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IE-NETs WP3 Workpackage report: Life Cycle Assessment (LCA) of GHG emissions and Techno-economic Analysis of Bioenergy Production in Ireland

posted Sep 4, 2019, 6:19 AM by Barry McMullin   [ updated Sep 4, 2019, 6:19 AM ]

The IE-NETs team is pleased to announce the availability of the WP3 workpackage report on "Life Cycle Assessment (LCA) of GHG emissions and Techno-economic Analysis of Bioenergy Production in Ireland". From the Introduction:

Bioenergy technologies are diverse and span a wide range of options and technological pathways. However, the most favoured options and technologies will be those with the lowest life cycle emissions. Evidence suggests that options with low life cycle emissions are site-specific and rely on efficient integrated ‘biomass to bioenergy’ systems with sustainable land use management and governances. Life cycle assessment (LCA) can provide a scientific foundation for evaluating the ecological and economic sustainability of biofuels. In WP3 we use life cycle assessment (LCA) analysis as a tool to identify potential environmental impacts of end products from the various processes in the whole life cycle. We also apply techno-economic analysis (TEA) to bioenergy production systems to provide a more detailed understanding of their likely economic and technical impacts, including parameters for cost-benefit assessment and evaluation of risk.

IE-NETs WP2 Workpackage report: Mechanistic Modelling of Bioenergy Resource Potential in Ireland

posted Sep 4, 2019, 6:10 AM by Barry McMullin   [ updated Sep 4, 2019, 6:21 AM ]

The IE-NETs team is pleased to announce the availability of the WP2 workpackage report on "Mechanistic Modelling of Bioenergy Resource Potential in Ireland". From the Introduction:

So-called Bio-Energy with Carbon Capture and Storage (BECCS) is recognised as one of the more plausible potential technological pathways to achieve net negative emissions at significant global scale within this century (Smith et al. 2015). Among currently considered NETs, BECCS is particularly relevant to Ireland given the potential to substitute indigenous bio-energy for imported fossil fuel energy, thus enhancing energy security, balance of trade, and indigenous employment (assuming internationally competitive biomass production costs). However, it is unclear whether the possible indigenous biofuel production capacity could be sufficient to achieve net negative emissions (after economically preferred allocation to displacement of direct fossil fuel use in heating and transport, which would be expected to have lower marginal abatement costs than bio-energy electricity generation with or without CCS). Importation of biofuel to support BECCS operations in Ireland can also be considered; however, that would forfeit the economic co-benefits of indigenous biofuel production (security, employment etc.). International trade and emission accounting rules (to reflect the implied territorial separation of atmospheric drawdown and long-term storage) are also currently unclear. Accordingly, assessment of maximum feasible indigenous biofuel production is an essential component of assessing the potential for effective BECCS deployment in Ireland.

Is the new Irish “Climate Action Plan 2019” Paris-aligned?

posted Jul 14, 2019, 10:07 AM by Barry McMullin   [ updated Jul 15, 2019, 2:23 AM ]


Our recently published journal paper, McMullin et al. 2019, assesses Ireland’s maximum prudent ‘fair share’ of the Paris-aligned global carbon (CO2) budget, here termed our national CO2 quota, as c. 391 MtCO2, dating from 2015. This represents our estimate of an upper bound on the nett remaining “fair share” cumulative CO2 emissions available to Ireland, from the aggregate sector of fossil fuel energy and industrial processes (FFI) and land use (LU), from that time onward.  The paper compared this estimate with the likely cumulative emissions arising from both top-down policy goals and bottom-up projections based on actual policy measures. It found that, in all the considered policy scenarios, the quota would, in fact, already be exhausted by around 2024. Ireland would then start rapidly accumulating an implied “CO2 debt” — a “debt of (national) honour” or tacit commitment, imposed rather unilaterally on young citizens today, not only to achieve “nett zero” CO2 emissions to stabilize the debt (stop it growing larger), but to then quickly transition to sustained “nett negative” CO2 emissions over the following 2-3 decades, to “pay off” the debt and return to good faith alignment with achievement of the Paris agreement temperature goals.

However, that paper text was finalised shortly before the publication of a new “all of Government”, Irish Climate Action Plan 2019 (CAP-2019). In this blog post therefore, we attempt to assess whether this new plan gives a basis for substantially altering the (negative) policy assessments of the original paper. [Spoiler alert: the answer turns out to be "no"..]

Climate Action Plan 2019: What pathway of CO2 emissions reduction?

As we do not have a time machine to retrospectively start strong mitigation from 2015, and the measures in the new plan are unlikely to substantially change emissions for either 2019 or 2020, we will consider a set of pathways that all start by assuming that emissions for 2015 to 2020 are as recorded/projected in the most recent EPA projections (using the “with existing measures” data). 

Beyond 2020, the Climate Action Plan 2019 does not, in fact, clearly describe any target pathway either for national greenhouse gas emissions as a whole or for individual gases (such as CO2, the specific focus of the current discussion). This is a significant shortcoming in itself. Instead the plan equivocates between discussion of sectors defined nationally (such as an aggregate of “electricity generation, built environment and transport”) and sectors defined relative to EU policy measures (specifically demarcated between the EU Emissions Trading Scheme, ETS, and the non-ETS emissions). These different sectoral aggregates relate to each other in complex ways that are not explicitly decomposed in the plan, which makes interpretation difficult (and speculative!). Nonetheless, we will present a “best effort” attempt to arrive at a coherent definition of future CO2 emissions pathway(s) that are at least consistent with, if not explicitly mandated by, the plan.

The plan targets what it describes as a “2% per annum” reduction pathway specifically for the non-ETS emissions sector from 2021 to 2030, based on attainment of our agreed national level commitment to EU-wide emissions reduction under the Effort Sharing Regulation (ESR). It goes on to state that:

“... in the period between 2030 and 2050, a much steeper decline of 7% per annum will have to be achieved based on achieving a minimum 80% emissions reduction by 2050, relative to 1990.”  [p.27] 

Strictly, compounding year-on-year reductions at any fixed percentage rate would yield pathway segments that are mathematically exponential. However, mathematically linear pathways (characterised by reduction by a fixed absolute amount in each year, rather than by a compounding year-on-year percentage) are more typical in EU policies (such as the ESR) and for the presentation of indicative CO2 decarbonisation pathways by the Irish EPA, CCAC and SEAI. Further, the chart presented in the actual plan, illustrating the non-ETS emissions pathway to 2030 (p. 19), does in fact show a linear rather than exponential form. 

Accordingly, we will assume that the action plan is best interpreted as proposing to achieve emissions pathways (across sectors and gases?) that are, generally, piecewise linear from 2021-2030, and then again from 2031-2050, but potentially with different linear reduction rates in those two periods. Further, we will assume that, for 2021-2030. the rate (linear slope) will be fixed at c. 2% of the 2020 emissions rate. As already noted, this is stated explicitly in the plan for the non-ETS sector; and in the absence of more precise guidance, we will therefore extrapolate this to all national CO2 emissions (i.e., across both ETS and non-ETS). Beyond 2030, the reduction rate will be determined relative to a targeted point-in-time level in 2050. This later level is indicated to be (for the time being) an overall reduction of 80% relative to 1990 levels (at least for CO2, if not other gases) based on long term targets originally contained in the National Policy Position on Climate Action and Low Carbon Development of 2014. Those long term targets have expressly not been superseded in the new plan; though the plan does also commit (Action 1) that early consideration will be given to a “more ambitious” long term target of achieving “nett zero” emissions in 2050.

This yields an interpretation of the Climate Action Plan 2019 as envisaging (or committing to?) the following possible pathways for total future CO2 emissions in Ireland:

  • From 2021-2030, a linear pathway characterised by successive annual reductions of 0.86 MtCO2 per year, each year, representing 2% of projected nett 2020 FFI+LU CO2 emissions, for an overall 20% reduction by 2030 relative to 2020.

  • From 2031-2050 a divergence between two possible pathways, both again linear, and differing only in the “point-in-time” emissions level in 2050, being either:

    • 80% reduction compared to 1990, implying annual reduction of 1.34 MtCO2 per year, each year, equivalent to 3.1% of the projected 2020 level; or

    • nett zero in 2050, implying annual reduction of 1.72 MtCO2 per year, each year, equivalent to 4% of the projected 2020 level.

