Category Renewable Energy

Central Receiver Systems

Central receiver systems are still in the ear­ly phases of commercial operation. Since the beginning of the 1980’s, around the world more than ten smaller demonstration plants with central receivers have been put into service (see Table 1 and Figure 1b).

Their operation was however terminated af­ter the end of the test campaigns, since they were too small to be operated cost effec­tively. Only since 2007 have the first com­mercial plants begun operation, especially in Spain. They have made use initially of rel­atively moderate steam parameters in order to guarantee safe and low-risk operation (see Table 1). In follow-up projects, it is planned to increase the operating tempera­tures step by step and thereby to improve their efficiencies [8].

The electric power was generated by a st...

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Genetic Technology for Biofuels

Around the world, a number of research groups are work­ing on the idea of employing genetically-modified mi­croorganisms to produce biofuels. The goal is to convert the bio-material into fuel in the gentlest possible manner with respect to resource consumption, for example via a highly efficient utilization of biogenic wastes.

A prominent example demonstrates the enormous in­terest in the applications of genetic technology on the part of industry: the Energy Biosciences Institute at the Lawrence Berkeley National Laboratory in California, found­ed in 2008 by the Nobel Prize winner and current US Min­ister of Energy Steven Chu, is being co-financed by the pe­troleum concern BP with a half-billion dollars [6]...

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Solar Energy

Solar energy is the renewable energy source par excellence. Its simplest form is the use of solar heat from collectors, in­creasingly employed for household warm water heating and for public spaces such as sports halls and swimming pools. More than 15 million square meters of collectors were in­stalled on German rooftops as of 2011 [14].

Solar thermal power generation has meanwhile also made the transition to commercial applications on a large scale (see also the chapter “How the Sun gets into the Pow­er Plant”). Parabolic trough collectors, solar towers or pa­raboloid dish reflector installations can produce tempera­tures of over 1000 °C, which with the aid of gas or steam turbines can be converted into electric power...

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The State of the Art

The annual growth rates of installed electric power gener­ated by photovoltaic systems in the past few years were around 30-60 %. The leading nation in sales of photovolta­ic modules is currently China, ahead of Taiwan, Japan and Germany (see Fig. 1). In the year 2011, new solar cells with a power output of over 37,000 MW were fabricated world­wide. By comparison, a nuclear power plant has an output power of 1,000-1,500 MW Since photovoltaic installations generate power only when the sun is shining, a realistic comparison of the energy produced by the two technolo­gies within a given year must take a conversion factor into account...

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The Current State of Development

Our work up to now in Karlsruhe demonstrates that even bioslurries with a high coke content resulting from biomass pyrolysis products can be completely and safely converted into a tar-free synthesis gas using pure oxygen in a flow gasi­fier at high pressures. This process is suitable for practical­ly all starting materials which yield a sufficiently stable con­densate for suspending the coke powder after rapid pyrol­ysis.

Подпись: FIG. 5Now that the technical feasibility of the process has in principle been demonstrated by experiments with our own and with industrial equipment, the overall process is being further developed as rapidly as possible. For this purpose, we are currently setting up a pilot plant in Karlsruhe with­in the framework of a public grant and with industrial co­operation partners...

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Nature Conservation and Public Acceptance

With increasing industrial exploitation in the form of large wind parks, wind power has experienced growing accep­tance problems. Yet, in comparison to other interventions into nature, such as the increasing concentration of CO2 and pollutants in the atmosphere, air and ground traffic, aerial transmission lines and many others, wind power in­stallations have however only local and minor negative ef­fects. In view of the directly perceptible consequences of traditional energy supplies, a clear majority of German cit­izens are still in favor of the continuing development of wind power. Nevertheless, a paradoxical behavior is often observed, accurately characterized by the NIMBY phe­nomenon, “Not in my back yard!”; i. e. wind power yes, but somewhere else.

Thus, for specific wind par...

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A new Coating Process

In order to produce high-quality films which yield high ef­ficiencies, two things are necessary: A high substrate tem­perature, over 500° C, and precisely the short source-sub­strate distance described above. In general, a simple rule of thumb holds: the higher the substrate temperature, the bet­ter the quality of the deposited layer. This however presents a technical challenge. In order to fabricate solar modules at a moderate price, common window glass is used as the sub­strate; but it begins to soften and flow at a temperature just above 500° C.

For this reason, sheets of window glass with a large sur­face area can be coated using the CSS process only up to about 520° C. Several manufacturers of CdTe solar modules however work with higher substrate temperatures...

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Installation, Retrieval and Maintenance

The installation, retrieval and maintenance of the plants should be as cost-effective as possible. If special ships or floating platforms are necessary, it must be possible to re­fit them in the simplest possible way. For the VH concept, a barge with a crane at its stern is required. The crane car­ries a framework, called the nacelle-retrieval module (NRM). It can be raised and lowered by chains and winches on the deck of the barge. Two guide chains are attached to the foundation of the plant.

Подпись:Подпись:Using a camera, or sonar if the water is cloudy, the NRM finds its way along the guide chains to the turbine (Figure 4). As soon as it has docked onto the turbine nacelle, it is locked in place by a hydraulic clamp. Then the NRM to­gether with the turbine nacelle is raised to the surface by

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