SHANGHAI, April 19 (Reuters) - The amount of electricity wasted by China's solar and wind power sectors rose significantly last year, environment group Greenpeace said in a research report published on Wednesday, despite government pledges to rectify the problem.
China promised last year to improve what it called the "rhythm" of construction of power transmission lines and renewable generation to avoid "curtailment," which occurs when there is insufficient transmission to absorb the power generated by the renewable projects.
But Greenpeace said wasted wind power still rose to 17 percent of the total generated by wind farms last year, up from 8 percent in 2014. The amount that failed to make it to the grid was enough to power China's capital Beijing for the whole of 2015, it added.
Wasted wind generation in the northwestern province of Gansu was 43 percent of the total generated last year, it said.
Solar curtailment rates across China rose 50 percent over 2015 and 2016. More than 30 percent of available solar power in Gansu and neighbouring Xinjiang failed to reach the grid.
In an earlier report Greenpeace said total solar and wind investment between now and 2030 could reach as much as $780 billion.
But, rising levels of waste had cost the industry as much as 34.1 billion yuan ($4.95 billion) in lost earnings over the 2015 to 2016 period, it said on Wednesday.
China produced 12.3 billion kilowatt-hours (kWh) of solar power in the first quarter of 2017, up 31 percent year-on-year but accounting for just 1.1 percent of total generation over the period, according to official data on Monday. Wind rose to 62.1 billion kWh, 4.3 percent of the total, but was dwarfed by the 77.9 percent share occupied by thermal electricity.
Grid construction has fallen behind, with China focusing on expensive ultra-high voltage cross-country lines, which are better suited to large-scale power generation projects, including large hydropower facilities in the southwest.
"Upgrades to the system are urgently needed, including a more flexible physical structure of the grid, efficient cross-region transmission channels and smart peak load operation," said Greenpeace climate and energy campaigner Yuan Ying.
Many regions have used wind and solar only as back-up electricity sources during peak periods, and much of it falls idle when power use drops.
According to official data, the renewables base of Zhangjiakou, north of Beijing, has more than four times the wind and solar installations than the local grid can handle, and capacity is still set to increase rapidly. ($1 = 6.8894 yuan) (Reporting by David Stanway; Editing by Christian Schmollinger)