Bhutan: Renewable Energy for Climate Resilience

Energy / Renewable energy generation - solar

Overview.

Bhutan is a landlocked and mountainous country in the Eastern Himalayan with elevations ranging from 160 meters to over 7,000 meters above sea level and abundant water resources. Climate varies due to the country's topography and geographical location. Summer monsoon typically lasts from June to late September and creates most of the annual rainfall in Bhutan.

The country's annual average economic growth of 7% between 2007 and 2019 far exceeds the average global growth rate of 3.2%. This high growth has contributed effectively to reducing poverty. Poverty rate in Bhutan declined from 12% in 2012 to 8.2% in 2017. However, the COVID-19 pandemic is taking a high toll, decreasing growth rates to -10.1% in 2020.

Climate-sensitive economy.

Bhutan's development has been heavily dependent on climate-sensitive sectors such as agriculture and hydropower, with hydropower making a major contribution to the growth and power export to India is an important source of revenue. Hydropower contributes about 25% to total gross domestic product (GDP) annually, accounts for 32% of total exports, and generates about 25% of the government's total domestic revenue. The power generation sector almost exclusively relies on hydropower, with an installed capacity of 2,326 megawatt (MW) and 2938 MW under construction. Bhutan has a per capita electric power consumption of 3,165 kilowatt-hours (kWh) which is in the range of the average of upper-middle-income countries and a peak system demand of 388 MW in 2019. The total techno-economically viable hydropower potential is estimated to be 23,760 MW.

Power sector vulnerability. More than 80% of annual precipitation in the central-eastern part of the Himalaya is delivered by the summer monsoon. While long-term future precipitation trends in the region, and in specific river basins, are subject to considerable uncertainty, several patterns have emerged. Based on the most recent global climate modeling experiments (CIMP5), summer monsoon rainfall is predicted to increase by mid to late 21st century in the central and eastern Himalayas, while winter precipitation is projected to decline.

Glaciers have strong modulating effect on flows ensuring uninterrupted water supply during droughts. Glaciers in Bhutan are retreating rapidly, with area loss between 1980 and 2010 in order of 20-25%. It is projected with high confidence that glaciers, snow-covered areas, snow and ice volumes will decrease within these regions over the coming decades in response to increasing temperatures. The hydrological system shifts towards a more rainfall dominated pattern. This can imply more frequent hydrologic droughts and periods of low flows outside the monsoon season, as well as more frequent extremely high flows or floods during the monsoon season. The loss of buffering capacity increases susceptibility to both extreme runoff due to increasingly frequent extreme rainfall events, and to prolonged low flows. Projected flows indicate longer flow duration outside the turbine design range and therefore less generation during the low flow season, particularly for systems with limited storage or run-of-river facilities which are common in Bhutan.

The climate risk and vulnerability assessment prepared for this project indicates changes in the discharge level of events with a 50-year return period to increase in Bhutan by around 40 to 180%, depending on the climate scenario. Such strong increase in extreme flows significantly increase the risk of damage to hydropower infrastructure and leads to an increase in the number of landslides and similar natural hazards. These types of events can be disastrous for hydropower infrastructure. Extreme flows also contribute to increased sediment loads, negatively affecting hydropower infrastructure, by increased abrasion of turbines, as well as filling of head ponds and reservoirs.

Another hazard which is increased by climate change is the risk of glacier lake outburst floods (GLOFs). With the retreat of glaciers, frequently proglacial lakes are formed between the former moraines and the retreating glacier front, filled with melt water. These can become unstable and burst, resulting in extreme flooding downstream. The Himalayas in Bhutan have more than 700 glacial lakes, of which several have the potential for severe GLOF. Hydropower infrastructure in the pathway of a GLOF is at risk of severe damage.

Diversification of generation portfolio for building resilience. Other renewable energy resources such as solar photovoltaic (PV) can complement hydropower in forming a more diversified electricity generation system, which, in healthy mix, creates resilience to the impacts of changes in seasonal weather patterns and weather extremes. Bhutan's run-of-the-river hydropower generation drastically drops during the winter dry season (December to March) due to low precipitation and snow melt, almost falling short to meet peak demand. The generating utility of Bhutan experienced poor hydrologic conditions in 2018 and 2022 and for the first time since its formation in 2008, required net energy import from India in the dry season of February and March. In future, climate change could amplify this effect. Renewable energy sources such as solar PV in Bhutan have complementary annual generation profiles to hydropower, producing most power during the dry season from December to March. Estimates for the technical potential of solar PV in the country is 12,000 MW.

Utility scale non-hydro renewable energy generation assets established and promoted

Knowledge in climate resilient renewable energy systems improved