Maanshan-1 returns but High Demand keeps Margins Tight

The Jingmei River behind NCCU was swollen with much needed rainfall, but most of Taiwan remained dry.

Amid torrential rains that potentially put water behind the dams at Taiwan’s hydropower plants as well as the restart of Maanshan Nuclear Power Plant(NPP3), Taiwan might expect that its energy squeeze would have eased today. Hydropower makes a small but important contribution to Taiwan’s power supply, and the end of the longstanding drought would improve Taiwan’s energy situation. Maanshan unit 1, which was offline for several weeks of annual maintenance, is a major factor in Taiwan’s power supply, and the restart of its 951 megawatts (MW) brought nuclear power once more to 10% of total power generation. The 800MW coal-fired Linkou unit 3 also returned to service, likewise adding to capacity.

Unfortunately, reserve margins remained stubbornly at Yellow, reading 6.01%. Below 6%, Taiwan’s power supply would be at risk of shortages.

Taiwan’s reserve margins flashed Yellow, for tight supply, despite a boost in capacity. Source: Taipower website

Several factors are contributing to this situation.

First, the rains were confined to northern Taiwan, while the bulk of hydropower is in the central and southern regions. Hydropower remains less than half of 1% of Taiwan’s total generation. Wind, never a big factor during the hot summer months, likewise generated less than 1% of Taipower’s load.

Heavy rains fell in northern Taiwan, but the rest of Taiwan remained hot and dry. https://www.cwb.gov.tw/eng/

Prevailing sunshine did enable solar PV to generate at high volumes, reaching 3,320MWh at 1pm, according to Taipower data, nearly 9% of the total at near peak demand and not far behind nuclear’ s 3,694MWh recorded at the same time. But solar drops off quickly and by the evening peak after 6:30pm, solar is almost nonexistent.

Screenshot of power supply by fuel — solar is topmost green, nuclear is bottom pink. https://www.taipower.com.tw/tc/page.aspx?mid=206&cid=404&cchk=8ccc1918-8cae-4f40-a2d0-b43454f4f218

Another issue is the number of large scale combined cycle gas turbines (CCGT) which remain offline. Datan CCGT unit 6, Xingda CCGT unit 2, Dalin CCGT unit 6, along with the 500MW oil-fired Concord unit 4, remain offline for maintenance. Together, they comprise 2,219MW of capacity that is not operating.

The single biggest factor, however, is demand that continues to exceed expectations. Sunshine and high heat result in high demand, and Taipower’s peak load at 1:50pm reached at least 37,763MWh. Taiwan’s industrial output apparently remains on track despite the pandemic, with no respite in demand from the industrial sector. Taipower says that demand has risen at least 3% in Q1 2021, and the Bureau of Energy forecasts a sustained annual rise of 2.5% through 2027.  

Coal remains vital to Taipower’s supply, and Taichung’s power plant continues to operate at nearly full power. Coal generated over 40% of the total load today, neck in neck with natural gas, while multiple other units were dragooned into service, including backup diesel power at 1.3% (greater than hydropower and wind combined) and pumped storage, which generated 2.5% of total load at the peak at 1:50pm, generating 940MWh.

All three units of Linkou’s ultrasupercritical power plant are operating at over 94% (top), while eight out Taichung’s 10 units are running full steam.

Supplies will remain tight through the week on extraordinary demand before finally easing up on the weekend. Next week will likely also be tight, as Kuosheng NPP2 unit 1 will be coming offline permanently perhaps as early as next week.

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