TECHNICAL DOCUMENTATION OF I3E MODEL VERSION 2. ESRI SURVEY AND STATISTICAL REPORT SERIES NUMBER 77 September 2019

This paper provides a technical description of the Ireland Environment, Energy and Economy (I3E) model. The I3E model is an intertemporal computable general equilibrium model with multiple firms, one representative household group, multiple commodities, government, enterprises, and rest of the world accounts. It describes the Irish economy in sectoral detail. This model includes a detailed description of energy inputs and concomitant greenhouse gas emissions and has been developed with the purpose of investigating the economic and environmental impacts of climate policies for Ireland

THE ECONOMIC AND ENVIRONMENTAL IMPACTS OF INCREASING THE IRISH CARBON TAX. ESRI RESEARCH SERIES NUMBER 79 OCTOBER 2018

This study investigates the economic and environmental impacts of increasing the current carbon tax in Ireland from C20 per tonne of CO2 to C25, C30, C35 and C40. For this purpose, an Energy Social Accounting Matrix (ESAM) is developed for Ireland with 33 activities, 39 commodities, and ten household groups based on disposable income. The ESAM reproduces the structure of the Irish economy including production sectors, households and the government and quantifies the nature of all existing economic transactions among the diverse economic agents. Furthermore, the ESAM includes the flows of energy and emissions, creating a framework that can examine how money as well as energy and emissions flows between production sectors, households and the government. In this way the carbon content of different products and different households’ consumption is estimated. The current carbon tax in Ireland stands at C20 per tonne of carbon and is levied to incentivise households and producers to reduce their use of carbon-intensive goods. The carbon tax is relatively low, however, and constitutes just 1.9 per cent of total taxes levied on commodities in Ireland. Carbon tax accounts for only 7.6 per cent of total excise duties levied on petrol and 14 per cent of all excise duties on diesel. Our results reveal that increases in the carbon tax affect the prices of diesel and petrol the most. A C5 increase will increase the prices of carbon commodities by on average 0.8 per cent, and a doubling of the carbon tax to C40 per tonne of CO2 will increase the prices of carbon commodities by on average 3.4 per cent. The diesel price is expected to increase the most due to an increase in the carbon tax, whereby a C25 tax would result in a 1.7 per cent increase in diesel prices. A C40 tax would result in a 7 per cent increase in diesel prices. Putting this into context, it can be noted that in 2018 alone consumers have faced much greater fluctuations in diesel prices. Consumers are accustomed to relatively large fluctuations in fuel prices and may not react to increases in prices, assuming prices will fall again. This makes it extremely important to communicate a clear commitment to an increasing carbon tax by the government

THE IMPACTS OF REMOVING FOSSIL FUEL SUBSIDIES AND INCREASING CARBON TAX IN IRELAND. RESEARCH SERIES NUMBER 98 December 2019

A subsidy is classified as potentially environmentally damaging if it is likely to incentivise behaviour that could be damaging to the environment irrespective of its importance for other policy purposes. Examples of such subsidies include providing fossil fuels (including diesel, kerosene, fuel oil, and peat) at lower prices to certain industries and providing fuel allowances to households to alleviate fuel poverty. While some publicly-funded supports can have important social and economic purposes, they can have a negative impact on the environment. While the main approach in Ireland to address this has been to use different excise duties, Ireland also introduced a carbon tax in 2010. The carbon tax is one of the primary fiscal policy tools used in several countries to reduce human-induced greenhouse gas (GHG) emissions. For the first time after the equalisation of its level on all fossil fuels in 2014, the Irish government increased the carbon tax from C20 per tonne of CO2 to C26 in 2020. It is expected that the total carbon tax revenues will increase by C100 million in 2020, compared to 2019. Notwithstanding this, the total budgetary cost of these fossil fuel subsidies, excluding the agriculturerelated ones, was around C2.44 billion in 2014, whereas the government’s total carbon tax collection was C390.9 million. In other words, the monetary value of environmentally damaging subsidies was over six times higher than carbon tax revenues. In 2017, the same ratio was slightly higher, since the total value of subsidies increased by 11.85%, whereas the growth rate of total carbon tax revenues was only 7.7%. This report analyses the economic and environmental impacts of the removal of eight different fossil fuel subsidies in Ireland by using the Ireland Economy-Energy-Environment (I3E) model. In addition, a separate set of scenarios in which the removal of each subsidy is accompanied by a gradual increase in the level of the carbon tax are run to quantify the combined effects of these policy instruments

THE ECONOMIC AND DISTRIBUTIONAL IMPACTS OF AN INCREASED CARBON TAX WITH DIFFERENT REVENUE RECYCLING SCHEMES. ESRI RESEARCH SERIES NUMBER 95 OCTOBER 2019

The recent all Government Climate Action Plan proposes an increase in the Irish carbon tax along a trajectory which reaches C80 by 2030. In line with this, this study investigates the economic, household level and environmental impacts of increasing the current carbon tax in Ireland from C20 per tonne of CO2 to C30 in 2020, further increasing it by C5 annually, thus reaching C80 (in nominal terms) by 2030. In our analysis, we examine not only the impacts of the increase in carbon tax alone, but also the impacts of how the carbon tax revenue is used, i.e. recycled. Our analysis shows that increasing the carbon tax will help Ireland reduce its emissions somewhat, but more initiatives are needed to reach the EU targets. Furthermore, an increase in the carbon tax will have limited impacts on GDP. The choice of how to use the revenues from the increased carbon tax will have significant implications for both macroeconomic impacts and household distributional impacts. Depending on the policy goal, the appropriate recycling scheme can reduce GDP impacts, decrease government debt, limit inflation or decrease inequality across households types

Reversible Pebbling Game for Quantum Memory Management

Quantum memory management is becoming a pressing problem, especially given the recent research effort to develop new and more complex quantum algorithms. The only existing automatic method for quantum states clean-up relies on the availability of many extra resources. In this work, we propose an automatic tool for quantum memory management. We show how this problem exactly matches the reversible pebbling game. Based on that, we develop a SAT-based algorithm that returns a valid clean-up strategy, taking the limitations of the quantum hardware into account. The developed tool empowers the designer with the flexibility required to explore the trade-off between memory resources and number of operations. We present three show-cases to prove the validity of our approach. First, we apply the algorithm to straight-line programs, widely used in cryptographic applications. Second, we perform a comparison with the existing approach, showing an average improvement of 52.77%. Finally, we show the advantage of using the tool when synthesizing a quantum circuit on a constrained near-term quantum device.Comment: In Proc. Design Automation and Test in Europe (DATE 2019