Using e-mobile storage potential for the energy system
The mobile storage capacity offers high potential in an energy system based on renewable energies. But for bidirectional charging, the framework conditions would have to be optimized. The bne names energy policy measures.
16.07.2024 – According to the German government, around 15 million fully electric vehicles should be on German roads by 2030. This would not only CO2-Save emissions – but could also make a valuable contribution to the integration of renewable energies into the electricity system: At around 750 GWh, the e-car fleet would have 20 times the storage capacity of all German pumped storage power plants, says the German Association of the New Energy Industry (bne) and has prepared an analysis with the resulting recommendations for action.
Only a small part of the battery capacity of an electric vehicle is used for daily journeys and electric cars are parked most of the time, according to the bne paper. The unused mobile storage capacity offers great potential in an energy system based on renewable energies if it can charge bidirectionally, because this enables energy exchange in two directions. At present, the legal framework for bidirectional charging is not yet sufficient.
Advantages of bidirectional charging
Bidirectional charging enables energy exchange in two directions: into the battery, but also back again. In the case of vehicle-to-home, the electricity from the vehicle battery is fed back into the building or to the energy management system, explains the bne. In conjunction with a photovoltaic system, this can ensure a greater degree of self-sufficiency. With vehicle-to-grid, on the other hand, the electricity from the electric vehicle is fed back into the distribution grid via the wallbox. The electric vehicle acts as part of the overall energy industry system by feeding back its stored energy when it is needed – as far as the technology goes.
Expanding renewables faster, more flexibility
In order to leverage this potential, the federal government must now create the regulatory framework, demands the bne and has submitted seven concrete proposals to this end. "Parallel to the accelerated expansion of renewables, we need more flexibility. It is the central mechanism in the energy system of the future that will make the comprehensive use of renewable energies possible in the first place," says bne Managing Director Robert Busch. "We need a legal framework that does not hinder grid-friendly flexibility. Electric cars offer exactly this due to their storage capacity. We just have to release them."
Regulatory amendments necessary for feeding back into the grid
The seven energy policy recommendations of the bne now include concrete proposals for the implementation of bidirectional charging. "Above all, the double burden on mobile storage systems through levies, levies and taxes prevents an economically sensible use of the technology," says Busch. Although the federal government has recently made initial improvements with the law to modernize the electricity tax, these do not go far enough. So far, only V2H use cases, i.e. feeding back from the car into the home, have been simplified. For V2G, the feeding back into the grid, a corresponding addition is urgently needed.
Reducing bureaucratic obstacles
The law on modernisation and bureaucracy reduction in electricity and energy tax law has already created a good basis, according to the study, but has only partially solved the bureaucratic problems. Clear requirements now prevent users of e-vehicles from becoming suppliers and tax debtors. The authors of the study take a positive view of the clarification that for V2H use cases, i.e. feeding back from the car into the home, the electricity tax is only payable once, namely at the end consumer.
However, with increasing registration numbers, the public charging infrastructure will also become more important in the future, so that bidirectional charging must also be considered for applications other than in the home. Against the background of the Energy Performance of Building Directive (EPBD) and the resulting expansion of charging infrastructure for non-residential buildings, special attention should therefore be paid in legislation to the use case of "bidirectional charging at the employer", the bne experts recommend.
This is because the unloading of fleet and employee vehicles could make a significant contribution to reducing the necessary grid expansion if they are used to optimise load profile curves. Therefore, the initiative in the law to modernize and reduce bureaucracy in electricity and energy tax law is not sufficient, the authors of the study criticize, as it would currently not bring any improvement for V2B applications – in the sense of vehicle to business – as well as V2G – i.e. feeding back into the grid. Here, a revision would be necessary in the sense of an expansion to V2B in the commercial environment as well as V2G, according to the bne's recommendation for action to politicians.
Testing the practicality of data transmission
Furthermore, according to bne, there is a lack of concrete legislative requirements for the exchange of data between vehicles and the charging infrastructure. As a competitive energy industry association, bne is committed to a market that is free of discrimination. There must be a level playing field for as many market participants as possible.
In principle, storage systems would have to be delimited in terms of measurement technology in order to be able to market their flexibility, but with regard to measurement technology, politicians should not lose sight of practice. "High security standards are necessary to ensure system security," explains Busch in this context, "but security is not synonymous with the use of the smart meter gateway." Mandatory data transmission via intelligent metering systems should therefore be limited to a practical minimum, advises the bne. well