Electricity-based mobility (EBM) refers to vehicles that use electricity as their primary energy source either directly such as Battery Electric Vehicles (BEV) or indirectly such as hydrogen (H2) driven Fuel Cell Electric Vehicles (FCEV) or Synthetic Natural Gas Vehicles (SNG-V). If low-carbon electricity is used, EBM has the potential to be more sustainable than conventional fossil-fuel based vehicles. While BEV feature the highest tank-to-wheel efficiency, electricity can only be stored for short durations in the energy system (e.g. via pumped-hydro storage or batteries), whereas H2-FCEV and SNG-V have a lower tank-to-wheel efficiency due to additional conversion losses, H2 and SNG can be stored longer in pressurized tanks or the natural gas grid. Thus, they feature more flexibility with regard to exploiting renewable electricity via seasonal storage. In this study, we examine whether and under what circumstances this additional flexibility of H2 and SNG can be used to offset additional losses in the powertrain and conversion with respect to greenhouse gas (GHG) mitigation of EBM from a life-cycle point of view in a Swiss scenario setting. To this end, a supply chain model for EBM fuels is established in the context of an evolving Swiss and European electricity system along with an approach to estimate the penetration of EBM in a legislation compliant future passenger cars fleet. We show that EBM results in significantly lower life-cycle GHG emissions than a corresponding fossil fuels driven fleet. BEV generally entail the lowest GHG emissions if flexibility options can be offered through sector coupling, short-term and seasonal energy storage or demand side management. Otherwise, in particular with a large expansion of photovoltaics (PV) and curtailment of excess electricity, H2-FCEV and SNG-V feature equal or – in case of high-carbon electricity imports – even lower GHG emissions than BEV. ; ISSN:0306-2619 ; ISSN:1872-9118
Ambitions to mitigate climate change, increase the pressure to reduce greenhouse gas (GHG) emissions across all sectors of the economy, with significant implications for the energy landscape as well as other emissions sources. Switzerland has committed to reducing its annual direct emissions of GHG by 50% by 2030 compared to 1990. A major share of this reduction shall be achieved domestically while some emissions can be based on measures abroad through the use of international credits. The Swiss government has also formulated the long-term goal to reduce GHG emissions in 2050 by 70-85% compared to 1990 levels (including measures abroad), and to achieve climate neutrality after 2050. Today, domestic GHG emissions in Switzerland originate by about 60% from energy conversion in the transport and building sectors, and by 40 % from other sources including industry. Carbondioxide (CO2) is the major GHG that is emitted with the transport sector being the sector with largest contribution. Given this distribution of GHG emissions, particularly CO2 emissions in the demand sectors attributable to energy conversion and industrial production processes need to be avoided to achieve the climate goals. As of 2017, the Swiss electricity sector is already almost CO2-free as electricity is mainly generated from hydropower (60%), nuclear (32%) renewable and non-renewable combustible energy (5%) and other renewable energy (4%). Future pathways for the developments of the Swiss energy sector are framed by the Swiss Energy Strategy 2050, which aims at discontinuing energy supply from nuclear power plants in Switzerland, and promoting renewable energy and energy efficiency. The transformation of the Swiss energy economy calls for the deployment of new low-carbon energy solutions while maintaining the high level of energy supply reliability, which in particular applies to the electricity sector. One option to provide low-carbon energy services is an increased electrification of energy demand services while using low-carbon generation sources. Against the background of a growing share of variable renewable energy sources in the electricity mix, such as wind and solar energy, the challenges of temporal and spatial balancing of supply and demand is expected to increase in future. Temporal balancing arises due to the inevitable mismatch between renewable electricity production and demand as a consequence of day/night cycles, weather effects and seasonal differences, while spatial balancing is resulting from differences between the locations of electricity production and consumption. A future Swiss energy supply substantially relying on large shares of intermittent electricity generation (mainly photovoltaics and wind power) will need sufficient flexibility options. These must allow for shifting energy between day and night as well as from summer to winter: roof-top PV installations, which exhibit the largest potential for new renewable electricity generation in Switzerland by far, show a distinct seasonal peak in summer and daily peak at noon. These peaks in electricity generation – if not to be curtailed – must either be stored and re-used as electricity at times without sufficient generation, or transformed into other energy carriers such as gases and liquids, which can be used as e.g. transport or heating fuels. In addition to the flexible power plants operated in Switzerland already today, i.e. dam hydro plants and pump storage power plants, increasing the system's flexibility and installing of further flexible power plants and storages becomes inevitable at very high shares of wind and solar PV electricity production in order to operate the electricity system cost-efficiently and to ensure the system's secure operation. A related aspect concerning flexibility options is their location in the system, which, preferably, is close to the Solar-PV generation sites which are often embedded in the consumption centres. There are multiple technologies and measures to avoid CO2 emissions and to increase the energy system's flexibility with Power-to-X (P2X) technologies representing one possible option of the technology portfolio. As defined in this White Paper, the terminology "P2X" refers to a class of technologies that use an electro-chemical process to convert electricity into a gaseous or liquid energy carrier or chemical product (and vice versa), and which may include energy storage. As such, P2X technology not only offers the possibility of enhanced sector coupling between the power sector and energy demand sectors but also to provide short and long-term supply and demand balancing. The objective of the White Paper its supplementary report is to collect the major existing P2X knowledge and to provide a synthesis and evaluation for the Swiss energy market. With the aim to derive a technical, economic and environmental assessment of P2X in the energy system, the gas market, the mobility sector and the electricity market are specifically investigated. Where possible, the White Paper also provides information on applications of P2X technologies in production industries. P2X technology stands for a cluster of technologies which use electricity and other inputs in order to produce other secondary energy carriers. Hence, P2X comprises multiple conversion pathways and energy carriers. In this White Paper we focus on the conversion to hydrogen as well as further gaseous and liquid energy carriers, such as methane, methanol, OME and FT-diesel, as well as the reelectrification where appropriate. For industrial P2X applications further energy carriers/conversion pathways might be included (depending on available information). Since this White Paper focusses on P2X technologies based on chemical conversion processes, technologies for the conversion of electricity with the purpose to produce heat as target product is not in the scope of this White Paper. The White Paper on Power-to-X Technology and its supplementary report emanate from the corresponding project of the Joint Activity of five Swiss Competence Centers for Energy Research (SCCER) funded by Innosuisse with complementary funding from the Swiss Federal Office of Energy (SFOE).
