I first came across the concept of a global grid during my diploma days. Those were the days when the then head of the department Mr Bhosale sir used to teach us transmission and distribution of electrical energy for hours and hours. Bhosale sirs teaching style was so appealing that there used to be pin-drop silence in the class while he was speaking. I always used to think that if all the things are in place then why don’t we interconnect all transmission lines in the world? As I learnt different courses during under graduation studies, I understood that reasons for not having global grid largely lies in the economic viability and geopolitical concerns.

     One day, I came across a tweet from Mr R. K. Singh, Minister of State (IC) Power and New & Renewable Energy, Government of India in which Prime Minister of India, Shri Narendra Modi pressed for the concept of one world, one sun, one grid. Here is what he actually said;

     I was fascinated to see an Indian politician talking about this globally challenging initiative. The tweet that actually made me write this blog post is from the International Solar Alliance. In the tweet, they said that they are developing the ‘Grid Manual’ for Global Grid. Here is the tweet;

    In this blog post, I will be covering the basics of the global grid, its benefits, requirements and technological barriers. I will try to avoid technical details and will keep my words as generic as possible.

What is the global grid?

    Many of us might be knowing that electricity is generated far away from where it is mostly used. Most of the power plants are located in remote places and power is transmitted from generation are to the cities and towns (consumers). Our dependency on electricity has increased over time due to modern energy-dependent lifestyle and industrialization. Today, the uninterrupted supply of electricity is very important. To improve reliability, we started connecting transmission lines and formed a network. Talking about India, we have 5 such gigantic areas called as regional grids. All these grids are interconnected to ensure energy security and reliability of power supply. It is now possible to transfer the electricity generated from fossil fuel as well as non-fossil fuels to any part of the country. We call it a national grid. The demand and supply of electricity in different parts of the country is continuously managed by using load dispatch centres.

    The demand for electricity by ever expanding and newly developed cities all around the world is increasing day by day. Moreover, transmission lines are needed to be protected against electronic and physical attacks. The limited reserves of fossil fuels and the need to build new energy infrastructure have triggered the concept of global grid. The idea is to interconnect all electric networks around the world. Most of the new energy infrastructure will be for solar and wind power plants. The fact that boosts the idea of global grid is that the sun will always shine on half of the earth. This means that we can generate solar energy for 24×7 and transfer it to any part of the world if we have a global grid!

global grid map
Image Courtesy: Clark W. Gellings

Benefits of having a global grid

  • Right now, while managing demand and supply, part of excess electricity is required to be dumped as we cannot store electric energy. Once generated, it must be consumed. With the global grid, we can export excess electricity to the locations where demand is high.
  • Curtailments in the generation of electricity from renewable energy sources can be avoided during demand-supply management
  • Once large scale economical options are available, we can store the excess energy.
  • Reliability of global electricity availability will improve which will further improve the standard of living.
  • Intercontinental business will rise and generate new job opportunities.

Requirements of the global grid

Following things are required in order to execute the idea;

  • HVDC (High Voltage Direct Current) Network
  • Globally accepted payment mechanism for trading electricity
  • Rules and regulations for energy trading
  • Technical standards and code of conducts for safe, secure and reliable operation

Why HVDC Network?

    The world has adopted AC electric systems for transmission, distribution and utilization. However, transmitting electricity for long distance in DC form is more economical than that of transmitting it in AC form. There is a break-even distance of 500 km above which HVDC lines have proven to be beneficial due to the following reasons;

  • AC transmission required 3 conductors while DC can be transmitted with only 1 conductor (the earth acts as the 2nd conductor). Hence less material is required in DC transmission
  • The right of way (the space taken by transmission lines) required for DC is obviously less than that of AC. For example, a 765 KV 6 GW capacity AC transmission line requires 180-metre-wide right of way. On the contrary, 800 KV DC transmission line will take only 80-metre space!

    Apart from the above, HVDC lines are more easy to control. Interestingly, with suitable changes in software, power can be transmitted in either direction if required! In past, HVDC lines were only designed for end-to-end connectivity. Nowadays, multi-terminal HVDC lines can be built.

    In addition to all, the converter station (part of the HVDC network) can convert AC electricity of different voltage and frequency into DC. It can also convert DC electricity into different levels of voltage and frequency which makes it possible to use HVDC on the global scale (i.e. the problem of different voltage and frequencies can be solved)

    First experimented in North America, HVDC has been adopted by many countries like Brasil, China, India, and western Europian countries. As of now, 9 HVDC lines are operational/under construction in India. They are as follows;

  1. Agra-Biswanath, 800 KV, 6000 MW
  2. Ballia-Bhiwadi, 500 KV, 2500 MW
  3. Champa-Kurukshetra, 800 KV, 9000 MW
  4. Chandrapur-Padghe, 500 KV, 1500 MW
  5. Mundra-Mohindergarh, 500 KV, 2500 MW
  6. Raigarh-Pugalur, 800KV, 6000 MW
  7. Rihand-Dadri, 500 KV, 1500 MW
  8. Sileru, Barsoor, 200KV, 100 MW
  9. Talcher-Kolar, 500KV, 2500 MW

Technological barriers:

  • Circuit breakers of very high (approx.. 60 KA) current quenching capacity are required. ABB and Siemens are developing solutions for this.
  • The use of superconducting material instead of conventional Copper or Aluminium results in less transmission loss. The feasibility of such an alternative should be studied in detail.
  • Electronic devices made up of materials with wider bandgap (Silicon Carbide and Gallium Nitride) perform better in wide temperature range than that of those devices which are made up of only Silicon. Electronic devices made up of such materials should be made commercially available.

Where to start?

    China and European countries have developed a gigantic HVDC network. Once international consensus over the global grid is built, these regions can guide the world in the implementation of the idea. It is estimated that the total distance of transmission line required to develop global grid will be 1,00,000 KM. It will need 115 converter stations.

    The concept like global grid takes decades to complete. A whole generation will have to take efforts to materialise the concept. However, once completed, it will not only benefit future generations but also change the way humans interact today.

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Image Courtesy: Clark W. Gellings, 'A globe spanning super grid',IEEE Spectrum, Vol.52,Issue:8,August2015