Environmentalists have cried foul over Egat's attempt to project coal, a fossil fuel contributing to global warming, in its advertisements as "clean energy".
A civic group, the Clean Coal is a Dirty Lie Network, launched an online petition on Change.org this week, calling on the Office of the Consumer Protection Board and the Office of the National Broadcasting and Telecommunications Commission to investigate Egat's advert on "clean" coal, alleging it gives the public false information.
The 30- and 60-second "Balanced Energy" advertisement was launched late last year and ran online, on TV and the radio.
It features groups of cyclists, each representing different types of energy, including renewable and natural gas.
The cyclists representing solar power disappear at nighttime while those representing hydropower cycle at a low speed, signifying an inability to meet demand.
Meanwhile, coal is represented by strong cyclists who ride day and night.
Rapeepat Ingkasit, the network coordinator, urged Egat to provide the "real" facts about coal as an energy source, as the ad simply portrays it as the most effective form of energy with no mention of its social and environmental impacts.
He urged Egat to retract the ad for discrediting alternative sources of energy, such as wind and solar energy. The ad fails to address the issues of climate change and the consequences of the advanced technology used to make coal clean, Mr Rapeepat said.
The petition alleged the ad may violate Section 22 of the Consumer Protection Act by providing false and exaggerated information.
Egat governor Soonchai Kamnoonsate refused to retract the ad, which he said portrayed each energy source straightforwardly and helped to remind the public of rising energy consumption and the risks of an energy shortage, which coal-fired energy plants help to address.
Prime Minister Prayut Chan-o-cha backed Egat's coal-fired energy project, saying coal is the cheapest form of energy and will enable Thailand to meet the energy demands of future generations.