From a technical and economic point of view, the targeted reduction of short-term peak loads is very interesting: even relatively small investments lead to high cost savings. Thanks to recent developments in battery technology, numerous possibilities are opening up for stationary electric battery storage systems to compensate for cost-relevant peak loads with short-term load shifts. However, this requires a thorough analysis of the current situation, tailor-made hardware and software solutions and intelligent control based on sophisticated algorithms.
Load peaks are high power references which are only available for a short time and which stand out clearly from the actual, typical load profile. The reasons for this are usually the switching on of large individual consumers, which are switched on or off briefly. This can have different effects on electricity providers, network operators and users. Due to the temporarily increased network load, a larger dimensioning of all network components is necessary, as the design is always based on the expected maximum load. Theoretically, energy suppliers must react very dynamically to a rapidly changing demand. However, this is only possible to a limited extent, if at all.
Electricity suppliers create incentives to avoid peak loads in the form of various price models. For example, a combination of performance price and reduced labour price often applies to larger customers. For the service price, the highest peak load that occurs during the billing period is relevant. These price models enable cost savings through peak load reduction. The prerequisite is always to influence the load profile in order to avoid peak loads. In the simplest case, electrical loads such as production or infrastructure systems can be switched off. Conversely, it would be conceivable to switch on one's own electrical generators. Both measures require intervention in the ongoing production operation and in the existing infrastructure. As a result, considerable costs can arise due to production stoppages.
One solution could be an intelligently controlled battery system with which the financial potential of peak load reduction can be exploited without influencing the production process. In principle, the battery storage is charged at low power levels and discharged at times of high power levels. The aim is to reduce the maximum power consumption: the resulting power price is reduced and electricity costs are reduced. In practice, cost savings of 70 to 90 euros per kilowatt can usually be achieved for reducing the annual peak load, depending on the power price.
The scientists at Fraunhofer IISB are testing how well this works live with a modular battery system with a capacity of 60 kWh. The researchers have developed an algorithm and software for control and regulation in order to make optimum use of the battery storage and to switch it on at the right time. With battery sizes of 60 or 100 kWh, a possible reduction of the peak load of 10 or 16 % is already possible for this application. With the current battery prices, amortization periods of five years are possible.
In the opinion of the scientists, the practical results at Fraunhofer IISB show a very good agreement with simulations carried out previously and are basically transferable to other consumers.
In addition to various energy suppliers and energy system operators, battery manufacturers also recognize the potential of peak load reduction. Together with a battery manufacturer, Fraunhofer IISB has designed a high-performance battery storage system for an industrial customer. Both the efficient intermediate storage of large amounts of energy and the delivery of high outputs had to be ensured. The result: an energy storage system of approx. 350 kWh would enable a peak load reduction of approximately 40 %, since many of the peak loads only occur for a very short time.
SEEDS project: https://www.energy-seeds.org/ (in German)