(We note that the 2031-2050 annual reduction rate of “3.1% of the projected 2020 level”, cited here as based on achieving 80% reduction relative to 1990 by 2050, appears substantially less than the 7% cited in the Action Plan. This discrepancy precisely illustrates the difficulties that arise due to the mixture of different and potentially ambiguous approaches to sectoral divisions, time baselines, and percentage and absolute reductions that are used at different points in the plan text, lacking clear cross-referencing, decomposition, or transparent mapping to public datasets, calculations or audit trails.) 

In Figure 1 we compare these two CAP-2019 based pathways with a reference linear pathway that is constrained to just use up (without overshoot or entering CO2 debt) our estimated maximum prudent ‘fair share’ quota of c. 391 MtCO2 (dating from 2015). Based on the projected accumulated emissions to 2020, this quota-constrained reference pathway would require successive annual reductions of 6.0 MtCO2 per year (representing 14% of the projected 2020 emissions level), each year from 2021 until it reaches nett zero, which would occur by about 2028 (and maintaining net-zero emissions thereafter). 

Figure 1: Annual emission pathways.

In figure 2 we show the corresponding cumulative depletion of the fair share quota (starting at the assessed prudent value of 391 MtCO2 as of 2015, in all cases). By construction, the theoretical Paris-aligned, no-overshoot, linear pathway would exactly exhaust the quota (c. 2028) and does not enter carbon debt (as there are no further nett emissions). By contrast, the Climate Action Plan pathways both exhaust the entire quota as early as 2024 and subsequently overshoot into CO2 debt. The pathway to -80% by 2050 reaches a cumulative CO2 debt of 615 MtCO2 (that would still continue to deepen even thereafter); and the pathway to nett zero by 2050 levels out (but does not yet start reversing) CO2 debt at 535 MtCO2 at that year. 

It is notable that the supposedly very significant increase of ambition represented by “nett zero” annual emissions by 2050 actually makes only a modest difference (c. 13%) to the level of CO2 debt accumulated by that time (albeit, it would at least have stopped growing under the nett zero constraint). Thus, the critical criterion in evaluating the effectiveness of CO2 mitigation is not some nominal “point-in-time” (2050) emissions rate, but the pathway toward such a point. Even for exactly the same “point-in-time” target (the same overall reduction in annual emissions), early cuts are much more significant than later ones, simply due to their additional duration in time. Conversely, procrastination not only implies that the deeper, presumably more politically challenging, reductions are kicked down the road, but that they may then have to be achieved against a background of potentially much more severe climate impacts (nationally and globally).

Figure 2: Ireland’s 2015 remaining quota of 391 MtCO2 is depleted by the nett CO2 emissions in each year for each pathway. CO2 debt occurs if or when the remaining quota becomes negative, tacitly implying a commitment to subsequent nett negative emissions to “pay back” this debt.

For comparison, our journal paper assessed inter alia the evolution of cumulative CO2 emissions that would have arisen if an exponential (consciously front-loaded) pathway toward even the nominally “less ambitious” 80% reduction by 2050 target had been immediately initiated when that point-in-time objective was originally adopted in 2014. While that would have still resulted in significant carbon debt (relative to our assessed prudent quota), it would have reached a level of only about 350 MtCO2 by 2050, substantially (35-45%) less than either of the pathways now suggested by the new 2019 plan. Thus, rather than representing increased ambition, this plan appears rather to retrospectively endorse a de facto erosion of ambition that has occurred since the National Policy Position was formally adopted (where “ambition” is here measured by cumulative CO2, as properly reflects the underlying physical science).

Conclusion: delay continues to undermine CO2 mitigation effectiveness

We conclude that the publication of the Climate Action Plan 2019 does not materially alter the (critical) findings of our earlier paper. The mitigation trajectories implied by the plan, insofar as they can be inferred, still prima facie suggest a very early exhaustion of our assessed prudent ‘fair share’ (Paris-aligned) CO2 quota, with consequent emergence of CO2 debt and tacit commitment to future “debt repayment” in the form of achieving large scale nett removal of CO2 from atmosphere, sustained over an extended period of time, currently with very poorly quantified cost and significant risk of failure.

On the positive side, the action plan does propose very significant strengthening of Irish climate action governance in the immediate future, including the introduction of a system of binding five-yearly “emissions budgets”, extending at least 15 years into the future. This is a very positive commitment which does represent significant opportunity for a step change in mitigation urgency and effectiveness. However, to realise this opportunity, it is strongly recommended that the governance reforms should also explicitly incorporate some overall binding cumulative CO2 emissions limit (quota), adopted on a statutory basis. While this statutory quota might, of course, still differ from the specific value identified in the current research, it is essential that it be scientifically and ethically informed on a basis of prudence and global equity, and be accompanied by a transparent articulation of how it is claimed to align with the Paris Agreement goals. Further, to the extent that any proposed sequence of five-year budgets would subsequently imply overshoot of this statutory quota, there should be a governance requirement to explicitly recognise this anticipated emergence of CO2 debt, and for that to be coupled with immediate planning for how the extent and duration of such debt will be limited.

Climate Emergency: How soon will Ireland's equitable, Paris-aligned, CO₂ emissions quota run out? [New ie-nets paper!]

posted Jul 8, 2019, 8:19 AM by Barry McMullin   [ updated Jul 14, 2019, 9:46 AM ]

Background: what is the problem?

The IE-NETs project is about investigating the potential for large scale deployment of "negative emissions", or "carbon dioxide removal", in Ireland, consistent with the Paris Agreement objectives. But why is this an issue of such critical societal importance? Simply because it has become starkly clear that, on a global level, there is now little or no atmospheric capacity left to "safely absorb" carbon dioxide (CO₂) pollution; and if — as now seems very likelywe collectively overshoot that level, then emergency measures to quickly achieve nett drawdown of CO₂ from atmosphere (removals exceeding emissions) will become urgently necessary.

By "safe" absorption of CO₂ into the atmosphere we mean having some reasonable chance of limiting global warming, and its associated deepening climate disruption, to a level where cascading collapse of global, and local, human civilisation can still be largely averted; indeed, ideally limiting to a CO₂ level where global humanity, and the wider biosphere, might still be able to flourish within the very real constraints of systemic planetary boundaries. We should however acknowledge that it is by no means certain that this is still feasible: and in such future scenarios, so-called "deep adaptation" responses may have to assume much greater priority; nonetheless, even from such perspectives, understanding the scope for achieving  nett drawdown of CO₂ (globally and locally) is still likely to be very relevant and important.

In any case, from this perspective of a finite, and rapidly dwindling atmospheric CO₂ capacity (the so-called Global Carbon Budget, or GCB), it is now a matter of central policy importance to understand how quickly this capacity will be exhausted. This is true at a global level, but, in the context of the "bottom up" architecture of the Paris Agreement, it is even more important to characterise this constraint at the level of the individual parties to that Agreement (where the capacity and responsibility for action actually lies). That is, we can, and should, ask what is the "fair share" of the remaining capacity for any given country to avail ofwhat we will here call the remaining "national carbon quota" or NCQ. The implication here is that continued nett emissions beyond the fair share NCQ will then carry a compelling ethical obligation to "clean up" or remove this (accumulating) excess before irreversible physical climate tipping points are triggered (i.e., within no more than a couple of further decades after the NCQ is exhausted). Formally, this is a good faith obligation to the other parties to the Paris Agreement; but properly, it should be seen as an obligation to all the people of the world, and most especially the young people of the world on whom the burden of discharging such "carbon debt" will be imposed.

