By EB Bureau
The world of electricity is being transformed by electronics. All the devices that we use today work on direct current (DC) supply. This includes LED (light emitting diode) lighting, CFLs (compact fluorescent lamps), computers and electronic devices. Laptops and mobiles come with adapters that convert the alternating current (AC) supply into a suitable DC voltage. Television sets are equipped with small adapters inside. The adapters take in an input voltage that varies between 110V – 240V AC, and produce a DC voltage ranging from 1V – 36V, and the electronic devices use this DC voltage. Input voltages have been standardised to 100V – 240V by the International Electrotechnical Commission (IEC), but output voltages have not been standardised.
It is evident that all devices ultimately use a DC supply. So, the current system could be modified to give a DC supply directly to these devices, instead of providing an AC supply that needs to be transformed to DC before it can be utilised. This would mean that only DC-DC step-down and step-up transformers would be used, instead of AC-DC transformers. This would save a lot of energy, because the existing AC-DC conversion method comes with energy losses. Even in the best cases, the efficiency of AC-DC conversion is 83-85 per cent, which means that there is a 15-17 per cent loss of energy when AC is converted to DC. This energy is lost in the form of heat, which is why laptop and mobile adapters start heating up after a while.
The need for DC supply
Around 85 per cent of electricity that is generated in the world is ultimately used by electronic devices, which need a DC supply. Consider the example of air conditioners— these utilise inverters with variable frequency drives to convert AC to DC. Thus, there is a need for utilities to supply DC itself, instead of AC, since the latter needs to be transformed to DC first, before being used by electronic devices. This is where the concept of LVDC (low voltage direct current) comes into the picture.
Another factor that has led to the need for LVDC is that a large percentage of the population in India doesn’t even have an electricity connection at home. So, electricity needs to be provided to all these households.
Over the years, the amount of electricity being generated across India has increased, but the transmission and distribution network has not kept pace with it. This means that there is still a shortage of electricity. In 2013, the government of India started to promote localised power generation to deal with the problem of power shortages. This was partly possible due to the decreasing cost of solar panels. Power could be generated locally in a village, using solar panels, and this could be distributed to the various houses in that village. Once again, the issue of AC and DC supply had to be addressed. The solar panels produce a DC supply, and the devices in the houses use a DC supply. But for the short transmission distance between the solar panels and the houses in the village, it has to be converted to AC. This leads to energy losses.
So there is a need for DC generation, transmission and distribution of electricity, with all of it taking place in a localised environment.
The high efficiency of DC-DC converters
DC-DC conversions have become more efficient today. The latest DC-DC converters offer an efficiency of about 98 per cent. This makes them very efficient compared to AC-DC converters. In India, lighting systems consume about 18 per cent of the energy produced. If LED lighting is used, this could come down to about 13 per cent in the future. In addition to this, if DC-DC converters are used, then around 15 per cent additional energy can be saved in the long run.
Around 1.5 billion people around the world do not have access to electricity. LVDC systems, along with solar panels and LED lighting, can help to solve the power shortage that the world is facing. In India, many homes are equipped with solar panels and this has led to DC being generated in smaller segments. Thus, people are now producing and consuming electricity at the same time.
The future of LVDC
LVDC is not meant only for India. It can prove to be beneficial in urban as well as rural areas, across the globe. Currently, the LVDC standardisation process has begun in India.
LVDC will have a very big role to play in the future. All technology trends such as IoT (Internet of Things), smart buildings, smart homes, smart cities, active assisted living, and solar photovoltaics will start converging in the future. Each of these will be linked to LVDC, which will play an important role in all these sectors.