By Henk Rotman
The invention and commercialisation of the incandescent lamp at the end of the 19th century triggered the rollout of the electricity grid.
The need for a standardised electricity network led to the so-called ‘war of the currents’ between Alternating Current (AC), promoted by Nikola Tesla, and Direct Current (DC), promoted by Thomas Edison. AC emerged as the winner, with DC relegated to niche applications such as transport (trains, ships). Today, the electricity grid is one of society’s most valuable assets and a cornerstone of the economy.
In recent years, however, the electricity landscape has been changing on both the supply and demand sides, with more electricity being generated by renewables (solar, wind) and more electronic devices consuming electricity. Since both renewables and electronic devices (think computers, LED lighting, and EV chargers) use DC, this has led to a situation where DC is converted into AC and then back into DC to power electronic devices, resulting in additional costs, potential points of failure, and energy losses.
While these factors favour a DC-based electricity grid, a repeat of the war of the currents is unlikely. A more probable scenario is the peaceful co-existence of ‘hybrid microgrids,’ with AC loads powered via a regular AC network and DC loads powered by renewables. Alternatively, we may see the development of standalone DC microgrids, particularly in areas where electrification is too costly. We can also envision applications such as street lighting or poultry lighting being powered by DC.
Although DC microgrids are still in their infancy, their use is expected to grow as more ‘Net Zero’ buildings emerge and the ICT sector, including data centres where DC usage is common, continues to expand.
In the context of lighting, the main impact of DC operation is on the LED driver, where DC enables the driver to be more efficient (by 5% to 10%), simpler, smaller, more reliable, and more cost-effective. The lower cost of DC-operated drivers could accelerate the adoption of dimmable drivers, further enabling energy savings through the use of lighting controls.
DC operation of lighting is not entirely new, as the concept of ‘Power over Ethernet’ (PoE) already exists, where Ethernet cables (usually CAT 5) provide a common wiring platform for a low-voltage DC power grid. However, PoE never really took off, mainly due to the costs associated with the required PoE network switches.
To summarise and conclude:
Driven by changes in both supply and demand, there is a growing interest in DC.
A repeat of the ‘war of the currents’ is unlikely; instead, we will see the coexistence of AC and DC grids or standalone DC microgrids.
Important drivers of DC grids will be the ‘Race to Net Zero’ and the growth of ICT.
The lighting industry should prepare for this change, particularly LED driver suppliers, to benefit from the increased efficiency and potential for further miniaturisation.