The physical climate system is, of course, very complex. The dynamics of global human systems are even more complex; and the judgement of how much risk of cascading collapse dynamics might be tolerated is deeply value laden and highly contested. All these factors mean that it is not possible to assign an arbitrarily precise value even to the global-level GCB, never mind the even more contentious national fair shares or NCQs.  Nonetheless, it is still possible to quantitatively assess the range of plausible values both for the GCB and subsequently for the NCQ for any given country, within appropriately stated or argued parameters of prudence and equity. This is precisely what has been attempted, for the specific case of Ireland, in a new paper from the IE-NETs project, accepted for publication in the peer-reviewed journal, Mitigation and Adaptation Strategies for Global Change, as of 1st July 2019. We are delighted to say that, in accordance with the Springer Policy on self-archiving, the full text of the Authors' Accepted Manuscript (AAM) is now freely available as: Assessing Negative Carbon Dioxide Emissions from the Perspective of a National ‘Fair Share’ of the Remaining Global Carbon Budget. (The final authenticated version will become available shortly, following publisher copy-editing, and subject to journal subscription access, at: https://doi.org/10.1007/s11027-019-09881-6)


We present an assessment of the plausible Paris-aligned fair share nett cumulative carbon dioxide (CO₂) quota for an example nation state, the Republic of Ireland. By Paris-aligned we mean consistent with the Paris Agreement adopted at the 21st Conference of the Parties to the United Nations Framework Convention on Climate Change, at Paris, France in December 2015 (UNFCCC 2015). We compare and contrast this quota with both the aspirations expressed in the current Irish National Policy Position and current national emissions projections. The fair share quota is assessed as a maximum of c. 391 million tonnes of carbon dioxide (MtCO₂), equal to 83 tonnes of carbon dioxide (tCO₂) per capita, from 2015, based on a precautionary estimate of the Global Carbon Budget (GCB) and specific interpretation of global equity. Given Ireland’s high current CO₂ per capita emissions rate, this would correspond to sustained year-on-year reductions in nett annual CO emissions of over ‑11% per year (beginning as of 2016). By contrast, the CO₂ mitigation target indicated in the National Policy Position corresponds to nett annual reduction rates in the range of only ‑4.7% per year (low ambition) up to a maximum of ‑8.3% per year (high ambition); and projections based on current and immediately planned mitigation measures indicate the possibility, instead, of sustained increases in emissions at a rate of the order of +0.7% per year. Accordingly, there is a large gap between Paris-aligned ambition and current political and policy reality on the ground; with a significant risk of early emergence of “CO₂ debt”, and tacit reliance on rapid deployment of currently speculative (at relevant scale and feasible cost) negative CO₂ emissions technologies to actively remove CO₂ from atmosphere. While the detailed policy situation will clearly differ from country to country, we suggest that this methodology, and its CO₂ debt framing, may be usefully applied in other individual countries or regions. We recommend that such framing be incorporated explicitly into global mitigation strategy via the statements of Nationally Determined Contributions required to be submitted and updated by all parties under the Paris Agreement processes.

Full-text access and citation

Update for the Irish Climate Action Plan 2019? Stay tuned...

Note that finalisation of this paper pre-dated the publication of a new Climate Action Plan by the Irish Government in June 2019, and that plan is therefore not considered explicitly in the paper. While the core findings (in relation to the estimation of a prudent, good-faith, Paris-aligned, national carbon quota) are not affected by this new plan, we will shortly release a further blog post update, specifically assessing the implications of the new plan for the early exhaustion of Ireland's NCQ, and the likely effect (if any) on the timing and scale of the emergence of national "carbon debt". 

New Working Paper: Role of NETs in Deep Decarbonisation of Energy in Ireland

posted Mar 31, 2019, 10:27 AM by Barry McMullin   [ updated Mar 31, 2019, 10:28 AM ]

The IE-NETs project is pleased to release a new working paper, the detailed report on Work Package 4: Investigating the Role of Negative Emissions Technologies in Deep Decarbonisation Pathways for the Irish Energy System (Barry McMullin and Paul Price, March 2019).


As indicated by the IENETS WP1 assessment of National Carbon Quota (MCQ) pathways for Ireland (Price et al.2018, Chapter 8) and largely borne out by the modelling developed in this work package, Ireland’s (prudent, minimally equitable) NCQ is likely to be exhausted by 2023-2025, tacitly committing to some level of NCQ overshoot dependent on nett cumulative CO₂ emissions thereafter. The overall structure and evolution of Ireland’s energy system will therefore need to change and decarbonise very rapidly to limit the scale and duration of such overshoot, lest effective reversal of it becomes infeasible. This is the essential physical consequence of good faith commitment to the Paris Agreement. Sufficient carbon dioxide removal (CDR) using negative emissions technologies (NETs) would then be needed to return to the NCQ level within a very few decades (assumed in this report to be by 2100 at the latest). Cost effectiveness analysis of alternative energy system transition options for national energy and climate plans should therefore account for the full aggregate costs of long-term strategies toward fulfilling the Paris temperature objective (EU 2018, Article 15:3(b)). These costs need to include risk averse estimates of projected negative emissions reliance in terms of technology and the uncertainty attached to policy reliance on NETs such as BioEnergy with Carbon Capture and Storage (BECCS) and Direct Air Carbon Capture and Storage (DACCS) that are not yet proven or available at scale. Carbon commitment analysis of policy and modelled energy system pathways to evaluate their likely cumulative CO2 outcomes (nett and gross) is therefore essential to economic and feasibility assessment of the alternatives that do plausibly meet the Paris-aligned NCQ.

This work package investigated modelling options that could complement energy system models currently used to guide policy-making in Ireland and potentially provide useful additional insights into Paris-aligned energy system decarbonisation. The outputs from such coarse-grained modelling are not comprehensive and all quantified results presented should be treated with due caution as outputs that are only indicative of the overall mitigation outcomes of the particular scenarios. Nonetheless, the modelling outputs clearly indicate serious carbon commitment concerns and critical risks related to alternative scenarios and sketched the possibility-space of energy system change constrained by a Paris-aligned carbon quota, with or without use of Carbon Cpture and Storage (CCS) or NETs.

Using a newly developed spreadsheet-based modelling tool, Anthem, the strong effect of CCS on primary energy options is made evident – both in limiting fossil carbon combustion emissions and in enabling permanent CDR via BECCS and DACCS to limit and potentially reverse NCQ overshoot – as are the associated tradeoffs in CCS energy penalty and requirements for large scale infrastructure investment to capture and store such large amounts of CO2. Incorporating the potential backstop economic costs of CCS options into decarbonisation analysis may well militate in favour of other mitigation options: near-term supply-side constraint (rationing, in effect) of unabated fossil fuel energy to drive more rapid deployment of non‑bio renewables and planned reductions in societal energy demand; or early deployment of other NETs including land carbon storage and Enhanced Weathering (EW) and ocean carbon storage.

These findings are potentially highly policy relevant for near-term choices that will now determine the availability of energy to society within an equitable Paris-aligned cumulative carbon constraint. The over-riding advice to policy makers, and society at large, from this analysis is to act on these options without delay. A plan for sustained and substantial reductions in absolute system CO₂ emissions is required, aiming for nett-zero CO₂ emissions from aggregate energy, cement and land-use, including a period of significant nett negative emissions to cancel accumulated carbon debt following overshoot.

The work package included an initial assessment of a range of freely available energy modelling tools, following which two were selected for detailed model development – EnergyPLAN and the Ireland 2050 Pathways Calculator (IE2050). These were used to examine the carbon commitment of scenarios in terms of annual and cumulative CO pathways relative to the NCQ. Despite differing limitations of EnergyPLAN and IE2050, and some technical difficulties encountered in extending them usefully, it was worthwhile to examine how the “possibility space” of an energy system model is bounded by its design. In particular, working with these models was effective in assessing the embodied expert assumptions regarding deployment extent, transition timing and the inherent risks of making essentially ad hoc user choices (including our own) that may be questionable in themselves and need to be very clearly identified and logged in presenting findings. EnergyPLAN is focused on achieving an energy system based on 100% renewables (excluding nuclear), predominantly reliant for primary energy supply on variable renewables (VRE), wind and solar, with limited availability of bioenergy, enabled by access to large scale system flexibility via heat and chemical (electrofuel) energy storage at multi‑TWh y‑1 level. CCS is only relatively simplistically supported in the most recent EnergyPLAN release and BECCS is not explicitly represented. In contrast, IE2050 is designed with the intention of being agnostic toward energy system outcome, using a range of user choices for supply and demand ambition levers (including nuclear energy). However, its detailed internal design means that, in addressing any given mitigation target, it tends to favour unabated bioenergy (assuming unproblematic carbon neutrality for all bioenergy fuels), and implicitly excluding the high VRE+electrofuel alternative configurations that EnergyPLAN accommodates. Our work with these models showed EnergyPLAN’s usefulness in examining energy supply options (assuming nuclear energy is excluded) and in exploring system design whereas IE2050’s usefulness was more limited to examining demand options, particularly through changing the internal effect of some high ambition levers to find potential opportunities for plausibly increased ambition.

EnergyPLAN was used to validate the Green Plan Ireland data and findings of Connolly and Mathiesen (2014) and explore the implementation of the specified transition steps in a hypothetical scenario, whereby each step was fully completed in 5-year stages. This indicated that the earlier delivery of all steps, but particularly early investment in ensuring availability of electrofuel infrastructure in combination with very large scale deployment of offshore wind energy are critical to limiting NCQ overshoot while still maintaining access to levels of final energy consumption comparable to the current system.

