Category: Carbon Dioxide Removal (CDR)

Without Article 6 there may be no 1.5°C (or even 2°C)

dchone May 30, 2023

The 58th session of the UNFCCC’s Subsidiary Body for Scientific and Technological Advice will take place in Bonn from June 5-15 and one of the features of the session is further progress in operationalising Article 6 of the Paris Agreement. My colleague, Malek Al-Chalabi, and I thought it would be useful to reflect yet again on the critical importance of this somewhat overlooked corner of the Paris Agreement.

Article 6 of the Paris Agreement is the section that formally promotes cooperative approaches between the Parties, but is widely recognised and is being negotiated as a carbon trading mechanism. The thinking behind Article 6 is profound, but the reality of a working mechanism is taking too long to appear in practice. Article 6 was the apparently the last piece of the Agreement to be completed in December 2015 and we all know that the completion of the so-called Paris ‘rule book’ was extended by two COPs (from Katowice in 2018 to Glasgow in 2021) because of Article 6. Now the fine detail of the mechanisms is trying to find a landing point.

One area that is really struggling, weighed down by constant challenge, is the incorporation of carbon dioxide removals (CDR) within Article 6.4, the project based mechanism under Article 6. A recent information note released by the UNFCCC seems to lean heavily towards land based removals (reforestation, ecosystem restoration, carbon farming etc.) but is particularly scathing on the prospect of engineered removals (direct air capture with geological storage or DACCS and bioenergy production and use with geological storage or BECCS), with statements such as;

Engineering-based removal activities are technologically and economically unproven, especially at scale, and pose unknown environmental and social risks. Currently these activities account for removals equivalent to 0.01 MtCO₂ per year (P15:a) compared to 2,000 MtCO₂ per year removed by land-based activities.
These activities do not contribute to sustainable development, are not suitable for implementation in the developing countries and do not contribute to reducing the global mitigation costs, and therefore do not serve any of the objectives of the Article 6.4 mechanism.

In any thorough analysis of net-zero emissions during this century, such as in the IPCC 6^th Assessment Report, both land carbon management and engineered removals are critical for achieving the net-zero goal, so to simply dismiss engineered removals now because they have yet to scale can only be seen as short sighted. In the recently released Shell scenario Sky 2050, the role of both in 2050 is very clear, as shown below. In 2050 the use of fossil fuels is far from over, so balancing remaining emissions against sinks via various removal mechanisms is critical.

While land-based removals are larger in 2050 than engineered removals, the longer term mechanism for correcting overshoot and addressing atmospheric CO₂ levels is engineered removals. By 2100 fossil fuel use is largely done with so the balancing of 2050 is not really required, but a robust business model will be needed to support ongoing negative emissions through engineered removals as a means of reducing atmospheric CO₂ levels. This will also require a trading mechanism.

Further to the above, there is an almost certain dependency on the structure of Article 6 in the delivery of large scale removals. This is because the countries and sectors that find themselves in the situation of needing removals to balance ongoing emissions or to finance long term negative emissions may not have local access to them, perhaps for reasons of geography. This was highlighted in the Shell Scenario Singapore Sketch released last year. Without Article 6 Singapore cannot reach it’s goal of zero CO₂ emissions, but with Article 6 in place net-zero emissions is achieved. Arguably the very essence and purpose of Article 6 is embraced within the word ‘net’ in net-zero. Eventually, removals become the only type of unit traded under Article 6 or created through the 6.4 mechanism.

The same clear message was also delivered in the IPCC AR6 Synthesis Report where CDR is shown to be vital if the world is to achieve 1.5°C, the more ambitious goal of the UN Paris Agreement. And similar to the case for Singapore described above, not all countries will have the same geographic and geological ability to harness or deploy CDR options or reduce emissions at the same rate, and the majority of countries cannot expect to reduce emissions to zero such that CDR is not needed.

In a previous blog post, we illustrated the importance of trade and how countries and sectors can work together in Article 6. This message can also be found in publication from a variety of organizations, including the International Chamber of Commerce, the International Emissions Trading Association (IETA), the International Energy Agency, and others.

There have been numerous examples that show how trade helps countries contribute to economic growth. This includes the trade of automobiles, medicines, clothing, electronics, and a variety of other goods. Not all countries will be automobile hubs, medicine hubs, clothing hubs, or electronic hubs. Trading allows countries to specialize in certain segments of the economy and trade with others that have other expertise in other goods – and it is a win-win for both countries. There have also been an equally abundant examples of how isolation or trade disputes can disrupt economic growth and progress.

Trading of carbon is a win-win – for economic growth and for decarbonization – and Article 6 has the potential to catalyse both elements. As such, in order to maximize the use of Article 6, IETA has identified the following elements for governments to consider (see the full IETA paper here):

Announce whether and how the country will authorize Article 6 credits and/or accept towards the achievement of its NDC.
Provide a clear strategy and stable guidelines on which sectors, activities and vintages will be eligible for Article 6 credits.
Articulate how the use of Article 6 will help achieve the goals of the Paris Agreement.
Elaborate what policy framework the host country will adopt and how it will interact with the receiving country.
Establish an effective interaction between compliance instruments and the voluntary carbon market (VCM).
Support the emergence of a widely accessible traded market for carbon credits.
Ensure a suitable digital registry or other infrastructure for GHG accounting and reporting is in place.
Address key risks in the activity cycle and identify mechanisms to reduce them.
Emphasize the areas where capacity building is required and the role of international organizations

But more recently, IETA and several other observers have called for the Article 6.4 Supervisory Body to take a more balanced approach to the assessment of removals. The IETA submission can be found here.

Carbon markets have the opportunity to contribute to decarbonization and economic growth. A recent example of this was highlighted at COP27, where the governments of Switzerland and Ghana agreed to the first government to government bilateral carbon trade. More signs of this are taking place, with Japan signing over 25 MOUs and other countries showing a keen interest, like the UAE, Sweden, and others. Further information on how carbon markets can assist decarbonization efforts can be found on a recent episode of the Energy Podcast (Season 5).

With the global stock take taking place in Dubai later this year, Bonn provides an opportunity for policy makers and governments to continue to encourage the use of Article 6 and embrace the role of removals, in all forms, within the 6.4 mechanism. Further government to government trade of carbon will be one of the cornerstones to limiting warming to 1.5°C.

Note: Shell Scenarios are not predictions or expectations of what will happen, or what will probably happen. They are not expressions of Shell’s strategy, and they are not Shell’s business plan; they are one of the many inputs used by Shell to stretch thinking whilst making decisions. Read more in the Definitions and Cautionary note. Scenarios are informed by data, constructed using models and contain insights from leading experts in the relevant fields. Ultimately, for all readers, scenarios are intended as an aid to making better decisions. They stretch minds, broaden horizons and explore assumptions.

