On the Techno-economic Benefits of a Global Energy Interconnection

1. Motivations underlying the research The global energy supply in the coming decades is framed by several challenges. Climate change mitigation requires defossilisation of energy supply by mid-21st century to a net-zero greenhouse gas (GHG) emission society. Renewable electricity has been utilised and expanded for more than 100 years for the case of hydropower to achieve an installed capacity base of more than 1100 GW for an excellent energy return on energy invested characteristics, based on highest technical lifetimes of all power generating technologies. Since the 2000s, two variable renewable electricity (VRE) technologies, solar photovoltaics (PV) and wind energy, have received very high growth rates of about 46% and 22% per year, respectively, leading to a total installed capacity of about 500 GW and 593 GW, respectively, by the end of 2018. The advantage of these two major VRE technologies is their enormous scalability and huge resource potential, exceeding total global energy demand by orders of magnitude, particularly for the case of solar energy. The achieved cost level of about 20-25 €/MWh and 25-30 €/MWh for solar PV and wind energy, respectively, at very good sites, brings both technologies to the forefront as a major source of energy in the 21st century. A future energy system will be mainly built on solar and wind energy and thus will have high shares of renewables in the energy system. The outline of the future energy system is based on solid fundamental insights and respecting sustainability guardrails. However, it is not yet discussed in broad what may be the optimised power system structure. Two poles are scientifically discussed and can be summarised as the Super Grid approach and a decentralised Smart Grid approach. The paper features the Super Grid approach from major regions and continents to a global perspective, so that the potential of a global energy interconnection can be discussed. 2. A short account of the research performed A global energy interconnection has been suggested first by Buckminster Fuller 1971. In 1992, the Global Energy Network Institute shifted the view for utilising renewable energy sources. Kurokawa linked the concept of a global grid to the abundant global solar energy resource available in the 2000s. Liu further lifted the discussion on global energy interconnection in recent years. Most of the studies outline the energetic benefits of the Super Grid approach, but often lack in comparative economic analyses showing that a Super Grid approach would lead to lower energy system cost than a decentralised energy system. The team of Breyer showed in recent years that major regions in the world would benefit from a Super Grid approach. The Super Grid results clearly reveal the enormous benefits of the Super Grid approach. The most remarkable research result is the cross-border electricity trade from the highly decentralised approach to the Super Grid approach of 17%. Consequently, it can be concluded that the cost optimised power system shows mainly decentralised characteristics which are further supported