By Fernando Nuno / Published on Fri, 2009-01-30 11:15
Leonardo ENERGY has launched a Spanish website aimed at providing information to the Spanish-speaking community of professionals.
More than 440 million people speak Spanish. It is the official language in 21 countries, and is also widely spoken in the US and Brazil. This language represents an enormous cultural, social and economic value. The growing environmental requirements for a sustainable world place these countries in a very relevant position thanks to their natural and renewable resources.
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By Stefan Fassbinder / Published on Fri, 2009-01-30 09:02
Last week we wondered why a PC power supply with “lower” losses needs 50% more airflow. Let us now decide that it’s just a sect’s belief, called “case modding” (at least in countries which don’t speak English – nearly all Google hits are in German). Let us decide what can be done to achieve what the “advanced fan speed control” was supposed to do but does not do. The solution is frighteningly simple.
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By Isabelle Heriakian / Published on Thu, 2009-01-29 10:19
In this guide, a design engineer works on a converter drive design and determines the voltage change coefficient during the drive start, compares it to permissible levels and suggests solutions to have it satisfying the limit.
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By Bruno De Wachter / Published on Thu, 2009-01-29 06:30
On blackouts and cascading failures
An article in Scientific American last month discussed an interesting analogy, namely the one between the electricity network and global financial networks.
According to the author Jeffrey D. Sachs, both are network systems in which a local problem can undergo a system-wide amplification leading to a general catastrophe. Such amplification is caused by what Sachs calls 'rational panics'. Each node in the network has certain rational rules that are created to protect its own stability. However, if all those rules should conclude simultaneously to withdraw from the system, the whole network starts collapsing.
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By Hans De Keulenaer / Published on Wed, 2009-01-28 19:50
Inês M. Lima de Azevedo, Climate Decision Making Center, Engineering and Public Policy Department, Carnegie Mellon University, USA
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By Hans De Keulenaer / Published on Mon, 2009-01-26 16:17
Of course, the emergence of such micro grids brings many changes. In a vertically integrated market, where generation, transmission and distribution assets are in the hands of a single entity, optimum decisions over the placement and connection of distributed sources can be sought relatively easily. When the distribution operator is no longer owner of the distributed sources, as can be the case in a free electricity market, conflicts can occur between the wishes of the grid operator and those of the owner. The owner is primarily interested in the profit of his installation, determined by the aggregated energy production, whereas the grid operator makes his plans with regard to the operation and expansion of the grid and the resulting necessary investments, principally from the perspective of the (maximum) energy. Measures must thus be taken to ensure that the distributed sources do not look only at the profits, but also contribute to attaining an optimal operation of the entire distribution grid.
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By Hans De Keulenaer / Published on Mon, 2009-01-26 16:16
The third and final type of micro grid is the so-called remote micro grid. For the provision of energy in remote areas, developing countries and (geographic) islands, locally available energy sources, often renewable, are usually chosen. Combined heat and power (CHP) may be used. An autonomous micro grid is a good network structure for such cases, where it can also be possible to connect this micro grid to the electricity grid in the future. There are often problems with extending the electricity grid to these remote areas, and it is necessary to work with a pure island grid. It is thus very important that the local generator is adequate and its energy production is sufficiently reliable to ensure that the local consumers receive the highest possible availability in the energy provision. Failing this, it is possible that certain loads would have to be disconnected on an irregular basis to guarantee the stability and correct operation of the net. The application of energy storage can help the spread of this type of micro grid to a large extent.
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By Hans De Keulenaer / Published on Mon, 2009-01-26 16:16
Industrial or commercial micro grids form a second class of micro grid structures. These are typically a collection of critical and/or sensitive loads requiring high power quality and reliability. Typical examples are a data centre or a university campus, but also a shopping centre, a factory, an industrial installation or even a residential neighbourhood. The principal aims of this variety are an increase of the power quality, better reliability and also frequently energy efficiency compared to the electricity grid. Potentially, different loads can be further sub-divided into groups within the micro grid according to the required grade of power quality and reliability. The micro grid can switch over to island operation in the event of a grid fault, during maintenance, periods of poor power quality, or when grid energy prices are high.
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By Hans De Keulenaer / Published on Mon, 2009-01-26 16:15
The first type of micro grid is a so-called utility micro grid. This is (part of) a feeder for a distribution grid, with local energy sources and consumers. This type of micro grid can facilitate a large-scale introduction of distributed sources and can locally receive the growth of the user’s power (either completely or partially), so that congestion problems can be avoided or reduced.
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By Hans De Keulenaer / Published on Mon, 2009-01-26 16:13
The aforementioned definition of a micro grid is a term that covers many possible implementations. This article attempts to give a concise overview of the different structures one encounters with micro grids. The choice of a certain structure is usually tied into its place in the grid, where the micro grid is to be connected, who the grid’s owner is and its principal aim.
Figure 1: Residential micro grid in Bronsbergen, Nederland [1]
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By Sergio Ferreira / Published on Mon, 2009-01-26 11:20
The
Energy Efficiency Watch
(EEW) has published a new brochure looking at best practices and opportunities for energy efficiency improvement across Europe.
This brochure is a non-technical document following an evaluation of the NEEAPs and building upon a set of identified best practices. The condensed document is to provide advice and support the redrafting of the new round of NEEAPs, complementing the evaluations done by the European Commission.
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By Stefan Fassbinder / Published on Fri, 2009-01-23 21:13
Last week we wondered why a superb fan control heavily tries to cool a 17°C cold PC power supply with 17°C cold air. Here you see the package of last week's PC power unit, which promises a “higher” air flow and 60% noise reduction. 60% of what? I can tell you from a disappointing experience that the reference must have been said vacuum cleaner.
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