How quickly can a synthetic aviation fuel industry emerge?

dchone May 15, 2023

In late April, the European Parliament and EU Member States reached agreement on new mandates for sustainable aviation fuels through to 2050. Under the final agreement, the percentage of sustainable aviation fuel (SAF) that must be blended with kerosene will start at 2% by 2025, moving to 6% by 2030, 20% by 2035, 34% by 2040, and reaching 70% by 2050. A dedicated sub-target for synthetic fuels derived from green hydrogen will also come into force from 2030. Although the final wording and requirements for these mandates have yet to be released, the headline numbers are clear even if the detail isn’t – starting at 1.2%, the synthetic fuel requirement will be scaled up to 5% by 2035, reaching 35% by 2050.

SAF is going to require a huge effort and should rightly be the immediate focus of attention, largely because of the state of technology and the amount of effort that has gone into preparing the groundwork for a SAF industry. But while the overall SAF target is challenging, given the small quantities produced today, the synthetic fuel mandate looks daunting. In EU parlance, synthetic fuels are renewable liquid and gaseous transport fuels of non-biological origin, meaning liquid or gaseous fuels which are used in the transport sector other than biofuels or biogas, the energy content of which is derived from renewable sources other than biomass. In the aviation industry this presumably means two types of fuel;

Hydrogen as a direct fuel derived from renewable energy sources.
Synthetic kerosene (also known as an e-fuel), produced by combining hydrogen derived from renewable energy sources (via electrolysis of water) and carbon from the atmosphere (via direct air capture or DAC), with the energy required for the capture and final synthesis also coming from renewable sources such as wind and solar PV.

For 2030, hydrogen as a direct fuel is a non-starter given that the planes don’t yet exist and probably won’t do so until 2040 at the earliest, although we might see some small commuter versions before that. So for 2030 and probably 2035, this mandate is really only about e-fuels. The synthesis of such a fuel is discussed in detail in a paper by Kraan et al., An Energy Transition That Relies Only on Technology Leads to a Bet on Solar Fuels, Joule (2019), with the energy schematic they developed shown below. This is to produce one barrel of fuel (5.5 GJ solar fuel on the right of the schematic).

The illustration above presumes feasibility and the availability of a wide range of thechnologies at large scale. In reality, that isn’t the case today. Clearly solar PV and synthesis technologies exist at scale, but Direct Air Capture (DAC) is still to be demonstrated at scale (i.e. 1 million tonnes per annum or more) and hydrogen electrolysis is only just reaching the sort of scale required for synthetic fuel production. As such, the discussion below should be viewed in that context and not just be a question of quickly building the necessary facilities.

In 2023 we can expect EU aviation fuel consumption to be somewhere around 1 million barrels per day, which includes both internal EU demand and international aviation bunkers for flights departing from the EU, for passenger and freight movements. So a 1.2% synthetic fuel mandate means the production of at least 12,000 barrels per day of e-fuel within seven years, or over 4 million barrels (600 kt) produced in 2030.

Jet fuel is mainly carbon in terms of weight, so 600 kt is about 500 kt carbon and 100 kt of hydrogen. This amount of hydrogen (but in practice more is needed) will require multiple 200 MW electrolyser projects, each similar to the project recently announced by Shell in Rotterdam that will produce 60,000 kg per day of green hydrogen, currently Europe’s largest such project. The Shell project will begin operation in 2025 after two years of construction, along with offshore wind capacity built in the Hollandse Kust Noord area.

The 500 kt carbon equates to nearly 2 million tonnes of atmospheric carbon dioxide capture in 2030, which is a scale of capture that doesn’t currently exist in the world. However, Occidental and its subsidiary 1PointFive announced in late 2022 they plan to begin detailed engineering and early site construction for their first large-scale DAC facility with start-up expected in late 2024. Upon completion, the DAC plant will be the world’s largest of its kind and is expected to capture up to 500,000 metric tons of carbon dioxide per year.

However, the provisions of the EU Directive on these types of fuels allows for other sources of CO₂ to be used, but in some cases for a limited time period. Up until 2041 it will be possible to use CO₂ from sources such as industry where allowances have already been surrendered against such emissions. It is also permissible to use the captured CO₂ from the production or the combustion of biofuels, bioliquids or biomass fuels. These provisions mean that an immediate relaince on DAC as a source of carbon for synthetic fuels isn’t required.

Producing sufficient hydrogen and capturing enough carbon dioxide is energy intensive and is just the start. These then must be combined to make the synthetic fuel, which takes even more energy and more hydrogen than the molecular weight of jet fuel points to. For example, a hydrogen based reaction is required to convert the carbon dioxide to carbon monoxide, which is required for the subsequent synthesis reaction. If the facilities designed to do this make use of Fischer-Tropsch technology, jet fuel won’t be the only product. Its yield might be as much as 67% (with the other 33% being lighter and heavier hydrocarbons, but this will require an optimised catalyst), which means that for the above jet fuel requirement the picture becomes more complex and bigger. The required production of synthetic fuels rises to 18,000 barrels per day, of which 12,000 is jet fuel.

The synthesis plants are not simple projects either, although the underlying technology is tried and tested in facilities such as the Shell gas-to-liquids synthesis plant in Qatar. That unit takes natural gas and breaks it down into hydrogen and carbon monoxide (synthesis gas) before recombining these into longer chain hydrocarbon molecules such as for jet fuel. That facility operates on a very large scale, producing some 150,000 barrels per day of product (of which some is suitable for jet fuel use). Building smaller versions is possible, although even the first Shell synthesis pilot plant, built 30 years ago in Malaysia and still operating today, produces 14,700 barrels of oil product per day. Even smaller scale gas-to-liquids is also possible, with Petrobras operating such a unit in a remote location as a pilot for the conversion of associated gas from oil production into useful liquids.

Given the rapid scale up of the synthetic fuel mandate (4x from 2030 to 2035), the sensible approach will be for the EU to build reasonably large from the start. A first facility might be the size of the Shell Malaysia unit (the illustration shows an 18,000 b/d unit but this is still small by global refining standards), but would also require about 3 GW of green hydrogen capacity and three million tonnes per annum of DAC. Apart from the synthesis unit which is arguably smaller than the desirable scale for modern refining, the hydrogen and DAC units are unprecedented in size. However, both hydrogen and DAC are scalable technologies, with the latter currently deployed on a modular basis, and as noted above DAC isn’t an immediate requirement.

Building an 18,000 b/d synthesis facility, 3 GW of hydrogen electrolyser capacity and 3 MT per annum of DAC combined with large scale renewable energy production (say 6 GW of offshore wind) is a formidable project, costing many billion euros and taking years in terms of planning, approvals, financing and construction. Such a project will also stretch the available technologies, given that DAC in particular doesn’t yet operate at scale anywhere. But the EU needs to start at least five such projects over the coming 2-5 years, not just to meet the synthetic fuel mandate of 2030, but also with an eye on the 2035 mandate and beyond.

