Here to save the day: 'Supergrids' in China and the U.S. (ClimateWire)

November 10, 2021
This article originally appeared in ClimateWire, the first Internet newsletter devoted to the policy, business, science, politics and social impacts of climate change.

BY: JOHN FIALKA | 11/03/2021 06:51 AM EDT 

CLIMATEWIRE | A massive grid that can route electricity over long distances may not seem like a useful response to climate change. But experts say so-called supergrids are critical to the mass adaption of renewable energy sources — and China and the United States both have made strides recently to help turn this vision into reality.

Here's why. A supergrid that can connect power systems across North America — an idea now under discussion — gives more flexibility to energy sources such as wind or solar, which often are dependent on the weather. In other words, a supergrid can help send wind power from Texas to California when the wind isn't blowing in the Golden State.

The idea hasn't always been popular. Engineers from traditional power plants in both China and the United States previously have expressed skepticism about the cost of creating supergrids, as well as the need to install high-voltage direct-current power lines, called HVDC lines. They were accustomed to moving electricity from local power plants, spanning relatively short distances to consumers.

But in 10 years, the basic economics have changed. The cost of generating solar and wind power has dropped, and in China, renewables have become competitive with the main fuel used to make electricity, which is coal.

“I would be very surprised if the Chinese government would not be extremely interested in this,” said Michael McElroy, a Harvard University professor. He has worked with teams of Chinese experts on supergrid plans since 1995.

The latest version of China’s plan was published recently in Joule, an American scientific journal.

The study was authored by eight scientists from China’s top universities and McElroy, who teaches about energy and the environment at Harvard.

It called for an enlarged and more integrated grid of HVDC power lines, including an array of offshore wind turbines along China’s heavily populated east coast.

That would help China fuel an expected fleet of 380 million electric vehicles by 2050. To eliminate daily spikes in electricity demands, drivers would be encouraged to use slow-charging facilities at home and work, rather than more disruptive fast-charging stations.

China’s plan suggests taking advantage of periods of low electricity demand by building facilities that use renewable electricity to make so-called green hydrogen by splitting it from water. The hydrogen then could be stored to generate electricity for use when electricity demand is high.

According to the study, in the approach to 2050, the influx of cleaner and cheaper electricity would begin sharply cutting the costs of power production, making the use of coal increasingly more expensive.

The resulting savings would allow China to use more expensive carbon dioxide removal methods, including direct carbon capture from the air, to become “carbon neutral” by 2060.

McElroy recalled that his meetings with Chinese experts began in 1992, and they sometimes included three-hour sessions with two former premiers. He recalled that they had many questions about how to eliminate the burden of China being the world’s biggest carbon emitter.

At the time, Harvard was putting together a universitywide environment and energy program, and one focus was China. During the Clinton and Obama administrations, McElroy explained, former Vice President Al Gore helped the university arrange contacts with Chinese officials. Harvard also reached out to scientists at Tsinghua University and Huazhong University of Science and Technology, among others.

China was interesting to Harvard because it was not just leading the world in emissions; it was also starting to lead the world in solar, onshore wind power and the use of HVDC power lines. McElroy encouraged his Chinese counterparts to learn more about U.S. efforts to develop offshore wind power off Massachusetts.

“We started to look at opportunities for offshore wind in China. It turns out that they’re enormous,” he said.

The experts were helped by 30 years of data provided by NOAA. It showed hourly estimates of wind power around the globe that included the energy that wind turbines might capture in the shallow waters off the east coast of China.

Historically, China has generated most of its electricity from coal-fired power plants in its west, but the abundance of offshore wind would allow it to create a newly shaped grid. According to a research brief on last week’s report titled "Rethinking Grid Integration," it would have a “Periphery-to-the-Center” shape that would send power into the middle from both sides.

In 2016, in the final days of the Obama administration, the United States also began looking at weather data as part of a plan to develop a future clean power plan. The initial effort was pushed by a meteorologist, Alexander "Sandy" MacDonald, director of NOAA's largest weather and climate research laboratory.

MacDonald stressed that a faster, more agile and enlarged transmission system was necessary to capture the enormous wind power of weather systems and then to move the resulting electricity to where it was needed the most.

“We kept saying, 'You know, wind and solar are never going to work very well unless you have a supergrid,'” said MacDonald, who is now retired.

At first, his idea ran into trouble. At the time, National Renewable Energy Laboratory experts were doubtful that a new grid would be required.

Meanwhile, the power industry, accustomed to short transmission lines, asserted that there was no market for a supergrid. Then President Trump came into office and put supergrid research on hold.

“There were a variety of challenges throughout the study. We got it out when we were satisfied with what we’d done,” was the way Greg Brinkman, the principal author of the NREL study that finally emerged last summer, explained it.

Called the “North American Renewable Integration Study,” it described the first detailed power system that could integrate large amounts of wind, solar and hydropower that would multiply connections among the three power grids in the United States — the Eastern, Western and Texas grids — and also with grids in both Canada and Mexico.

The intended goal, according to the study, was "to create a reliable, cost-effective, low-carbon grid in North America."

As Brinkman explained it in an interview, the result would be daily exchanges of renewable energy that could help all three countries. Canada could bolster U.S. clean electricity with its abundant hydroelectric and wind power. In exchange, it would receive solar power from the United States for periods of high Canadian electricity demand.

At various times, Mexico could supply more solar and wind power to Texas and California in exchange for wind power from the western United States when that became more abundant.

The evolving grid would require a network of HVDC lines — particularly better transmission connections with Mexico. “Based on the results of our study,” said Brinkman, “there were a lot of potential opportunities for expanding the grid we have today.”

Models, he said, showed a future grid system that could cut electricity costs by as much as $200 billion between now and 2050, as solar and wind power replaced coal- and natural gas-fired generation.

The cost reductions, he added, won’t appear quickly because long-distance power lines can take a while to build in the United States, in part because of the time it takes to settle fights over legal rights of way.

The new study points out that “North America has some of the best wind and solar resources in the world.” It notes that many previous grid integration studies started out with a given system and then added wind and solar piecemeal, “without additional retirements or changes to the rest of the generating fleet.”

The planned grid, it says, “optimized” what might be done with wind and solar power with an improved multinational grid and expanded transmission structure through 2050.

The point of the study, it says, was to get more people thinking about a supergrid and to "help guide stakeholders to understand how the components of the power system can help work together to create a reliable, cost-effective, low-carbon grid in North America.”