appropriately transported by pipeline and stored in geological storage, which is dependent on a very small number of stakeholders, namely OCAP, Porthos and Aramis.

OCAP is currently the only pipeline linking Amsterdam to the larger CO₂ infrastructure hub in Rotterdam, and is majoritarily focused on CO₂ usage in greenhouses rather than storage. Individual projects are generally unable to finance the required CO₂ collection and disposal infrastructure. Additional connections would be needed to connect further CO₂ sources to existing pipelines for more decentralised removals. Expanding the pipeline network requires huge investments, which may only be feasible if sourcing carbon streams in large quantities.

be clearer and more attractive for emitters. Conversely, the availability of CO₂ is needed to signal the need for investments in transport and storage infrastructure. Public perception: NGOs and social acceptance BioCCS and CDR may be perceived as mitigation deterrence, distracting from essential emission reductions. Other concerns include the relative novelty of the technologies, the perceived competition of CCS biomass inputs with food production and other land uses, or the prioritisation of nature-based solutions over ‘engineered’ solutions. Issues of social acceptance have led CCS projects in the past to be cancelled. However it has been noted that a lot of research on CCS has since been done in the Netherlands (e.g. this recent study), and it is generally well-received by the general public. As a nascent sector, bioCCS and CDR are complex subjects, on which politicians are not well-versed and the general public lacks awareness. Concerns are still being strongly raised about possible mitigation deterrence and other environmental impacts of CCS by some CSOs and NGOs, such as Greenpeace. While there is motivation from the public sector on bioCCS projects, interviewees have noted that this is not translated into actual concrete support, with no formal positions taken on CCS or CDR.

Porthos and Aramis will be the first two large-scale carbon storage initiatives in the NL, the former taking five years to plan and two years to build. Since the SDE++ started to include CCS, there has not yet been enough time for the development, construction and commissioning of new projects. Similarly, while many offshore gas field operators are working towards permit applications for storage, this is also likely to take significant amounts of time. Once the infrastructure to transport and store large volumes of CO₂ is in place, the bioCCS pathways – logistically and financially – will

38

Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

4.4.2 Potential enablers for bioCCS development Legislative and regulatory drivers:

Other drivers:

•

Streamlined permitting process: National legislation is needed on the end-of-waste status to enable regional authorities to take a clear position on the issue.

•

•

CDR-specific policy and targets: CCS- and CDRspecific policy targets (at municipal, regional and national levels), to encourage development and send clear signals to industrial players operating along the supply chain (biogenic CO₂ supply, demand and transport), both in the medium and long term.

Transparency: Transparency in communicating the envisaged role of bioCCS in the municipal and regional strategies, to industrial players, civil society and the general public, to raise awareness, improve social perception, and ensure inclusivity.

•

Stronger political support: At the municipal, regional and national levels. Municipal support for CDR-related solutions, including through e.g. investment, public procurement policy and support for pilots. Stronger support should be provided, with formal positions taken on CCS or CDR.

•

Pilot projects: Pilot projects to test/ demonstrate the technical and financial viability of bioCCS activities could serve to fill existing knowledge gaps.

•

Research and data: Filling the data knowledge gaps – e.g. conducting full LCAs for processes – would help emitters understand the full picture of the net reduction or removal potential for CCS and CDR and assess their options accordingly.

•

Clarified role and use of CDR: A clear CCS and CDR roadmap, detailing the sequencing for their development, including target industries, use case and geographic scope would provide industry with the foresight required for long-term planning.

Financial drivers: •

Infrastructure development: Public intervention may be needed to finance – and/or invest in – infrastructure as a public good (akin to waste collection or sewage processing) to unlock decentralised biogenic emission sources for CDR. Infrastructure development may well be led by emitters of fossil CO₂ for CCS purposes; once existing, the infrastructure could similarly be used by emitters of biogenic CO₂ for CDR purposes.

•

Increased demand: The fate of the carbon produced (i.e. emission vs storage vs use) is largely determined by the demand for biogenic CO₂, the valuation of carbon and the ease of access to use or storage sites.

•

Higher subsidies: Financial support through higher, and more comprehensive, subsidies committed to for the longer-term, particularly as relating to the storage element, for a stronger business case.

•

Valuation of CO₂: Valuation of CO₂ can be a sustainable driver for investment, as CDR project operators can monetise removals on international carbon markets to enable buyers to meet obligations.

