Coal accounted for a little over 20 percent of daily energy needs, when the first plant was commissioned.
Liquid thermal plants brought 50 percent of the energy, with plants owned by state-run Ceylon Electricity Board generating 8.0 GWh or 22.5 percent and private plants bringing in 9.99GWh or 27.7 percent.
Amid a drought hydro power was down to 13.4 percent.
The second Chinese-built plant is not in commercial production and will be put through series of tests by its builders over the next few months, before being handed over to the CEB, Senajith Dasanayake, deputy general manager and business and operational strategy said.
Depending on the test schedule and problems identified during the testing process, the plant will be shut down from time to time, he said.
Dasanayake said the plant could be shut down more than a week allowing it to cool, access components.
On several days however it had been running at full 300 MegaWatt capacity.Unlike a typical hydro plant of a similar capacity a thermal plant driven by coal or diesel can deliver about twice or three times the energy as they are run throughout the year.
Hydro plants in Sri Lanka typical have plant factors (the proportion of time it can operate in a year compared to the total time available) of around 30 to 40 percent depending on water availability and size.
This compares to 80 percent or more for a coal plant, which includes shut downs for annual maintenance. Most of Sri Lanka's large hydros are now used as peaking plants during the night except for small plants with minimal storage.
In 2013 the plant had been available for operations (availability factor) 76 percent of the time, CEB General Manager Shavi Fernando told LBO in January.
In practice however the plant is operated at a lower factor due to fears of system stability during the night off peak. The latest Central Bank data shows that it was operated at 55 percent plant factor.
The increase in coal power in Sri Lanka is coming as some researchers are blaming Chinese coal plants for so-called 'global cooling' or more accurately the 'pause' in global temperatures seen during the past 15 years or more, despite earlier predictions off catastrophic warming.
The 15-year pause or 'hiatus' in global warming despite billions of tonnes of carbon dioxide being put into the atmosphere over the period is thought to be partly caused by aerosols from Chinese coal plants which reflect sunlight back to space.
Sri Lanka however uses low-sulfur coal, which is said to contribute less to global cooling.
Other research had pointed to ocean absorption of heat. Skeptics of 'man-made global warming' draw parallels with solar cycles and earlier cooling and warming periods on the earth.