Finally, an EU foot in the removals door

dchone March 6, 2023

As the EU continues to develop and progress legislation around its 2030 and net-zero emissions goals, one key proposal has surfaced that will be with us for decades to come. It is the EU proposal to create a certification framework for removals – i.e. measuring and certifying the amount of CO₂ that is removed from the atmosphere and permanently stored through some anthropogenic activity. Examples might include direct air capture with geological storage (DACCS) or reforesting an otherwise barren land area (nature base solution or NBS). The proposal includes the very clear reason why it is needed;

The European Climate Law provides for the EU to become climate neutral by 2050. This requires that GHG emissions are significantly reduced, and that the unavoidable emissions and removals should be balanced within the European Union at the latest by 2050, with the aim to achieve negative emissions thereafter. To achieve this objective, both natural ecosystems and industrial activities should contribute to removing several hundred million tonnes of CO₂ per year from the atmosphere. Today and with current policies, the EU is not on track to deliver these quantities: carbon removals in natural ecosystems have been decreasing in recent years, and no significant industrial carbon removals are currently taking place in the Union.

Readers of my previous posts will know that this is something of a pet subject for me and so it is pleasing to see that the EU if finally recognising the importance of removals. The need for a tradable carbon dioxide removal unit is essential for net-zero emissions, in fact it is the essence of the phrase because of the use of the word ‘net’. However, while a first step is important, time is not on the side of the EU, so they will have to move much faster.

In a 2022 post I noted that the revised EU ETS allowance decline rate built into the Fit for 55 framework would take the system to zero new allowances in 2040, but that would almost certainly be ahead of the point in time at which there would be zero emissions in the covered sectors. As such, some form of new allowance would be needed, with the obvious candidate being a carbon removal unit brought in as an external credit. That would make the EU ETS a vibrant carbon removal trading platform, creating a market for carbon removals and establishing a clear price.

But it would seem that the EU is not yet prepared to take such a step. While the certification proposal is important, it lacks one key element, a business model to encourage businesses to use it. The EU appears to be pinning its hopes on voluntary activities, or companies looking to create or acquire certified removals to use for their net-zero commitments. This will happen to an extent, but mainly at the lower cost end of the spectrum such as soil carbon projects, land use change projects and similar. These do form an important part of the EU Fit for 55 framework, but so does the need for DACCS and bioenergy with CCS (BECCS).

The voluntary market and a certification process are no match for the $180 per tonne CO₂ on offer in the USA for DACCS under the Inflation Reduction Act (IRA). In the EU there is the Innovation Fund to help drive technologies such as DACCS, but it isn’t operating on the same scale as the IRA. The Innovation Fund could provide EUR 40 billion of support over 2020-2030 for the commercial demonstration of innovative low-carbon technologies, whereas IRA is around USD 330 billion. And IRA has a specific and clearly defined incentive for carbon dioxide removal, which isn’t the case for the EU Innovation fund, although a DACCS would be considered within the framework. It’s therefore not difficult to guess where the DACCS projects will end up and which country will benefit from the investment. That being said, ETS revenues and other mechanisms could bridge this gap if directed more towards energy technology development and demonstration.

The EU could create demand for DACCS and BECCS on a large scale if it opened the EU ETS up to such units, recognising that they will be needed by 2040, but almost certainly prior to that as the ETS reaches reductions in excess of 80%, a point it will hit around 2035. That is in 12 years. The EU Commission may well have such a move in their future plans, but history would argue that if they don’t start now, time will defeat them. Major changes in direction for the EU ETS take at least 5-10 years to be developed and bed in. For example, the Market Stability Reserve (MSR) started life in about 2011 with proposals for a set-aside of allowances to remove the post financial crisis surplus, then came backloading and finally the first implementation of the MSR and some tweaks a bit later. In 2023 it operates very well.

Given the need for a clear market price signal, i.e. the €100 per tonne CO₂ price now available from the EU ETS, a clear set of implementation rules to support projects, and recognition that a functioning DACCS industry will take at least a decade to establish, if not more, the inclusion of removals within the EU ETS becomes rather urgent. Encouraging the use of Article 6 of the Paris Agreement to facilitate carbon dioxide removal technologies is another area that I have written about and is also relevant to the EU in this context. At the moment, the only signal on offer is an indication of a review of negative emissions and trading in a few years’ time.

New business models required

dchone December 6, 2022

With COP27 now behind us and no significant changes to Nationally Determined Contributions (NDC) on offer (e.g. from China), various commentators are now remarking that meeting the goal of 1.5°C may be in doubt. This means passing the 500 Gt carbon budget that the IPCC linked to the 1.5°C goal.

I have discussed this in many earlier posts, for example here and here. However, passing 1.5°C in the short term certainly isn’t the end of the story.

Many recent IPCC scenarios also show 1.5°C being breached, but deploying removals later in the century to draw carbon dioxide out of the atmosphere is then used in the scenario to reverse the balance and at least meet the 1.5°C goal by 2100. In the IPCC Special Report on 1.5°C released in 2018, all four model pathways required some form of future removal, ranging from very little in P1 to significant in P4, depending on the lifestyle and transition pathway the particular scenario embraced and the level of overshoot of 1.5°C. Both nature based and technological removals are required. In the 2018 report technological removals were shown as bioenergy processing with carbon capture and storage (BECCS), but today we could realistically envisage both BECCS and direct air capture with CCS (DACCS) playing a role. The latter has advanced considerably in just five years.

**Source: IPCC SR15 Summary for Policy Makers**

So as well as requiring CCS to get to net-zero emissions, society will almost certainly have to consider removals as a technology to deliver negative emissions globally, i.e. after the goal of net-zero emissions is achieved. Large scale removals might also offer the much longer-term prospect (i.e. in the 22nd century) of winding the atmospheric carbon dioxide levels back towards pre-industrial levels.

While global net-negative emissions on a scale that shifts the atmospheric concentration of carbon dioxide is technically possible, the contrast with the very limited scale of deployment of BECCS and DACCS today seemingly takes the task into the realms of science fiction. Yet a century ago the scale on which energy is generated now would also have seemed like science fiction, so the task should not be dismissed. Nevertheless, the longer term could require these technologies and changes in land use to scale to many billions of tonnes of carbon dioxide removal per year. The question this poses is not whether it is possible, but how can it be made to happen.

Carbon capture and storage has become a commercially available technology over the past twenty years, yet global deployment remains very limited. The technology itself isn’t the issue, it is the lack of sustainable business models for deployment. There is a carbon price in Europe, but for many years it languished at just a few Euros and other similar systems currently operating throughout the world typically maintain prices at levels well below what is required for CCS and therefore, not surprisingly, well below the levels required for a 1.5°C transition. Bespoke CCS deployment policies are almost non-existent outside the United States. In the USA a specific tax-credit mechanism exists at the Federal level and the California Low Carbon Fuel Standard will allow the use of credits based on DACCS. As a result the USA is the global leader in CCS deployment and the pipeline of projects looks impressive, largely based on the revised tax credit available through the Inflation reduction Act. There are also DACCS projects emerging and a BECCS ethanol facility has operated in Illinois for some time now.

