“The Paris Agreement and mid-century carbon-neutrality goals call for an urgent global energy transition, which is expected to include a steep increase of renewable power generation. The endowment of renewable energy sources (RESs) (solar photovoltaic (PV), wind and hydropower) varies across regions in terms of both quantity (total potential) and quality (capacity factor). Unlike fossil fuels, which are frequently transported and traded globally, RESs are commonly utilized only in local energy systems. Moreover, electricity demand varies considerably among world regions. A region with high electricity demand due to population and economic growth may not be endowed with sufficient RESs, whereas its neighbouring regions might have a surplus of electricity from RESs.
The advance of ultra-high-voltage (UHV) transmission technology over the past decade offers a solution for overcoming the technical barrier of trading renewable electricity across large world regions. UHV lines can transmit electricity over long distances (2,000–3,000 km) with relatively low losses (around 2–4% per 1,000 km depending on voltage levels). This technology has been commercialized since 2010. As of October 2021, 26 lines in China and one line in Brazil have been constructed with a total length of about 40,000 km. UHV technology exists for both alternating-current (AC, ≥ 1,000 kV) and direct-current (DC, ≥ ± 800 kV). UHVAC transmission technology is usually adopted for synchronous networks within a single region or country, while UHVDC is adopted for remote, large-capacity and long-distance transmission. Recently, a global electricity interconnection network was proposed to transmit large-capacity renewable-based electricity to form an electricity-centred, renewable energy-dominant and interconnected energy system.”
Excerpt from Guo, F., van Ruijven, B.J., Zakeri, B. et al. Implications of intercontinental renewable electricity trade for energy systems and emissions. Nat Energy 7, 1144–1156 (2022). https://doi.org/10.1038/s41560-022-01136-0