During the nineteenth century, the second industrial revolution saw electricity replace steam as the main source of power in industry. The resulting ‘electrification’ of society changed almost every aspect of human life, but the path was not as straightforward as many of us would imagine.
It was the time of Edison and Tesla, and a ‘power’ struggle that came to be known as The War of Currents. On the one side was GE who backed Edison and wanted a distribution system based on DC. On the other side was Westinghouse, firmly behind Tesla they pushed back and put all their effort into promoting the benefits of AC. Based on the best engineering compromises for the technology of the era, AC won the day mostly due to the relative ease with which it could be converted to the voltages required for long distance distribution at acceptably low line losses.
Little changed over the intervening years and alternating current remained the de facto standard for global power distribution. That is until we discovered the threat to our planet’s atmosphere posed by carbon emissions; a harmful by-product of our fossil burning lifestyle. Now the pressure is on. If we continue to generate greenhouse gases at the present rate, the earth’s environment will become overheated, possibly to the point at which life as we know it is no longer sustainable.
These threats together with advances in technology are driving an increasing demand for cleaner energy – particularly renewable types in the form of solar and wind. There is talk of building giant solar farms in northern Africa, and then exporting this sunlight derived electricity via undersea cables for eventual distribution in Europe. As it turns out, high voltage direct current (HVDC) transmission lends itself more easily to distribution through underwater cables than its AC counterpart. When one considers that the electricity produced by solar panels is DC to start with, it makes economic sense for the creation of new HVDC grids that ‘feed’ the existing AC infrastructure in the power-hungry developed regions of the world. Are we about to witness a ‘second electrical revolution’? Who knows, but it does seem likely that Edison and Tesla may finally bury the hatchet. Nick Denbow has more on the subject in this month’s report from Europe (see ‘Modern trends in long distance power links’).
The Synlight high-flux solar simulator
Speaking of renewable energy sources, hydrogen is considered an attractive alternate combustible because it burns without producing carbon dioxide. The only drawback is that producing it in sufficient quantities requires splitting water into its constituents of hydrogen and oxygen, a process which itself requires significant amounts of energy. But in the future, this will be obtained from the sun.
To facilitate the necessary development, the German-based DLR Institute of Solar Research recently commissioned its Synlight high-flux solar simulator. This artificial sun is comprised of 149 individual radiators, each with the power of a large cinema projector. When operated together, the generated light intensity corresponds to about 10 000 times the levels of solar radiation measured at the earth’s surface.
The purpose of the Synlight facility is to allow researchers to investigate the development of solar fuels independent of outside weather conditions. In the case of hydrogen production, the solar simulator is used to heat metal to a temperature of around 800°C. When steam is added to the system, the metal reacts with the oxygen in the water vapour and the hydrogen component is released.
In order to generate the intensity required to achieve the 800°C temperature, the individual light sources must be precisely coordinated. Not as easy as it sounds considering each 7 kW lamp is surrounded by a 1 metre elliptical aluminium reflector.
Beckhoff Automation solved the problem using three embedded PCs connected with the 447 stepper motor terminals required for this precision application. For more on this intricate control solution (see the report ‘ Compact drive technology used in Synlight radiator’.)
Buyers’ Guide 2018
A special vote of thanks from the I&C team to all those suppliers who once again took the trouble to update their company information so that we could compile the 2018 edition of the annual Buyers’ Guide.
Steven Meyer
Editor,
SA Instrumentation & Control
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