Will DC be the standard in future?

AC grids have become the standard worldwide for generation, transmission and distribution of electricity. But with increasing use of DC powered devices and breakthrough in technologies of  Supergrids and HVDC, DC may become the standard in near future.

Thomas Edison was a staunch supporter of DC. In a notorious incident in 1902 as a last ditch effort to convince public about the dangers of AC and establish DC as a standard, Edison electrocuted animals with AC in open public. But he lost.

AC grids have become the standard worldwide for generation, transmission and distribution of electricity. In generation stage, 3-phase AC is generated which is then stepped up through a transformer, transmitted across the regions through AC grids and finally voltage is stepped down for distribution to the end-consumer. However, recent trends and breakthrough in new technologies in each of the stages (generation, transmission and consumption) strongly suggest the inevitability of DC standard.

In the distribution stage, consumption of electricity in DC form is rising fuelled by increasing use of electronic devices (TV, mobile phones, etc.) in our homes. In generation and transmission stage, the focus is shifting towards renewable energy sources (which again generates DC) and HVDC (High Voltage DC) lines are being used for Supergrids. ABB Ltd. has already come close to developing a high power DC circuit breaker that will enable HVDC transmission of renewable energy from far off places and even from other countries. It seems that Edison may have the last laugh!

Rise of DC consumption

Today, DC consumption accounts for 20% of total electricity in the world. And, this is expected to rise to 50% in next 20 years. The rapid rise of DC power consumption has been due to increasing use of digital devices which run on DC power. Laptops, Tablets, Mobile Phones, Television, etc. all run on DC. There sockets/ chargers have an AC-to-DC converter attached. Apart from digital gadgets, DC consumption has also been increasing due to adoption of LED lighting and solar panels.

Almost 15% of energy is lost in conversion from AC to DC. With more number of devices running DC consumption, significant amount of energy can be saved if the devices are directly fed DC power instead of through AC-to DC conversion.

Already, "DC micro-grids" are being set up by various institutions to save the energy losses from AC-to-DC conversion. China's Xiamen University has developed a 150 KW solar-based DC micro-grid spanning across its three campus buildings. DC energy loads such as LED lighting, data-centers, electrical vehicle charging, etc. are expected to provide energy saving. Currently, data centers (which are powered by DC) consume 1.3 percent of total electricity consumed worldwide. Intel estimates that a medium-sized data center can save as much as $1.2 million annually by switching to direct DC power instead of AC-to-DC conversion.

Supergrids: To connect world's renewable energy sources

Electricity generated at power plants near city regions is in AC form which is then transmitted at high voltages over AC grids (HVAC) and finally stepped down near load centers for distribution to the end-consumer. So, the generation and as well as transmission is in AC form. HVDC (High Voltage DC) lines is not the preferred mode for transmission as at these distances, energy loss is substantial than HVAC.

The trend these days has been to shift towards renewable energy sources. Governments across the world are promoting clean and renewable energy sources. Wind and solar power are witnessing increasing investments from the companies. However, renewable energy sources are intermittent and are often located at far off distances from cities and load centers. But, advances in HVDC (High Voltage DC transmission) and Supergrids-internationally connected grids- may be changing that.

Supergrids are internationally connected electric grids that transmits electricity at great distances. Since clean energy sources are often located in distant regions, Supergrids is seen as the solution to connect renewable energy sources across the world. That means, solar power from Sahara region may bring power to cloudy Germany and wind power can be exchanged across the Europe using Supergrids.

Supergrids - Internationally connected grids.

For Supergrids, HVDC transmission is preferred over HVAC for a number of reasons. Supergrids are used for transmission at long distances. And at distances greater than 700 KM, HVDC offers very low line losses than HVAC. So, clean energy resources like solar or wind power can be transmitted at large distances efficiently. Another advantage comes from the compatibility that HVDC offers. Many times, it is difficult to interconnect AC grids due to differing frequencies or other incompatibilities. Also, wind or solar power generated is in DC form which can be directly transmitted over DC grids.

Recently, HVDC technology has seen significant breakthroughs that makes adoption of HVDC and Supergrids even more compelling. Researchers at ABB have developed High Voltage DC circuit breakers that can disconnect part of the grids that have a problem. MIT Technology Review listed it as among Top 10 breakthrough technologies in 2013.

Researchers at ABB working High Voltage DC Circuit Breakers

Supergrids and HVDC lines are already seeing huge investments from the companies and governments across the world. Alstom recently completed a project connecting electric grids of Sellinge (UK) and Les Mandarins (France) regions through under-sea electric cables. In another project being set-up, hydroelectric power produced in Porto Velho (Brazil) will be transmitted through Supergrids using HVDC line to Araraquara region in Brazil which is located located 2375 KM far away. Supergrids are expected to interconnect World's clean energy resources.


With rise of DC run devices, breakthrough in the HVDC technology and the focus to shift towards renewable energy sources, the day may not be far away when DC will become the overarching standard for generation, transmission and distribution.

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