A senior power expert has urged authorities to narrow the gap in energy usage between peak and off-peak hours by setting different prices, as an addition to the progressive pricing system to be released this year.

Cai Guoxiong was speaking on Wednesday at the launch of a study conducted by Friends of Nature, a Beijing-based environmental NGO, about the attitude of city residents toward electricity prices and the tariff system.

"We need to distinguish the situations when talking about energy saving, because the electricity generated at night will be wasted if few people are using it," said the assistant chief engineer at China Electric Power Research Institute.

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Last October, the National Development and Reform Commission, the nation's economic planner, released a draft multi-step pricing system, in which household tariffs will increase with usage.To encourage energy conservation, the first step was set as low as 110 kilowatt-hour or 140 kWh, leaving 70 to 80 percent of Chinese homes almost unaffected.

Additional power use will be charged at a higher price below a level roughly double the base tier and at an even higher price beyond that level.

Cai said even though the proposal might reduce total residential electricity consumption, that is not what the power companies need right now.He showed a graph that outlined the power load at different times of the day during summer. The peak is several times greater than the low late at night.

"The peak load of the power system is designed to stay above the highest figure in this graph, to ensure there is enough electricity when it is needed most," he said.

"If we can get the public to use more electricity in off-peak hours by making it more expensive during the day and cheaper at night, the gap between high- and low-usage times can be narrowed, so that the peak load of the power system can be reduced," he told METRO.

Cai said Hong Kong has been applying separate electricity prices for 20 years.Each family is equipped with two ammeters, one for the day and one for the night. These are operated by remote control by the power supply bureau, which switches between the two depending on the time.

Officials with the NDRC and Beijing development and reform commission were not available to comment on Wednesday.

According to the Friends of Nature study, Beijing citizens are very aware of energy conservation, with more than 80 percent applying all kinds of power-saving measures, such as using electricity-saving lamps and fridges.

Almost 85 percent of residents have called for the government to play a bigger role in promoting power-saving measures.

"Faced with such enthusiasm about energy saving, pointing them the right way appears important," said Cai.

He did not approve of the "Earth Hour" activity that has spread like wildfire across the world. This involves tens of millions of people turning off their lights at the same time. Cai said it could cause the power system to collapse if more people take part in it.