An explanatory note on guiding concepts, technical approaches, design choices, and their underlying rationale

The CCS+ Initiative was established in 2021 with the mission to scale cutting-edge climate technologies by developing a robust accounting infrastructure for a set of emissions reduction and carbon removal techniques/value chains with environmental integrity at the core. The approach taken to the development of the carbon accounting methodologies departs from prior common practice to better track CO2 molecules in a fully-fledged carbon management economy. 

CCS+ is a unique multi-stakeholder initiative with over 55 members. Through close collaboration, this heterogeneous membership of technology and solution providers, large emitters, professional service providers, academia, and civil society, is well–placed to address the myriad carbon accounting challenges in an increasingly integrated market for carbon capture, removal, transport, utilization and storage. The work is intended as a public good.      

This explanatory note lays out the approach, specific design choices, and underlying rationale. It describes three connected concepts that underpin the Initiative’s work: carbon management economy, carbon accounting infrastructure, and the plug-and-play approach. Taken together, these concepts make for a unique approach suitable to the requirements of a net zero future and the inherent uncertainty of the pathways to achieve these emission reductions and removals.   

Carbon management economy

The world is moving towards a carbon management economy, with new economic opportunities for capturing and sequestering carbon, complementing urgent and deep decarbonization efforts to slash emissions in the first place. Where CO2 was once a mere pollutant, it is now rapidly becoming both a commodity as a valuable feedstock and a commodity that has a higher value when it is durably stored in the geosphere or in materials and end-products. This may seem mutually exclusive. After all, how can something be both valuable for use and for not using it? But it becomes clearer when placed against the background of the global carbon budget. 

The global carbon budget sets out how much CO2 can still be emitted without likely exceeding global average warming of 1.5°C. In 2022, the concentration of CO2 in the atmosphere reached close to 420 ppm averaged over the year, which is approximately 50% higher than pre-industrial levels. Urgently curbing emissions is, therefore, priority number one in order to prevent the accumulation of more carbon in the atmosphere. Depending on its economic activity, there will be many different interventions that a company can take across the mitigation hierarchy to reduce the carbon intensity of its commercial activities. Some sectors, where low carbon alternatives are not (currently) available or cost-prohibitive,  will have access to carbon capture and sequestration or utilization opportunities. 

There is a growing emphasis on the need for a society-wide systemic approach to manage carbon flows within our own economy more sustainably and to close carbon cycles in order for the planet’s carbon cycle to gradually restore itself. Carbon naturally passes through the atmosphere as it cycles between a limited number of global sources and sinks, including the oceans, soil and non-woody plants, forests, fossil biomass, rocks and sediments, and living organisms. CO2 molecules are constantly on the move, in gas, liquid and even solid states in the form of carbonate minerals or trapped in fossilized biomass, what is generally called fossil fuels. Humanity has disrupted this natural cycle by dramatically increasing emissions from fossil sources leading to accumulation of CO2 in the atmosphere and oceans. Restoring it means taking action in two ways: 1) preventing CO2 from entering into the atmosphere in the first place and 2) lowering the concentration of CO2 in the atmosphere through active removal efforts. Various technologies help achieve this and some of them can contribute to both.

By capturing and storing carbon, CCS (“Carbon Capture and Storage”) can prevent hard-to-abate emissions from point sources from energy intensive industries, such as cement, chemicals, and steel. Carbon Capture and Utilization (CCU) solutions can help industries that rely on CO2 as a feedstock to displace virgin CO2 by accessing recycled CO2. A particular form of CCU (also called CCUS to stress the role of durable storage) offers an alternative to geological storage by durably binding the carbon in materials. The letters in CCS, CCU, and CCUS describe technology-elements of carbon-management value-chains. In contrast we also speak of climate change mitigation results, which can either be a relative reduction in emissions, or a permanent removal of CO2 from the atmosphere – depending on the origin (directly from the air or from biogenic emission) and the destination of the CO2. The latter is also referred to as carbon dioxide removal (CDR) and it can be achieved via a range of techniques. What they have in common is that they all either directly remove CO2 from the atmosphere or from gas streams that would have entered the atmosphere.. All techniques – whether they achieve emissions reductions or removals – differ in the inherent durability of storage and origin of the CO2; carbon removals can only be realized by capturing and durably storing CO2 of a biogenic or atmospheric origin.

Together, these solutions make up an integrated carbon management economy. It requires a vast CO2 transport and storage infrastructure, including an extensive pipeline network, specific CO2 cargo ships and river barges, trucks and trains that can bring the CO2 from where it is captured at the fluestack or directly from the atmosphere and transport it to where it will be used or stored, either in a product, onshore or offshore, above ground or underground. The versatility requirements of the infrastructure is comparable to the vastness of the infrastructure used in today’s oil and gas industry. Tracking the molecule from source to destination requires an equally integrated approach, which the CCS+ Initiative provides through its comprehensive carbon accounting infrastructure.

