Take a look around you. Is there anything we can do without electricity? Be it lighting, education, healthcare, productive work of almost any kind—everything requires electricity.
Today there are around 1.1 billion people worldwide without any electricity at all. In 2015, more than 196 world leaders committed to 17 Sustainable Development Goals (SDGs) to end extreme poverty, fight inequality and fix climate change. Twelve of the 17 SDGs are directly impacted by electricity or the absence of it. Number seven is specifically about ensuring access to affordable, reliable, and clean energy for all by 2030.
In most countries electricity is produced in large power plants as alternating current (AC). More often than not, these power plants operate on fossil fuels and add to global pollution and degrade the environment. (Clearly, the problem is not AC, but rather the use of fossil fuels.) Plants tend to be located far from cities or areas of consumption and so electricity has to be brought in via long transmission lines.
In direct current (DC), the electric charge (current) flows in one direction—plus to minus. That is why you see the (+) and (-) symbols on all batteries. Electric charge in alternating current, on the other hand, changes direction periodically. AC is better for transmission over long distances, while DC is great over short distances.
There are three main reasons why DC is now considered the key innovation for 21st century electrical systems:
1. Most consumption devices have electronic components these days, and all electronics simply run on DC. This is the reason why we get AC in our homes and offices, but use transformers, adaptors or drivers like these to adapt electricity from AC to DC. Each time we do this conversion, adaptors lose up to 20% electricity as heat energy. That is why you see your phone chargers or laptop adaptors becoming hot.
2. From generating power at large utilities in the middle of open spaces, we are moving to an era of rooftop power generation through solar panels. This saves space and brings power generation close to power consumption, thereby eliminating the need for power transmission lines across long distances.
3. The last and perhaps most significant reason is that politicians and administrators are under pressure to address climate change, increase energy efficiency and provide electricity to the millions who do not have it. Locally-produced renewable energy is the only answer to rapidly moving away from fossil fuel-based electricity to green electricity for all. This means that especially for rural areas not connected to the grid, small-scale direct current grids, or solar home systems are key to providing affordable and clean electricity to all.
You might ask if DC is only relevant in the context of supplying electricity to those homes which do not have it. The answer is the opposite: it is equally and perhaps even more relevant in areas where electricity may be in abundance.
DC is impacting data centres. There are about 125 DC-powered data centres worldwide. It is not hard to imagine why; all computers work on DC. In data centres, which are densely packed with computers, DC is more efficient and affordable.
It is the same with greenhouses, which are now beginning to generate electricity on the roof, and grow plants and flowers below. DC is consumed locally at the same greenhouse for light, heating, ventilation and irrigation. This reduces the total electricity consumed and avoids reliance on the electric grid.