CCS requires a very long term business model, based on some form of market pull. Today the support for CCS comes largely from direct government grants and support mechanisms for early stage technology, but there is always a limit to such incentives. However, with net-zero emissions now becoming a clear goal in most energy system policy frameworks, a more sustainable model is likely to emerge as businesses seek to mitigate their own emissions, either due to direct policy requirements or indirect consumer preference for zero carbon emission goods and services. A balance will be found between the cost of new technologies such as green hydrogen for industry and making use of CCS in industries that continue to use fossil fuels. Society will find ways to absorb these costs over time as net-zero emissions is reached and whether this results in large or small scale deployment of CCS remains to be seen, depending on the relative costs between competing pathways.

But the next stage of the CCS journey, possibly commencing as early as the 2040s for some, will be to deliver net-negative emissions via DACCS and BECCS, i.e. drawdown of carbon dioxide from the atmosphere. While this may seem like a long way off, the history of creating basic CCS business models points to the need for an early start. The journey probably commences at the UNFCCC level, where a framework for net-negative emissions would need to be established including a global goal, some form of burden sharing agreement between nations and a discussion on the role of nature versus the role of technological drawdown solutions. Unfortunately, with history as a guide, this could take some time. But perhaps the bigger challenge will be for national governments to cascade the need into the economy and find ways to spread the cost of net-negative emissions across society within goods and services and even through taxation. This may not be popular given the net cost of the task, yet with no immediate tangible benefit. Imposing deep emission reduction goals is still proving to be a difficult task in some economies today, let alone asking the population to pay for atmospheric drawdown of carbon dioxide. However, the very long term benefit can be measured in practical terms, such as avoiding metres of sea level rise.

With the prospect of a 1.5°C overshoot scenario looking likely, future biological and geological storage of atmospheric carbon dioxide becomes essential. This task may lead to the development of huge industries engaged in such activities, or very little activity at all, depending on the policy frameworks and business models that emerge.

And just like that, zero emissions looms

dchone October 14, 2022

Some time ago I posted a discussion on the allowance decline within EU Emissions Trading System (EU ETS), with no new allowances available after 2058 based on the proposed linear rate of decline of 2.2% each year, but assuming that this would be brought forwards to 2050. Back in early 2020 the EU was in the first stage of laying out its ambition for the 2020s and I noted then;

Based on a continuation of the EU ETS under the current trajectory it won’t reach zero until the late 2050s. . . . Under a revised EU ETS, from January 1st 2050 (or perhaps 2051) there will be no further allocation of allowances, either by auction or freely given. Yet this may not be a time in which there are no emissions – thirty years is possibly insufficient time for the complete turnover of everything in the large emitters system.

A great deal of water has passed under the bridge since then and today as we look at the EU ETS, a radically different picture emerges. The EU has announced its Fit for 55 package and as part of that has also announced a significant change for the EU ETS. Notably, they have said;

In phase 4 of the EU ETS (2021-2030), the cap on emissions continues to decrease annually at an increased annual linear reduction factor of 2.2%. The Union-wide cap for 2021 from stationary installations is fixed at 1,571,583,007 allowances. The annual reduction corresponding to the linear reduction factor is 43,003,515 allowances. . . . . The Commission is proposing a new target to reduce emissions from the EU ETS sectors by 61% by 2030, compared to 2005 levels. This represents an increase of 18 percentage points compared to the -43% target under the existing legislation. To reach this target, the Commission proposes a one-off reduction of the overall emissions cap by 117 million allowances (‘re-basing’), and a steeper annual emissions reduction of 4.2% (instead of 2.2% per year under the current system).

The above is more easily viewed graphically and is shown below. As previously discussed, the original 2.2% line meant that the EU ETS finally reached zero new allowances in the late 2050s, but the changes proposed under Fit for 55 bring that forwards. Note that the rebasing proposal is a one-off reduction of 117 million allowances to bring the cap in line with a pathway that would have materialised if the 4.2% reduction factor would have been applied from 2021 onwards, but the chart below shows the new line as continuous from 2021.

The market doesn’t currently know what the plans are for post 2030 when annual allowance allocation will be around 800 million tonnes, but if the 4.2% linear reduction factor continues, then new allowance allocation will cease in 2041. That would bring the date for zero allocation forwards 17 years from the current 2.2% reduction factor line.

Zero emissions for the ETS sectors (power generation, industry, aviation and soon to include marine) in 2040 is incredibly ambitious and I could argue with some certainty that those same sectors won’t be emissions free in that time. There is no doubt that significant progress will have been made, but the idea that every plane will run on 100% sustainable aviation fuel or a new fuel, e.g. hydrogen, or that every cement plant will incorporate carbon capture and storage in just 18 years is unlikely. As such, the Commission will either have to alter the post 2030 trajectory or plan on a somewhat different outcome.

Altering the post 2030 trajectory such that the system reaches zero allowances in, say, 2050 may seem like the simple solution, but by the late 2020s when this could be under discussion, society may well be facing a situation where Europe both wants and needs to reach net-zero emissions prior to 2050. This would be linked with the global emissions pathway relative to the meagre carbon budget remaining for 1.5°C (now <400 Gt). In short, we will be heading for over-expenditure, which in turn means at least some regions reaching net-zero emissions even earlier than 2050. However, incorporating other sectors into the EU ETS, such as road transport, could also offer some flexibility with regards the decline rate of the cap.

The second approach is one that I have written a great deal about (e.g. here and here), but one that is still not part of the current EU ETS. It is to embrace net-zero and recognise that the ETS will need to become a platform for trading and surrendering carbon removal units against ongoing emissions. Removal units might come from within the EU in the form of units representing Direct Air Capture with geological storage (DACCS) or from outside under Article 6 of the Paris Agreement. The latter could include a much broader range of removals, such as the capture and storage of CO₂ from ethanol manufacture in a country such as Brazil. Whatever is included will need to be the subject of extensive consultation, but without it the EU ETS will likely become an infeasible system (meaning that the only option for emitters is to default or shut down) as the zero allowances point is approached. The earlier that zero allowances is set, the more likely is the infeasibility.

Removals are near to becoming essential in Europe and it is important that the Commission accelerates its thinking on incorporating them within the EU ETS. Removals need to form part of the system within the 2020s, such that during the 2030s the mechanisms to create them can flourish and deliver.

Article 6 and 1.5°C

dchone June 20, 2022

The 56th session of the UNFCCC’s Subsidiary Body for Scientific and Technological Advice took place in Bonn over the past two weeks and one of the features of the session was further progress in operationalising Article 6 of the Paris Agreement, particularly after completion of the rule-book at COP 26 in Glasgow. But like many other aspects of the Paris Agreement and the global effort to significantly reduce emissions, Article 6 is making good progress but not rapid progress, yet it is rapid progress that is needed. My colleague, Malek Al-Chalabi, was in Bonn for SBSTA 56 and together we thought it would be useful to reflect yet again on the critical importance of this somewhat overlooked corner of the Paris Agreement. Article 6 was the last piece of the Agreement to fall into place in December 2015 and the last part to have its rule-book agreed, taking three years longer than every other part of the Agreement (but addmitedly not helped by COVID-19).

The importance of Article 6 stems from the clear message delivered by WGIII of the recent IPCC 6th Assessment Report; that carbon dioxide removals (CDR) are vital if the world is to achieve 1.5°C, the more ambitious goal of the UN Paris Agreement. This includes direct air carbon capture and storage (DACCS), afforestation (NBS or nature-based solutions), and bio-energy with carbon capture and storage (BECCS).

