Sources of renewable energy such as solar and wind power are highly variable, not only over time (the sun doesn’t shine at night) but also in space (some places are just windier than others). This variability poses a major challenge to shifting to a 100% renewable electric grid. But according to a new analysis, zipping electricity back and forth over high-speed power lines at a continent-wide scale could enable renewable sources to easily meet all the world’s power needs.

Transcontinental trade in electricity isn’t a new idea. There are regional power pools operating in Europe, North America, and southern Africa, and transmission lines connect the UK and the Netherlands; Sweden and Lithuania; and Norway and the Netherlands, for example. But the new work is the first to examine how such trade could contribute to a 100% renewable power system at a fine scale of both demand and supply, while taking into account the limited space available for renewable energy development.

In the study, researchers drew on existing databases and models to analyze hour-by-hour electricity demand and renewable supply worldwide for the year 2050. They calculated the availability and cost of electricity if each country generated and consumed electricity only within its own borders compared to a situation in which electricity is freely traded within each of six global regions: Sub-Saharan Africa; East, South, and Central Asia and Russia; Europe, the Middle East, and North Africa; North America; South America; and Southeast Asia and Oceania.

If all feasible sites are available for renewable energy development, electricity sourced within each country’s borders would fall only 2% short of global demand in 2050. But transcontinental trade in electricity could still reduce the cost of electricity by 5-52%, depending on the region, the researchers report in the journal Nature Communications.

And in the real world, all feasible sites aren’t available for renewable energy development. So the researchers also analyzed what would happen if only the top 10% of renewable energy sites globally were developed. And here the importance of international trade in electricity really became clear.

In this space-limited scenario, electricity sourced within each country’s borders would fall 12% short of meeting global annual demand. In nearly one-third of countries, domestic renewable energy would fall at least 20% short of demand.

But with transcontinental power pools, renewable energy could easily do the job even if space is limited. What’s more, the trade would reduce the cost of electricity by up to 23% compared to the domestic-only situation.

“Our research proves that, without long-term storage, 100% renewable electricity is reliable and economically feasible by expanding transmission lines within continents,” the researchers write.

In 2020, about 2% of the total global power supply was traded across international borders. In the new analysis, cross-border trade of electricity would account for about 16% of global demand if all suitable sites for renewables were developed, and about 30% of global demand if only the best sites were developed.

In some ways, the uneven spatial distribution of renewable energy is a familiar situation: some countries have a lot of fossil fuels, and others don’t. In the current fossil fuel economy, that unevenness mostly benefits exporters of fossil fuels, which reap huge profits and massive geopolitical influence from their control of energy sources.

Against this backdrop, renewable energy is often touted as a means of achieving energy independence. The new analysis cuts against that aim, proposing that the green transition should involve more international integration, not less. “Geopolitics would be a barrier to building a transcontinental power pool,” the researchers acknowledge, understatedly.

But the benefits could be widely shared. Nations that import green electricity are spared the cost of developing less desirable renewable projects or investing in expensive battery storage. And for many exporting nations, having a destination for excess electricity would reduce the need to curtail generation and improve the economics of renewable energy development. “Building transcontinental power pools is likely to benefit both importers and exporters of renewable energy,” the researchers argue.

Source: Yang H. et al. “Global transcontinental power pools for low-carbon electricity.” Nature Communications 2023.