The e-car as a flexible power storage device

Energy cannot be generated or consumed, but only converted into another form (Mayer, physicist, 1842).



It is a matter of using energy sensibly and converting it in such a way that energy can be used one hundred percent. The electricity energy from the PV system is converted 1:1 into thermal energy by our energy storage heating system without any energy losses (Hemstedt, A., 2022).


Using your own e-car not only to power your own house, but to strengthen the entire power grid

Electricity is the energy that can be generated most easily and efficiently - and above all almost everywhere - from the inexhaustible power of the sun in a completely climate-neutral and clean way: be it solar power, wind energy, hydroelectric or tidal power. The only important thing is a well-organized use of this energy - and HEMSTEDT has the right ideas for this:


Energy storage - the night storage heating of tomorrow!

The GREEN ACCU MAT® is laid deep in the ground and uses concrete and screed as a storage medium for thermal energy. Thus, in phases of energy surplus (from own generation or e.g. from nightly wind energy) the floor can be heated up and afterwards the heat can be released again for hours without reheating (see Fig.1). In principle, the idea of night storage heating is quite simple - but in the course of the energy turnaround, surplus and anyway available wind energy is used here at night, for example!


Bidirectional charging

When the sun is shining and the wind is strong, the electricity produced is temporarily stored in the car battery. When there is no wind during the day or at night, the smart dual charging box provides the energy return (see Fig. 2). This makes wind turbines that have to be shut down because the grid can't absorb power a thing of the past. But it's not there yet. While there are already some bidirectional DC fast chargers, they are expensive and currently only of interest to fleet operators. The Volkswagen Group has big plans for bidirectional charging. The batteries of all ID models should soon be able to deliver electricity again. The Volkswagen brands ŠKODA and SEAT as well as the Volkswagen subsidiary AUDI are to follow in the foreseeable future (AUTO BILD, 2022, pp. 16-17).


In today's world, the topic of energy storage is becoming increasingly important. For example, a BMW storage farm with up to 700 BMW-i3 battery storage units was already put into operation on the plant premises in Leipzig in October 2017. The "Battery 2nd Life" development project launched by BMW, Bosch and Vattenfall back in 2016 was also heading in this direction. Here, an electricity storage system was set up with 2,600 battery modules from more than 100 electric vehicles (output 2 MW) (Soller, 2019).


Affordable and sustainable energy of the future

Automakers are getting deeper into the secondary marketing business of used vehicle batteries. Likewise, they are looking at smart bidirectional charging technology and thus stable grids - the classic infrastructure issue. In the future, electric cars will not only be able to store energy, but also release it when needed. They will thus be the mobile storage unit for electric floor heating systems and other electric consumers in households. This opens up completely new possibilities for operators of electric underfloor heating systems, for example.


International award for innovative climate protection!

The fact that the GREEN ACCU MAT® is an outstanding contribution to active environmental protection has already been confirmed several times, e.g. with the "Green Product Award" or most recently with the nomination for the "EUROPEAN GREEN AWARD", which makes a significant contribution to Europe's transition to a modern, resource-efficient, fair and competitive economy of the future. As part of the company's sustainability strategy, the networking of renowned companies such as Hemstedt with students and start-ups plays an important role in continuously raising awareness of climate protection and sustainability.


Feeding into the home to reduce electricity bills

In addition, the smart energy control system detects grid peaks or idle phases in which, for example, wind or tidal energy is available but not needed in the grid. Then home batteries or vehicles are automatically charged or consumers such as washing machines, dryers or other appliances are started. An e-car allows green power to be fed into the grid for a three-person household for at least 3 days. This helps to make the best use of available energy, reduce grid peaks and stabilize power grids.


A battery-powered car as an emergency generator

In a further thought, the electric car can, for example, be charged with emission-free solar power at the workplace and serve as a power supply for the house in the evening or take over the power supply for the apartment or home in the event of a power failure. Of course, an intelligent control system keeps enough energy in the battery to get back to work reliably and comfortably the next day. Of course, this also applies to the classic second car, which can be used temporarily as a mobile or stationary storage unit.


Sustainable energy for commercial purposes

In a pilot project, 20 Nissan Leafs in front of the company headquarters supported the power supply of all offices. As a positive side effect, this resulted in a 20 percent reduction in energy costs. By comparison, a directional charging box for pickup trucks is being used for outdoor and construction site applications in the United States (AUTO BILD, 2022, pp. 16-17).


Clean energy sources are a key factor in environmental and climate protection

The consumption of fossil fuels and conventional electricity is anything but resource-efficient. The primary energy factor shows that in the case of coal, oil and gas, 1.1 kilowatts of energy have to be put in to generate one kilowatt of effectively usable energy, for example. With renewable energies, on the other hand, only a few watts have to be invested to generate one kilowatt (see Fig. 3). Electricity from such energy sources therefore moves us all forward!


Press contact

Hemstedt GmbH

Schleicherweg 19

74336 Brackenheim


Contact person: Andreas Hemstedt


Phone: +49 (0) 7135-98980


(Header: Excerpt of presentation of technician's work A. Hemstedt, "Analog signal transmission by means of laser diode in the LF range", 1997)