Frequently asked questions
In this section we would like to answer some questions about electric mobility. Please click on a question to view the answer. Explanations of vehicle concepts can be found in the technical overview.
Broadly speaking, electric mobility is a collective term for all modes of transport which acquire a certain amount of their drive energy from electric power. In a narrower sense, the term refers to vehicles used in motorised private transport which can be driven exclusively by an electric motor without the use of an internal combustion engine, at least temporarily.
The German government’s National Electric Mobility Development Plan defines electric mobility as all types of electric vehicles which can be recharged directly with electricity from the grid. This includes both pure battery electric vehicles and plug-in hybrid and electric vehicles with a range extender. According to this definition, hybrid vehicles (which are not charged from the grid) are not electric vehicles. In this case, however, hybridisation accounts for a reduction in fuel consumption.
Plug-in hybrids are vehicles with at least one internal combustion engine and an electric motor and a battery, which is usually smaller than in the case of fully battery-powered vehicles. As in the case of the latter, the battery can be charged using a power socket. With sufficient battery capacity, the vehicle can be operated primarily in full electric mode for the journeys undertaken. The environmental effects are significantly reduced by using electricity from additional renewable energies.
The plug-in hybrid concept allows the user a “soft” transition from conventional to electric drive. Regular charging can reduce the environmental footprint and reduce costs, but is not necessarily required for the use of the vehicle. This helps to assuage the range angst many users have regarding electric vehicles. On the other hand, it also carries risks: if PHEVs are powered mainly by combustion engine, the higher weight and higher production costs for the dual drivetrain have a negative impact on the environmental record.
The range extender is a combustion engine, or less often a fuel cell, that serves to extend the range of a battery-operated electric vehicle in exceptional cases. The battery in the vehicle is sufficiently large enough to cope with most day-to-day journeys. When the battery capacity is exhausted on a longer journey, the range extender uses a generator to provide electricity. This enables the electric motor to continue operation and simultaneously recharges the battery. This means that the range extender is operated under optimum loading, in which consumption is kept as low as possible.
The electrification of conventional vehicles reduces energy consumption by recuperating braking energy and avoiding the inefficient partial loading of the combustion engine. The vehicles are also emission-free during electric operation. If the vehicles are charged using electricity from additional renewable energy plants, electric vehicles have almost no use-related emissions. Electric vehicles also favour the further expansion of renewable energies, if they are charged preferred by intelligent power networks in times of high renewable energy production (e.g. in the case of strong wind). This creates a buffer for peak loading of the mains and increases the security of supply throughout the entire network.
Direct emissions from transport account for approximately 20% of all German CO2 emissions. A reduction is therefore urgently needed.
Hybridisation of combustion-engined vehicles makes them more energy-efficient and reduces carbon emissions. Due to the small number of electric vehicles on the road, their initial contribution to reducing greenhouse gas emissions is limited, even if they use renewable energies. The German government has set the target of putting 1 million electric vehicles on the roads by 2020, which corresponds to approximately 2.5% of the country’s passenger car fleet. However, a significantly larger market share of electric vehicles can be expected in the medium to long term.
Electric vehicles are virtually silent and so can contribute significantly to the reduction of the inner city noise pollution. Electric cars are also increasingly appealing in terms of operating costs owing to the comparatively high efficiency of the electric powertrain for urban driving.
To date this has been almost entirely dependent on fossil fuel energy sources and is therefore a main consumer of oil in Germany. However, almost all energy sources can be used to generate electricity, including renewable energies such as wind, hydropower and photovoltaics. This also reduces our dependence on fossil fuels.
Electric vehicles are also superior to their conventional counterparts in certain ways, for instance acceleration.
Parked electric vehicles can be connected to the mains power network for long periods and are therefore flexible in terms of when charging takes place. By controlling the retrieval of electricity from the mains, electric vehicles can be consumers during peak generation periods of fluctuating renewable energies – the term for this is “intelligent charging”. This could be an advantage especially in Germany with its plans for a high proportion of wind power.
Generally, electricity can also be fed back into the mains from the batteries in electric cars. This means that electric vehicles in larger numbers can function as consumers and temporary storage for fluctuating renewable energy in the longer term. The appropriate management technologies and calculation models are feasible, but the expansion of an intelligent mains power network is required to integrate them into the mains as temporary storage devices.
The growing number of electric vehicles would create a new consumption segment which would require new power stations to be built. If this capacity increase is achieved with modern coal-fired power stations (assumption: 800 g CO2 per kWh), the carbon dioxide emissions for an electric vehicle with an electricity consumption of 20 kWh per 100 km would be 160 g CO2 per km and therefore a great deal higher than for comparable conventional vehicles.
