Scenarios description

Results for five sets of scenarios are presented: each set of scenarios represents a particular balance of effort sharing between agriculture on one hand, and energy and industry on the other.

As agriculture is the source of approximately one-third of Ireland's emissions (34% of Irish GHGs in 2018, largely methane and nitrous oxide), for every change of two percentage points in the mitigation achieved by agriculture, energy & industry must make a change of one percentage point in the opposite direction.

Within each set of scenarios, the main scenario is presented, along with four variants. The scenario sets, and their variants, are described below.

All scenarios presented (with the exception of the WAM scenario, which describes the previous Cimate Action Plan with additional measures) meet the Climate Action & Low Carbon Development (Amendment) Act 2021 targets to reduce greenhouse-gases [GHGs] by 51% by 2030, and net-zero GHGs from the energy system by 2050. The purpose of these scenarios is to inform the Climate Action Plan, 2021, (CAP2021), which will set forth sector-by-sector measures to achieve the Programme for Government mitigation targets.

Scenario sets

  • A25E65: 25% reductions from agriculture by 2030, 65% reductions from energy & industry
  • A33E61: 33% reductions from agriculture by 2030, 61% reductions from energy & industry
  • A40E57: 40% reductions from agriculture by 2030, 57% reductions from energy & industry
  • A51E51: Equal mitigation, 51%, from agriculture and from energy & industry
  • A55E49: 55% reductions from agriculture by 2030, 49% reductions from energy & industry

Scenario variants

The baseline scenario is presented as the first scenario in each set.

Early Action

As interventions often take longer to introduce than anticipated, and their outcomes can take longer to materialise, it is expected that action will be front-loaded, in order to give time for these effects to materialise in good time to deliver the budgets and targets, and to allow time for additional corrective measures if required. To force TIM to take actions in good time, rather than leaving everything to the last possible moment, the Early Action variant uses emissions constraints in the early years. The constraints are there so that the pathways reflect real-world constraints caused by uncertainties and unforeseen delays.

Late Action

This is an unconstrained scenario variant. It does not have the constraints on early emissions imposed in the Early Action scenarios. As such, the outcomes represent a “last minute dash”, where implementation of each measure is put off until the latest possible moment to take advantage of declining costs and improved supply chains (typically brought about by earlier interventions in other countries). The model does not introduce any unforeseen shocks or delays, and has perfect foresight, so a last-minute dash still leads to the targets being theoretically delivered on time.

LED

The Low Energy Demand (LED) variants represent the energy sector meeting the CAP2021 objectives through structural changes in energy service demands. Broadly, this encompasses densification of settlement patterns, very significant investment in public transport and walking and cycling transport, and de-materialisation of the economy, which enables large-scale modal shifts in transport, lower heat demand in buildings and lower demands for materials such as cement. A full outline of assumptions for the LED scenario are detailed here.

Tech-Optimism

  • Faster builds of on- and off-shore wind, and PV, are possible.
  • Bio-energy imports are available.
  • Hydrogen imports are available.
  • Carbon Capture & Storage available for fossil gas & bio-energy from 2027.

Assumptions and constraints

There are a number of assumptions and system-wide constraints common to all scenarios:

  • Emissions constraints are implemented from 2030 and linearly reduced to net-zero by 2050. The scope of the model extends to energy- and process- CO2 emissions only. Following the emissions inventory methodology, international aviation and shipping emissions are not counted in the emissions constraint.
  • There is a negative emissions “backstop” technology which the model can all upon to meet the emissions constraint, at €2000/tCO2, if no solution is available to it. In this set of model results, this backstop is only used in the "NAAM" scenario.
  • Model results are very sensitive to assumptions on the future availability and price of bioenergy supply (both indigenous and imported). In these scenarios it is assumed that bioenergy imports are limited to biodiesel and ethanol meeting strict sustainability criteria – no import of wood is enabled. All bioenergy production met with domestic resources as assessed by the Sustainable Energy Authority of Ireland’s Bioenergy Supply in Ireland, 2015-2035, which found that the total amount of solid, liquid and gaseous bioenergy produced in Ireland could reach 138 PJ by 2035.
  • Carbon Capture and Storage (CCS) technologies are constrained to start at 2030, with a 5-year lead time for construction required.
  • In the transport sector, it is assumed that electric vehices reach purchase-price parity with internal combustion engines by 2025, and that bioenergy can supply no more than 20% of existing internal combustion engine technologies, and vehicles powered by 100% biofuels are not enabled.
  • Other core assumptions and constraints are included in the documentation.