There has been no change to electricity for more than one hundred years: alternating current has been the standard for distributing electrical energy for all this time. There are many positive aspects to the upcoming change, which will see old technology – alternating current – come up against stiff competition. In other words, it is direct current’s time to shine.
The history of electrification began with a miscalculation: in the 19th century, inventor Thomas Edison sided with direct current transmission, even though the competing technology, alternating current, clearly had the edge over it. And so began what is now known as the ‘War of Currents’: direct current versus alternating current. DC versus AC. Thomas Edison versus George Westinghouse. With Nikola Tesla caught up in the middle. In the end, AC technology saw off the competition and became the benchmark. Until now.
Because 86 years after Edison’s death, everything is about to change. The direct current technology favoured by Thomas Edison for America’s large-scale energy supply has many supporters today. Why? The methods we now use to generate, distribute and consume electricity have fundamentally changed, and the obstacles encountered back then are no more. Many factors that once counted against DC are now easy to manage, not least as a result of specialised switches and connectors and the invention of power electronics. So is it time for a paradigm shift?
6,500 trips to the sun and back
48% of net electricity in Germany is used in industry: around 250 terawatt hours per year. An electric car such as the e-Golf could cover a distance of 1.97 billion kilometres – the equivalent of 6,500 trips to the sun and back.
Direct current may be the future
Less conversion loss, more stability in the energy grids, saving on components, improved integration of renewable energies – there are plenty of arguments in favour of direct current. The technology enables large capacities to be transmitted across long distances with far fewer losses than seen in alternating current. This is why direct current is booming in countries such as China: this is the only way to transmit huge amounts of energy from the large dams to the megacities and hubs of industry.
More savings, less energy loss – no wonder there are lively debates, for instance in industry, on direct current, both with regard to transmitting energy across great distances and distributing electricity to consumers. This discussion is also being held within the Lapp Group, which is an associated partner in the "DC Industrie" research project. What does direct current mean for cables? This is being investigated at an early stage in this project and other initiatives.
Yet direct current is not uncharted territory for Lapp. We already have many years of experience as a result of products used in direct current applications, for example cables used to distribute energy through photovoltaic systems or charging systems for electric vehicles and hybrid cars, and we are well prepared for this revolution in the power grid.
The actual level of efficiency
When power plants feed alternating current into the grid and and all kinds of appliances, from vacuum cleaners to industrial drives, use this energy, the level of efficiency is around 65%. In other words, around 1/3 of the energy is lost, e.g. through thermal loss as a result of several conversions from AC to DC and back again. By contrast, an electricity grid systematically configured to direct current would achieve an overall efficiency of 90%.
On this topic, Georg Stawowy, Member of the Board and CTO at Lapp Holding AG, said:
“The most convincing argument for change is efficiency”
“The possible impacts on low-voltage cables have so far been overlooked, so we plan to bring our in-depth knowledge to the project.”