Although useful in giving a limited assessment of the speed and extent of overshoot relative to different supply and demand policies, in the different ways discussed for each, neither EnergyPLAN nor IE2050 proved adequate to investigating substantive NCQ overshoot scenarios requiring significant and prolonged CDR from NETs. A new modelling tool, Anthem was created to provide specific additional insight on this question. Anthem is coarse-grained and schematic, based primarily on the thermal combustion emissions of hydrocarbon fuel pathways through time and any nett capture rate to storage. Despite this comparatively schematic approach, it proved effective in providing rapid carbon commitment analysis (CCA) for a variety of scenarios of carbon-based primary energy supply, with or without CCS and NETs. It yielded high-level, but correspondingly robust, insights into the annual and cumulative outcomes for energy availability to society, CO (nett value, gross emissions and gross removals) and quasi-permanent CO storage requirements for CDR and for CCS used for capture of emissions from cement production and continued fossil fuel combustion (FFCCS). Anthem was also specifically used to assess the energy system scenarios presented in the Draft National Energy and Climate Plan (NECP) for Ireland (DCCAE 2018). All of these scenarios indicate steadily increasing total primary energy supply (up to an horizon of 2040), without a committed or quantified use of CCS. Accordingly, they do not show a significant reduction in annual emissions, and would lead to overshoot of the Paris-aligned NCQ by 600 MtCO2 to 750 MtCO2 already by 2040. Separately, Anthem was applied to assess a Long Term Resilience Study of the Irish Energy system (GNI and Eirgrid 2018). This study envisaged increased use of lower carbon intensity methane (mainly natural gas, but including some limited biomethane), to replace the other fossil fuels currently used in the Irish energy system. The Anthem analysis shows that this would have a relatively minimal effect on emission reduction unless and until large scale CCS is also applied.

Climate mitigation is usually described in policy terms of “reducing emissions” within a “low carbon transition” but this framing is becoming progressively less useful as NCQ overshoot is approached. Within good faith commitment to the Paris Agreement, the overriding climate action objective and narrative is arguably now better focused on: radical, near-term and sustained reductions in unabated carbon combustion (fossil and bio‑energy) usage to near-zero as soon as possible; and, in parallel, investing in development of sufficient gross CDR capability, made available as soon as possible, to offset ongoing gross CO emissions and, in excess of that, to progressively cancel carbon debt within a very few decades by achieving nett negative emissions at least until returning to the NCQ level.

BECCS and DACCS remain highly speculative technologies with uncertain costs, energy input or output, and CO₂ removal capability. Therefore, their early delivery by 2030 shown in the various scenarios assessed, represents a likely upper bound on what might be technically feasible; in that sense the outputs of this research are coarsely informative in indicating the most optimistic relative availability of carbon-based energy and associated annual and cumulative emissions between scenarios over time. Continued high, near-term fossil fuel emissions and delayed negative emissions (gross removals) will inevitably tend to lock in progressively more cumulative CO₂ overshoot relative to the NCQ limit. In all of the scenarios, the ambitious but highly uncertain assumptions of a substantial indigenous supply of bioenergy of about 40 TWh y‑1 by 2050 while meeting stringent sustainability criteria and CCS availability, allows a supply of nett-negative-CO energy from BECCS which theoretically also enables a far slower reduction in fossil energy supply. However, as for the tradeoff between early unabated FF and later FFCCS, high levels of BECCS may therefore require limiting near-term harvest of forestry biomass, particularly avoiding its relative emissions-inefficient use in unabated bioenergy production, so that it can be conserved to allow much greater total carbon-based energy if or when harvest can be allocated to use in BECCS. DACCS is currently even more speculative than BECCS, likely requires large nett energy input (i.e., is not in itself a source of energy supply, but rather would result in a reduction in energy supply to conventional societal needs as DACCS deployment ramps up).

Ideally, all carbon removed from atmosphere into biomass should be prevented from re-release to atmosphere. So, specifically, in biomethane pathways, the CO that is present in the raw biogas, and separated during "upgrading for grid injection" should not simply be re-released to atmosphere. It can either be directly consigned to geo-storage, or used as a feedstock for P2M (producing "synthetic natural gas" or SNG by combining CO with H from water electrolysis using excess variable renewable energy (VRE) sources, especially wind; but in the latter case, the produced SNG should still be routed to some CCS combustion pathway to minimise CO release to atmosphere.

Unlike current energy projections, or energy system modelling results underpinningIreland’s National Mitigation Plan, the research in this report clearly indicates that an escalating level of climate action and intensive energy system planning is now appropriate in the very near-term to limit NCQ overshoot and deliver socio-politically manageable decarbonisation in accord with the Paris Agreement. As a matter of urgency, Irish society and its policy makers need to address very challenging near-term energy and climate planning decisions that could deeply affect economic and societal planning, with rapidly escalating future CDR costs for every year that required reduction pathways are not met. 

Key Policy Recommendations

Across all modelling frameworks studied, Paris-aligned mitigation, without national CO quota overshoot, would equate to achieving extremely rapid and immediate absolute reductions in near-term fossil fuel usage, at a year-on-year rate of c. 20%, falling effectively to zero within 10-15 years (c. 2030-2035). Due to the time lag of large scale infrastructure turnover and deployment, this finding remains robust even with the fastest technically plausible roll-out of fossil fuel carbon capture and storage (FFCCS). That is, a CCS “bridge” strategy would no longer be able to avoid overshoot; at best, FFCCS deployment can now contribute only to limiting the scale and duration of overshoot.

In fact, on current projections and policies, including those included in its Draft National Energy and Climate Plan [NECP] (DCCAE 2018), Ireland is likely to overshoot its prudent maximum Paris-aligned CO quota (estimated as 378 MtCO from 2015, here denoted LowGCB:pop) as early as 2023-25, representing a tacit commitment to carbon debt and implying significant future energy system costs for large scale carbon dioxide removal [CDR] via Negative Emissions Technologies [NETs]. Due to the low current Technology Readiness Level [TRL] of proposed NETs, these costs are subject to high uncertainty. Nonetheless, prudential estimates of such costs should now properly be included in any notional cost effectiveness analyses of future energy policy interventions.

In all scenarios with significant quota overshoot, deployment of NETs then becomes unavoidable to reverse such overshoot (assuming continued good faith participation in the Paris Agreement). The feasibility of doing this at required scale is highly uncertain and is likely sharply constrained by absolute cost. Indigenous territorial potential is further severely limited by bioenergy resource availability for bioenergy with CCS [BECCS], total low/zero-carbon energy availability for direct air capture (of CO) with CCS [DACCS] or enhanced weathering [EW], and relatively very limited total territorial CO geo-storage potential (required for all forms of CCS deployment).

Accordingly, even in the (likely) quota overshoot scenarios, near-term deep reduction in unabated fossil fuel use to limit the extent and duration of overshoot remains a key national risk management imperative. This suggests that, even in the short term, the finalised NECP (to be properly Paris-aligned) should show a national annual CO emissions pathway to nett zero with minimum quota overshoot: that is to say, achieving nett-zero annual CO emissions much earlier than 2050.

Coupled with rapid reductions in fossil fuel CO emissions, early deployment of BECCS could, in principle, contribute to achieving nett-zero and then nett-negative total energy system CO emissions (to reverse accumulated quota overshoot). However, this would inter alia imply early prioritising of bioenergy fuel use into BECCS in preference to unabated end use in transport and small or medium scale heating. Of course this does not dilute the requirement for deep decarbonisation of the latter energy use sectors; rather it points at the need to focus primarily on strategies for those sectors which are not based on unabated bioenergy use (e.g., direct electrification and/or end use substitution with non-carbon electrofuels such as hydrogen).

Projected cumulative nett CO emissions in the LULUCF sector significantly impacts on quota available for energy (or, conversely, requires significantly greater cumulative nett-negative emissions in the energy sector to compensate).

In parallel, early demand reduction in all sectors, and early investment in low-regret or no-regret mitigation options are likely needed to achieve sustained reductions in nett absolute emissions.

Low regret energy system decarbonisation options, including large scale wind and solar energy development, non-carbon electrofuels produced at periods of excess variable renewable energy as large scale energy storage, for grid backup and direct end use in heat and transport, and limited CCS + NETs are likely all now essential components to prudent and effective climate mitigation action.

