The electric car as a global battery

Published on : 21 January 20215 min reading time

Energy recovery requires the conversion of power generation into regenerative sources. However, solar and wind energy have the disadvantage that they may not necessarily be available when they are needed. Electricity storage systems could solve this problem, but they are expensive. This is where electric cars come in, with large batteries whose capacities are not always fully utilized. Electric mobility, which today enjoys particular support in many countries, is not limited to obvious environmental objectives that can be achieved in the short term. The main attraction of electric mobility lies in its potential function in implementing the reversal of energy production from conventional to regenerative generation.

Disadvantage of energy reversal: the temporal disparity between production and consumption

The production of solar and wind energy is extremely environmentally friendly, but it has a small flaw. Electricity is not necessarily produced when it is needed. However, an unavoidable law of the electrical industry is that the production of electricity, or rather its supply, corresponds to its consumption in fractions of a second. Unlike power plants, however, the sun and wind produce electricity as they see fit. They do not take into account the requirements of consumption. Photovoltaics certainly has the advantage of supplying a lot of electricity, especially when, according to experience, consumption also peaks, i.e. at noon. But when the clouds move in front of the sun, nothing works.

And what happens when the sun is shining brightly and a cool breeze turns the wind turbines? Even today, we still produce more electricity than we can consume. In short, with regenerative energy production, the production and consumption of electricity do not necessarily coincide in time.

How can we solve the problem of the temporal disparity between production and consumption?

Traditionally, electricity storage has always existed, albeit on a small scale. Most of them are pumped-storage plants. In these plants, water is pumped on a gradient when there is an excess of electricity, which is then drained when there is a shortage of electricity and driven out by power generation turbines. However, existing storage solutions are far from sufficient to provide European industrial companies with storage solutions. A professor at the University of Applied Sciences in Furtwängler calculated that the entire Black Forest would have to be converted into a pumped storage power station to ensure Germany’s electricity supply for two days. This seems unrealistic.

Scientists from all over the world are therefore looking for storage solutions. High-pressure compressed air in underground caverns, energy-absorbing salts, lithium-ion batteries the size of a garage, a complete hydrogen cycle. There are many ideas that a revolutionary storage solution has not yet been able to develop.

Electric cars: electric storage on wheels

Electric vehicles are nothing more than rolling batteries. A modern mid-range electric car is usually equipped with a battery system with a capacity of 20 to 30 kWh. For a range of 100 to 150 km, consumption is therefore between 15 and 20 kWh per 100 km. The idea now is to use the unused capacity of electric car batteries as short-term energy storage for the power grid. The technical term for this technology is “bi-directional charging” and charges in two directions. When this idea is presented to the public, skepticism is usually palpable, as many people are afraid of not having electricity in their car batteries when they want to leave. But two-way charging scenarios are a little more complex, and no one should fear it. This concept only works in the smart grid, the smart grid of the future. The intelligence of the Smart Grid is based on information about the current state of the grid and its future status. Information about the future is based on empirical values or should be provided by consumers themselves.

Scenario of electric mobility in the Smart Grid

A scenario of an electric car as a storage device for electricity in the Smart Grid could therefore look like this :

In the morning, the electric car driver drives to work in his electric car. As in most cases, this is only a short distance, say 30 kilometers. His vehicle battery is almost empty when he arrives at work. The owner of the electric car connects his car to a charging station in his employer’s parking lot. It’s a sunny day and a cool breeze is blowing on it. Optimal conditions for regenerative energies: the solar panels are sizzling, the wind turbines are running non-stop. There is cheap electricity in abundance. The car batteries are fully charged and the price of electricity, which is regulated by supply and demand, is low. The driver returns home in the evening and connects his car to his wall box, the charging station for the house. He uses a smartphone application to inform the power grid that he won’t be going to work until tomorrow. The Smart Grid can therefore use half of its battery to produce electricity, because unfortunately it’s dark at the beginning of October and the wind has calmed down. As a result, electricity is expensive tonight, and your car owner can now even sell his electricity, which he bought cheaply during the day, profitably.

The future is possible

It becomes clear that this scenario is based on certain preconditions that have not yet been implemented. For example, the real-time price signals issued by energy suppliers to guide the behavior of electricity consumers in a direction favorable to the power grid are still pure dreams of the future. However, two-way charging technology already exists and could quickly become a reality if electric vehicles were distributed millions of times over.

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