Direct Current, Renewables and the Energy Transition

Nonso Asuoha
5 min readAug 17, 2020

Direct Current (DC) has a great role to play in enabling renewable technologies advance the transition to clean energy and sustainability.

LED lights source : hang niu on unsplash

Electricity helps power the things that matter to us, bringing so much comfort and efficiency to our everyday routines. This convenience is what we pay for each time we settle our light bills!

In the Beginning there was War…

During the ‘war of the currents’ in the late 1880s between Thomas Edison, who developed the DC system and George Westinghouse, who promoted the Alternating Current (AC) system, AC became the ‘winner’ due, largely to the better efficiency of AC in long distance electricity transmission.

Interestingly, AC was also adopted for utility distribution and home energy use to power appliances, even though these appliances actually utilize DC.

Today, however, a lot has changed because of the breakthrough innovations of renewable energy technologies that are generated closer to where they will be utilized, with decentralized off-grid models that require little or no transmission of power.

NEEDLESS CONVERSIONS

Renewable energy sources, especially solar and wind generate Direct Current but our present-day power infrastructure necessitates that they are converted to Alternating Current to conform to grid standards.

This system of converting generated DC to AC using inverters is increasingly becoming unsustainable, especially given that the converted AC power will again be reconverted to DC at the end load, both processes with significant energy losses.

Electronic appliances operate on DC power, losses as high as 20% are incurred when generated DC power is converted to AC, in addition to the cost of conversion equipment like inverters.

Significant energy losses are inherent in conversions from Direct Current to Alternating Current and back again at the end load.

Eliminating these conversions and associated financial costs become even more important in the quest to extend electricity access to unserved and underserved communities in an affordable way.

“The parallel rise of DC power sources in buildings (such as on-site solar and associated battery storage) presents an opportunity to avoid these conversion losses.” — Alliance to Save Energy

DC power is significantly more energy efficient than AC, and is even enhanced when combined with off-grid renewables. Therefore, ensuring that the energy is consumed in that form by using appropriate mechanisms to deliver it to appliances will be a major boost to not only renewable energy but the drive to switch to sustainable electricity generation and utilization.

While a lot of progress is being made in this regard, Afrinet Power Tech, working to deepen clean energy access in Nigeria has developed a DC solar wall socket to drive their ‘Inverterless’ solar power model. This will enable easier integration of DC power in homes.

OLD TECH IN THE NEW ERA!

The current electricity distribution system, adopted over 100 years ago is no longer keeping up with today’s energy needs, and with current focus to transition to a more sustainable alternative, it’s no doubt that we must adopt more decentralized, distributed models that enable smooth usage of direct current (DC) systems and appliances to maximize energy efficiency and cost savings.

Last century’s AC infrastructure was designed at a time when today’s energy demands and energy supply sources, especially renewables, were unavailable. Globally, thousands of kilowatts of solar energy generation systems are installed on rooftops, parking lots and even footpaths every day in a major challenge to traditional electric utility service models.

Also, uptake of DC-ready devices are on the rise, while manufacturers are making it possible for appliances to easily plug in to either a DC or AC power source. DC motors and appliances in addition to their better energy efficiency, equally support enhanced integration of energy storage, which helps improve capacity utilization of generated renewable energy.

Lack of grid access and poor power quality in underserved areas can be improved through DC-based decentralized electricity schemes powered by renewable energy

Several initiatives have been ongoing in parts of India, China to power homes completely in DC. These are places without grid access with off-grid DC electricity proving to be safer, faster to deploy and more affordable than grid extensions.

With grid extensions no where near catching up with energy demand and population growth, Nigeria and parts of sub-Saharan Africa with large gridless communities will in no doubts see improvements in energy access through adoption of decentralized DC electricity to power off-grid communities.

As new cities across Europe and Asia are being planned to run completely in DC power in a bold effort to actualize smart city projects, while the US Green Building Council now has a new LEED credit that provides incentives to building developers to incorporate Direct Current in buildings for greater energy savings, there’s great potentials for DC power systems.

TRANSMISSION EFFICIENCY

HVDC transmission lines from China’s Three Gorges Dam, the largest power plant in the world. DC is now also replacing AC in energy transmission. source : National Geographic

On the transmission side of things, an improved high to ultra high voltage version of DC known as HDVC is fast becoming the transmission standard of the future as a result of its ability to enable long distance transmission of electricity with even fewer losses than AC.

HVDC can also be implemented through underground and underwater cables, which has been very difficult to achieve with AC.

Power technology giants, ABB, based in Zurich, Switzerland that pioneered the HVDC technology hasn’t only become one of the most valuable power equipment brands but has also positioned the solution as key enabler in the future energy system that’s based on renewables.

In a report by IEEE Spectrum, HVDC is “readily available and increasingly affordable, and could replace the old equipment to make long-distance electric power transfers possible”

DC continues to drive the core components of modern day electronic systems. Direct Current now powers more than a third of household electricity consumption.

With the rising number of modern consumer electronics, efficient LED lighting, DC cooling systems and other motor-driven appliances as well as proliferation of electric vehicles, the tide will only continue to tilt in favor of Thomas Edison’s DC.

My Twitter handle is @Nonso_RE

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Nonso Asuoha

Renewable energy professional | Electronic/Computer Engineer | Web developer | SDG7&13 paladín