OREANDA-NEWS.  The move toward alternative forms of energy is taking shape in Kelsterbach, a town close to Frankfurt, Germany. Bosch is supplying a flexible energy storage system for a housing complex that is currently under construction there, which comprises 180 townhouses. The system has an installed capacity of 135 kilowatt-hours. “On paper, this is the equivalent of the daily power requirements of ten average four-person households,” says the Bosch project manager Wolfgang Mollenkopf. The customer is Sьwag Erneuerbare Energien GmbH, which is promoting the move toward alternative forms of energy with a concept of its own. The start of operation is planned for the middle of May.

Contribution to a decentralized power supply
The energy storage system meets one of the greatest challenges of decentralized power supplies. The housing complex's combined heat and power unit and solar power station do not always generate power when it is needed. Thanks to the battery, the extra power can be stored and made available later on. “We are pleased that our technology is helping Sьwag implement its pioneering concept,” says Cordelia Thielitz, who is in charge of stationary energy storage systems at Bosch.

The highest possible level of self-sufficiency
“Enka,” as the new housing complex is called, is being built on the site of a former factory. The construction company Deutsche Reihenhaus AG is building 180 townhouses there. A mixed-use development and a business park will be built in a second phase of construction. When completed, the neighborhood should be able to meet a large share of its own energy needs, since it will be equipped with two combined heat and power units in addition to peak load boilers, solar power, heat storage, and electricity storage systems. The system will use the power generated in the complex in the best way possible. The efficient combined heat and power unit will meet the base load. A natural gas-powered internal combustion engine in the unit will generate electricity with the help of a generator. The heat generated in the engine as a result of combustion will be used to heat buildings or water.

Since less power is consumed at night, the large Bosch battery stores energy and releases it whenever it is needed, for instance in the morning. “It's a similar picture with solar energy,” says Cordelia Thielitz. “The sun shines and delivers a lot of energy during the day, when families aren't generally at home. The battery stores the energy until it is needed in the evening.” In terms of its power supply, Sьwag aims to make the complex as self-sufficient as possible. “Every kilowatt hour that doesn't need to travel great distances reduces the need to invest in and expand the grid. It also makes integrating renewable sources of energy into the wider system easier,” the company says.

Consumers within the residential complex are directly connected to the power generation system. As a result, there are no transmission charges or similar costs. And for residents, electricity rates are significantly cheaper than usual. The Frankfurt University of Applied Sciences is providing the project with scientific support.

Turnkey energy storage systems
The Bosch turnkey energy storage system makes use of lithium-ion technology. The storage unit is some seven meters wide, about 60 centimeters deep, and 1.8 meters high. It is located in a machine room on site. Its capacity and electronics are precisely aligned to the needs of the complex's power grid.

The storage system has an output of 50 kilowatts and can be charged or discharged within two hours. Thanks to its inverter, power can be fed into and drawn from the customer network. The right battery system management and Bosch experience in the area of battery charging and discharging increase battery life. Bosch plans, engineers, and builds a range of storage systems, up to megawatt-hour capacity. In this way, Bosch makes an important contribution to sustainable power supplies, true to the company's strategic imperative “Invented for life.”

Background: energy storage systems
Energy storage systems are a key element in the move toward alternative forms of energy. They make it possible to better utilize wind and solar power, whose availability can fluctuate widely. Solar power can be made available at night, and wind power can be stored for times when winds slacken. A Bosch-commissioned study published by Цko-Institut e.V. in Freiburg rightly describes energy storage as a strategically important field of technology. Such systems will play a decisive role in the development of a decentralized power-supply infrastructure.

First and foremost, they can compensate for fluctuations in power generated from the wind and the sun. At the same time, they can act as a buffer for use in the event of unforeseen fluctuations. As a result, energy storage systems make it easier to integrate renewable sources of energy into existing power networks. This makes them an important part of smart grids, as well as an alternative to network expansion. Moreover, they help harmonize power supply and demand.

Background: combined heat and power units
Combined heat and power (CHP) units generate electricity and heat with either fossil fuels or renewable sources of energy. CHP uses the same amount of energy to generate twice the benefit. With conventional technologies, heat and power are generally generated separately. CHP combines the two, thus reducing the need for fuel. In a study written for the state of North Rhine-Westphalia, the government energy agency EnergieAgentur.NRW writes: “Its application offers enormous potential for protecting the climate and conserving resources.” If a CHP unit is needed to generate heat on a cold winter's night, for instance, the power generated at the same time can be stored in the battery until the next morning.