WP4 Report Full Text (PDF)

Publication: "Assessing the terrestrial capacity for Negative Emission Technologies in Ireland"

posted Mar 27, 2019, 9:10 AM by Barry McMullin   [ updated Mar 27, 2019, 9:22 AM ]

The following article, based on work completed in the ie-nets project, has now been published (21 Jan 2019)

Alwynne Hannah McGeever, Paul Price, Barry McMullin & Michael Bevan Jones (2019) Assessing the terrestrial capacity for Negative Emission Technologies in Ireland, Carbon Management, DOI: 10.1080/17583004.2018.1537516 [Open Access Accepted Manuscript]


Negative emissions technologies (NETs) and their potential role in meeting emission targets is a rapidly growing and contentious area of climate change mitigation research. The literature ranges in scope from general reviews of NETs options to research and development through applied case studies. Within this field, a gap exists in the application of this growing body of research to the unique limitations and opportunities of a specific nation. Ireland is a small developed island nation in the EU with a unique emissions profile, as 32% of the total comes from agriculture due to the high number of cattle. In this study we aim to assess the potential capacity of terrestrial NETs options for Ireland and review the nation-specific context for their deployment. Despite the proportionally high representation of biochar and carbon capture and storage in the international NETs research, in an Irish context afforestation and bioenergy crops are much more established practices and could  readily be considered in possible emission pathways that use NETs. Higher capacities were found for NETs options that are currently unavailable (direct air carbon capture and storage and bioenergy with carbon capture and storage), while options available to deploy at scale (afforestation, soil carbon management and biochar) have capacities limited by saturation of soil carbon stock and have higher risk of reversibility due to impermanence. Hence, while we estimate a reasonable technical capacity for NETs in Ireland, emission reduction remains the highest priority for feasibly meeting a Paris-aligned carbon quota for Ireland. 

Prof. Mike Jones from the IENETS project discussing bioenergy and negative emissions on RTÉ

posted Dec 31, 2018, 6:29 AM by Paul Price   [ updated Dec 31, 2018, 6:32 AM ]

Available now on the RTÉ Player:  10 Things to Know About...Bioenergy: Prof. Mike Jones of IENETS  (from 18min 30sec into the video) discussing bioenergy and negative emissions in terms of future land use policy and farming choices, in particular stressing the urgency now needed in making science-informed decisions regarding bioenergy and negative emissions to complement direct emissions reduction. 

Prof. Mike Jones of IENETS on RTÉ 10 things to know about bioenergy

Assessing the role of (fossil and biomethane) gas in Ireland's Paris-aligned energy future

posted Nov 28, 2018, 7:31 AM by Paul Price   [ updated Nov 28, 2018, 9:01 AM ]

In this extended blog post we will look at two, highly contradictory, reports recently released on the future of natural gas (fossil methane) and biomethane in meeting Ireland’s future energy demand within long term decarbonisation objectives.

The first, McMullin et al. (2018), is a commissioned academic peer review (two of the IENETS team are co-authors) which concluded that plans to increase fossil gas dependence would be counter to Ireland’s commitment to aligning climate action with the Paris Agreement and would seriously undermine Irish long-term energy security compared to a wind and solar dominated energy system, combined with lower total energy use and renewable power-to-fuel (e.g., hydrogen or ammonia) for large scale (seasonal) energy storage.

The second report, a Long Term Resilience Study (hereafter we’ll call it the LTR Study) aiming to project future gas demand and examine the security of gas supply, was produced by Gas Networks Ireland (the Irish national gas network operator) and Eirgrid (the Irish national electricity transmission system operator), at the request of the Department of Communications Climate Action and Energy (DCCAE). Contrary to McMullin et al. and also at odds with ‘least cost’ studies previously produced for DCCAE for the National Mitigation Plan, the LTR Study advocates increased gas dependence, thereby inferring a pressing need for investment assessment of additional gas infrastructure (including a storage facilities and a floating Liquid Natural Gas terminal), a significant commitment to scaling up indigenous biomethane production and continued promotion of oil and gas exploration. However, as this blogpost analysis details, the LTR Study fails to address the national energy greenhouse gas emissions implications of such increased gas use within the necessary context of rapidly decarbonising the entire energy system. This failure to address these urgent decarbonisation in line with Ireland's commitment to the Paris Agreement fundamentally undermines the report’s projections and cost benefit analysis recommendations.

For the current IENETS project, projected gas supply and usage is highly relevant to aligning Ireland’s CO2 emissions and low carbon transition with equitably meeting Paris Agreement temperature targets and related global carbon budget. If projected emissions from proposed scenarios are likely to overshoot Ireland’s ‘fair share’ quota of the global carbon budget then Paris-aligned action would logically need to also include the costs of commitment to achieve planned carbon dioxide removal (CDR) from the atmosphere – using negative emissions technologies – to return Ireland’s nett cumulative emissions to its Paris-aligned quota level as soon as possible.

Two very different views of the future for gas

The LTR Study’s single mention of the Paris Agreement is that:

Ireland, in line with other EU member states, has signed up to the Paris Climate Change Agreement, and is fully committed to delivering on its climate change objectives within the current EU frameworks. p.8

The trailing caveat here, “within the current EU frameworks” is worth comment. Firstly, Ireland is an independent Party to the UNFCCC, so Ireland’s commitment to Paris is not solely through the EU. Additional national climate leadership by Ireland is not restricted to EU decisions and Ireland, as a full EU member state, can choose to advocate for higher EU ambition. Ireland has independently ratified the Paris Agreement and is therefore committed in any case to mitigation action aligned with meeting the agreement objectives, according to science and equity. Separately, EU frameworks are evolving such that the new National Energy and Climate Plans currently being produced by EU Member States will need to be show coherence with all relevant overarching targets, including the Paris agreement in particular.

In advocating continued and increased gas use the LTR Study cites the 2015 Energy White Paper Ireland’s Transition to a Low Carbon Energy Future, referencing it as a basis for stating that:

“as Ireland makes this transition the development of Ireland’s indigenous oil and gas resources has the potential to deliver significant and sustained benefits, particularly in terms of enhanced security of supply, import substitution, fiscal return and national and local economic development.” p.9

And then suggests that, therefore, further exploration for gas in Irish offshore is justified:

“there is presently significant interest in exploration for oil and gas offshore Ireland, following the 2015 Atlantic Margin Licensing Round. The discovery of a new indigenous gas source would reduce Ireland’s import dependency and diversify its gas supplies, thereby strengthening Ireland’s gas supply.” p.9

The LTR Study then describes a need for proposed infrastructure developments to improve the security of supply for gas and stresses an increasing economic importance of gas in future for electricity, transport and heating. In arguing that substantial continued reliance on natural gas specifically is critical and unavoidable (up to at least 2040) the LTR Study is very much in agreement with another report produced independently earlier this year by the Irish Academy of Engineering (IAE 2018).

However, strongly contesting these views, McMullin et al. in Is Natural Gas “Essential for Ireland’s Future Energy Security”? presents a highly critical analysis of the IAE’s report, a critique which now similarly applies in large part to the new LTR Study. While agreeing that relying on imported natural gas does result in very serious security-of-supply issues for the Irish energy system, McMullin et al. finds that:

  • Good faith commitment to the Paris Agreement requires far higher emission reduction rates than acknowledged by the IAE report (or, now, the LTR Study).

  • Displacing other fossil fuels in favour of increased use of gas will only escalate security-of-supply risk through escalating system reliance on a single fossil fuel.

  • Prioritising early exit from all fossil fuels, including gas, is now increasingly feasible, more certain in CO2 mitigation and more secure than a “gas bridge” transition.

  • Near-term and sustained energy demand reduction and progressive electrictrification of transport and heating would be critical to meeting a Paris-aligned pathway.

  • Excess wind and solar periods enable power-to-fuel (P2X) production of electrofuels: chemical gas or liquid storage of energy to ensure continuous, on-demand, energy supply.

  • All low and negative decarbonisation pathways are now extremely challenging, but rapid fossil fuel phase-out would deliver greater economic and social resilience.

  • Therefore, increases in (methane) gas dependence, new gas infrastructure and continued natural gas exploration are not advised for Ireland’s sustainability, economic development or energy-security objectives.

A key basis for these conclusions is the very limited time available for climate action given Ireland’s limited remaining CO2 quota, relative to the Paris global temperature targets. Note this is a quota allocation of total cumulative CO2 emissions because CO2 accumulates in the atmosphere to cause very long term warming. Our previous IENETS analysis concluded that precautionary climate risk management should be based on the low-end of an assessed scientific global carbon budget range, especially in light of Ireland’s significant land use emissions and high non-CO2 emissions (from agriculture) that are not projected to fall substantially. Allowing for even a minimal interpretation of meeting the “well below 2ºC” Paris temperature goal on a basis of equity, we assessed a “fair share” remaining CO2 quota for Ireland as a maximum of about 378 MtCO2 (80 tCO2 per capita) from 2015.

