Flywheel storage

U.S. Department of Energy. (1995). Flywheel Energy Storage Workshop. Springfield, VA U.S. Department of... 

The fact that solar energy is an intermittent energy resource means that energy storage systems (e.g., batteries, ultracapacitors, flywheels, and even hydrogen) will be required if solar energy is to be utilized widely. In addition, a variety of toxic chemicals are used in the manufacture of PV cells however, studies of the risks associated with their manufacture and disposal indicate little threat to surroundings and the environment. 

One possibility to avoid this limitation is the conversion of heat into another kind of energy like mechanical or electrical energy. In this case (see Figure 231) the converter is producing entropy free work, which can be stored without theoretical limitations. Examples are pump storages, where water is pumped to a higher level, or flywheels, where kinetic energy can be stored. 

Flywheel Energy Storage Systems Photovoltaic Conversion Systems... 

Fig. 5.15 Principle of operation of a vehicle using a flywheel as auxiliary energy storage...

In this section, the main characteristics of alternative electrical energy storage systems, such flywheels and super capacitors, are described, as these devices might play an important role in the development of vehicles powered by electric propulsion systems. 

Super capacitors have relatively high specific power and low specific energy, like flywheels. For this reason both these devices can be used as energy storage... 

Super capacitors and flywheels, as high power storage systems, can be used in a wide range of hybrid vehicles, combined with one or more power energy devices. 

As part of an interdisciplinary study we are working on emission control catalysis for an extended parallel hybrid concept [1-5]. The main elements of the experimental car developed at the Swiss Federal Institute of Technology are the combustion engine, operating in a fixed cycle mode, a flywheel as a short term energy storage device, an electrical machine and a continuous variable transmission. One of the features of this hybrid vehicle is the so called intermittent... 

Energy can be stored using pumped storage reservoirs, compressed air in tanks, flywheels, or hot water.406 Fly-... 

The content of Figs. 10.1 and 10.2 is summarized in Fig. 10.3 by showing power as a function of discharge duration for both applications and energy-storage technologies. Supercapacitors, flywheels, and SMES are shown to be primarily useful for power-quality applications. Batteries are suitable for a broad spectrum of applications, and pumped-hydro and CAES are shown to be primarily useful for load levelling [9]. 

MW for about 10 s, or about 4.5 kWh. They are often used in uninterruptible power supply (UPS) applications. Flywheels are much less costly than SMES and supercapacitors, and they compete with batteries in high-power, low-energy applications. The response time of a flywheel energy-storage system is of the order of a few milliseconds. 

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