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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

Electric cars: technical characteristics and environmental impacts

The electric car seems to be a suitable instrument and a sustaining measure towards a more sustainable mobility future since it is four times more energy efficient compared to internal combustion engines (ICEV). Therefore, it is seen as a milestone towards a “Great Transformation”. The tank-to-wheel (TTW) efficiency advantage of battery electric vehicles BEV over ICEV, together with the efficiency jump by Li-ion batteries, enable the electrification of the automobile as long as it is moved in regional ranges of up to 100 km per day. However, the well-to-wheel (WTW) efficiency of electric cars can reach exemplary figures only when electricity is provided by very efficient power plants and infrastructure, best with renewable energy production. Also, electric cars should be incorporated into a variety of modern mobility concepts. Energy efficiency of a fuel cell vehicle (FCV) propelled with hydrogen is only slightly lower compared to BEV; however, a lot of energy is lost during production and provision of compressed H2 even in the case of water electrolysis powered with renewable electricity. Also, hydrogen filling station infrastructure is missing and would be very expensive to build up, different to the charging infrastructure needed for electric cars. Life cycle assessment of electric car mobility according to the literature already available is complex. Most life cycle assessment (LCA) data deal with the global warming potential. Since CO2-equivalents emission during the operation is dominating the LCA in total, an electric car can already have ecoefficiency advantages when charged with grid electricity (500 to 600 g CO2/kWh presumed). However, charging the electric car with renewable electricity (30 g CO2/kWh) improves its LCA performance significantly. Ecoimpact of smaller BEV is also much better according to the high ecoimpact of the battery, which must increase parallel to the size of the car. Some LCA studies published so far modeled quite heavy BEV, which are additionally assumed to drive periodically at higher speeds, both inefficient for a BEV. In contrast, a small BEV like the electrified Smart presented here and moved locally as well as regionally only can have the most beneficial CO2-impact. During an e-conversion of a used car, as shown with the Smart, life cycle CO2 emissions can be reduced by more than 80% compared to that known from ICEV. However, this is a first estimation under optimistic assumptions (e.g., battery lifetime), which is planned to be critically reviewed in a more detailed model later. Life cycle impact of BEV in categories other than the global warming potential reveals a complex picture, although BEV demonstrates advantages over ICEV in most categories. Some authors even conclude that ‘carbon footprint is not sufficient as environmental performance indicator’ here. One disadvantage of BEV is the acidification potential associated with the smelting processes of Cu, Ni, and Co since a lot of Cu and, in some battery types, Ni and Co also are essential elements of electrical components. Additionally, there are acidifying emissions of coal-fired power plants depending on the local value of this type of power production. However, to what extent the local nearly zero-emission advantage of electric cars is incorporated into LCA models is still a question. Toxic emissions like NOx and fine dust are today shifted to power plants through the use of BEV, where it is easier to limit and control them. The BEV advantage of a much lower noise emission, for example, is not appreciated so far (a guideline is in preparation). (A)

Language

  • English

Media Info

  • Media Type: Web
  • Features: References;
  • Pagination: 18p
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 01559894
  • Record Type: Publication
  • Source Agency: Bundesanstalt für Straßenwesen (BASt)
  • Files: ITRD
  • Created Date: Apr 7 2015 11:34AM