Based on a direct emissions analysis of SEAI fossil energy supply projections, Ireland’s continuing, high per capita energy CO2 emissions will exhaust this quota and Ireland will enter “carbon debt” by c. 2025, thereafter requiring (on a basis of good faith climate action) compensating negative emissions, in order to return to the quota level.

Therefore, based on this quota and current projections, all fossil and land use CO2 emissions from about 2025 onward will accumulate an increasing carbon debt or quota overshoot relative to Ireland’s good faith Paris commitments. This translates directly into an ill-defined but very high risk obligation imposed unilaterally on future Irish citizens as they must attempt to somehow reverse this overshoot by removing that excess CO2 from the atmosphere and return the associated carbon to secure (ultimately geological) storage. Further, this obligation will, by definition, may fall to be discharged against a background of severe societal stress due to intensifying climate disruption, locally and globally. Given good faith commitment to Paris-aligned climate mitigation and climate leadership, minimising this obligation, by minimising the extent of such carbon debt, is now a key imperative both for effective climate action and for protecting intergenerational trust and solidarity.

Having set out a cumulative CO2 framing for energy projections analysis, let’s look in more detail at the LTR Study in terms of annual emissions and the now binding constraints of conforming (in good faith) to a Paris-aligned cumulative CO2 quota.

LTR Study gas relative to Ireland’s remaining Paris CO2 quota

The LTR Study states that:

“The median demand scenario is aligned with Ireland reaching long-term decarbonisation targets.” p.11

We can examine this statement using the LTR Study projections and translate them into emissions to compare with the national CO2 quota. The study gives two scenarios of future annual gas usage, median demand and high demand, as shown in Figure 4.4 of the study, reproduced below.

Using the Paris Agreement year of 2015 as a start point for long-term decarbonisation targets we can use SEAI projections for gas usage for the data up to 2024 that is missing from this chart. The LTR Study also includes a plan for rapidly increasing Irish indigenous production of biomethane. Energy from biomethane combustion is assumed to be carbon neutral under EU energy-emissions accounting and could displace the use of fossil natural gas.

[It is important to note that the EU’s approach to overall bioenergy carbon accounting has been very strongly contested by numerous scientific reviews and papers (EEA 2011; EASAC, 2018). But we set that aside for the current discussion, and also accept the best case projection for biomethane production proposed in the LTR Study, in order to allow the most generous possible assessment of its emissions implications.]

By charting the LTR Study gas energy projections we can then compare them with a modelled projection of notional least cost energy-emissions for the minimum ambition “CO2-80” pathway aiming for an 80% cut in emissions by 2050 compared to 1990 (Deane et. al 2013). This pathway was previously produced for DCCAE using the IrishTIMES energy system model to inform the National Mitigation Plan (2017) climate action measures. That projection (starting from 2005) gave higher gas usage in 2015 than actually came about, therefore to give an indicative comparison in the charts below we adjust the Deane et al. IrishTimes modelled gas pathway to start from the actual usage and then, from 2020, mirror the CO2-80 relative changes over time.

As a result, in the chart below, we see the gas-only energy projection for annual energy from 2015 onward for these alternatives. The biomethane production projection is shown as a dashed brown line – assuming linear increases between the LTR Study data points in its Table 6.1. The total gas demand from the LTR Study Fig. 4.4, including projected biomethane, is shown by the dashed blue (median demand) and red lines (high demand). Subtracting the biomethane energy from the projected total gas energy gives the projected use of natural fossil gas for the two scenarios in the solid lines: blue (median demand) and red (high demand).  

Looking at this chart, the projected rise in total gas demand for both LTR Study scenarios is far greater than the modelled ‘least cost’ CO2-80 pathway, which projects a 15% reduction in natural gas primary energy supply from 2010 to 2050. By comparison, the more stringent CO2-95% emissions pathway requires a far greater 73% reduction in natural gas primary energy supply by 2050. Further, if the projected production of carbon neutral biomethane does not materialise then the shortfall in total energy from gas would need to be replaced by some combination of demand reduction and zero carbon energy sources to avoid any increase in emissions from use of fossil fuel energy, including natural gas.

The corresponding chart of CO2 emissions is shown below. The brown dot-dash line shows a bioenergy credit for (temporary) CO2 removal from atmosphere , arising from the photosynthesis process in growing the biomass used to produce the biomethane, corresponding directly to the CO2 that is regenerated in subsequent biomethane combustion (normally simply returned back to atmosphere). The solid blue (median demand) and red lines (high demand) show the projected nett emissions from the combustion of all gas, allowing for the bioenergy credit. The dot-dash blue and red lines show the level of gross gas-combustion emissions for the LTR Study scenarios including biomethane consumption, but exclusive of the bioenergy credit.

As already noted, EU energy emissions accounting treats bioenergy combustion as carbon neutral – any bioenergy combustion emissions are assumed to be exactly compensated by the bioenergy credit. However, a quantified carbon balance for the energy use would depend on the actual sustainability criteria and land use accounting basis for assessing the bioenergy credit. If bioenergy is supplied on the basis of a lack of enforced sustainability criteria or without verifiable, detailed land use accounting and strict monitoring of anaerobic digestion plants for methane leakage then the amount of bioenergy credit accounted to compensate for biomethane combustion emissions may need to be validated or estimated to allow for net emissions.

From these annual charts it is evident that even the median demand scenario of the LTR Study describes much higher gas supply and emissions rates than the notional least cost decarbonisation pathways described by IrishTIMES cost optimisation modelling previously commissioned by DCCAE. The difference between the IrishTimes and LTR Study scenario pathways would appear to suggest the LTR Study pathways are not aligned with the notional least cost decarbonisation, even for a (minimal) 80% CO2 reduction target by 2050. Although this economic modelling has similarly been produced for DCCAE to be ‘policy relevant’ it is not referenced in the LTR Study (nor, for that matter, in the IAE’s report).

Moving toward carbon quota analysis, cumulative CO2 emissions trajectories for gas only shows that, even if natural gas were the only fossil fuel in use and even if the projected carbon neutral biomethane production occurs, the LTR Study scenario natural gas usage alone would exhaust Ireland’s entire post-2015 carbon quota by about 2050. Of course, in reality, in the absence of radical, very near-term, reduction in fossil fuel use (not discussed in any material way in the LTR Study), the projected usage of oil, coal and peat, as well as gas, can be expected to exhaust the full quota even before 2025. As shown in the chart above, the natural gas usage projections of the LTR Study from 2025 to 2040 alone would then result in cumulative CO2 debt of 150 to 200 MtCO2, based on 9 to 15 MtCO2/yr annual emissions, requiring similar CDR, almost certainly dependent on using large scale geological CO2 storage, combined with either biogenic or technological removal of CO2 from atmosphere. However, the viability of such a sustained scale and quantity of negative emissions capacity would need to be assessed and costed within a full-energy-system cost-effectiveness analysis, under the constraint of meeting the required Paris-aligned nett cumulative CO2 quota.

Current government climate policy (based on the National Policy Position) suggests the use of nature-based land carbon sequestration (in forest and soil) to offset other land use (mainly agricultural) emissions. Therefore, any production of bioenergy will need to result in no additional land use emissions, particularly avoiding any nett additional N2O emissions by limiting or, ideally, decreasing total nitrogen fertiliser use in Ireland.

Carbon capture and storage (CCS) could possibly greatly reduce territorial emissions intensity of gas power plants by perhaps 90% assuming that investment in CO2 capture and storage infrastructure was achieved. If biogas or bioenergy combustion CO2 was captured and stored via CCS also then nett negative emissions could be achieved. The Irish Times energy system modelling for the National Mitigation Plan shows rapidly increasing amounts of gas CCS, but only from 2040 onward. Curiously, the LTR Study does not refer to CCS at all, even though Gas Networks Ireland and its parent company Ervia have been promoting the potential use of CCS for the gas-fired power stations in Co. Cork to take advantage of the geological storage potential of the now nearly exhausted Kinsale Gas Field. Estimated total CO2 storage capacity in the low pressure Kinsale field is 330 MtCO2, roughly the same as the gas-only CO2 emissions to 2050.