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

4.5 BioCCS options summary Several bioCCS pathways exist, comprising a capture stage, transport stage and storage stage. Identified opportunities are summarised below.

CO₂ transport: Pipeline (OCAP): Transport of gaseous CO₂ via pipeline infrastructure.

Biogenic CO₂ capture: Combustion of biogenic waste (AEB; Cargill): Wasteto-energy plants which combust municipal waste for heat and electricity.

•

Connection to CO₂ hub in Rotterdam

•

Costs of expanding network

•

Ease of transport for large volumes

•

Trade-offs with CO₂ for CCU

•

Large biogenic emissions

•

Sustainability of biomass

•

Existing infrastructure network

•

Trade-offs with CO₂ for CCU

Key challenge: Financing infrastructure for CCS → Large investments for carbon capture and expansion of carbon transport network Biofuel production plants (Advanced Methanol Amsterdam; Future Biogas; Bio Energy Netherlands): Biogas produced from fermentation of biomass; biomethane production already involves separating CO₂ . •

Low-hanging fruit

•

•

Increased supply expected with H₂ production

Depending on input, competition for land-use

•

Trade-offs with CO₂ for CCU

Key challenge: Sustainability credentials of non-waste biomass sources → Full LCAs required Wastewater treatment plants (Waternet): Treating wastewater and sewage sludge, with multiple streams of biogenic CO₂ generated. •

Steady supply of CO₂

•

Pilots planned for green gas

• •

Relatively small CO₂ streams Knowledge and data gaps

Key challenge: Capture not financially viable → Knowledge building to fill gaps

Key challenge: Limited and expensive infrastructure network → Financial incentives to increase demand for CO₂ transport Rail, trucks and ships: Transport of liquefied CO₂ via trains, trucks and ships. •

Possibility of decentralising bioCCS

•

Expensive liquefaction process

Key challenge: Cost of liquefying CO₂ → Process learning and innovation Permanent CO₂ storage: Geological storage: Storing CO₂ underground in e.g. offshore depleted oil and gas fields. •

Very limited risk of reversal

•

Massive storage opportunities in North Sea

•

Currently limited number of projects

•

Costly expansion of pipeline infrastructure

Key challenge: First project only coming online in 2025 (and sold out) → Proof-of-concept leading to development of additional storage sites Carbon mineralisation in durable products: Storing CO₂ in long-lived products e.g. construction materials. •

Easily deployed

•

Contributes the decarbonisation of a hard-to-abate sector

•

Increase in sales price of mineralised products vs conventional

•

Availability of biogenic CO₂

Key challenge: Unclear scale of removals possible in the region → Knowledge building to fill data gaps 40

Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

5. Quick scan: Standalone CDR This section presents the main results of the data collection process, and assessment of the CDR potential in the wider Amsterdam Metropolitan Area and NSCA, applied to standalone CDR options (Table 4). Annex 7.1 describes the methodology under which the data was collected and assessed for the purpose of this report. More comprehensive data collected during interviews with players along the CDR chain are presented in Annex 7.3. The companies interviewed are an indicative representation of the types of players present in the area, but are not exhaustive. BioCCS is one of several CDR technologies. The advantage of bioCCS is that it is particularly suited for dealing with industrial CO₂ emissions that are already biogenic or cannot currently be abated by other means, such as electrification using renewable energy, or switching to carbon-free processes and feedstocks. However, there are other CDR activities that could be used to supplement bioCCS. These include: direct air capture with storage; enhanced weathering of minerals; accelerated carbonation of mineral wastes; soil carbon

storage; biochar; and afforestation. Each of these is presented briefly below, including their mechanism of action, primary considerations for implementation, and the available data for the Amsterdam context. Five interviews were conducted with stakeholders involved in non-bioCCS CDR, including one each with stakeholders involved with biochar, enhanced weathering, direct air capture, soil carbon storage, and mineralization of demolition wastes. The early state of development of these CDR technologies make it difficult to quantify or assess their realistic regional removal potential. In particular, for all of the standalone CDR options, long-term real-world studies on removal rates, storage permanence, and co-effects are lacking. While geologic or mineral storage of gaseous CO₂ is likely to be effectively permanent, some CDR options have higher (afforestation, soil carbon storage) or uncertain (biochar, enhanced weathering) risks of reversal that must be considered, as re-emission of stored CO₂ must be accounted for.

