A study of the 10% electric vehicles target of the single electricity market

In late 2008, the Government of the Republic of Ireland set a specific target that 10% of all vehicles in its transport fleet be powered by electricity by 2020 in order to meet European Union renewable energy targets and greenhouse gas emissions reduction targets. International there are similar targets. This is a considerable challenge as in 2009, transport accounted for 29% of non-emissions trading scheme greenhouse gas emissions, 32% of energy-related greenhouse gas emissions, 21% of total greenhouse gas emissions and approximately 50% of energy-related non-emission trading scheme greenhouse gas emissions. In this paper the impacts of 10% electric vehicle charging on the single wholesale electricity market for the Republic of Ireland and Northern Ireland is examined. The energy consumed and the total carbon dioxide emissions generated under different charging scenarios is quantified and the results of the charging scenarios are compared to identify the best implementation strategy. Introduction Transport represents one of the fastest growing contributors to greenhouse gas (GHG) emissions worldwide [1]. This is particularly relevant with concerns over global warming, security of energy supply and environmental pollution. Even though current car sales are sluggish in Europe and North America brisk growth is predicted in China mostly, with more modest increases in India due to economic development [2]. It is well established that car ownership, economic development are linked to increases in transport related energy demand and GHG emissions [3]. The use of oil as a fuel for transport is almost universal. For example in Ireland, it accounted for 98.4% of all transport fuel in 2009 and led to the transport sector accounting for about a third of Ireland’s carbon emissions and 41.4% overall energy demand [4]. The transport sector in Ireland has seen a reduction in carbon emissions and energy demand since 2007 after the economic downturn with carbon emissions and the transport energy falling by 10.1% and 9.6% respectively in 2009 [4]. The transport energy demand however is expected to grow annually at 3.2% until 2020 despite this reduction [5].The Irish government must reduce GHG emissions, fossil fuel energy demand and improve energy efficiency to comply with national policies and strict European Union (EU) directives. Electric vehicles (EV) are suited to adhere to these various commitments and reduce dependency on imported oil as a fuel for transport. The government recognised this in 2008 and set a target of 10% of all vehicles to be powered by electricity by 2020 [6]. The electrification of 10% of the transport in the Republic of Ireland will have implications for the single wholesale electricity market on the entire island of Ireland. The main impact associated with EV charging is the additional electrical load and the related changes or movement in transport-related energy demand and GHG emissions from the exhaust pipe or tailgate to the power system. These impacts are dependent on a variety of factors including battery charging efficiencies, time of charging, charge duration, the utility factor, the generation portfolio mix as well as the level of EV penetration in the transport fleet. Hadley (2007) found for a plug-in hybrid electric vehicle (PHEV) with an electric range of 20 miles and the emissions associated with charging to achieve this range that there was a reduction in carbon emissions compared to driving a conventionally vehicle for 20 miles [7]. Gerbracht et al (2010) found that some EV modelling preferred to dispatch interconnection power as a means of not exceeding CO2 emission limits [8]. This study also concluded that Foley, Tyther, O Gallachoir: 10% Electric Vehicles & the SEM 31st August – 1st September, University College Cork Proceedings of the ITRN2011 a review of vehicle emissions limits would need to be conducted if the transport sector became too reliant on external power to charge EVs. Yu (2007) found that additional nuclear and renewable energy sources would need to be dispatched to limit impact of EV charging associated emissions [9]. Foley et al. (2010) indicated that off-peak charging was the most beneficial for emissions reductions as it could achieve 1.4% of the 20% reduction for Ireland’s non-emissions trading scheme emissions target [10]. Although Marano et al. (2008) concluded that the introduction of EVs into a power system facilitates the economic viability of renewable energy sources which in turn will reduce carbon dioxide emissions [11]. Most of the work undertaken to date has been carried out using a battery to tailgate type analysis from the transport sector perspective with limited power system assumptions or with a plug to power station analysis from the electricity sector perspective looking at grid operation and impacts [12]. Methodology This section introduces the methodology developed to analyse the impact that EV charging may have on the single wholesale electricity market of the Republic of Ireland and Northern Ireland, called the SEM. A brief overview of the software used called PLEXOS for Power Systems by Energy Exemplar, the actual and a description of the power system in Ireland is provided. Foley et al (2009) compares PLEXOS to other similar power system software [13]. The EV charging profiles were built in PLEXOS from the model developed by Calnan (2011) using the Redpoint Energy Ltd., (2011) validated single electricity market (SEM) model [14 and 15]. The Redpoint SEM model was expanded by Calnan (2010) to account for the changes to the generation portfolio up to 2025. Generator properties including heat rates, forced outage rates, start costs, variable operation & maintenance (VOM) costs and loss factors, wind capacity on grid and interconnector data were gathered from EirGrid, the transmission system operator and the single electricity market operator (SEMO) in Ireland [16 and 17]. PLEXOS develops solutions by taking the input data operational and market constraints from the generation portfolio to dispatch power to meet demand as a series of models. Electric vehicle charging profiles create an extra demand load in the SEM. The EV load is imitated in PLEXOS using the purchaser function. These purchasers buy power causing the system to produce more generation to satisfy the load demands. The model is run with and without the purchaser EV load and the differences between the different simulations shows the impact that the EV charging profiles have on the power system.