Industrial hubs and clusters

The complexity of the value chains is already reflected in the major storage projects that are currently coming off the ground, such as Northern Lights in Norway or Greensand in Denmark. They are agnostic to the source of the CO2 being stored. Government interventions also take an approach whereby the hard CO2 infrastructure is to be used for a combination of commercial and climate services.

For example, the foreseen Direct Air Capture (DAC) hubs in the US are defined by the Department of Energy as a “network of projects, potential CO2 utilization off-takers, connective carbon dioxide transport infrastructure, subsurface resources, and sequestration infrastructure located within a region.” Meanwhile, the proposed EU Net Zero Industry Act defines a “Union target of 50 million tonnes of annual operational CO2 injection capacity by 2030 … [that will] also support further CO2 storage in a 2050 perspective. According to the Commission’s estimates, the Union could need to capture up to 550 million tonnes of CO2 annually by 2050 to meet the net zero objective, including for carbon removals.”

Both examples highlight how the transportation and storage of CO2 will form the beating heart of a new carbon management economy, servicing a variety of project types that capture or remove CO2. This infrastructure is highly capital intensive and will need large amounts of private capital and public funding to be built out over time.

Carbon accounting infrastructure

The variety of the full-chain emissions reduction and carbon removal pathways covered may seem confusing at first. Why not develop carbon accounting methodologies that are suitable for specific project value chains? It is certainly true that the CCS+ approach is more complex. Yet, as outlined above, that complexity reflects the integrated industrial infrastructure needed to deliver a fully-fledged carbon management economy where many different project types connect up to a common hub of CO2 transport and storage infrastructure. 

Existing practices in carbon accounting methodologies cannot appropriately cater to this carbon management model as they narrowly address the project value chain, rather than the complete industrial cluster. The reality is that the rules, requirements, criteria and procedures to generate credible emission reduction or removal carbon credits from high quality carbon management projects have not been consistently available or have been limited to certain geographies or project types. The table below illustrates the proliferation of approved methodologies for carbon crediting from such projects in the voluntary market.

Table 1. Current proliferation of methodologies for carbon crediting from carbon management projects (June 2023)

Methodology (Standard)Activity ScopeGeographical ScopeICROA endorsement
Alberta Quantification Protocol for CO2 Capture and Permanent Storage in Deep Saline Aquifers
(Alberta Government)
CCS in aquifers and EOR projects (ER)Alberta (Canada)No
Carbon Dioxide Removal by Direct Air Capture & Permanent and Secure Geological Storage of CO2 by In-situ Carbon Mineralization
(ISO 14064-2)
DAC, storage by carbon mineralization (CDR)GlobalNo
Methodology for the Quantification and MRV of GHG emission reduction and removals from CCS projects 
(American Carbon Registry)
EOR; DAC and BEC with storage in saline formations and depleted oil and gas reservoirs (CDR (only for DAC) and ER)US, Canada, MexicoYes
Geologically Stored CO2 Methodology 
DAC and BEC with storage in deep geological formations and reservoirs (CDR)GlobalYes
Carbon sequestration through accelerated carbonation of concrete aggregate
(Gold Standard)
CO2 sequestration in demolished concrete based on DAC or BEC (CDR)GlobalNo
California Carbon Capture and Sequestration Protocol 
(Low Carbon Fuel Standard)
CCS projects with onshore sequestration (either saline aquifer or depleted oil and gas reservoirs) + EOR (ER)US + selected countriesNo
Carbon Capture and Storage Method (Australias’ Emission Reduction Fund, ERF)Applicable to a wide range of CCS technologies, explicitly excludes DACAustraliaNo
Source: Compilation by the Secretariat of the CCS+ Initiative

What we found when analyzing the methodologies is that some lack clear and consistent definitions of project eligibility and project boundary, whereas others have unclear guidance on the implementation of additionality testing. Various cases were found where the authors failed to offer methodological solutions for differentiating between emission reductions and removals and lack proper accounting procedures for emissions related to shared transport and storage infrastructure. To earn the long-term trust of society, there must be a more comprehensive and consistent approach to carbon accounting that facilitates the responsible implementation of these activities and drives down cost by scaling up their deployment.

The CCS+ Initiative is putting in place a comprehensive and integrated carbon accounting infrastructure that offers a home for a wide array of project types that logically fit together due to their potential reliance on a shared physical infrastructure. This contrasts with the standard practice of developing ‘narrow’ methodologies for very specific project types. As we have written above, that practice is increasingly less relevant as societies move from counting molecules in single point-to-point projects towards a fully-fledged carbon management economy. The CCS+ approach is a response to this development. 