This carbon quota analysis suggests that to meet a precautionary Paris-aligned CO2 quota, CCS is needed as soon as possible if any fossil fuel use is planned after 2025, let alone increased gas use in addition to projected oil use. Inevitably, the energy penalty for CCS and the cost of additional infrastructure (capture plant, pipelines, injection and storage) add significant cost to future fossil fuel use, particularly if all CO2 released in Ireland by unabated combustion from 2025 will need to be compensated by subsequent permanent removals from atmosphere.

Decarbonising also implies gas+oil sector reductions

A key framing for the LTR Study is that:

”In the transition to a more sustainable future, and the phasing out of more carbon intensive fuels such as peat and coal, gas is likely to become increasingly important for electricity, transport and heating.”

This framing is commonly appealed to in the energy policy community, most particularly by those holding or responsible for significant existing natural gas assets or infrastructure. However, it is potentially misleading in terms of effective climate action. Above all, climate mitigation requires ongoing rapid reduction of absolute emissions, not just reductions in the carbon intensity of the different fossil fuels (or activities). Although the thermal combustion emission intensities of natural gas (205 g/kWh) and oil (264 g/kWh) are indeed lower than coal (341 g/kWh) and peat (415 g/kWh), total energy emissions in Ireland are dominated by oil (about 21 MtCO2/yr including jet kerosene) and gas (about 10 MtCO2/yr) whereas coal and peat already account for comparatively much smaller shares (about 6 MtCO2/yr and 3.5 MtCO2/yr respectively).

Therefore, although removing higher carbon intensity peat and coal from the energy supply is important, the future projected combined use of all fossil fuels is critical to any discussions of low carbon transition, including projections of future gas supply as in the LTR Study. As shown below, based on current policies and ESRI economic projections, SEAI project Ireland’s use of oil will not reduce (it may even increase) and gas use is projected to increase. Comparing with the previous charts, these SEAI projections are more in line with the high gas demand scenario. As before, the bioenergy credit is shown as negative emissions, without which the gross gas and total emissions are higher as shown by the orange and black dot-dash lines.

This chart shows additional emissions from gas and oil simply replacing the projected reduction in coal and peat emissions. Total nett emissions stay more or less unchanged (i.e., even if the bioenergy credit for biomethane is included). The most recent SEAI National Energy Projections to 2030, based on ESRI modelling, now show some reductions in energy CO2 by factoring in additional National Development Plan (NDP) and oil price assumptions but, as consequential rebound effects are not assessed by the SEAI, it is unclear to what extent spending cost savings from energy efficiency and conservation might result in emissions-causing activities likely to limit nett mitigation from policies.

For the same annual emissions but now looking at the cumulative CO2 emissions in total and by fuel compared to a Paris-aligned CO2 quota, in the chart below we can see Irish total cumulative emissions exceeding the national quota by 2024. A cumulative emissions pathway will only level out if the nett annual CO2 emissions go to zero, and nett negative emissions are required to then bring nett cumulative CO2 back down. The oil and gas lines continue upward because annual emissions are not going to zero, rather they are high and stable or increasing. Oil-related emissions alone are currently likely to emit a 2015-2035 total of 475 MtCO2, greater on its own than a 378 MtCO2 total CO2 quota, and gas could emit an additional 270 MtCO2 by 2035 in the high gas scenario.

As this chart makes clear, single fossil fuel or single sector analyses such as the gas and electricity-focused LTR Study are, on their own, insufficient to conclude that the scenarios given are “aligned with Ireland reaching long-term decarbonisation targets”. It seems evident that near-term reductions in the Ireland’s supply and demand for oil and gas combined are needed to limit the amount of CO2 quota overshoot and the scale of the corresponding tacit commitment to achieving subsequent nett negative emissions. Therefore, all carbon emitting fuels (especially oil) and technologies must be included in energy-emissions analysis of decarbonising Ireland’s entire energy system.

Based on the SEAI projections but using the LTR Study biomethane projection, the cumulative CO2 analysis shows that the projected rapid increase in biomethane production makes very little difference to cumulative CO2, even if achieved at the ambitious level suggested by the study. Although the gas energy-emissions projection in these charts is similar to the LTR Study high scenario, the median gas scenario would still have 2040 fossil fuel emissions of 9 MtCO2/year from gas alone (assuming zero nett climate emissions from sustainably produced biomethane) requiring the corresponding energy system analysis projections of oil, coal, peat and negative emissions in order to provide an appropriate decarbonisation assessment.

Paris-aligned energy choices require carbon quota analysis

In summary then, the LTR Study claim that its medium demands scenario is aligned with Ireland reaching long-term decarbonisation targets appears highly questionable in terms of Ireland’s fair share carbon quota and even in terms of published least cost analysis. The LTR Study’s cost-benefit analysis does not provide a comparison with the lower cost IrishTimes pathway, or include quota-alignment costs of carbon dioxide removal needed to compensate for unabated gas combustion (without CCS). Such costs would also need to include the upstream emissions related to natural gas, and the energy penalty of CCS. Similarly, the costs of assuring strict sustainability criteria for bioenergy are not stated. For example, biomethane produced from grass silage requires enforcement of limits on nitrogen fertiliser for grass growth and on fugitive methane emissions in in anaerobic digestion plants.

In the absence of a whole energy-emissions system analysis, the LTR Study is too narrowly focused on gas and electricity to make this claim. It also overlooks both ‘least cost’ decarbonisation analysis previously produced for DCCAE (Deane et al. 2013) and Paris-relevant cumulative carbon budget analysis (Price et al. 2018; Glynn et al. 2018). If energy emissions reduction is indeed the imperative that it is generally claimed to be, by government and in reports such as the LTR Study, then policies must, with high certainty, deliver a near- and long-term pathway of emissions reductions.

As McMullin et al. points out, there are also the costs of energy-supply risk in over-reliance on imported gas supply, and in the highly uncertain presumption of future discovery of more natural gas. Furthermore, there is the uncertain but multi-generational risk and long-term cost to our future of failing to restrict emissions in line with the Paris targets. In this context, nett zero or negative carbon energy should logically have an even higher energy and climate policy priority than short horizon energy security or current cost. Omitting costs skews cost benefit analysis, making options appear far less costly than they are within a system analysis demanding Paris-alignment of system decarbonisation.  

Viable options to stay within 1.5ºC or well below 2ºC are becoming ever more urgent, even with radical emission reduction and some limited commitment to nett negative emissions. As nuclear energy has been ruled out to date in Ireland and CO2 quota analysis shows continued fossil fuel dependence must rapidly come to an end, the only viable answer appears to be near-term and sustained energy demand reduction, combined with rapid roll-out of a 100% renewables energy system, primarily based on wind and solar generated electricity with a range of battery and pumped hydro for short-term grid balancing and chemical energy storage to provide seasonal or even multiannual security of supply.

McMullin et al. concludes that:

While the electrofuel storage element of this pathway is challenging in terms of technology maturity and immediate investment cost, this is true of all decarbonisation pathways that might credibly be commensurate with meeting the Paris climate goals; but this pathway has the unique advantages of high confidence in the effectiveness of decarbonisation and relatively rapid achievement of very high national energy security. Such a rapid fossil fuel phase out would additionally bring very significant co-benefits in balance of payments and overall national social and economic resilience.

Energy and climate policy requires a broad basis for the increasingly difficult energy and climate choices society and government now have to make. To be ‘policy relevant’, study scenarios and cost benefit analyses need to address cumulative emission quota analysis and how conclusions will assist in meeting a Paris-aligned energy and emissions pathway for Ireland. Cost-effectiveness analysis, as demanded by the Climate Act and as described by the Public Spending Code, requires such a Paris-aligned “national transition objective” to be defined and met by collective climate and energy policy. Without this overarching system perspective both costs and risks are likely to be greatly underestimated by narrowly focused or short-term studies.

Radical energy conservation measures to cut near-term fossil fuel use and early investments in large scale wind and solar with electrofuel back up, may be apparently expensive in the current absence of strong carbon management, but in a cost-effectiveness context aligned with meeting Paris commitments, thus requiring a national “fair share” cumulative CO2 quota to be met without fail, they may well be the optimal choice.


DCCAE, 2017. National Mitigation Plan 2017. pp.1–200.

Deane, P. et al., 2013. Technical support on developing low carbon sector roadmaps for Ireland Low Carbon Energy Roadmap for Ireland. ESRI e4sma UCC.

Gas Networks Ireland and EirGrid, 2018. Long Term Resilience Study 2018. Pp.1–42.

Glynn, J. et al., 2018. Zero carbon energy system pathways for Ireland consistent with the Paris Agreement. Climate Policy, 52, pp.1–13.

