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.