Light + Building 2014: energy storage devices play a central role in the implementation of decentralised energy provision
Units for generating electrical energy from regenerative sources, such as sun and wind energy, have enjoyed a boom in recent years in Germany, not least because the guaranteed feed-in tariffs have been relatively high. In order to combat the current rises in the cost of electricity prices, the feed-in tariffs are, however, being successively cut. As a result, it is becoming more attractive to use the home-generated electricity largely for one's own needs, because the feed-in tariffs are lower than the current price for electricity taken from the grid. Besides, the German law on renewable energies (Erneuerbare-Energien-Gesetz – EEG) provides a financial incentive for people to use their home-produced energy, specifically in respect of smaller photovoltaic installations that began operation between January 2009 and March 2012. (Personal consumption tariff).
Photovoltaic and wind energy installations have one major disadvantage: they produce electricity only when the sun is shining or the wind is blowing, as the case may be. These times do not, however, always coincide with those when the electrical energy is needed. The result is that not all the locally produced electricity can always be used directly or, alternatively, not all the requirements for electricity can be met. In order to increase the personal consumption of energy generated by such installations and to raise the levels of self-sufficiency, the electrical energy produced needs to be stored.
Efficient ways of storing electrical energy
Electrical energy can be stored in a variety of ways. As far as the macro-scale technology is concerned, the storage of electrical energy is necessary, above all, to ensure the stability of the grid. For this, pumped storage hydroelectric power stations are employed, for instance. These use the electrical energy to pump water into a storage basin on a higher level. When electrical energy is needed, water from the storage basin drives turbines and thus generates electrical energy once more. And storing the energy in the form of flywheels or compressed-air storage also offers possible ways to contribute to the stability of the grid. Current field trials are looking at the manufacture of hydrogen or methane that can be stored or fed into the natural gas network. In power-to-gas units like these, the transformation to cogeneration units can generate heat for heating purposes (combined heat and power units).
When it comes to buildings, the smart money is massively on accumulators, which store electrical energy through an electro-chemical process. The oldest form of accumulator – the lead-acid accumulator – was developed as far back as the mid 19th century. Lithium-ion batteries have been available for about 20 years. These offer an electro-chemical storage medium, which has a variety of advantages when compared to the lead-acid accumulator, such as higher levels of energy density and a slower drainage rate.
Lithium-ion batteries are widely found in mobile telephones and laptops and are thus well tried and tested. And the use of this storage medium also has a decisive role to play in the development of electric vehicles. At the same time, systems are required in buildings to store electrical current in the form of heat. If, for example, the heating system operates with a heat pump, then the electrical energy from solar or wind power can be used to store it as hot water.
Battery storage with intelligent energy management
Recently, solutions based on battery technology have become available not only for larger residential and commercial premises but for smaller trade premises and even for single occupancy housing, too. The storage capacity can vary from kilowatts in single figures to megawatts. And, of course, the size of the energy store is also dependent on the capacity; for a small commercial unit the size is roughly comparable to a traditional refrigerator. Calculations of the appropriate size of storage are based on, amongst other things, the profile of demand, cost-benefit analyses and electricity prices.
An intelligent control system – an 'energy management system' as it is generally called – ensures that current requirements at any given time are first met by the home-generated electricity. Excess electrical energy is then used to charge the energy store. And only when the latter is completely charged does the energy management system feed the excess energy into the regional / national grid. For example, at night, when the photovoltaic system cannot generate electricity, it is the energy storage unit that provides for the electrical consumption. Only when the energy store is exhausted, does energy then have to be brought in from the grid. Energy stores have another advantage, if variable electricity prices are going to be introduced across the board. By charging an electricity storage unit at times of little demand, and discharging at times of peak demand, they reduce the electricity used from the grid at times when prices are high.
Light + Building exhibits local, decentralised energy storage units
At Light + Building, which will be taking place from 30 March to
4 April 2014 in Frankfurt am Main, market-ready solutions for localised energy storage in buildings will be a major topic of interest. In the special exhibition, "Smart Powered Building – your building in the smart grid", there will be a display of pioneering system solutions that combine photovoltaic and wind-power units with local energy stores such as batteries and heat pumps, thus increasing significantly the level of self-sufficiency of a building in terms of its energy provision. Using interactive computer simulations, trade visitors can check out solutions that optimise the provision of energy in commercial buildings, involving energy production, consumption, storage and connection to the 'smart grid'. The special display was created by Messe Frankfurt with the support of the Central Association of the German Electrical and Electronics Industry (Zentralverband Elektrotechnik- und Elektronikindustrie – ZVEI). It presents a particularly good and accessible example of the practical application of the many products and solutions relating to house and building automation and electrical engineering on show at Light+Building.
To complement the special exhibition, the E-House in Hall 8.0, created by the Central Association of the German Electrical and Information Technology Industry (Zentralverband der Deutschen Elektro- und Informationstechnischen Handwerke - ZVEH), realistically demonstrates the possibilities afforded by 'intelligent buildings' with regard to energy efficiency, comfort and security. Equally, it demonstrates multifunctional and multi-generational concepts for buildings based on a network principle.
Background information on Messe Frankfurt
Messe Frankfurt is one of the world’s leading trade fair organiser, with 536.9 million euros in sales and 1,833 employees. The Messe Frankfurt Group has a global network of 28 subsidiaries and approx. 50 international Sales Partners, giving it a presence for its customers in more than 150 countries. Events "made by Messe Frankfurt" take place at more than 30 locations around the globe. In 2012, Messe Frankfurt organised 109 trade fairs, of which more than half took place outside Germany.
Messe Frankfurt’s exhibition grounds, featuring 578,000 square metres, are currently home to ten exhibition halls and an adjacent Congress Centre. The company is publicly owned, with the City of Frankfurt holding 60 percent and the State of Hesse 40 percent.
For more information, please visit our website at: www.messefrankfurt.com
www.light-building.com (30. März - 4. April 2014)
