Batteries of the future

Today, when someone says battery they are primarily referring to lithium-ion batteries. These batteries power laptops, mobile phones, lawnmowers and electric vehicles. However, they are also used as stationary energy storage devices to balance out grid fluctuations.

Battery storage systems will be an important element in the energy turnaround. Power from new, renewable energy sources does not always flow when it is needed, but rather when the sun shines or the wind blows. Energy flow and energy demand rarely coincide. This power can be stored for a few hours or days – and different kinds of power storage systems exist for this purpose. However, there is a lack of solutions to store large volumes of energy from summer production for the winter.

Today, batteries are mainly used as power grid stabilisers. For example, Steag, the fifth largest German power producer with headquarters in Essen, operates battery storage systems (lithium-ion batteries) with an output of 15 MW each and a total storage capacity of 120 MWh at six different locations. The batteries are used for primary control to balance the German power grid (also see: balancing energy works magic).

Business in Switzerland

Energy supply companies here in Switzerland have also recognised the opportunities offered by battery storage systems. EKZ (the utilities of the Canton of Zurich) in Volketswill have commissioned the largest battery storage system in Switzerland (see details here). The battery has a maximum output of 18 MW and a storage capacity of 7.5 MWh. The system stores energy by means of lithium-ion technology and is also used in the area of control energy.

Axpo was recently awarded its first contract from Elektrizitätswerk Jona-Rapperswil for the construction and operation of a battery storage system with an output of 2 MW and a storage capacity of 2.17 MWh. The system is used to prevent power peaks and in the primary control market (more information here and coming soon in Energy Dialogue Online).

Technology potential exhausted

Lithium-ion batteries were introduced to the market about 30 years ago and Frankfurter Allgemeine Zeitung FAZ sums up "since then, they have experienced an unparalleled success for a wide range of applications." Laptops, mobile phones, lawnmowers and electric vehicles draw their energy from these batteries. However, researchers agree that the lithium-ion technology has more or less exhausted its potential – one reason being that the material used for the cathodes comprises lithium cobalt oxide. Cobalt is relatively rare, poisonous and expensive, and it is mined in the Congo or Zambia largely by child labour. The element is also used to produce steel – so demand is high. As a result, cobalt will become an unaffordable, scarce commodity in a few decades (more on the topic here).

Research work

Scientist are already working on the batteries of the future. Research focuses on various alternative materials to replace combustible lithium-ion batteries. For this purpose, all battery components were examined: Cathode (+ pole), anode (- pole) and the electrolyte through which the ions travel.

Researchers are focusing on less critical materials such as sodium, magnesium, aluminium, calcium or zinc. Research is also being conducted with cobalt and nickel, and US researchers think that copper and iron have potential for use in batteries writes the trade magazine "Nature".

The most developed product, which is on the verge of series production, is currently the sodium-ion battery reports Süddeutsche Zeitung. The advantages: No poisonous, expensive cobalt. Sodium is a sustainable raw material (from common salt). The disadvantages: Sodium does not equal the energy density produced by lithium, and accordingly these batteries are not suitable for electric vehicles. However, they could be used as large storage batteries.

Work on the magnesium battery will take longer, but it is considered the new favourite among rechargeable batteries. Research in this area is also being supported by the EU. The researchers' goals, among others at the German Helmholtz Institute in Ulm, are ambitious: They want to develop prototypes that are more reliable and cheaper, and that have more output. The target is a price under 100 Euro/kilowatt-hour of electricity and a capacity of 400 watt-hours per kilogramme. As a comparison: Today's lithium-ion batteries deliver up to 250 watt-hours per kilogramme and cost about double.

Whether researchers will achieve their goals with the magnesium battery remains to be seen. However, it will certainly take time before truly satisfactory alternatives to the market dominant lithium-ion batteries become available.

(Additional information - in German - on the topic of batteries, energy density, charging cycles and much more here)