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

Table 3: Overview of interviewed standalone CDR options Note on headers: •

Scale of removals: volume of atmospheric CO₂ which can potentially be removed, under specified time indication

•

Potential by 2030/2050: relates to the potential of the CDR option to remove CO₂ from the atmosphere – in Amsterdam and the NSCA, specifically – by 2030/2050, if implementation and scaling begins in the near-term: not promising; less promising; promising; very promising

Name

Description

Potential scale of removals

Potential for large-scale implementation by 2030

Potential for large-scale implementation by 2050

Biochar (Bio Energy Netherlands)

Pyrolysed biomass, which is then buried or used as a soil amendment.

Bio Energy Netherlands currently produces 1 kt per year biochar from 2 gasifiers, currently sent to landfill, roughly translating to 3,000 t CO₂e removed.

Less promising

Less promising

Biochar’s legal status is currently unclear and substantial uncertainties remain on its impact on soil, as well as risk of reversal (e.g. from fires).

If biochar does not prove to have any unanticipated negative impacts and sustainable biomass stocks are available, quality-regulated biochar has the potential to be a flexible carbon storage option if it is stored in bulk (e.g. buried), and is a co-product of biosyngas, which can be used both as an energy source and feedstock for platform chemicals. However, if biochar is used only as a soil amendment, then total potential is limited, with an application rate of 20 tonnes per hectare, resulting in total storage potential of 2 Mt)

Enhanced Weathering (CNI)

Ground silicate minerals spread on large surfaces to increase their rate of CO₂ dissolution to a period of years or decades.

Currently zero. CNI estimates a cumulative maximum potential of 1 Mt CO₂ (cumulative) within the region, requiring almost 1 Mt of ground olivine.

Not promising

Less promising

Enhanced weathering requires the grinding and transport of large quantities of minerals and application over large quantities of land. Even if applied at scale before 2030, it could take years to decades for removal of CO₂ to accumulate.

Due to the slow uptake rate, enhanced weathering would require large-scale application before 2030 to see appreciable removal in 2050. Even with high application rates, density of removal is low (65 t of olivine per hectare leads to cumulative maximum removal potential of 78 t CO₂).

Still many unknowns, but the development of robust methodologies to monitor CO₂ uptake could change this assessment. Direct Air Capture and Storage (Carbyon)

The use of fans, chemicals, and energy to extract atmospheric CO₂ into a solvent or sorbent, after which it is transported and stored permanently, e.g., in a geological formation

Currently zero. Carbyon has a 1000 t CO₂ per year Netherlands pilot planned for 2024, with an ambition to scale to 1 Mt CO₂ by 2030.

Not promising

Promising

Needs to improve energy efficiency and cost; main focus is on CCU (business case)

This could be a promising option for decentralised CDR, if improvements are made on the energy efficiency of the process, conditional on an abundant supply of clean energy and subject to demand competition. It could also be located close to offshore geologic storage.

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

Name

Potential for large-scale implementation by 2030

Potential for large-scale implementation by 2050

Description

Potential scale of removals

Soil Carbon Storage (Wij.land)

Increasing organic carbon content of soil through land management practices that must be indefinitely maintained.

Unknown. Wij.land estimates a potential removal rate of 1 t CO₂ per hectare per year, which could lead to a maximum removal rate of 35,000 t CO₂ per year in the area. Soil carbon storage is subject to sink saturation and a higher risk of reversal.

Not promising

Less promising

Soil carbon storage requires further work to tailor both land management and monitoring practices to regional soils, as well as the need to convince and compensate farmers for changing agricultural practices.

Soil carbon storage has a higher associated risk of sink saturation and reversal. The density of removal is also low. However, land management practices that lead to increased soil carbon have ancillary benefits on land quality and resilience.

Afforestation

The deliberate cultivation of long-term biomass stocks that are indefinitely maintained.

Unknown. Temperate afforestation can remove 2.5–25 t CO₂ per fully-planted hectare per year. Afforestation is subject to sink saturation and a higher risk of reversal.

Less promising

Less promising

Even with widespread deployment, newly planted trees have a low initial uptake rate and the density of removal is very low.