However, if electric cars run on electricity from renewable energies, this would result in a very significant reduction of carbon dioxide emissions for electric cars to around 6 g CO2 per km (assumption: 30 g CO2 per kWh). The benefits of electric cars in terms of climate protection only become apparent when electricity from renewable energies is used. In this regard, the use of electricity from renewable energies in plug-in hybrids and fully electric vehicles is a great opportunity to reduce greenhouse gas emissions alongside the local ecological benefits. This would provide an effective opportunity to further reduce climate gases in the transport sector.
Electricity from renewable energies is a scarce resource and will remain so for a long time to come. Its use should therefore generate the greatest possible effect for CO2 reduction: one kilowatt hour for an electric car replaces 4.5 km of mileage for a corresponding fossil fuel operated passenger car and therefore around 650 g of fossil fuel CO2. When the upstream chains are taken into account, this corresponds to over 900 g of CO2 equivalents for a petrol passenger car and around 730 g of CO2 equivalents for diesel passenger cars. The substitution effect corresponds to the replacement of the electricity from coal-fired power stations with wind power. In this case, this would result in a reduction of greenhouse gas emissions by approximately 800 g of CO2 equivalents per kWh. Energy management analyses show that renewable energies are primarily a substitute for coal-fired power plants and, to a lesser extent, lignite power stations.
If the prices of CO2 certificates rise, renewable energies will increasingly displace gas-fired power plants.
For example: one kilowatt hour of electricity, e.g. from an offshore wind farm, can avoid between 600 and 800 g of carbon dioxide emissions through this substitution. So the reductions that can be generated in electric cars through renewably generated electricity are similar to those in the electricity sector. This makes it equally important in terms of climate policy whether renewable electricity, produced under the Renewable Energies Act (EEG), is used for electric cars or replaces fossil fuel energy sources in the existing mains network. The additional localised ecological benefits support its use in electric cars, but the current implementation costs oppose it. The fundamental potential for stabilising the mains network cannot currently be estimated. The electric vehicle therefore represents a priority for climate politics, especially when it does not use the EEG electricity from existing facilities but incorporates additional generation options with renewable energy sources. For this reason, the BMU places great value on the electricity for electric cars coming from additional renewable sources.
The electricity requirements of electric vehicles will remain low in the medium term. For one million fully electric vehicles, the proportion of the entire gross electricity consumption would be around 3% of the current total consumption. There is sufficient potential to cover the electricity demands for electric mobility using renewable energies but it is currently limited by the relatively high costs. Financial leeway must be gained in order to tap into the additional potential from renewable energies for the transport sector. The time dependency for potential electricity requirements for electric vehicles therefore fits well with the Federal Environment Ministry’s expansion strategy for renewable energies, and does not conflict with the phase-out of nuclear energy in Germany at any point.
Even if there is a further growth in electric mobility, the electricity requirement remains comparatively low. The electric battery covering of one third of today’s car mileage would require around 5% of the current gross electricity consumption. As plug-in passenger cars run only partly on electricity, their electricity requirement is significantly lower, as is the increase in electricity demand connected with their introduction.
The theoretical potential for renewable energies amounts to many times the current electrical energy consumption and would be sufficient to cover the electricity requirement for electric mobility.
The potential for inland roof spaces for photovoltaics alone is around 700 square kilometres, when considering all competing uses, and this corresponds to an electricity generation potential of 105 TWh per year and has not yet even nearly been exhausted by the EEG.
Photovoltaics can therefore also be brought into connection structurally with mobility (roof installations on garages and car parks, noise barriers, systems on the vehicle). Furthermore, there is great potential for the importing of electricity from solar thermal power stations in the Mediterranean area.
The CO2 avoidance costs for the use of additional renewable energies in electric vehicles may well be higher initially than for some simple measures such as tyres with low rolling resistance, direct injection or improved gear ratios, which are still possible in conventional cars. However, the reductions achieved through cost-effective measures of this kind only amount to a few percent, and the overall achievable reduction is therefore limited.
More ambitious reduction targets are likely to require hybridisation of the power train in conventional vehicles, thus increasing the costs significantly. An almost complete avoidance of the CO2 emissions arising from the use of vehicles – for instance, when running an electric vehicle entirely on electricity from renewable energies – can never be achieved using cost-effective conventional measures.
Electric vehicles have numerous environmental advantages compared to conventional cars and should therefore be used more intensively.
However, as a new technology line, they have not yet reached market maturity and they also require an expansion of the infrastructure.
This requires targeted political action. However, it is not enough to simply bring electric vehicles onto the market: the political parameters are also important when it comes to the environmental impact. The full potential climate protection benefits of electric vehicles will only be realised when used with electricity from additional renewable energies.
The development of electric vehicles requires innovations in relation to the powertrain, the refuelling infrastructure and connection to energy management systems. As with other energy and transport technologies, which have not yet reached maturity, both funding for research and development and also support for the learning process, e.g. through field testing, are required. It is therefore important to improve battery performance and set value-added chains in motion. This is the only way to rapidly reduce the currently high additional procurement costs and enable electric vehicles to gain prevalence on the market.
- Last Updated on Friday, 22 November 2019 14:44