Battery storage systems have long been a topic in the discussion on how to shape the energy turnaround. In view of falling prices for lithium-ion batteries and other technologies, development has picked up speed again. What has been working for some time on a small scale for households with solar power systems and on a large scale as a power plant and contribution to grid stability is now increasingly being used in trade and industry as well. But what tasks can batteries take on in operational energy supply? What savings potentials and further advantages are associated with this? And what needs to be considered when designing storage solutions?
In the following article we would like to present an overview of the most important applications of electricity storage systems in companies.
Decentralised generation systems such as photovoltaics or combined heat and power (CHP) have found their place in many industrial and commercial enterprises. However, in view of falling remuneration rates for grid feed-in and simultaneously rising electricity prices, it is becoming increasingly lucrative to consume the electricity generated yourself as far as possible.
Self-production plants are generally designed for operating loads. However, if there is only a basic load on weekends or public holidays, the own requirements are often covered more than just. In addition, excess electricity is fed back into the grid.
However, very few companies can adapt their electricity consumption to their own generation and „wait until the sun shines“. Batteries can decouple generation and consumption through intermediate storage and thus reduce electricity costs without disrupting operating processes. In addition to own generation, electricity can also be intermediate stored which is generated by operating facilities with energy recovery (e.g. crane systems, braking) and otherwise – usually without compensation – fed back into the grid.
Short-term feedbacks are characteristic of systems with energy recovery.
When purchasing electricity, the pure working price for the kilowatt hour makes up an ever smaller proportion. The various fees, levies and allocations can be responsible for up to 50% of the costs. In the case of large customers, the power price per kilowatt and any costs for increased reactive power consumption are usually added. Battery storage systems offer different levers for reducing the above-mentioned costs:
The greatest savings potential is usually offered by peak load reduction. Battery storage systems can also reduce costs here by decoupling the time required by covering part of the power supply from the storage system above a certain operational power requirement. This saves costs – and also reduces the load on the local power grid.
The smoothing of peak loads is an important lever for reducing electricity costs.
If electricity is not consumed itself, it can also be offered on different markets at certain times. Electricity storage facilities with a high capacity are free to participate in the balancing energy market (if necessary, the required capacity can also be achieved by the virtual combination of several storage facilities – so-called pooling). But also the sale (and the purchase) at the power exchanges with their temporally fluctuating prices becomes clearly simpler and more lucrative by batteries, since the times of generation/receipt and feed-in/consumption can be decoupled.
While in most companies an interruption of the supply can have serious consequences due to the costs of operational breakdowns alone, certain facilities such as hospitals can even be a matter of life and death. Despite the high supply security of our power grids, it is therefore often necessary to set up an emergency power supply. They are also widely used for emergency lighting of escape routes and for IT and communication systems to prevent data loss.
As such emergency power systems are very rarely used in Germany, the battery storage systems used can also be used for other applications and can therefore be made more economical – as long as the task of uninterruptible power supply is not impaired. Battery storage systems can also increase the quality of the power supply by, for example, balancing the reactive power balance, acting as a mains filter (and thus eliminating flicker or harmonics) or increasing the short-circuit voltage. All these factors increase the service life and ensure the proper operation of sensitive equipment.
Companies connected to the medium-voltage grid are responsible for the installation and operation of their own transformers, which entails high investment costs. If the operational power demand increases over time, this may lead to transformer overload and may require replacement unless the purchased load is adjusted accordingly. Battery storage can also be used here for load shifting; in addition to reducing the power price, the purchase costs for the new transformers can also be saved and the existing ones can be operated more efficiently by adjusting the operating point.
A special case of the storage application is the so-called island operation of off-grid systems with electricity demand, provided that a connection to the supply network for these systems is subject to high technical or financial hurdles. In many cases, a combination of own generation (e.g. with photovoltaics) and battery storage can make the connection superfluous.
Battery storage systems offer industrial and commercial enterprises a variety of potential savings and can significantly increase the safety and quality of the power supply. If correctly designed and managed, their (still quite high) investment costs pay for themselves very quickly; operation is low-maintenance and only associated with low running costs.
At the same time, operating procedures are not impaired and the service life of systems is increased. The most lucrative option is to purchase storage tanks if several of the applications presented can be combined. Even batteries which are already in operation and which already fulfil one of the functions can take over further tasks in the operational power supply through an adapted operational management. However, this multifunctional use of storage systems places high demands on planning. Detailed information on the temporal distribution of electricity consumption in the company is particularly important for the precise design and control of storage systems.