Arguably, there is no net-zero emissions without Article 6. Not all countries will have the same geographic and geological ability to harness or deploy CDR options or reduce emissions at the same rate, and the majority of countries cannot expect to reduce emissions to zero such that CDR is not needed. This is where trade is relevant.

Trade underpins economic activity and offers society the flexibility to provide the wide range of goods and services that we all benefit from. Trade is often the underpinning reason for foreign direct investment. It encourages the business sector to engage in projects and activities outside their traditional base with a view to bringing goods and services into that base. Cooperation between nation states is often pursued through some form of trading arrangement.

Article 6 of the Paris Agreement is a tailored and comprehensive policy that can enable cost reductions for lowering emissions via trade between nations. It allows countries to work together via ‘cooperative approaches’ through its voluntary nature. An International Emissions Trading Association (IETA), University of Maryland, and Carbon Pricing Leadership Coalition (CPLC) study has shown that cost reductions from cooperative implementation under Article 6 can be achieved through improved economic efficiency over independent implementation of countries’ nationally determined contributions (NDCs). According to the trade models used by the University of Maryland, the potential benefit is up to ~$250 billion per year in 2030.

In addition to the direct commercial benefit, it is the ‘net’ of ‘net-zero emissions’ that Article 6 unlocks. Large scale cross border investment that would otherwise not take place can result from the development and trading of carbon removal units. This is why Article 6 is so important – it helps all sectors and Parties to the Paris Agreement reach net-zero emissions. This can be illustrated with a simple example shown below. The country and the aviation sector both have a target of zero emissions, but neither is able to realise that goal through direct reductions. A regional partner has untapped carbon removal potential, but no need to use it as emissions are already at zero. By cooperating through the trading provisions of Article 6, the end result is that net emissions of 200 units CO₂ across the three are brought to net-zero emissions.

While removals such as afforestation are well known, DACCS and BECCS have growing but still limited experience. That is why further international cooperation is needed alongside Article 6. In order to bring technologies like DACCS and BECCS to scale at an economic price and to further afforestation, cross border capacity building, joint research and development opportunities to pilot CDR options, and integrated policies and funding will also be required. This can make CDR more economically viable.

There are encouraging signs of international cooperation taking place, including countries agreeing to pilots and agreements using Article 6. However, these agreements are few and at the moment not used at scale. In order to maximize the use of Article 6, IETA has identified the following elements for governments to consider (see the full IETA paper here):

Announce whether and how the country will authorize Article 6 credits and/or accept towards the achievement of its NDC.
Provide a clear strategy and stable guidelines on which sectors, activities and vintages will be eligible for Article 6 credits.
Articulate how the use of Article 6 will help achieve the goals of the Paris Agreement.
Elaborate what policy framework the host country will adopt and how it will interact with the receiving country.
Establish an effective interaction between compliance instruments and the voluntary carbon market (VCM).
Support the emergence of a widely accessible traded market for carbon credits.
Ensure a suitable digital registry or other infrastructure for GHG accounting and reporting is in place.
Address key risks in the activity cycle and identify mechanisms to reduce them.
Emphasize the areas where capacity building is required and the role of international organizations.

Article 6 remains an innovative and new policy framework which has not been globally tested and used and it is understandable why some countries and regions may look to meet their own NDCs targets domestically instead of internationally. There are many areas to align, including how to formalize reporting mechanisms and ensuring that the deals that are made between countries (either directly or through business-to-business transactions) are set at prices and in frameworks that are transparent and benefit both.

However, if countries are to reach their NDCs independently of one another, it will be more expensive than working together and net-zero emissions will become an elusive goal. Article 6 has the potential to improve economic efficiency while helping reduce emissions across countries and sectors and provide access to opportunities only possible through cooperation. The opportunity exists to use it – and hopefully that can be maximized.

Creating a 21st century energy hub in Singapore

dchone February 17, 2022

About a year ago the Shell Scenario Team released the Energy Transformation Scenarios, which looked in detail at possible pathways the world might take in this century as society responds to climate change and other pressures. The scenarios were built on earlier work that focused on the more immediate changes that society could see in the 2020s as a result of the pandemic. But the global story is just the tip of the iceberg; there is a wealth of national and regional detail below the surface of the Energy Transformation Scenarios thanks to the team’s energy modelling capacity.

One region that is of particular importance to the energy system is Asia and within the region Singapore is a key oil products supply and distribution hub. Given its unique geographical location and history as a major trading port, Singapore supplies some 20% of global marine bunkers, 3% of aviation fuel and exports a sizeable portion of the oil products used throughout the region.

*Singapore is a major oil products supply hub today (Source: Shell analysis of various data sources)*

But as the energy system shifts and oil products are replaced with electricity and fuels such as hydrogen, how might Singapore adapt to the transformation and what might this mean for its role as an oil products supply and distribution hub? To help people think about these key questions for Singapore, Shell has released a new Scenario Sketch, Singapore: A 21^st Century Energy Hub. The Sketch makes extensive use of the regional and country data within the Energy Transformation Scenarios, setting out three possible scenarios for the region.

These scenarios are not forecasts, predictions or plans, but possible pathways that could emerge if certain trends take hold. Only one scenario meets the goals of the Paris Agreement, which implies that very deliberate steps will need to be taken to ensure the goals are met. Scenarios can help craft our thinking about the future and catalyse the actions required to shape a particular outcome.

The three scenarios are known as Waves, Islands and Sky 1.5 and they reflect the underlying trends that can be seen across society as a result of the pandemic.

Waves: A focus on wealth and economic recovery, but this results in a late start to the rapid transition required to reach net-zero emissions around the middle of the century. Rather, the energy required to support growth in the 2020s comes from conventional sources. The transition is rapid from the 2030s, with a clear focus on ending fossil fuel use rather than directly managing emissions. Net-zero emission is reached around the end of the century.
Islands: National sentiment shifts inwards and security issues prevail. The transition slows along with economic growth. Although the transition eventually takes hold, net-zero emissions is not reached until well into the 22^nd century.
Sky 1.5: The pandemic leads to structural change across society, significant green investment and a realisation that the broader health and well-being of society is fundamental. In this scenario the goals of the Paris Agreement are met.

All three scenarios see the role of electricity expanding, for example in transport, the further emergence of biofuels and the introduction of hydrogen as an energy carrier for certain applications. But the time lines are very different. However, these shifts in the energy system all challenge the supply and distribution model that Singapore has established for oil products and tend to favour local production. This is certainly the case for electricity, but may also be true for biofuels where feedstocks are available on a local level and hydrogen should electrolysers become the preferred mode of production. However, hydrogen supply may also lend itself to a distribution model if significant renewable electricity is available in a particular area, although this is not currently the case for Singapore.

