Japanese thermal output sinks to historic low in May

Weak overall power demand, strong nuclear output and record solar generation cut Japanese thermal generation to at least a six-year low in May.

Japanese thermal generation fell by nearly 3TWh on the year to 44.3TWh in May, according to data published by the country's 10 major utilities.

Coal-fired generation accounted for 38pc of thermal output in January-March — the latest period for which granular government data are available — and the same share in May would have put coal burn at around 16.8TWh, compared with 18.4TWh in the same month last year. Gas-fired generation accounted for around 53pc of thermal output in the first quarter, which would equate to 23.5TWh in May, compared with 26.1TWh 12 months earlier.

Nuclear generation grew strongly on the year in May, but the pace of growth slowed compared with the December-March period following the onset of planned maintenance across a number of units. Nuclear output fell to an eight-month low of 5.4TWh in May, but was still 2.1TWh higher on the year.

Growth in solar output was almost as strong as nuclear generation in May, rising by 1.9TWh on the year to a record 7.7TWh, with the impact on thermal generation compounded by a 1.5TWh drop in overall power demand.

Thermal output to recover?

Japanese thermal generation totalled 278.1TWh in January-May, representing a 7pc decline on the year from 300TWh in the same months of 2018. The country's imports of coal and LNG fell by 2pc and 9pc to 45.9mn t and 33.2mn t, respectively, in the same period.

But fossil fuels could recover some ground in the second half of the year, as planned maintenance across the country's nuclear fleet is likely to leave a shortfall in output. The latest maintenance schedules indicate that Japanese nuclear availability will be down by around 656MW in the second half of the year, reducing output by up to 2.9TWh over July-December compared with the same period of 2018.

A full schedule of Japanese nuclear availability is available to download via Argus Data and Downloads.

The shortfall in nuclear generation is scheduled to be most severe during the fourth quarter and early in 2020, potentially supporting greater demand for fossil fuels, particularly in the event of unusually cold conditions this winter. Nuclear output would be down by 3TWh on the year in the fourth quarter and by 5.3TWh in the first quarter of 2020, if all the capacity that is scheduled to be available is used. 1TWh of power generation is the equivalent of 400,000t of NAR 5,700kcal/kg coal burn at 38pc efficiency, or 130,000t of LNG use at 55pc efficiency.

Nuclear availability in June was sufficient to support up to 4.9TWh of output, which would be up from 3.9TWh in the same month last year, but output is likely to fall slightly on the year in July from 4.7TWh in 2018.

Japanese nuclear generation TWh

Coal/gas imports (L) vs thermal gen. (R) mn t, TWh