Downstream fears as China powers ahead with new dams

Canberra Times
Wednesday 29/9/2010 Page: 19

China's already the largest generator of electricity from river water trapped by giant dams, recently announced plans to nearly double its hydroelectric power capacity by 2020. This is good news for those concerned about China's impact on climate change. Coal, the dirtiest and most carbon-intensive of the fossil fuels, is the main source of energy for China's turbo-charged economic growth. But South-East Asia and South Asia, which depend on the regular flow of major rivers that start in China before crossing the border into downstream states, will be watching closely where the new Chinese dams are built and how the huge amounts of water in their reservoirs is regulated.

These decisions will affect the flow of water in trans-boundary rivers that begin and run for much of their course in China, such as the Mekong, South-East Asia's longest river, and the Brahmaptttra, that winds for 1700km through the highlands of Tibet before crossing into India and Bangladesh. About 83% of China's electricity comes from burning coal. The air pollution blights Chinese cities and damages public health.

Massive amounts of CO2 released into the atmosphere from coal-burning by power stations and heavy industry have made China the leading source of this global warming gas, surpassing even the United States a few years ago. When all generating units began running last month at the Xiaowan hydroelectric-power dam on the Chinese section of the Mekong in south-western Yunnan province, China's hydroelectricity capacity became the world's largest. Xiaowan is the fourth of eight dams being built on the upper Mekong. Its completion brought China's nationwide hydroelectricity generating capacity to a little more than 200 millionkWs.

Chinese officials say that had they not tapped river water for power, thermal plants of equivalent capacity would have been built, burning 288 million tonnes of coal annually and releasing 855 million tonnes of CO2 and 5.4 million tonnes of polluting sulphur dioxide Into the atmosphere each year.

Hydroelectric power produces no toxic air pollutants or carbon emissions. China aims to generate 15% of its power from non-fossil sources by 2020, up from 7.8% now. It has also promised to cut its carbon emissions per unit of economic output by 40 to 45% by then. As the most competitive renewable energy, hydroelectricity is a key to achieving emission cuts in China, although rapid expansion of nuclear power will also help.

Director of China's National Energy Administration Zhang Guobao told the official Xinhua news agency last month that hydroelectricity projects with another 70 millionkW capacity were under construction. "If all the planned hydropower projects begin construction in the next three years, it is still possible to expand the current installed capacity to 380 millionkW by 2020", he said. "We need careful and detailed planning and imperative approval procedures". If done well, hydroelectric power can be a sustainable and nonpolluting power source that helps decrease dependence on fossil fuels and reduces the threat of global warming.

However, blocking rivers with massive dams and reservoirs can create serious social and environmental problems, including displacement of local communities, forest and wildlife habitat destruction and preventing movement of migratory fish. There is also the risk of damage or even a catastrophic breach in an earthquake. Because of such concerns, the central Government in China had put a freeze on dam building. However, in July, the Chinese Government gave the go-ahead to two hydroelectricity projects, one in Yunnan and the other in Tibet. They were the first approvals in more than two years.

Will intensified dam building result in lax regulation? Zhang said that even as China accelerated hydroelectric power development, approval procedures would be stricter and focus on issues like protection of the environment and the rights of people relocated to make way for the projects. He did not say where all the new dams would be constructed. India is concerned that China may decide to meet some of its hydroelectric power needs by building giant dams on the upper reaches of the Brahmaputra River, but China has denied this.

However, China now appears certain to finish its planned cascade of dams not only on the upper Mekong but also on the upper Salween River, before it flows into Burma. For downstream countries in South-East Asia Burma, Laos, Thailand, Cambodia and Vietnam this raises two points of concern. The first is how much water will be impounded in Chinese reservoirs behind the dams. The second is how hydroelectric power operators, all of them state owned firms, will regulate the flow of water once the reservoirs hold enough water and the generating units are ready to run.

The four completed dams on the upper Mekong have a capacity to hold back over 18 billion cubic metres of water. This is 70% of the total storage capacity of all reservoirs on the Mekong and its tributaries. After the fifth upper Mekong dam at Nuozhadu is finished in 2014, China's share will rise to nearly 90%.

There are two basic ways of regulating the outflow of this water. One is to hold it back in the wet season to prevent flooding downstream and to release it in the dry season when it is most needed by farmers and others. The other way is to release more of the turbid water in the wet season before the sediment has a chance to settle, and store extra water in the dry season to make up for these releases. Chinese hydroelectric-power operators reportedly prefer the latter method because it evens the flow of water throughout the year and increases both the reliability and efficiency of electricity generation. However, it raises the risk of wet season flooding and dry-season water shortages for downstream states in South-East Asia.