Being the seventh longest river in Asia and the 12th longest in the world, the Mekong river provides a great deal of potential as a clean energy source through hydropower. The 4,350-kilometre long river runs from the Tibetan Plateau through China’s Yunnan Province, Myanmar, Lao PDR, Thailand, Cambodia and Vietnam.
According to river protection organisation, International Rivers, the Lower Mekong Basin itself has a hydropower potential of 30,000 megawatt (MW), while the Upper Mekong Basin – mostly located in China – has a hydropower potential of 28,930 MW.
China has built six dams in the mainstream of the Upper Mekong Basin. The United States Energy Information Administration reported in 2015 that between 2006 and 2011, Chinese investors financed 46% of all hydroelectricity capacity additions in Cambodia, Lao PDR and Myanmar. Voice of America (VOA) Cambodia reported in January, 2018 that the 30 hydropower dams being constructed in Lao PDR and seven in Cambodia are predominantly funded by China.
The International Energy Agency (IEA) Southeast Asia Energy Outlook 2017 report highlighted that hydropower was the biggest contributor from a renewable source to power generation, with capacity doubling since 2000 to 14% in 2016.
However, the development of hydropower in the region has raised the eyebrows of environmentalists and scientists, globally. China Dialogue reported in 2017 that Chinese dams on the Upper Mekong Basin are disrupting river flow and affecting fisheries in the lower basins. The report also showed that the changing flow of the river will affect the biodiversity of the Mekong.
A more recent study by Environmental Research Letters (ERL) in 2018 has found that hydropower in the Mekong River Basin, may not be very climate friendly. The median greenhouse gas (GHG) emission of hydropower was estimated to be 26 kg CO2e/MWh over a 100-year lifetime, which is within the range of other renewable energy sources (<190 kg CO2e/MWh).
"The hydropower related emissions started in the Mekong during the mid-1960's when the first large reservoir was built in Thailand, and the emissions increased considerably in the early 2000's when hydropower development became more intensive. Currently the emissions are estimated to be around 15 million tonnes of CO2e per year, which is more than total emissions of all sectors in Lao PDR in 2013," stated Timo Räsänen, the professor who led the ERL study.
Source: International Rivers (2017)
The impacts of hydropower development are increasingly well understood in the Mekong River Basin; these include impacts on hydrology, ecosystems, sediment, and fisheries. At the same time, the hydropower's GHG emissions have received less attention and are not systematically assessed, although concerns on potentially high emissions have been raised over the years.
The Mekong River is important to the region for a number of reasons. First of all, it acts as an important fishery resource for the countries the river flows through. According to the Mekong River Commission (MRC), fisheries is the main job provider for the Mekong’s population. Fisheries account for nearly 12% of Cambodia’s gross domestic product (GDP) – contributing more to the nation’s economy than their entire rice production. In Lao PDR, fisheries contribute to around 7% of the nation’s GDP. This shows how significant the health of the Mekong’s ecosystem is for the countries that depend on it.
The GHG emissions are expected to increase when more hydropower is built. However, if construction of new reservoirs is on the pause, the emissions will decline slowly in time.
With Southeast Asia’s overall energy demand expected to rise up to 60% by 2040, countries affected would need to work hard and fast to find ways to lower these emissions. One alternative would be the deployment of small hydropower instead of large hydropower projects. Advanced research on the GHG emissions of hydropower and improved inclusion of climate impacts in strategic environmental assessments (SEA) of hydropower in the Mekong also needs to be carried out to help eliminate projects that could be harmful to its surrounding communities.