Lights Out at Maanshan

An island grid without nuclear

Taiwan’s grid has no connection to any neighbouring system, and domestic sources cover less than 5.4% of its energy needs. The rest arrives by ship. In 2016 the government wrote its “2025 Nuclear-Free Homeland” goal into the Electricity Act, targeting 50% LNG, 30% coal and 20% renewables. Chinshan and Kuosheng were shut between 2018 and 2023, leaving Maanshan’s two Westinghouse pressurized water reactors, 936 MW and 938 MW, as the island’s last nuclear plant.

Taipower shut Unit 1 on 27 July 2024 and Unit 2 on 17 May 2025 as their forty-year licenses expired, removing 1,874 MW of net capacity. After the second unit closed, fossil fuels supplied 86.5% of Taiwan’s electricity.

Coal, ships and emissions

For each hour from July 2024 to October 2026, the report measures the shortfall against Maanshan’s net capacity and assumes the missing output was replaced by coal, the most polluting fuel the grid can dispatch. The result is 30.28 TWh of lost low-carbon electricity, 27.98 million tonnes of extra CO₂eq and 15.66 million tonnes of coal, enough to fill 196 Panamax carriers.

At the Markandya and Wilkinson rates, the replacement coal accounts for an estimated 742 premature deaths, 6,813 serious illnesses, mostly heart and lung hospital admissions, congestive heart failure and chronic bronchitis, and 402,380 minor cases of respiratory disease.

A month of fuel on hand

Taiwan’s legal minimum coal stocks last 30 to 42 days. Fuel already loaded in a reactor lasts 18 to 24 months. Replacing Maanshan with coal means a shipment every few days through a strait where military pressure is rising, and a grid that cannot import power from neighbours if deliveries are disrupted.

In May 2025 the Legislative Yuan amended the Nuclear Reactor Facilities Regulation Act, and Taipower began preliminary safety reviews for Maanshan in 2026 under the Nuclear Safety Commission. Reactors of the same Westinghouse design run for sixty years in other countries. Inspections, seismic reassessment, refurbishment and new fuel all take time, and a restart is not expected before 2028.

What the report covers

• Timeline of Taiwan’s nuclear phase-out, from Fukushima to a possible Maanshan restart.
• Hour-by-hour lost generation from both Maanshan units.
• Coal burned, Panamax shipments and CO₂eq under a coal-displacement scenario.
• Estimated deaths and illnesses from the replacement coal.
• Fuel reserves and energy security for an isolated island grid.