August 13th, 2020
Category Renewable Energy
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 .
The electric power was generated by a st...Read More
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 ...Read More
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 .
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...Read More
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...Read More
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.
Now 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...Read More
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...Read More
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...Read More
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.
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