Government of Ireland, 2015. Climate Action and Low Carbon Development Act 2015. pp.1–25.

IAE (2018) Natural Gas: Essential for Ireland’s Future Energy Security. Irish Academy of Engineering. Jul 2018.

McMullin B, Price P, Carton J, Anderson K, 2018. Is Natural Gas “Essential for Ireland’s Future Energy Security”? Pp.1–21.

We need to talk about aviation…

posted Nov 15, 2018, 7:04 AM by Barry McMullin   [ updated Nov 15, 2018, 7:05 AM ]

We need to talk about aviation…

Barry McMullin, DCU School of Electronic Engineering
Twitter: @autofac
email: barry.mcmullin@dcu.ie
November 2018

[This is a slightly revision version of a post that first appeared on the DCU Brexit Institute Blog.]

I recently received an invitation from the DCU Brexit Institute to its next seminar, on the subject of Brexit and Aviation. It seems like an important and timely topic, with an excellent line up of expert and well informed speakers. Unfortunately, due to other prior commitments, I was unable to sign up to attend. Nonetheless, it did stimulate me to wonder what the scope of the discussions may be; and whether, in particular, it may venture into the truly challenging conversations that, I believe, we all need to be having about aviation (and much else besides!)...

The conversations I have in mind would go rather far beyond the most immediate headline concerns of aviation licences, approvals, certificates, and specific aerospace projects or collaborations (e.g., UK-Ireland flights will be grounded without post-Brexit deal, Irish Times; Hard Brexit will fail UK aerospace, Flight International; European Aerospace Braces for Hard Brexit, AIN Online). Instead these more profound conversations would start with the pressing global context of existential threat to our shared living environment: most urgently in the form of rapid, human-caused, climate disruption, but more generally in systemic overshoot of multiple planetary boundaries. It’s not that this context is unknown, hidden, or even seriously contested: but nonetheless we seem to still be sleepwalking in a parallel universe of cognitive dissonance and implicatory denial, where we can “know”, fully, that human society is plunging rapidly into deep ecological crisis, while simultaneously celebrating the joys of ludicrously “cheap” flying visits to Kiev, Kraków, Lisbon or Transylvania, and aspiring to seemingly insatiable growth in our collective aviation appetite.

But is it fair to pick on aviation as a special target for such difficult (and, let’s admit, potentially rather dismal) conversation? Even if we focus on climate specifically, and acknowledge that, of course, aviation does contribute to some extent, it is still surely only a small part of our overall planetary footprint (perhaps only 2-3% of current annual climate pollution? pffft!). And anyway, surely this is all well under control, and isn’t the aviation industry already leading the way in setting ambitious and robust targets for fully “green and sustainable growth”?

Sadly, of course, it is not as simple as that. In truth, the aviation sector has a number of more or less unique features which mean it really does need to be singled out for special discussion:

And then again, in “good news” (of a sort) our conversation might go on to reflect on the fact that aviation is, after all, not absolutely essential to human health or wellbeing. It is actually perfectly possible to envisage highly fulfilling ways of life that involve a lot less flying: and many people are actively starting to explore this.

Recent progress in communications technologies mean that many professional and business activities can now be effectively decoupled from long distance physical travel. There is an active petition for Universities and Professional Associations to reconsider their practices in relation to flying. And, without abandoning flying completely, the fundamental social inequity of the current model of global aviation could actually be actively moderated — if we can muster the collective will, and collective solidarity, to do so. And perhaps — just perhaps — if Brexit were to have the effect of slowing or even reversing some of the recent headlong growth of aviation in these islands, there may be ways to ensure that this is not the wholly negative outcome that might at first appear!

In closing, let me wish the participants in the seminar on Brexit and Aviation every success in your discussions and explorations. Managing a creative and constructive response to the challenges of Brexit is a worthy endeavour across all sectors, and is, of course, acutely impactful for those of us living in all parts of the island of Ireland. But I do hope you will still find some time to look beyond Brexit, and even beyond aviation, to view those specific topics in the wider context of our shared global predicament, a context that will necessarily transcend this (relatively) localised upheaval. Regardless of our current political affiliations and divisions, our cultural or ethnic backgrounds, our creeds or genders, this wider context surely suggests ethical demands that must (ultimately?) unite us in securing the future of our common home.

How much of our CO₂ budget is needed just to rebuild our energy system?

posted Aug 28, 2018, 4:00 AM by Barry McMullin   [ updated Aug 28, 2018, 4:04 AM ]

[Spoiler alert: I’m not actually going to answer the title question above — not quantitatively at least. But I think there is some merit even just in drawing attention to the fact that there is a question here that can usefully be asked!]

Early in the excellent book Our Renewable Future by Richard Heinberg and David Fridley (full text available online, open access), they present the following “big picture” perspective on the challenge of rapidly decarbonising our energy systems (locally and globally):

[Original image source: Michael Carbajales-Dale, “Fueling the Energy Transition: The Net Energy Perspective,” presentation at the Global Climate and Energy Project Workshop on Net Energy Analysis, Stanford University, Stanford, CA, April 1, 2015.]

Notwithstanding the notional quantitative units on the two axes, the graph is, of course, purely qualitative, but it does still convey an important heuristic insight: building energy infrastructure itself takes energy, and we only get a net energy (or energy service) “surplus” if or when that initial investment is “paid back”.

Unpacking this slightly, given that the technologies of a decarbonised energy system (energy sources, conversions, end uses) are, in significant measure, very different from those of our existing fossil fuel based systems, an awful lot of physical infrastructure will have to be replaced during the decarbonisation transition. And physical infrastructure all involves so-called embodied energy — as opposed to the operational energy that we are more generally familiar with:

  • Operational energy is energy used directly to provide some function or service. Thus the heat cooking food in an oven, the electricity lighting a bulb, the liquid fuel burned to produce thrust in an aviation engine are all examples of operational energy.

  • By contrast, the energy required to manufacture an oven or a light bulb or an aviation engine (or complete aircraft) is referred to as embodied energy.

Quantification of embodied energy can be contentious as it depends on choices of exact system boundaries: but in general it is intended to include all upstream operational energy required to create the target product or device. The concept of embodied energy applies equally to infrastructure, such as roads, railways, buildings, and energy system components including power stations, electricity grids, oil tankers, pipelines, vehicles, aircraft, refuelling networks etc. In the specific case of renewable energy systems, renewable source technologies such as wind turbines, solar panels, hydroelectric stations, etc. all have associated embodied energy. Similarly, to the extent that use of low-carbon or renewable energy sources may require progressive electrification of heating and transport, then new battery electric vehicles or heat-pumps, or additional grid infrastructure, all with associated embodied energy may be required. And in complementary manner, even interventions to enhance energy efficiency, such as in retrofit and renewal of the built environment, may involve associated embodied energy. (And in relation to energy efficiency, we will not even start on the complicating issues of rebound here…)

Given the current dominance of fossil fuel based infrastructure in energy systems (at global, regional, or national levels) it follows that the decarbonisation transition itself will involve a great deal of embodied energy. While some of that might substitute for energy that would otherwise be embodied in maintenance or refurbishment of the existing energy system, a great deal of it is likely to be additional i.e., it would not be required but for the decarbonisation of the system. At any given point in the decarbonisation of renewable energy transition, it will be the energy system of that time, and the carbon intensity of energy at that time, that determines the emissions associated with that embodied energy. Toward the end of the transition, that intensity will have become low (by definition); but early on, it will still be very high.

In effect then, decarbonisation itself involves a large scale commitment to additional CO₂ emissions, over and above emissions from all “ongoing” human activities (not directly associated with the decarbonisation transition).

As CO₂ is effectively cumulative, any given climate change temperature constraint (such as now embodied in the Paris Agreement) implies a limit on the total further amount of  CO₂ that can be released to the atmosphere, the so-called remaining global carbon budget. But the analysis above indicates that a potentially substantial component of this must be ring-fenced for emissions associated with the embodied energy essential to the construction of the new, decarbonised, energy system.

While precise quantification of this commitment (of embodied energy and associated emissions) is difficult, it strongly suggests a need to absolutely minimise, as far as possible (technically, socially, politically), the amount of operational energy used for any purposes other than for the energy system transition, until that transition is substantially achieved.

As far as I know, this heuristic system-level insight has not, as yet, been incorporated in any explicit way in practical energy transition policy (certainly not in Ireland?)... but comments/pointers are definitely welcome via our project twitter feed @ie_nets or direct email to ienets@dcu.ie.

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