THE ENERGY REGULATORY COMMISSION (ERC) has asked the public to submit comments on its proposed interim benchmark for reliability of power generation units in the country, especially in terms of allowable outage days per year.

“The commission intends that the outage allowance in days per year, as determined herein, will serve as the maximum or cap per technology for all power plants,” the ERC’s proposal said.

The benchmark sets varied number of days during which power plants using specific technologies can go on planned and unplanned outage. Technology classifications consist of: pulverized coal, circulating fluidized bed, combined cycle, gas turbine, diesel, geothermal, hydroelectric, oil-fired thermal and biomass.

In order to address the need for a standard on outage allowance of power generating plants, the ERC reviewed their performance, particularly in terms of outages. The commission took into account the monitoring and evaluation of the performance of conventional generating plants with total capacity of at least 20 megawatts (MW).

From 2015 up to the first half of 2019, the ERC’s review showed that, on the average, oil-fired thermal power plants had the most number of outage days per year at 84.5, of which 50.4 were unplanned.

Diesel-fired plants had the least number of outage days at 15.8, followed by combined cycle plants at 19.1 days.

Pulverized coal power plants had average outage days of 50.1, of which 28 were unplanned. Circulating fluidized bed coal power plants had outage days per year of 40.8, of which 24.3 were unplanned. Coal-fired power plants account for the biggest share of the country’s generating capacity.

The ERC used data from the grid reliability monitoring system, a Web-based application that encompasses report submission by power generation companies and generation of reliability performance indices.

In terms of availability factor — or the ratio of available hours to total hours that a generating unit should be operating — the power plant technology without the highest average reliability performance is diesel at 95.66%, followed by combined cycle at 94.78% and geothermal at 94.40%.

Biomass plants are the least reliable at 72.91% followed by oil-fired power plants at around 76.86%.

The ERC said it also looked into the 50th, 60th and 70th percentile of reliability performance indices of generating units with the lowest outage rates or better performance.

It said it was considering the 50th percentile as the interim reliability performance benchmark.

The regulator is giving interested parties until July 26 to submit their comments on the proposed benchmark. — Victor V. Saulon