Energy storage

These considerations of the today's energy generation are examined under the aspect of the approaching nuclear power phaseout. There are cited arguments of an upcoming scarcity against the nuclear phaseout and demands on new buildings of nuclear power plants.

The fossil energy sources oil, coal and gas have two essential disadvantages: they are not unlimited available and their combustion creates harmful emissions - with extensive consequential damages and costs.

Since the usage of energy doesn't normally take place at the same time and at the same location like the energy generation, storage is required for every energy source, whether it is about renewable or non renewable energies: dams, coal dumps, oil- and gas tanks and much more. The energy storage happens usually before the refinement and usage of the energy source.
The different storage media are just as adequate for renewable energies, except for solar energy and wind power, which can be stored not until their conversion. The storage of both of these most important sources of renewable energies is the technological key to a new energy era. The dynamic of introduction of renewable energies can be accelerated and extended with that. Even the productivity can decisively be improved and the difference between the comprehensively natural capability and the technical useful capability can be resolved in order to achieve the goal of a 100% supply through renewable energies. Therefore today realised examples of solar full supply need special attention at the conference.

In the end of 2005 17.574 windmills with a capacity of 18.420 megawatt were ready for the power generation. With it the wind power made the biggest contribution to the power generation within the renewable energies in 2005. EON has published a wind report 2004, which gave us the reason to deal with the possibilities of storage of this energy and any other electrical energy.

Arguments to storage plants of the University of Karlsruhe:

Storage of electrical energy to provide a high power requirement over a long time simply serves to configure all in all the power generation more beneficial. The basis of an economical storage of electricity would be removed in the first place, if the demands of electrical energy would show no essential fluctuations during the course of the day. Even if you could adjust the energy production without technical restrictions, degradation of efficiency or increased wear and tear of the machines to the unsteady power requirement of the consumer.
Through the storage if electricity it is impossible to save electrical energy. But the accounting of the whole system showed that the whole energy input can be reduced for a unit of effective energy by appropriate end conditions.

The electricity storage systems for this application are primary evaluated in the economy of electricity by their possibilities to reduce the costs of power generation including the overall efficiency and costs. But for both the consideration of costs and the evaluation of chances and risks of big systems we have to keep in mind that the technology is still relatively young.
Completed systems have storage contents of maximal a few megajoule and a capacity of up to 10 MVA. Although bigger inductors for physical experiments were already produced (with a few hundred megajoule energy content) but they are not constructed for the application as energy storages.
Therefore many constructions for big systems remain with great uncertainties.

In the fact to the application of the peak load coverage you can compare the efficiency of storage systems with primary generators (gas turbines, combustion motors, maybe in the future fuel cells too) of storage systems as well as other EVU-measures to control the power requirement like load management or demand-side-management-activities.

On status quo conditions (dominance of industrial power production, currently composition of power plant parks with a high percentage of fossil fuels in basic and average load, just limited development potential for conventional hydroelectric plants, de-facto-moratorium in nuclear energy) the application of daily storages for the EVU is only then economically lucrative, if this would be operable with low costs yearly (and accordingly low investment- and operating costs).

At extensive storage applications the main part of the offerable electricity of the storage during the night would be provided through the average load power plant (mainly with mineral coal fired). The storage of electrical energy to immediate provision or reception of electrical capacity in case of need as well as the periodic capacity supply with a periodic time on the scale of seconds requires a release and reception of high electrical capacity very quickly. Since the most applications merely require this for a short time, low amounts of energy are often just needed (big cost value ratio).

A save and high quality power supply is attached importance for both on the part of the EVU and on the part of the costumer, whereas the essentially technical quality requirements of the costumer are very different. For physical as well as for infrastructural and economical reasons there are no different quality standards conceivable on high network levels. The equipment is technically configured on a high quality- and reliability level. The required costs are born by the customers.

Electricity storage systems for high peak load coverage are currently just in exceptional cases economically attractive. This could change if the systems would be realizable under low costs or if the economical, organizational and social basic conditions of the economy of electricity would change.

A few possible examples would be:

  1. Mainly fossil fuels with high-quality (oil products and natural gas) are used in conventional peak load power plants (and in recommended fuel cells in the future for this purpose). Should these products increase significantly in their price or for some other reasons their application doesn't appear to be opportune anymore (for example emissions), peak load power plants can be replaced by storage systems.
    Such a scenario would involve an intensified construction of base load power plants with low specific costs in their power generation. If this works on a basis of coal, we can't expect any decrease in the balance of emissions. Whether power plants will be built in the future are controversially discussed and is subject to the social consensus building.

  2. Various presently in the politics discussed considerations about the competitive configuration of the power supply would cause interferences in the organizational structure of the economy of electricity. This would originate the central -in the German electricity supply unknown- figure of the network provider in the new system. The network provider is responsible for security, reliability and capability in his area -voltage maintenance and load balance- as well as the network extension.
    There were many possibilities for the network provider to conform to the feedback control problems in his subnetwork. Beside contractual regulations with the providers of the power plants or the allowance of control reserve exclusively in their own power plants the network provider could realize the feedback control problems using their own storages, which they can charge depending on the offers of pool prices and which are available for load balance, voltage maintenance, reserve supply ect. and according to this configured.

  3. New areas of application for energy storage will be opened at increased input of intermittent renewable energies in the future. Even on days with good weather bumps of voltage capacity can't be ruled out. Such a situation makes demands at the controllability of conventional power plants on high percentage of induction.
    Hereby the application of quick electricity storages can be provided and - aside from the common economical problems - their availability possibly enables the renewable energies to make inroads into the market of power generation.

  4. Nuclear production plants require stable condition of operation and they are not qualified to cover load variations. Should the idea of a nuclear energy supply - be that fission or fusion - be realized in the distant future, the structure based on this would comparatively necessitate bigger and faster storages.


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