Professor Barry McMullin:

I thank the joint committee for giving me the opportunity to contribute to its deliberations on this important topic. As I have made a written submission, I will just try to pick out its key highlights. I also express my personal appreciation for Professor Howarth's authoritative presentation. I cannot compete with his expertise, on methane in particular. I will briefly discuss the overall context of climate action, the general role of natural gas in the energy system and the specific question of the importation of liquefied natural gas.

The first questions are how urgent climate action is and what pathways are required to deal with it. The best scientific understanding is that to hold the long-term global temperature rise to a specified level, the total cumulative release of carbon dioxide, in particular, must be capped. Beyond that, we need to be at net-zero carbon dioxide emissions to stabilise the carbon dioxide concentration. This means that there is a finite global CO₂budget for further emissions of CO₂. The question then arises of who gets to emit it?

In recent work at DCU, in collaboration with Trinity College Dublin, we have attempted to assess the equitable share of the remaining global carbon dioxide budget that is available to Ireland, aligned with the temperature goals of the Paris Agreement. This yields a so-called national carbon dioxide quota. We arrived at a prudent, minimally equitable, Paris Agreement-aligned national quota of just under 400 megatonnes of carbon dioxide from 2015. Given that we emit approximately 40 megatonnes of carbon dioxide per year, this gives us a period of about ten years. In other words, our quota will be exhausted around the middle of the next decade, in 2024 or so. Climate action consistent with this quota will require the achievement of cumulative net-zero carbon dioxide emissions from 2025 onwards. This should be contrasted with even the most ambitious mitigation action envisaged in the 2019 climate action plan which targets net-zero carbon dioxide emissions no earlier than 2050 and possibly significantly later. The large discrepancy between these measures of the urgency of climate action may be accounted for by a variety of factors which I mention in my written submission. While there is scope for some debate over exactly how severe the challenge is, it is clear that for relatively wealthy nations with high per capitaCO₂emissions such as Ireland, net-zero annual CO₂emissions must be achieved much earlier than 2050 if the temperature and equity objectives of the Paris Agreement are to be respected. Therefore, the talk of 2050 as being the timescale we have available is not compatible with the objectives to which we have signed up in the Paris Agreement if we are to be equitable in delivering climate actions.

Natural gas plays a central role in the energy system. It is frequently asserted that natural gas has significantly lower CO₂emissions intensity than other fossil fuels and that it can, therefore, usefully function as a "bridge" or "transitional" fuel in overall energy system decarbonisation. In the case of Ireland, it has been argued on this basis that, even under plans for deep decarbonisation, natural gas can and should continue to be used at significant scale, at least until 2050 and perhaps beyond, and that, even with the most rapid possible roll-out of wind and solar electricity generation capacity, natural gas will still be "essential" as a "fuel of last resort" to cover periods when these intermittent sources of energy are not available. However, there are two key difficulties with this approach. First, it assumes a relatively late net-zero CO₂emmissions date of 2050 or beyond which, as I have just mentioned, is not compatible with our collective goals. Second, the assessment of lower CO₂emissions intensity is strictly correct only at the point of combustion. When the natural gas is burned, one gets more energy for a given amount of CO₂emissions at that point. If "upstream" emissions in extraction, processing and transport are accounted for, the value of a switch to natural gas is much more complex to assess. As Professor Howarth has discussed, particularly in the case of fracking but also for natural gas generally, any release of methane contributes disproportionately to the climate impact over and above the carbon dioxide on combustion. Given that such releases of methane are a specific attribute of natural gas use, in particular, a "substitution" of other fossil fuels by natural gas does not necessarily yield nearly the degree of climate mitigation that is claimed on the narrow basis of combustion emissions only. Furthermore, carbon capture and storage, typically cited as a mechanism that would allow much longer term combustion of natural gas, only happen at the point of combustion. They do nothing whatsoever to mitigate upstream emissions of methane or carbon dioxide. As to whether the use of natural gas is "essential" to reliable electricity generation, even under conditions of large-scale deployment of wind and solar energy generation, there are, in fact, multiple technologically feasible alternatives, but it would require another full session to unpack them in detail.

Regarding LNG, the general case for natural gas as a transitional lower intensity fossil fuel is relatively weak, but in the specific case of liquefied natural gas, it is undermined by two further critical factors. First, as Professor Howarth has mentioned, liquefaction and liquefied transport are in themselves energy intensive processes which require continuous refrigeration at minus162°C, which reduces the net energy yield and thus generally increases the emissions intensity compared with conventional, purely gaseous supply chains. This is true of conventional natural gas, as well as of fracked natural gas. Second, it is widely understood, as we have heard, that the primary source of LNG for importation to Ireland is likely to be gas extracted by way of fracking. There are very strong indications that such extraction is significantly more vulnerable to methane release than even conventional extraction. Again, it must be emphasised that such upstream emissions cannot be mitigated in any way by downstream interventions such as carbon capture and storage.

Like all industrialised countries, Ireland faces an acute challenge in rapidly decarbonising its energy system. Their scale and urgency are not widely appreciated and there are no simple or easy solutions. It appears clear, however, that deployment and the potential lock-in of additional fossil fuel infrastructure of any sort will not help and will most likely hinder an effective response.

I commend the joint committee on its careful and reflective deliberations. I will be happy to elaborate further on any of the points raised.