The more immediate change for Singapore comes in the aviation and marine sectors, where airlines and shipping companies are beginning to plan and implement strategies to make use of sustainable fuels and develop possible roadmaps for hydrogen as a future energy carrier. Although progress is slow in Islands, both Waves and Sky 1.5 see early developments. This opens up the prospect of Singapore leading the way in supplying such fuels, maintaining its role as a supply hub.

In Sky 1.5 another opportunity emerges for Singapore through Article 6 of the Paris Agreement. A feature of Sky 1.5 is significant activity to develop carbon removals, both through reforestation and carbon capture and storage technologies. The use of removals to balance continued use of fossil fuels in some sectors is an important part of the global strategy for limiting warming to below 1.5°C in 2100, but catalysing the investment required for removals and directing the benefit to emitters requires a carbon trading market to emerge. With it’s strong history as a commercial and financial centre, Singapore could lead the way here, particularly as the region holds significant opportunity for removals and Singapore itself is a centre for the two sectors that may make greatest use of them, namely aviation and marine.

*Singapore could become a major carbon trading hub*

A feature that does emerge across the stories is just how long Singapore may find itself as an important regional distributer of oil products, even as the transition gather pace. The Asian region is still developing rapidly, with some 2 billion people (ASEAN and China) moving from modest to middle income and making use of a broader range of energy services in the process. Immediate growth in the region will draw heavily on existing energy sources and services, given their availability and scalability. Only in the fastest of transitions is this trend overcome with new energy sources scaling quickly enough to match new demand.

Where Singapore stands as an energy hub in 2050 and beyond has yet to be established. But now is the time for the bold decisions necessary to create the best possible future. Scenario analysis is a useful tool for understanding new trends and directions. We hope this publication helps inform readers about an otherwise uncertain future and positions them for the journey ahead.

Also check out the scenario infographic here.

Shell’s scenarios, including this Singapore Sketch, are not intended to be projections or forecasts of the future and they are not Shell’s strategy or business plan. When developing Shell’s strategy, our scenarios are one of many variables that we consider. Ultimately, whether society meets its goals to decarbonise is not within Shell’s control. This Singapore Sketch is based entirely on the data and findings of the Shell Energy Transformation Scenarios, released in February 2021. Please read the full cautionary note at: http://www.shell.com/investor and http://www.sec.gov

Article 6 at COP26

dchone October 11, 2021

My home country, Australia, seems to reside permanently in the international climate doghouse, but a closer look reveals that they have made steady progress on some of the less advertised fronts related to mitigation. This was highlighted again recently when the government’s Energy and Emissions Reduction Minister Angus Taylor announced that carbon capture and storage (CCS) projects would be eligible for emission reduction credits.

This might seem like a distraction to some, but Australia has been forging a clear path towards growing its carbon removal capacity for some years now. The Federal Emissions Reduction Fund (ERF) has long targeted opportunities in soil carbon, forest management and reforestation and now CCS is added to the list. Short of a miracle in energy technology development and deployment, the current mechanisms for energy supply do not hold within them a net-zero emissions solution available within 30 years, so it is only through the addition of direct carbon dioxide management in the form of removals that the goal of the Paris Agreement can be met. Unfortunately, this doesn’t seem to be widely appreciated, with the exception of the United States and their 45Q tax incentives for CCS, Canada with their early demonstration projects and Australia with its behemoth Gorgon CCS project, creation of the Global Carbon Capture and Storage Institute and domestic focus on removals. Other countries are now scrambling to establish similar initiatives, but are somewhat lagging.

The case for CCS and carbon removals is an easy one to make – it emerges from any credible analysis of the energy system that accounts for likely future energy demand, real world deployment rates and the expected fossil fuel legacy that will persist into the 22^nd century even as significant reductions in use are made. Depending on assumptions, removals can stretch to a trillion tonnes of carbon dioxide over the course of the century. It is only in a scenario with a very constrained future energy demand that removals become less important, but still don’t disappear. The chart below, which I have posted before, shows the four IPCC 1.5°C archetype scenarios (P1, a high sustainability consciousness develops across society, to P4, a technology driven society with high energy demand and technical solutions to environmental issues) and the Shell Sky 1.5 scenario – all require carbon removals. In the P1 scenario sink use is quite low, highlighted by an end to land based anthropogenic emissions and the subsequent development of the land as an enhanced sink from mid-century on, at about 5 Gt per year drawdown of carbon dioxide. P1 makes no use of geological storage. By contrast, the P4 scenario makes very extensive use of geological sinks with BECCS playing a substantial role even as land based emissions are eventually reigned in.

So how does all the above relate to COP26? Of course ambition is very much on the agenda and removals are required to deliver on that ambition, but so are many other steps. However, one of the features of carbon removals is that they will likely have to emerge through cooperative action between governments. Remaining emissions and the availability of removal sinks probably won’t exist in the same geographies, so a global trade in emission sinks will need to emerge. This would happen under Article 6 of the Paris Agreement, which still remains as unfinished business after the rulebook negotiations at COP24 in Katowice. Article 6 establishes a framework for cooperative action between countries in realizing their NDCs, which includes trading carbon units across borders.

The charts below illustrate how a standstill in global emissions (at 300 units in the illustration) is brought to net-zero through cooperative action between governments and the aviation sector. Large scale cross border investment results from the development and trading of carbon units, including removals, that would otherwise not take place. This is why Article 6 is so important – it helps all sectors and Parties to the Paris Agreement reach net-zero emissions.

While the UK Government has many ambitious plans for COP26, and Article 6 is certainly among them, I believe that agreement on the Article 6 rulebook is the most important outcome needed from Glasgow. Apart from its future value to society, an agreement on this difficult piece of rule-making would demonstrate that countries can work together to achieve an outcome that may not be in their immediate self-interest. Article 6 brings a rigour to emissions reporting and accounting that we must have for net-zero emissions. It introduces concepts such as carbon budgets and emissions inventory adjustments for trade to take place, which progressively caps the emissions of nationally determined contributions and forces them towards exact quantification, rather than narrative description. Of course nations aren’t required to use Article 6, it’s voluntary, but once they choose to they must also choose accounting rigour.

After the failure to agree on the Article 6 rule-book at Katowice, great progress was made at COP25 in Madrid, but final agreement still wasn’t possible. Nevertheless, a text emerged that would do the job, although it was entirely bracketed. But the text did capture the key elements that are required for Article 6 to function;

Removals specifically referenced.
A simple but robust approach for adjusting nationally determined contributions (NDC – the national plan for emissions reduction and adaptation put forward by a country) when an Article 6 transfer takes place.
A centralized accounting and reporting platform, with a clear focus on the avoidance of double counting of mitigation actions.
The creation of a supervisory body for the 6.4 mechanism.
Specifications for the design of a 6.4 activity and subsequent issuance of associated emission reduction units.
An approach to meet the requirements for adaptation funding required under 6.6 of the Paris Agreement.
A transition arrangement for ending the Clean Development Mechanism (CDM) of the Kyoto Protocol. The CDM has left several countries holding project carbon units that they are keen to monetize so as to support the underlying internal project investment.
A simple framework giving some structure to Article 6.8, the non-market approach cooperation.

Nevertheless, some disagreement between countries remains and these issue will need to be resolved in Glasgow.

