Hydroelectric Power in Thailand: Complete Guide 2026

Hydroelectric power in Thailand accounts for about 3% of the country’s electricity generation — roughly 7 TWh per year (Low Carbon Power / Ember, 2024). That sounds insignificant. But add the electricity Thailand imports from hydropower dams in Laos, and the combined hydro share jumps to around 18% of the national supply.

This guide covers Thailand’s major dams, the massive pumped storage expansion EGAT is planning, what hydropower actually costs, the Mekong River risks that threaten future supply, and whether small-scale hydro makes sense. Whether you’re interested in Thailand’s energy mix or evaluating how it affects electricity prices, this is the full picture.

TL;DR: Thailand has 3,869 MW of domestic hydropower capacity across EGAT facilities, but the real story is the ~15% of electricity imported from Lao dams (EGAT, 2026). The country isn’t building new large dams — instead, EGAT is investing 90 billion baht to convert existing dams into pumped storage “batteries” and adding floating solar on reservoirs.

What Is Hydroelectric Power and How Does It Work?

Hydroelectric power converts the energy of flowing or falling water into electricity. A dam stores water in a reservoir, then releases it through turbines that spin generators. Thailand’s entire domestic hydropower fleet — 3,869 MW — is operated by EGAT across facilities ranging from massive storage dams to small run-of-river plants (EGAT, 2026).

There are three main types used in Thailand:

• Storage dams hold water behind a large wall and release it on demand. Bhumibol and Sirikit are the biggest examples. They’re dispatchable — EGAT can ramp generation up or down in minutes.
• Run-of-river plants like Pak Mun use the natural flow of a river without a large reservoir. They generate less power and can’t store energy, but cause less upstream flooding.
• Pumped storage facilities pump water uphill to an upper reservoir when electricity is cheap (at night or during peak solar hours), then release it back down to generate power during peak demand. It’s a giant rechargeable battery.

One misconception worth clearing up: hydropower isn’t “old” technology being phased out. It’s being repurposed. EGAT’s strategy isn’t to build new dams — it’s to retrofit existing ones with pumped storage and floating solar. The infrastructure already exists. The investment goes into making it do more.

Why Does Hydropower Matter for Thailand’s Energy Mix?

Domestic hydropower alone generates about 3% of Thailand’s electricity — roughly 7 TWh out of 234 TWh total (Low Carbon Power / Ember, 2024). Not much on its own. But Thailand also imports approximately 15% of its electricity from Laos, nearly all of it hydropower (Stimson Center, 2024). Combined, that’s about 18% of the national electricity supply coming from water.

Why does this matter? Unlike solar panels that produce nothing at night, or wind turbines that depend on weather, storage hydropower is dispatchable. EGAT can spin up a turbine at Bhumibol Dam in minutes to cover an evening demand spike. That makes hydro a grid stability tool — not just a generation source.

Thailand also sponsors 4 in 10 hydropower projects currently under development in Laos — four times as many as China (Stimson Center, 2024). That creates energy security, but also geopolitical entanglement. More on that below.

Where Are Thailand’s Major Hydropower Dams?

Thailand’s largest hydropower dams cluster in two regions: the northern highlands along the Ping and Nan rivers, and the western mountains of Kanchanaburi along the Khwae (Kwai) river system. There’s also one significant plant in the south.

Northern Dams

Bhumibol Dam in Tak province is Thailand’s largest hydroelectric facility at 779 MW. Commissioned in 1964 on the Ping River, it runs six Francis turbines, one Pelton turbine, and one pump-turbine unit (EGAT, current). It sits about 480 km north of Bangkok.

Sirikit Dam in Uttaradit province adds another 500 MW on the Nan River. Operating since 1972, it’s the second-largest conventional hydropower dam in the country.

Western Dams (Kanchanaburi)

Srinagarind Dam produces 720 MW total — including 360 MW from two pumped storage units. In late 2025, EGAT awarded a contract to ANDRITZ to replace both pumped storage turbines, a mid-double-digit million euro modernization (ANDRITZ, Oct 2025).

Vajiralongkorn Dam (formerly Khao Laem) generates 300 MW on the Khwae Noi River.

Southern Dam

Rajjaprabha Dam in Surat Thani has 240 MW from three 80 MW units, operating since 1987. All three turbines are being modernized under a separate ANDRITZ contract awarded in Q3 2025 (ANDRITZ, Nov 2025).

What Is Pumped Storage and Why Is EGAT Investing 90 Billion Baht?

Pumped storage hydropower works like a giant rechargeable battery. During off-peak hours — when electricity is cheap or solar is overproducing — water gets pumped from a lower reservoir to an upper one. During peak demand, that water flows back down through turbines to generate electricity. The round-trip efficiency is about 70-80%.

Thailand’s only current pumped storage facility is Lam Takhong (Lamtakong Jolabha Vadhana) in Nakhon Ratchasima. At 1,000 MW, it’s Thailand’s only underground power plant — built 350 meters below the surface with an upper reservoir holding 10.3 million cubic meters (EGAT, current). Operational since 2004, it handles peak demand on the northeastern grid.

The 90 Billion Baht Expansion

EGAT plans three new pumped storage plants totaling 2,472 MW at a combined investment of 90 billion baht (Bangkok Post, 2024):

• Chulabhorn — 801 MW, COD 2034 (EIA approved April 2024)
• Vajiralongkorn — 891 MW, COD 2036
• Kathun — 780 MW, COD 2037

EGAT targets a generation cost of approximately 2 THB/kWh for pumped storage — competitive with global hydropower averages (Nation Thailand, 2024).

