Gigantic storage volume on four wheels

How electric cars will stabilise the power grid and reduce energy costs in the future

The discussion about the pros and cons of electromobility is full of blossoms. Sceptics like to argue that the electricity grid is not at all designed for this additional load.

The Bayreuth Guild for Electrical Engineering and Information Technology simply turned the tables at its recent annual general meeting in Oberobsang. A current research project on "bidirectional charging" clearly shows: as soon as energy can also be fed back from an electric vehicle, the power grid has immense storage capacity. This "battery on four wheels" can not only buffer the surplus from renewable energies, but also feed it back into the grid in times of high demand, thus stabilising the overall system. Electric cars thus become the ideal partner for fluctuating generation from sun and wind.

Bernd Zeilmann, head of the guild, tried to put the fear of an impending blackout due to electric mobility into perspective right at the beginning: The German petrol station network would also collapse if all internal combustion vehicles wanted to use the pump at the same time. It is just as nonsensical to assume that all electric car drivers would want to charge at the same time. However, when setting up the charging infrastructure for e-vehicles, it is very much possible to use intelligent measurement and control technology to ensure the most even distribution possible and to relieve the strain on the networks. In this context, the members of the Bayreuth Electricians' Guild have high hopes for so-called "bidirectional charging". Therefore, they had invited Erdem Uzun from the transmission grid operator TenneT and his colleague Wolfgang Duschl from Bayernwerk Netz GmbH to report on a joint research project with the car manufacturer BMW.

Using 65 specially converted BMW i3 vehicles, the project partners have investigated various use cases in private households and commercial enterprises over the past few years, all of which can be realised by drawing electricity from the storage system. In practice, it became apparent that the solutions found are beneficial for all parties involved: The vehicle manufacturer benefits because his car offers an additional benefit. The power grid is relieved because power fluctuations can be balanced out via the battery. And the customer is also happy because he can make better use of flexible electricity tariffs or the energy from his own roof and thus save money.

The fact that electricity can also be drawn from a vehicle battery is not a new idea. Some manufacturers already offer the possibility of operating 230-volt electrical appliances via a permanently installed socket on the car. But the actual benefit of an electric car fleet can be much greater than the occasional operation of a hand-held circular saw in the wilderness. According to current estimates, around 20 million electric vehicles could be registered in Germany as early as 2035. With an average battery size of around 50 kilowatt hours per vehicle, a storage facility of around 1,000 gigawatt hours would then be available, which is about 25 times the capacity of all German pumped-storage power plants. The experts firmly believe that this huge storage capacity can also be used to balance out fluctuations in the electricity grid and buffer surpluses from renewable energies. Of course, this only works if the vehicle is connected to the grid. However, this should be the smaller problem, because usually a vehicle in Germany is only moved for one to one and a half hours a day. The rest of the time it spends in the garage, on the company car park or elsewhere, often within reach of a grid connection.

The research project, which was launched three years ago, has since been able to impressively prove that the implementation also works technically. According to Erdem Uzun, a whole range of new applications for the electric car storage system can be realised in combination with intelligent measuring systems and specially developed software. On the customer side, of course, the optimal utilisation of the cheap energy from one's own PV system is at the top of the wish list. But in addition to this optimisation of self-consumption, a vehicle battery can also be used, for example, to absorb power peaks. This application offers considerable potential for cost savings, especially for companies. In addition, it has been shown that the storage units could also be profitably used for electricity trading on the stock exchange in the future. The vehicle batteries could also be used to stabilise grid fluctuations or provide an emergency power supply. According to TenneT's vision, bidirectional charging will be an integral part of the energy system as early as 2030.

The partners in the research project pioneered the development of the necessary software and hardware components. New interfaces and communication profiles had to be created for the interaction between the vehicle and the power grid. In combination with the new, intelligent electricity meters, solutions were created that could fulfil much more complex tasks than simply switching on or off, said Wolfgang Duschl from Bayernwerk Netz GmbH, who was live from Regensburg.

Even though renowned manufacturers such as VW have already announced that they will soon equip their vehicles with the corresponding capability, there is still a long way to go before bidirectional charging can actually be used on a broad scale. So far, the federal government has not yet created the necessary framework to map the sometimes complicated processes of charging and feeding in electricity in a legally secure way. However, a whole series of recommendations could also be derived from the research project, which must now be discussed with the federal government in the expert committees. According to the experts' optimistic assessment, the rules should be in place in one to two years. Then the vision of a rolling battery storage system that accelerates the energy transition could finally become reality.


Digital planning and building

Earlier, Peter Kaiser, a specialist planner from Forchheim, had spoken to the guild members about the serious changes in the planning and construction of buildings. The so-called "Building Information Modelling" (BIM), a new, very detailed level of digitalised planning, will radically change the entire process of creating a building. This will also affect the electrical and IT sectors, Kaiser warned, and not just in the distant future, but basically as of now.

In the planning process using BIM, a digital copy of the building is created in an unprecedented level of detail. This goes far beyond the previously known 3D models that have been used for years in the field of architecture. Even all levels of technical planning for building services, including cable routing and the exact position of individual components, are digitally and multi-dimensionally recorded. Even the make and colour of a light switch can be stored in the plan.

Basically, says Kaiser, the entire building is reproduced on the computer. Even the function of the individual components can be recreated so that, for example, switches can be operated and actions triggered. Through the detailed representation with real components, the expert planner hopes, problems can be detected and remedied at an early stage. Incorrect planning in fire protection or space problems in cable routing - basically classic errors that still cause trouble and additional expense on almost every construction site today - could be avoided in the future because the digital building model makes these errors visible already in the planning process.

Kaiser predicted that BIM would make tendering and bidding much easier. Thanks to the digitalised planning process, a detailed bill of quantities could be issued at the push of a button. This would save an enormous amount of time for both the building owner and the trades. According to Kaiser, the Free State of Bavaria also relies heavily on the advantages of fully digital planning. Every state building authority is required to carry out three BIM projects this year. From 2025, Building Information Modelling is to become the standard for state planning.


Honours for the best in the examinations

During the meeting, Michael Schübel (Schwender Energie- und Gebäudetechnik GmbH), Marvin Markhof (Elektro-Markhof) and Maxim Leonhardt (Fränkische Baugesellschaft, Freileitungsbau und Elektroinstallation GmbH), the best examinees of the journeymen's examination, were awarded. They received their journeyman's certificate together with a small gift.

Editorial Peter Kaiser
Peter Kaiser

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