There is a set of issues related to the scope of an NDC and whether some activities that are in addition to the NDC and involved in a transfer should be subjected to the same adjustments as the Madrid text outlines. This feels like a distraction for two reasons; the NDCs should rapidly expand to cover all activities within an economy and if there are activities still not covered by the NDC, they have no place under Article 6 anyway as this provision of the Paris Agreement is about cooperation to achieve NDCs.

Another tough issue has been the need to give meaning and substance to 6.4 (d) To deliver an overall mitigation in global emissions. The proposal in the Madrid text is to cancel a portion of the emission reduction units issued to the 6.4 activity, but this is unnecessarily punitive. It also risks pushing all activities into simple 6.2 transfers, which would undermine the whole purpose of having a project based mechanism which is more suited to many countries. The discussions in Glasgow simply need to recognize that, by definition, a 6.4 activity and related transfer with NDC adjustments always results in an overall reduction in global emissions. This is illustrated in the diagrams above and is the inherent purpose of an emissions trading structure.

Finally, there is the lingering problem of how best to wind up the CDM and what then becomes of the projects still delivering reductions and the legacy unused CERs sitting in registry accounts. For projects that continue to deliver reductions, the answer seems straightforward – they continue to operate, produce CERs and these are transferred under the provisions of 6.2, which ensures corresponding adjustments to NDCs. In the case of legacy units, I think the IPCC have answered the question, both in the 2018 SR15 and the 2021 AR6 reports. Both reports show that the temperature rise is now around 1.2°C and both offer a carbon budget requirement from 1.1.2018 and 1.1.2020 respectively to ensure that 1.5°C isn’t passed. By rebasing the climate issue in 2020 (in the case of AR6), anything that happened before that is now irrelevant in that it is part of the 1.2°C baseline. The carbon budget they developed has subsequently informed Parties on their NDC requirements and is already being used by the UNFCCC to assess the NDC gap . Adding pre-2020 units to current mitigation activities is simply undermining the carbon budget calculation.

With an agreement hopefully reached on Article 6 in Glasgow, the spotlight will then turn to national governments to open up the possibility of cooperative arrangements. This could come through linking of trading systems, opening up trading systems to external units and encouraging the private sector to develop mitigation projects through Article 6.4. Importantly, governments should also follow the lead of Australia and develop protocols for removals, as these are the units that will be in particular demand as net-zero emission goals and targets need to be met. Europe, in particular, will need to accelerate its removals thinking, an area where it is lagging in its mitigation efforts.

On to Glasgow!

The simple climate maths the IPCC didn’t fully explain

dchone August 19, 2021

When I first started delving into the issue of climate change about 20 years ago, the clarion call of the day was to reduce emissions by 50% by 2050. Today, as we all know, the call is for net-zero emissions by 2050. Last week we also heard again from the Intergovernmental Panel on Climate Change (IPCC) with the release of the first part of the 6^th Assessment Report (AR6), which the United Nations Secretary General called a ‘code-red for humanity’. But both the call in 2001 and again in 2021 are entirely consistent. It’s not the climate science that has changed, just the carbon maths associated with it.

As the IPCC clearly state in Part D of the Summary for Policymakers of AR6-WG I;

This Report reaffirms with high confidence the AR5 finding that there is a near-linear relationship between cumulative anthropogenic CO₂ emissions and the global warming they cause. Each 1000 GtCO₂ of cumulative CO₂ emissions is assessed to likely cause a 0.27°C to 0.63°C increase in global surface temperature with a best estimate of 0.45°C. This is a narrower range compared to AR5 and SR1.5. This quantity is referred to as the transient climate response to cumulative CO₂ emissions (TCRE). This relationship implies that reaching net zero anthropogenic CO₂ emissions is a requirement to stabilize human-induced global temperature increase at any level, but that limiting global temperature increase to a specific level would imply limiting cumulative CO₂ emissions to within a carbon budget.

While the biggest difference between now and 2001 is the shift in the goal from below 2°C to 1.5°C which in turn has contributed to the change in required emissions trajectory, this is not enough to explain the shift in the required outcome by 2050. That change is more a function of the cumulative carbon math associated with any level of warming.

To limit the temperature rise to 1.5°C, the notional carbon budget based on the above best estimate of TCRE is 1.5/0.45*1000 = 3330 Gt CO₂ and for 2°C it is 4440 Gt. This is effectively targeting the central estimate in a range and is a calculation you might do before emissions start. However, we already know from IPCC AR6 that cumulative emissions of 2390 Gt correspond to a 1.07°C temperature rise in 2010-2019 vs. 1850-1900. They also indicate that the remaining carbon budget from 1.1.2020 for 1.5°C is 400 Gt and 2°C is 700 Gt for a 67% likelihood, which implies an overall carbon budget of 2790 Gt for 1.5°C and 3090 for 2°C with a good degree of certainty.

In the following calculations and accompanying charts I will work on the basis of a simple linear reduction in emissions to net-zero from a particular point in time to calculate the overall cumulative emissions. Returning to 2001, the annual CO₂ emissions (from energy, cement and land use) were approximately 30 Gt, the cumulative emissions from 1850 at that time were about 1700 Gt and a linear reduction pathway from 2001 for 2790 Gt final cumulative emissions (1.5°C) means net-zero emissions in about 2073. This is illustrated in the chart below.

As noted for 2001, cumulative carbon dioxide emissions since 1850 were at 1715 Gt (Source: Our World in Data), which means net-zero emissions in 2073 for 1.5°C and 2123 for 2°C. Back in 2001 the focus was more on 2°C, so targeting well below 2°C, to completely avoid the 2°C threshold, would mean net-zero emissions around 2100 and therefore a 50% reduction in emissions by 2050 assuming a linear decline.

But twenty years later the story is very different. At the time of the IPCC Special report on 1.5°C cumulative carbon dioxide emissions had reached 2300 Gt, so a linear reduction to net-zero had a target date of 2040. For 2°C it was 2077. In fact the IPCC opted for scenarios with a steeper early reduction pathway, and therefore targeted 2050 for net-zero emissions, but that means a very steep early reduction of over 50% by 2030 to balance the longer tail to 2050. With twenty further years of rising emissions, a considerable portion of the 2001 carbon budget had been consumed and therefore the date for net-zero emissions had moved forward in time dramatically.

In fact, for each year that emissions don’t reduce, the requirement for net-zero emissions comes towards us by a year, effectively narrowing the gap for action by two years. The IPCC Special Report on 1.5°C was baselined from 1.1.2018, so another four years has passed (or will soon pass). Even the recent IPCC AR6 is two years out of date now in terms of its carbon budget baseline. This rapidly shifting picture is shown below. In 2015 the target year for 1.5°C is shown to be 2042, a gap of 27 years, but by 2019 the target year is 2038, a gap of only 19 years.

Should carbon dioxide emissions remain at 40 Gt (below the pre-COVID high) for the coming few years, the available carbon budget for 1.5°C is rapidly consumed, as illustrated in the chart below. By 2025 net-zero emissions would be required by about 2033 and by 2029 net-zero emissions would be required before 2030, in other words the available carbon budget will have been consumed.

