How China threatens to force Taiwan into a total blackout

Recent Chinese drills showed how China would encircle and strangle Taiwan by blocking its life-sustaining shipping lanes, a strategy with potentially less risk than staging a full-scale invasion, as Beijing pursues its stated goal of gaining control of the self-ruled island, by force if necessary.

The challenge of steeling Taiwan against a blockade starts with energy, in particular the liquefied natural gas used to generate nearly half of Taiwan’s electricity.

Some 97% of Taiwan’s energy is imported by sea. If completely cut off, its LNG inventory would be fully depleted within days, crippling the island’s ability to produce electricity.

Taiwan’s government is increasing energy storage and rethinking the island’s energy mix. It is looking anew at nuclear power, just months after it shut down its last reactor.

But Taiwan’s drive for energy self-sufficiency has a long way to go, leaving the island more immediately focused on a U.S. assessment that Chinese leader Xi Jinping wants his military to be ready to seize Taiwan by force by 2027.

Two U.S. senators introduced legislation in September that would support Taiwan’s ability to secure a reliable supply of American LNG, including providing U.S. insurance for shippers to keep deliveries flowing if the island is threatened.

Sen. Pete Ricketts (R., Neb.) said he co-sponsored the legislation with Sen. ​Chris Coons (D., Del.) after participating in a wargame that showed Taiwan running out of LNG within 11 days in a blockade.

“It really highlighted how this could be the Achilles’ heel of Taiwan," Ricketts said of the wargame, which was run by the Washington-based Foundation for Defense of Democracies, or FDD, and the Taipei-based Research Institute for Democracy, Society and Emerging Technology, or DSET.

While Taiwan could temporarily resist a Chinese blockade and briefly sustain its output of power, the island would require U.S. intervention to restore electricity over a longer period, according to the results of a series of wargames run by the Washington-based Center for Strategic and International Studies.

Any Chinese use of force to subdue Taiwan would quickly test President Trump’s appetite for military intervention against Beijing.

U.S. policy about whether to come to Taiwan’s defense in an invasion is intentionally vague. While an overt Chinese attack would force Washington to act quickly, a more subtle interruption of Taiwan’s seaborne trade, including of fuel, would complicate decision-making in Washington.

For example, Beijing could subject vessels serving Taiwan to inspection by declaring a law-enforcement or health action, allowing Beijing to quietly raise pressure on Taipei. Since a blockade is an act of war against an enemy state, China would call its action something else, such as a quarantine.

A Chinese quarantine would force Taiwan and the U.S. to decide whether to take military action and potentially be accused of starting a war.

“This is the kind of coercion that flies under the threshold of war, but could still bring Taiwan to its knees," said Craig Singleton, senior China fellow at the FDD, who testified Tuesday about the topic on Capitol Hill at a hearing chaired by Ricketts.

In a blockade, Taiwan’s LNG supplies would last under two weeks, while coal would last seven, the CSIS wargames concluded.

“LNG is the real weakness, energy in general, LNG in particular," said Mark F. Cancian, a senior adviser in the Defense and Security Department of CSIS.

Energy supplies would last longer if electricity rationing is imposed, a step that would ripple through Taiwanese manufacturing, including the semiconductor industry, whose shutdown would have a global impact.

“The real shock is how quickly a low-grade quarantine can expose those vulnerabilities and force Taiwan’s leaders into politically costly rationing decisions," said Singleton.

A Taiwan national security official suggested that supplies would last longer than the wargames projected. “Under a blockade, or in a quasi-wartime state, your industry and pretty much everything else would have to slow down," the official said, citing an internal estimate that wartime would cut the island’s energy consumption by two-thirds.

“If the supply is cut to just one-third of the usual levels, that essentially means most industrial sectors have to go dark," said Tsaiying Lu, a research fellow on energy security at DSET.

Taiwan’s electricity output is already tight. On a recent day, generating capacity fell to just 4% above peak demand. Electricity provider Taiwan Power blamed routine peacetime hiccups, including an accident at an LNG-fueled power plant and maintenance disruptions at two coal facilities.

A full blockade would also halt the delivery of basic supplies to the island. Taiwan wouldn’t starve: It could feed itself for nine months, albeit on an increasingly basic diet, considering some 70% of food is imported, CSIS concluded.

But industrial output would plummet as imports decline, even if the factories had the power to keep running.

Nuclear power accounted for as much as 52% of Taiwan’s electricity in the mid-1980s. But a popular campaign driven by safety fears and backed by the current ruling party led to the shutdown of all of the island’s reactors. The last operating plant was taken offline in May.

An August referendum on restarting the reactor, held just three months after it closed, failed to attract a quorum, though the yes votes outweighed the noes.

While the ruling Democratic Progressive Party has long championed an antinuclear platform, President Lai Ching-te, who has made national resilience against China a political rallying cry, said after the vote that Taiwan’s nuclear safety commission would consider how nuclear-power generation could be restored.

Solar and wind power, meanwhile, don’t yet come close to making the island self-sufficient.

“We aim to maximize renewable energy as much as possible, because this will be better for Taiwan’s security," said Wu Chih-wei, deputy director general of Taiwan’s Energy Administration​. “Given how reliant we are on imports, this isn’t something that can change overnight​."

Taiwan aims to use renewable sources for as much as 70% of power generation by 2050, from the current level of under 12%, said Wu.

For now, the focus is how to secure Taiwan’s supplies of LNG.

Taiwan’s current reliance on Qatar for 30% of its LNG is seen as a pressure point, according to FDD. China is a much bigger buyer of Qatari gas, adding to Beijing’s potential leverage over the emirate.

Raising imports of American LNG from the current 10% would help, according to analysts at the Atlantic Council, who said that binding the island’s energy security more closely with the U.S. would “reduce the probability of Chinese aggression."

Taiwan oil group CPC signed a letter of intent this year to buy millions of tons of Alaskan LNG and potentially invest in a pipeline and liquefaction project that would one day allow the state to directly export gas.

U.S. allies Japan and South Korea could also enhance their security by increasing American LNG imports, the Atlantic Council said. Japan has LNG storage capacity that could serve as a crucial backstop in a U.S.-led effort to resupply Taiwan in a blockade.

Blockades have a long history in warfare, and for just as long navies have challenged them. But it has been decades since the U.S. Navy has led ship convoys or broken blockades on the scale Taiwan would require.

Ricketts, the U.S. senator, said one goal of his legislation is to sow doubt with China’s leader that his military could defeat Taiwan.

“Every time we put a new wrinkle in what we’re doing for Taiwan, they have to change their planning as well," he said.

Write to James T. Areddy at James.Areddy@wsj.com, Joyu Wang at joyu.wang@wsj.com and Roque Ruiz at roque.ruizgonzalez@wsj.com