Category Renewable Energy

Drive-Motor Power and Battery Capacity

In designing the electrical drive components of a hybrid or all-electric vehicle, the drive power and the weight of the on-board battery must be optimized. One of the great ad­vantages of an all-electric drive is the possibility of operat­ing the drive motor for a short time at a multiple of its av­erage maximum power. The average power can then be chosen to be considerably less than the peak-load power, making the electric drive train smaller, lighter and more economical.

We have simulated these requirements with software tools that we developed ourselves. If we insert the design electric drive into a power-consumption simulation, we ob­tain histograms for the energy used (Figure 3)...

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Cost-Effective Power from Sustainable Energy Sources

Through worldwide installation of solar-thermal power plants, the cost of solar power will be reduced at a progress ratio of 85 to 90 % each time the installed capacity doubles, due to learning and rationalization effects [7]. Here an ex­ample: A solar thermal power plant at present, depending on the insolation at its site, can generate power for 0.15 to

0. 20 €2000/kWh, assuming a capital interest of 6.5 % per year and a plant lifetime of 25 years. With 10,000 MW installed power capacity worldwide, this cost would decrease to around 0.80 to 0.10 €2000/kWh, and with 100,000 MW in­stalled capacity, to 0.04 to 0.06 €2000/kWh. Similar learning curves can be observed for all of the sustainable technolo­gies.

A cost reduction of this order would be achieved for an assumed expansion of ...

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The Goals of Building Thermography

In the course of the energy-efficiency discussion, buildings in the private as well as the industrial sector have become a focus of attention. Since they are usually heated using fos­sil fuels, better thermal insulation automatically results in a reduction of CO2 emissions. Furthermore, fuel costs play an increasing role. This has resulted in political efforts to pro­mote better building insulation (for German regulations, see e. g. [6,7]). One of the results is “energy passports”, which document the energy consumption of buildings.

Fig. 1 Infrared images of buildings such as this one are frequently found in the media. The false-color representation is reasonable, but its interpretation is demanding. Untrained users often reach completely invalid conclusions.


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Example: The Max-Planck Campus in Golm

In Golm, near Potsdam, in 1999 the Max Planck Society founded a new science campus, comprising three institutes. The energy management system is based on a combined heating-cooling-power system, making use of a geothermal borehole field for storage (Figure 6). This concept includes a cogeneration plant driven by an internal-combustion en­gine; the excess heat is used for space heating and warm water.

The DHE field contributes to cooling in the summer months, and in the process it stores heat energy. In the win­ter, it serves as thermal reservoir for a heat pump to supply heat energy to the buildings, and is thereby cooled, causing the temperature in the borehole field to sink below that of the surrounding earth...

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Technological and Economic Questions

Why does wave power not yet come “out of the wall socket“? As we have already described, the installation of the power plants in the rough loca­tions where they must be operated is difficult. Their design must guarantee a long operating life. A further hurdle is the developement of turbines which are suitable for OWCs. The turbines used up to now do not perform satis­factorily: Their efficiencies are too low and their constant velocity operation is problematic. Wells turbines so far achieve efficiencies only in the range of 50 to 70 %. Conventional turbines, in contrast, operate with up to 90 % efficiency. Even though they produce elec­trical power in only one flow direction, they can still be con­sidered as serious competition for new designs.

OWC designs have also been tested whi...

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Battery Management System

These large high-power batteries require a battery man­agement system with refined monitoring and protection functions for the battery (Figure 4 [5]). In normal operation, only the monitoring functions are active; their principal tasks are:

• Voltage, current and temperature monitoring: These primary data are used to derive other values. These in­clude for example the internal electrical resistance, which gives information about the charge state and the general condition of the battery;

• Charge equalization: Since the characteristics of the battery cells are never precisely the same, and further­more, the temperature may vary at different points with­in the battery pack, charging and discharging can load the cells differently...

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An Alternative to Climate Change and Nuclear Power

Implementing our scenario could lead to a reduction of car­bon dioxide emission values to a level which would be com­patible with the goal of decreasing the carbon dioxide con­centration in the atmosphere sufficiently to limit global warming to the range of 1.5° to 3.9° C. Assuming 1790 mil­lion tons of CO2 emissions per year in the year 2000 for the EU-MENA region, these emissions could be reduced to 690 Mt/a by 2050, instead of increasing to 3700 Mt/a. The attainable level of 0.58 t/cap/a for the emissions per person and year due to electric power by 2050 is acceptable, in view of the recommended total emissions of 1.0-1.5 t/cap/a

image172given by the Scientific Council on Global Environmental Change (WBGU) of the German Federal government...

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Hidden Structures made Visible

Thermography is by now a well-established method in mon­ument preservation for making structures hidden behind walls visible. In Figure 2, the example of a half-timbered house is shown; the faqade has been covered with stucco. The wooden beams and the filler material in the partitions between are clearly visible in the IR image, owing to their differing heat capacities and heat-transfer characteristics.

Thermography is also suited to the detection of other hidden building structures. Among these are the location of bricked-up and plastered-over windows, or finding piping in floor heating systems (Figure 3). Images of this type al­low a view through the floor screed and floor coverings and can therefore serve to locate leaks.

View Factor and Thermal Time Constants

Figure 4 shows two neigh...

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