Study shows Mekong droughts drive up carbon emissions, energy costs as dams go dry

Mae Moh power station, Lampang, Thailand. Photo: watanyou intachai shared under a Creative Commons (BY) license

New research shows hydropower in the Mekong region will become far less sustainable as droughts force countries to rely on coal and gas power plants, driving up carbon emissions and electricity costs. The findings present a problem for Mekong countries’ dam building plans, as hydropower appears far less green and less reliable than other renewable sources.


Prolonged droughts in the Mekong region may be causing spikes in carbon emissions, according to a new study by researchers at the Singapore University of Technology and Design (SUTD) and the University of California, Santa Barbara.

The study published in February in the journal Earth’s Future found that extended droughts reduce the Mekong region’s hydropower supply dramatically, causing electricity providers to ramp up gas and coal power production. The shift results in higher fossil fuel emissions as well as higher energy production costs.

Based on energy demand and power infrastructure from 2016, the study found that droughts in the Mekong increase power production costs by US$120 million per year and carbon emissions by 2.5 million metric tonnes per year.

The findings suggest that hydropower will become far less sustainable as the impacts of climate change increase and droughts become more intense and more frequent.

The paper adds to a growing body of evidence showing how large infrastructure projects and top-down economic change can make communities in the Global South more vulnerable to climate change.

Model of Thai-Lao power grid shows hydropower may not be so green

Map of the Thai-Laotian grid. Reproduced with kind permission of Stefano Galelli. Link to original.

Rather than focusing on the development potential or the social and environmental impacts of dams along the Mekong, the study aimed to assess their actual performance. The researchers modeled the power system of the Thai-Laotian grid and used climate data from the Mekong and Chao Phraya basins over a 30-year period from 1976-2005. The model showed that prolonged drought causes hydropower production to drop by 4,000 gigawatt-hours per year, or around one-third of the hydropower available on the Thai-Lao grid in 2016.

According to Stefano Galelli, associate professor at SUTD and lead author of the study, modeling power grids and climate data may be key to making power development plans more sustainable.

“Our study builds on a new generation of high-resolution water-energy models that explain how each individual power plant reacts to external conditions, such as droughts or increased electricity demand,” said Galelli.

As of 2016, according to the study authors, Thailand was importing nearly 90% of the hydropower produced by nine dams in Laos, with a total capacity of 3,485 megawatts (MW). Thailand also purchases power from the 1,878 MW Hongsa lignite coal power plant, which depends on water from the Mekong for cooling.

Inside Thailand, the study looked at 14 dams, five in the Mekong basin, two in the Chao Praya and seven located in smaller river basins. It also considered thermal plants around Thailand, such as the 2,400 MW Mae Moh coal-fired plant in Lampang province, which draws water from the Chao Phraya basin.

As a whole, the Thai-Lao grid can produce about 30% more power than it needs at peak demand. When droughts hit the Mekong region and hydropower availability drops, Thailand and Laos are able to tap in to excess coal and gas power capacity.

The findings present a problem for mainland Southeast Asia’s regional power plans. “Extreme weather events doom long-distance power transfers between Laos and Thailand to temporary failures,” the authors write. 

The Nam Ou 3 Dam between Muang Khua and Muang Ngoi Neua. Photo: Christophe95, CC BY-SA 4.0, via Wikimedia Commons

Global South climate vulnerability on the rise 

The authors’ findings also strengthen the case that large-scale infrastructure and top-down economic change can expose populations to more severe climate impacts, especially in the Global South.

Rather than focusing explicitly on human-driven climate change, the paper tries to quantify the effects of climate variations that have already been recorded. The droughts considered in the study are tied to a weather pattern known as the El Niño Southern Oscillation (ENSO), in which warm weather systems in the tropical pacific reduce the Mekong region’s monsoon rainfall. 

The 30 years of climate data used in the study included seven El Niño years. ENSO-related drought now leads to increased carbon emissions and higher energy costs only because Thailand, Laos and foreign investors have pushed large hydropower and fossil fuel plants.

Previous research has also looked at how new infrastructure and economic integration worsened the impacts of climate variations like ENSO. Historian Mike Davis makes the case that much of the Global South saw severe famine in the late 1800s chiefly because European colonizers imposed globalized economic policies that decimated local populations’ ability to deal with climate variation. 

In Late Victorian Holocausts: El Niño Famines and the Making of the Third World, Davis shows how tens of millions died from famine and disease in British India and other colonies as Europeans refused to change their economic policies and continued to export grain, largely via railroads. When a series of ENSO-related droughts hit India, Brazil, China and elsewhere, local populations were no longer able to cope.

Historically, societies in the Mekong region have built strategies to adapt to natural variation in climate, from local economic networks to locally-stored crop surpluses. Building the region’s power infrastructure around large-scale hydropower can worsen climate impacts as electric grids rely on coal and gas.

Within the Mekong basin, a number of reports suggest that relocating people for large dams or other infrastructure projects often exposes them to more intense climate impacts. In northern Laos, over 12,000 people were relocated to build a string of seven dams along the Ou river, a tributary of the Mekong. In November 2020, when much of mainland Southeast Asia saw typhoon rains and flooding, some of those displaced began reporting that their new homes were unsafe due to the threat of landslides. Residents in at least one relocation site say they asked government officials to address the situation but received no response. 

In the Mekong region, shifts in climate now mean large hydropower directly contributes to higher carbon emissions and energy costs, largely because Thailand and Laos have built excess capacity in coal and gas plants. As Mekong countries push ahead with dam building plans, the new data presents a problem, as hydropower appears less sustainable and less reliable than previously thought.

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