With climate-adaptive species selection and continuous maintenance, biomass carbon stocks could be greatly increased in the next thirty years, but is land-intensive and reversal risks must be well managed.

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

5.1 Direct Air Capture and storage Direct air capture removes CO₂ directly from ambient air using chemical (or mineral) solvents or sorbents and a lot of energy. The CO₂ is then separated from the chemicals and sent to geologic or mineral storage (Figure 15). Direct air capture is a new technology, with the largest plant capturing and storing 4,000 t CO₂ per year in Iceland. Current prices range from USD 600–1,000/t CO₂ captured and stored, with costs expected to go down to USD 150–200/t CO₂ within the next 10–15 years.

Figure 15: Direct air capture and storage process (stylized; supply chains not shown)

Key considerations •

DAC is very energy intensive, especially as compared to industrial CCS. CO₂ capture energy demand increases as the concentration of CO₂ decreases, and atmospheric CO₂ is very dilute, around 0.04% by volume, compared to 5–30% for industrial flue gas. Current DAC processes use 6–10 GJ/t CO₂ of energy to separate CO₂ from the atmosphere, compared to 3–5 GJ/t CO₂ for industrial CO₂ capture. Reducing the energy demand is the primary focus of most DAC technology companies.

•

DAC can be flexibly sited, such as near available CO₂ transport and storage and/or low-carbon energy sources.

•

To be a CDR technology, DAC requires permanent storage. If the removed CO₂ is reused in short-term processes, such as for fuels, chemicals, plastics, fertilisers, or greenhouses, it is not a removal, but a delayed emission.

Local drivers and barriers The Porthos and Aramis pipelines to geologic storage (see BioCCS: Overview of sinks) could also be used to transport atmospheric CO₂ captured via direct air capture, and the modularity of many DAC designs facilitates siting DAC facilities near transport. Alternatively, DAC could be sited in urban areas, where it could contribute to reducing local air pollution, though this would increase the complexity of transporting the CO₂ to storage. DAC would compete with local demand for energy resources, such as waste heat that could be used to facilitate industrial CO₂ capture. As the energy demand for DAC is currently 2-4x that of industrial CO₂ capture, capturing industrial CO₂ is more energy efficient at reducing net emissions than DAC. Furthermore, the average CO₂ intensity of the Dutch grid is 333 g CO₂eq/ kWh (in 2020), which, if used to meet the energy demand of DAC, would emit 500–900 kg CO₂eq/tCO₂ removed. For DAC to be efficient in the Dutch context, the energy demand of DAC needs to be optimised and additional renewable energy is needed. Direct air capture is a novel technology that requires substantial investment and 'learning by doing' to decrease energy demand and costs.

Once CO₂ transport and storage infrastructure is available, the NSCA could speed DAC development by funding the development of an 'off grid' DAC facility, with independent renewable energy generation (e.g., wind, solar, geothermal) to prevent grid stress.

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Carbon removal potential in the Amsterdam Metropolitan Area and the North Sea Canal Area

5.2 Enhanced weathering Weathering is a normal geologic process by which certain rocks react with CO₂ and H2O in the atmosphere, which slowly dissolves the rock as it binds to the CO₂ and H2O. This dissolved rock (along with the CO₂) then ends up in the soil, as soil inorganic carbon, and eventually leaches into the ocean or underground aquifers. This process takes thousands to millions of years. Enhanced weathering is the attempt to accelerate this process by increasing the surface area of the minerals exposed to the atmosphere by grinding it into sand-sized particles (Figure 16). Silicate rocks such as olivine or basalt are most commonly proposed for enhanced weathering projects. One tonne of olivine can, at maximum, remove 1.25 tonnes of CO₂ from the atmosphere.

•

Monitoring the fate of dissolved CO₂ is currently difficult. In enhanced weathering, the CO₂ is not absorbed into the mineral, but rather dissolved into the soil below as inorganic carbon. While much of this CO₂ is assumed to remain stored, the final fate may be unverifiable.

•

Methodologies are currently being developed to monitor CO₂ uptake from projects; further evidence through this monitoring may make enhanced weathering projects more promising

•

Silicates such as olivine or basalt may affect soil chemistry if applied to agricultural soils, such as reducing soil acidity, increasing mineral levels in the soil for both nutrient minerals (e.g. magnesium) and toxic minerals (e.g. nickel, chromium)