All the above presupposes that emissions cannot go below zero in the future, thereby drawing carbon dioxide out of the atmosphere and eventually correcting any overshoot of the carbon budget and its associated temperature goal. But negative emissions are a possibility, through the implementation of large scale air capture systems with geological storage (BECCS or DACCS) and enhancement of natural carbon uptake in the biosphere via programmes such as those that increase global forest cover and improve soil carbon management in agriculture.

Today, the carbon budget is still a rather arcane subject, well understood by a few but not widely appreciated in terms of relevance to managing surface temperature. That understanding will need to improve rapidly so policymakers can develop better mechanisms to manage it, also ensuring large scale deployment of atmospheric drawdown practices and technologies.

Pathways to 1.5°C

dchone June 11, 2021

In 2018 when the IPCC released their Special Report on 1.5°C, they presented four archetype scenarios to help readers understand that there were fundamentally different approaches to limit long term warming to 1.5°C or below. The scenario pathways are shown below and vary significantly in their approach, time horizon and use of sinks.

All four scenarios (P1, P2, P3, P4) are based around the same carbon budget, or total cumulative emissions of 420 Gt from 1.1.2018 consistent with providing a 66% chance of limiting warming to 1.5°C. Whether the carbon budget is aligned with 420 Gt (67^th percentile) or 580 Gt (50^th percentile), it represents a very limited amount given that annual CO₂ emissions are in excess of 40 Gt, so these represent 10-15 years of emissions at current levels. Since this IPCC publication, a further 160 Gt will have been emitted by society by the end of 2021, meaning that the budget is reduced to 260 – 420 Gt.

In attempting to align with a very limited carbon budget, the P1 scenario imagines a world of falling overall energy use and a very rapid shift away from fossil fuels. There is no use of geological storage of CO₂ and a modest reliance on natural sinks, although in doing so the world must shift away from net-deforestation by the 2040s. By contrast, the P4 scenario sees increasing demand for energy and as a consequence, a much more difficult decarbonisation journey that involves considerable use of sinks in the second half of the century. Notably, the P4 scenario exceeds the carbon budget by quite some amount with peak emissions to the atmosphere of 900 Gt, before reining in the amount to 200 Gt by 2100. This results in P4 being a so-called overshoot scenario, in that the world exceeds 1.5°C during the century before returning to 1.5°C and below by the end of the century.

All the above might seem a bit academic, but it became very real recently when the IEA released their 1.5°C scenario and some commentators began comparing it to one of the very few other 1.5°C scenarios, notably Sky 1.5 from Shell.

In fact, the two scenarios are at near opposite ends of the P1 to P4 spectrum.

The IEA 1.5°C scenario looks at the period from 2020 to 2050 and presents a proposal for the problem of containing emissions to a 500 Gt carbon budget (the 580 Gt IPCC number less 80 Gt for the years 2018 and 2019). Apart from recognising that the land based system is likely to reduce this budget by a further 40 Gt over the period (i.e. reducing it to 460 Gt), the analysis limits itself to the energy system and the changes that would be required to meet a 460 Gt cumulative emissions constraint within a 30 year time frame. As is the case in similar scenarios, including Sky 1.5, their analysis assumes rapid electrification of final energy (e.g. electric cars instead of gasoline) and makes use of renewables and nuclear power generation to produce the electricity. They introduce hydrogen as an energy carrier, make use of bioenergy and include carbon capture and storage (CCS) where fossil fuel remains in use. For the latter, the IEA deploy CCS directly on facilities that use fossil fuels and indirectly through direct air capture for fossil fuel use in applications such as aviation.

All the above steps are well understood, but even given rapid and stretching deployment rates of all technologies, these steps are unlikely to contain emissions to less than 500 Gt in under thirty years. This is because of the expected increase in overall energy use, a consequence of economic growth, the general rise in population and the shift of billions of people from very low energy use lifestyles to at least modest energy use, a simple outcome of development and the provision of basic services like lighting, clean water, food refrigeration and some mobility.

As such, energy modelers looking at a very constrained time frame of 30 years must make the assumption that energy growth can be contained or even fall, as in the IPCC P1 scenario. This is exactly what the IEA have done to meet the carbon constraint. In the 1.5°C Scenario primary energy demand falls from 612 EJ in 2019 to 543 EJ in 2050, a drop of over 10%. Efficiency will certainly help deliver such an outcome and the use of renewable electricity gives the story a big boost as the thermal losses in power stations vanish, although new losses emerge through the use of transmission and storage. But the big story is the widespread assumption of behavioural change across society to reduce energy demand. The chosen measures include steps such as;

Ride-sharing in all urban car trips
Reducing motorway / freeway speeds to below 100 kph / 60 mph.
Increasing temperatures in air conditioned vehicles and buildings.
Lowering temperatures in heated buildings.
Replacing short flights with high speed rail.
Limiting long haul air travel to 2019 levels.

With low energy demand and high deployment rates of new energy technologies it then becomes possible to resolve the carbon budget within a 30 year time frame.

At the other end of the spectrum is the Sky 1.5 scenario, which tackles the problem of a limited carbon budget in a very different way. Sky 1.5 looks at the period from 2020 to 2100, an 80 year time frame, and starts with an expectation of rising global energy demand, even assuming significant energy efficiency improvements across society. The growth in population and the demand for energy services, including significant new demand from developing countries for basic services, cannot be contained and energy demand rises. This immediately poses a challenge in that rising demand more quickly consumes the available carbon budget at the front end, when alternative energy technologies and sinks have not been deployed.

Sky 1.5 also recognises that for many energy technologies, the 2020s still remain a period of development and limited deployment and even for more mature technologies such as solar and wind, a period of early growth where change on a global scale will remain limited.

The solution to this approach is to accept that, at least in the short term, the carbon budget may be consumed and the temperature it is linked to (1.5°C in this case) potentially surpassed for a period of time. The subsequent rapid deployment of sink capacity, both manmade in the form of air capture with geological storage and natural as reforestation, then offers the possibility of a period of net-negative emissions later in the century, to redress the imbalance and reduce cumulative carbon dioxide emissions and therefore temperature. This is the approach that Sky 1.5 takes, as do the IPCC P3 and P4 scenarios. Sky 1.5 takes this approach out of necessity, in that the scenario reaches a limit on energy technology deployment and does not foresee a fall in energy demand.

The end carbon budget for both the IEA 1.5°C scenario and Sky 1.5 are similar, but the IEA restricts itself to a thirty year time-frame, whereas Sky 1.5 operates over an eighty year time-frame. Sky 1.5 is also remodeled by MIT within their integrated assessment model to give a temperature outcome, rather than simply using the IPCC central estimate for a carbon budget. The two scenarios are attempting to answer the same question, but take very different approaches to doing so. There is no right or wrong here, just different ways of solving a tough problem.

Note: Scenarios don’t describe what will happen, or what should happen, rather they explore what could happen. Scenarios are not predictions, strategies or business plans. Please read the full Disclaimer here.