Its carbon accounting infrastructure is composed of various framework methodologies, underpinned by modules covering individual capture, transport or storage processes, leading either to emissions reductions or removals. A set of tools are developed to support the proper functioning, such as tools to distinguish in a single project between emissions calculated for the purpose of monetization in the voluntary market and those covered under a given compliance market. Another tool is used to differentiate between the origin of the emissions in projects involving both fossil and biogenic emissions, such as waste-to-energy plants. 

The CCS+ Initiative is clearly distinguishing between emissions reductions and carbon dioxide removal results at methodological level, ensuring the distinct accounting of the mitigation outcomes. Two dedicated capture modules – direct air capture and capture from biogenic sources – enable project developers to generate removals when coupled with a durable storage module, either geological or through product mineralisation. In line with the latest climate science and developments in the policy space, the Initiative is committed to exploring additional ways to enable a strict differentiation between reductions and removals at the methodological level. 

Plug-and-play approach

Differentiated accounting of mitigation outcomes does not make the solutions entirely different as they draw on shared technology elements. To speak of conventional (fossil) CCS and CCUS, versus CDR (BECCS, DACS and others), as entirely separate technologies is therefore a simplification and inaccurate. Not only do they often rely on a shared physical infrastructure, but the concepts and technologies also in themselves overlap.

That is why the CCS+ accounting infrastructure is designed in a plug-and-play manner. Each activity in the value chain is represented by a methodological module that can be seamlessly combined with the relevant modules of other activities. For example, the DAC module can be combined with the transport module and the module for storage in saline aquifers. But the DAC module could also be combined with use in cement (a form of CCUS achieving removal results), or the module for mineralization of CO2 in igneous rock formations or any other “storage” modules. This approach allows more flexibility for project developers, who can pick and choose the respective modules in a given project value chain. 

The CCS+ carbon accounting infrastructure caters to the growing versatility of the carbon management economy. The modular structure that is at the heart of it allows project developers to plug-and-play with the modules and tailor the carbon accounting to the specific capture, transport and storage processes covered in a given project value chain. New processes may find a home over time where the technical overlap allows this. 

The governance question

The landscape of carbon accounting approaches is a patchwork, with few universally accepted guiding principles to measure and verify the performance of industrial carbon management projects. There is a risk of fragmentation across the voluntary and compliance markets in the absence of a credible authority to standardize high quality carbon accounting practices. It is, however, not clear what that authority should look like and to what extent it should build on existing efforts. 

As it stands, especially for CDR, the dominant approach for monitoring reporting and verification (MRV) has been a combination of project-specific carbon accounting methodologies, project-level due diligence and bespoke verification. CCS and CCUS projects with fossil emissions tend to have MRV requirements already regulated. This characterizes a market that is still nascent with a limited variety of both buyers and suppliers of carbon removal credits. This model is not scalable and is generally time consuming. It also does not ensure the environmental integrity of the voluntary carbon market, nor can it serve as a bridge to compliance markets.   

The mitigation impact and therefore value of similar projects cannot be compared without a basic common alignment on carbon accounting criteria. This is also important for assessing the performance of different CDR approaches. A useful starting point for this endeavor is the work of carbon credit standards such as Verra and the Gold Standard, both accredited under the International Carbon Reduction and Offsetting Accreditation (ICROA), that have two decades of experience in developing high-quality frameworks for measuring, reporting and verifying the mitigation outcomes of projects. They maintain a wide range of methodologies and tools for the purpose of accounting project-based climate impacts. This includes, for example, project definitions and eligibility conditions, project boundary definitions, definitions of permanence and procedures for demonstrating additionality and dealing with potential reversals. 

Recent criticism of such carbon credit standards in the context of REDD+ projects seeking to counter deforestation should be a reminder that the carbon accounting framework needs to be high-quality by principle and evergreen in its applicability. This relates to the transparent use and regular updating of counterfactual baseline scenarios, preventing conflicts of interest in the verification of mitigation outcomes, and applying carbon accounting methodologies effectively and consistently. Building on those solutions while pushing the boundaries of today’s carbon credit standards for carbon management would allow for greater consolidation of quality assurance approaches across markets and could reduce transaction costs in the market significantly. Time and money is gained if project developers do not have to accommodate too many different requirements across the markets they operate in. 

Unleashing a race to the top

The reality is that the rules of the game are developed today. This game is not only about unlocking a trillion dollar voluntary carbon market, but also about creating a new yet fundamental life-saving carbon management operation that humanity will add to its toolbox to stave off climate catastrophe. It is important that the tracking of mitigation impacts is transparent, universal and continuously evolves to ensure ever greater quality as the market matures and new scientific insight is gained.  

The CCS+ Initiative is making a contribution. Our first methodological outputs consisting of the framework methodology for CCS, as well as modules for DAC, CO2 transport, and storage in saline aquifers have been issued for public consultation under Verra (available here). We encourage everyone with an interest to participate in our future consultations and help unlock carbon finance for carbon management projects by working together towards a high-quality accounting framework for the carbon management economy.

For more information, please contact the CCS+ Secretariat at