Supergrids: Need it or Leave it?
By Cameron Reaves
In the final project for the Harvard University Clean Energy Group (HUCEG) comp, I am presenting research conducted on “supergrids.” A report by the International Renewable Energy Agency (IRENA) defines supergrids as “high-capacity power transmission lines using either high-voltage direct current (HVDC, above 500 kV) or ultra-high-voltage direct current (UHVDC, above 800 kV) power lines” (IRENA). Supergrids are useful because they would be able to transfer large amounts of energy efficiently from regions with dense but variable renewable energy resources to regions with high energy demand (IRENA). Historically, the benefits of alternating current (AC) transmission infrastructure, namely that it can more easily reach high voltage levels, prohibited direct current (DC) transmission infrastructure from being built. However, improvements in DC technology from research and development has made deployment more feasible. Unlike AC, electricity in a direct current is transferred at a constant voltage which is easier on the conductor and requires less space, thereby being cheaper to build (GE). Furthermore, with HVDC, up to 3 times more electricity can be transmitted on conventional HVAC lines while reducing energy losses (GE). Supergrids can improve energy reliability, increase availability of generation, and add greater system flexibility (IRENA). Amazingly, HVDC can connect places separated by more than 3,000 km, making their implementation usually transnational or transregional (IRENA).
Along with its benefits, supergrids face several challenges. Further development will require “international political collaboration on grid ownership, rights and revenue allocation, amongst other matters” (IRENA). But these intense linkages between countries and regions could also foster peace, cooperation and security. So far, there are several supergrids being built or planned: Europe, India–Bangladesh–Nepal–Bhutan, North Asia (China–Japan–Russian Federation–Republic of Korea– Mongolia), United States, and Africa (IRENA). By connecting all these supergrids, countries could create a global supergrid! This proposal is called the Global Energy Interconnection (GEI), “a transnational, transregional and transcontinental UHVDC smart grid that will be primarily used for transmitting clean energy” (IRENA). An international organization called the Global Energy Interconnection Development and Cooperation Organization (GEIDCO), made up of global energy firms, utilities, associations and institutions has proposed a global system operation by 2050. To implement this global supergrid, these authors argue that several requirements be met: widespread DC transmission and interconnection, multinational policies on ownership rights, stakeholder roles, responsibilities, obligations and financing, and an international wholesale market for electricity power (IRENA). A global wholesale electricity market would result in the lowest-cost form of energy being accessible anywhere at any given moment, while guarding against blackouts (GE). With a global supergrid, developing countries can have access to dependable energy for economic activity without having to build cheaper, but more carbon intensive coal and natural gas power plants (GE). Localized power grids will increasingly be at risk of going offline due to storms or malfunctions caused by global warming and climate change (GE).
However, there isn’t quite consensus that a global supergrid is the most beneficial developmental pathway for a carbon zero economy. The authors of a paper titled, On the Techno-economic Benefits of a Global Energy Interconnection, conclude that the benefits of a globally interconnected world would be lower than those provided by interconnections at the national and subnational level. Basically, there would be gains that push down the price of electricity, but the management and technology costs make this policy marginally worse than a simpler energy regime with just local intraregional connections. The authors argued that there was considerable uncertainty about the effectiveness of long-distance energy transmission of high-density energy forms, such as liquefied synthetic natural gas, synthetic liquid fuels, methanol and ammonia. Understanding more about these high-density energy forms would certainly affect to what extent that long-distance power lines are necessary for global clean energy demand. Similarly, another group of researchers compared the supergrid and the smart grid, as strategies for integrating intermittent renewables. Using a case study on West Denmark, they argue that these strategies are mutually exclusive; supergrid development can harm domestic smart grid development. In the long term, they expect that these two strategies can merge into one system, a “super-smart grid”, but policy should be implemented to protect local, decentralized smart grid infrastructure from competing with supergrids.
In conclusion, supergrids are exciting and promising technological developments, but barring serious political cooperation, will remain underutilized. The most likely policy regime will be the build out of regional supergrids using novel HVDC transmission infrastructure. Perhaps one day, a globally interconnected supergrid will exist, but we are a long way from achieving that marvelous feat and who knows if it is even necessary!