Building a Power Grid to Span the World

“The sun never sets practically, you know—it’s setting here, rising somewhere else,” Mr. Sareen says. “If we could connect, voilà! You would have green electricity everywhere.”

Such is the promise of transnational super grids—the vision of globe-girdling power networks that could ship electricity, particularly renewable energy, from areas where it can be produced in abundance to wherever it is needed—across continents, weather systems and oceans.

The grand idea has been around for decades—and has always run up against daunting technical, economic and political barriers. Even now, turbulence around the Ukraine has quickly changed the energy landscape, highlighting the huge challenges of such transnational efforts.

Among efforts that never got off the ground: In the mid 2000s, officials in Germany and Jordan pitched a plan that would power Europe with solar energy collected in the Sahara. In 2011, Japanese billionaire and

SoftBank Group Corp.

CEO

Masayoshi Son

proposed an Asian super-grid that would funnel renewable energy from Mongolia, through China, South Korea and Japan. One of the most ambitious proposals came from China’s state utility, State Grid Corp., whose former chairman Liu Zhenya in 2016 unveiled a plan to pull power from solar and wind installations in the arctic and at the equator, and send it around the world in ultra-high-voltage cables. The estimated price tag: $50 trillion.

Nevertheless, many energy experts argue super grids’ time is coming, driven by technological advancement, declining costs and the growing determination of governments to shift from fossil fuels to renewable energy in their quest to curb global warming.

“We need the super grids both to deliver the bulk clean energy but also to make sure it’s cheap,” says Nicholas Dunlop, secretary-general of the Climate Parliament, a network of legislators focused on climate change that has long championed its own Green Grids Initiative for transnational renewable power. At the November Glasgow climate summit, that U.K.-backed initiative joined with the India-led ISA project to become the Green Grids Initiative-One Sun One World One Grid. Their ultimate aim is to create a network to connect the power markets of 120-plus countries.

Around 90 countries have endorsed the project, the World Bank has signed on as a partner and French electricity supplier Electricité de France SA, or EDF, is conducting a study on how best to put it in place. If regulators, governments and development banks like the World Bank can be persuaded to underwrite the risks of various legs of the project—each of which could cost billions of dollars when the price of adding renewable-energy installations is included—private financiers will jump in, ISA’s Mr. Sareen says.

Cross-border power trading in relatively small quantities is common now—between the U.S. and Canada, for instance, or within Europe. But the prospect of super-sizing such linked electricity grids is becoming more important, those in the industry say, because it could help mitigate the inherent capriciousness of power sources that depend on the weather.

A grid that stretches past local weather systems could potentially ship electricity to areas whose supply has been hit by disasters. It could absorb surplus energy from a region with lots of wind farms on gusty days, for instance—and tap the greater network to supply that region with electricity when turbines are becalmed. Such flexibility is becoming especially important as the percentage of renewable power in the energy mix goes up.

“I see long-distance electrical transmission as part of the energy-storage system,” says Steven Chu, a Nobel Prize-winning Stanford University physicist and former U.S. Secretary of Energy who has long championed transnational grids.

The ability to send electricity long distances is also important for tapping resources in the often-remote areas where renewable energy is best produced—like uninhabited, windy plains that can host acres of windmills or scorching deserts that can be sites for solar panels. Countries with that type of topography and small populations, like Mongolia, see the growing global demand for green power as an export opportunity. Places with big energy appetites and no space for solar sprawl, like Singapore, are looking to import.

In the past, shipping electricity many hundreds of miles over conventional alternating-current lines wasn’t economical because of power losses that mounted rapidly the longer the distance. But improvements in the technology, hardware and cost needed for ultra-high-voltage direct-current lines, where losses are radically lower, have made trans-continental power shipment much more economical than in the past, industry experts say.

At the end of 2018, China’s State Grid, the world leader in stringing long-distance cables, announced it had powered up a 1,100-kilovolt, 2,000-mile line running diagonally across the country, from the Xinjiang region in the northwest to Anhui Province in the east.

Long-distance undersea cables are trickier and more expensive. Laying the lines in deep water is costly. The cables must be insulated, and no materials currently exist that can handle the heat from the highest-voltage lines, transmission experts say. That means developers have to make do with lower-voltage cables and larger power losses.

Some are taking the plunge anyway. Australia- and Singapore-based Sun Cable has proposed a 2,600-mile undersea line that would ship solar power from northern Australia to Singapore; U.K.-based Xlinks Limited is planning a line nearly as long to ship power to the U.K. from Morocco. Both companies are private, and say they plan to raise money largely from private investors.

Singapore

Power arrives here

Darwin

Start of undersea cable

Elliott

Solar farm with battery storage

Undersea

cable, about

2,600 miles

Overhead

power line,

about 500 miles

Singapore

Power arrives here

Darwin

Start of undersea cable

Elliott

Solar farm with battery storage

Undersea

cable, about

2,600 miles

Overhead

power line,

about 500 miles

Singapore

Power arrives here

Darwin

Start of undersea cable

Elliott

Solar farm with battery storage

Undersea

cable, about

2,600 miles

Overhead

power line,

about 500 miles

Overhead

power line,

about 500 miles

Undersea

cable, about

2,600 miles

Elliott

Solar farm with battery storage

Darwin

Start of undersea cable

Singapore

Power arrives

here

Politics remain a huge obstacle to cross-continental power trading. Governments would need to agree how to pay for and manage any long-distance electric lines or new connections between their current grids—complex topics that run up against vested interests.

Sharing power is harder when countries aren’t close allies.

“People get very nervous about their supply of electricity” because you can’t effectively store large quantities of it, so any disruptions hit the local grid immediately, says Mr. Chu. “It’s in a totally different realm than the supply of oil or the supply of natural gas.”

Today’s super-grid planners, who have learned from years of stalled ideas, make the case for building large networks by using what already exists. Many of South Asia’s power grids are linked together already; ditto the Gulf nations of the Middle East; and Africa has several regional networks, says Philippe Lienhart, an expert on power grids at EDF who is leading the interconnection study for the project formed at the Glasgow summit.

By adding lines strategically between regions and bolstering grids where connections are weak, you could potentially patch together something very big, he says: “It’s a story of interconnection of regional interconnections.”

It’s also important to look at the path of least resistance. Take the power line between India and Oman. There are two ways to link the countries: a cheaper route, largely overland, through Pakistan, Afghanistan and Iran, and a more expensive and technically difficult route straight across the Arabian Sea.

The land route is much less costly, says ISA’s Mr. Sareen. “But you won’t find a single expert—technical or non-technical—telling us that it is doable.” Super grids will have to start, he says, where “political will is the strongest.”

Write to Phred Dvorak at phred.dvorak@wsj.com