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Integration of e-vehicles into the grid reduces power fluctuations, but ….

Integration of e-vehicles into the grid reduces power fluctuations, but ….

Technology News |
By Christoph Hammerschmidt



Increasingly, flexible local energy units such as photovoltaics roof installations, wind generators and cogeneration units generate electric current. However, they are subject to external factors such as sun radiation or wind occurrence. This causes fluctuations in the grid, adding to the effects of varying energy consumption. On the other hand, the batteries of electric vehicles can represent a significant buffer storage capacity, offering the possibility to compensate such oscillations.

This option has been predicted theoretically earlier in smart grid scenarios involving the batteries of electric vehicles. However so far nobody was really sure if such a scheme would really work. In the research Project INEES, scientists and engineers from Volkswagen AG, green energy provider Lichtblick SE, photovoltaics systems vendor SMA Solar Technology AG and the Fraunhofer Institute for Wind Energy and Energy Systems Technology (Fraunhofer IWES) have investigated the preconditions and parameters necessary to achieve a stabilizing effect to the grid by pooling the batteries of multiple electric vehicles.

The combined batteries establish an energy storage close to the consumer capable of compensating fluctuations in the grid. In this system, the vehicles could charge their batteries to create additional consumption in times when wind or sun radiation were high, or provide electric energy to the grid in times when demand was high and supply low.

The concept has been implemented during a fleet trial lasting 12 months. Within the project, SMA Solar developed an experimental bi-directional DC charging station and produced a small series of 40 units. Carmaker Volkswagen equipped 20 electric subcompact vehicles (type e-up) with a bi-directional charging function and added a communications device between charging control and a backend computer. The company also developed a smartphone app as the user interface. Thus, the participants of the fleet test could evaluate how their personal driving behavior and the energy demand from the grid interacted. They could enable the grid to access their batteries to support the voltage. The result: In the first place they did not notice any limitation to their daily mobility. To motivate the participants to share their battery the scientists established a bonus scheme.

Through its control software, Lichtblick integrated the vehicles into the energy market. The result of the trial: Electric vehicles can provide a power reserve to the grid with high reliability and at very short notice. The energetic and economic analysis of the experimental setup however showed that under current legal and business conditions (in Germany) its is not profitable to use a pool of electric vehicles to yield balancing power. Legislative changes which are already planned as well as technical progress could significantly improve the profitability of such schemes in the future.

Fraunhofer IWES was responsible to perform the accompanying scientific research as to the load for the distribution power network and the economic benefit of providing balancing power with electric vehicles. According to the research, the economic benefit of such a setup lies in the energy efficiency in the first place. It is likely that this scheme can be rather successful amidst a market environment characterized by increasing significance of energy storage in the secondary balancing power market. It however appears difficult to achieve complete coverage of the operation costs of the pool.

The INESS project has been funded in part through the Germany Federal Ministry of the Environment.

Further information: https://s.fhg.de/abschlussinees  

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