Why pump water uphill instead of just building batteries? Scale. Thailand’s AEDP 2024 targets 24,412 MW of solar by 2037. All that solar produces during the day but nothing at night. Pumped storage can absorb gigawatts of midday solar surplus and release it during the 6-9 PM demand peak — something lithium batteries can’t yet do economically at this scale. EGAT is essentially turning existing dams into the grid-scale batteries that Thailand’s solar buildout requires.

How Is Thailand Combining Dams with Floating Solar?

EGAT targets 2,725 MW of hydro-floating solar hybrid capacity by 2030 (SolarQuarter, Nov 2025). The concept is straightforward: install floating solar panels on existing dam reservoirs and feed the power through the dam’s existing grid connection. No new transmission lines needed.

Two projects are already operational:

• Sirindhorn Dam — 45 MW floating solar, one of the largest hydro-solar hybrids in Southeast Asia
• Ubolratana Dam — 24 MW floating solar

Two more are in development:

• Srinagarind Phase 1 — 140 MW, COD approximately 2027
• Bhumibol Phase 1 — 158 MW, COD approximately 2027

The hybrid approach solves two problems at once. Solar panels generate during the day when the reservoir doesn’t need its full turbine capacity. Then at night, the dam takes over. The result is a more consistent power output from a single grid connection point. It also reduces water evaporation from the reservoir surface — a side benefit in drought-prone years.

Does this affect electricity prices? Not directly for consumers. EGAT sells power wholesale. But more efficient use of existing dam infrastructure means less need for expensive new gas plants, which should moderate long-term costs.

How Much Does Hydropower Cost Compared to Solar and Wind?

The global average levelized cost of hydropower is USD 0.057 per kWh (IRENA, 2024). That’s more expensive than solar (USD 0.043/kWh) and onshore wind (USD 0.034/kWh) on a pure generation-cost basis. But those numbers don’t tell the whole story.

Hydropower’s value lies in dispatchability. Solar produces only when the sun shines. Wind produces only when the wind blows. A hydropower dam produces when you tell it to. That’s worth a premium — especially during the 6-9 PM demand peak when solar output drops to zero and Thailand’s grid is most stressed.

EGAT’s target for its new pumped storage plants is approximately 2 THB/kWh — about USD 0.056/kWh (Nation Thailand, 2024). That’s competitive with the global hydro average and significantly cheaper than natural gas generation in Thailand (estimated USD 0.075/kWh). For consumers, pumped storage won’t lower your electricity bill directly, but it reduces Thailand’s reliance on imported natural gas — which is the biggest driver of Ft charge fluctuations.

What About Small-Scale Hydropower in Thailand?

Thailand has an estimated potential of 1,500 MW from small-scale hydropower across 25 river areas (ScienceDirect, 2015). Yet only 66 MW is actually installed — across 12 small EGAT facilities (EGAT, 2026). That’s less than 5% of the identified potential.

Why so little development? Several reasons:

• Geography — Thailand’s terrain is mostly flat outside the northern and western highlands. You need elevation drop (head) to generate power, and most Thai rivers don’t have enough.
• Environmental permitting — New dam construction faces strong opposition after the Pak Mun experience (see below). Even small weirs require extensive environmental review.
• Cost competition — Rooftop solar at 3-4 THB/kWh is cheaper and easier to install than a micro-hydro system that needs water rights, civil engineering, and regular maintenance.

Can a small hydro system power a Thai home? Technically, micro-hydro units (5-100 kW) work well in hilly areas with year-round streams — parts of Chiang Mai, Chiang Rai, Nan, or Kanchanaburi provinces. But for most of Thailand, solar is a faster, cheaper, and simpler option. If you’re in a flat area near Bangkok or in the central plains, don’t bother looking at hydro.

The AEDP 2024 reflects this reality: it targets only 99 MW of new domestic hydropower capacity out of a total 73,286 MW renewable target (Nation Thailand, 2024). Solar gets 24,412 MW. The government has essentially moved on from small hydro expansion.

How Does Thailand’s Mekong Dependence Create Risk?

Thailand imports roughly 15% of its electricity from Laos, and that share was expected to reach 15.7% (38,146 GWh) in 2025 (Power Technology / Stimson Center, 2024). Almost all of it comes from hydropower dams on Mekong tributaries — or the Mekong mainstream itself.

The Xayaburi Dam, the first mainstream Mekong dam in the lower basin, generates 1,285 MW and sends 95% of its output to Thailand via EGAT purchase agreements (Wikipedia / EarthRights, current). It’s been commercially operational since October 2019.

The Upstream Problem

China operates 11 dams on the Lancang — the upper Mekong — with six more planned. The two largest, Nuozhadu and Xiaowan, alone store 37.5 cubic kilometers of water, roughly 8% of the Mekong’s total annual discharge (Stimson Center, Dec 2024). The Lancang contributes 45% of Mekong dry-season flow.

What does this mean in practice? Chinese dam operations can increase dry-season flow at Chiang Saen (northern Thailand) by 100% — but reduce wet-season flow by 30%. Downstream dams in Laos that Thailand depends on for electricity can’t generate reliably if upstream water flows become unpredictable.

The Ecological Cost

The Mekong River Commission projected that dam development could reduce fish biomass by 35-40% by 2020 and 40-80% by 2040 (MRC / International Crisis Group, 2024). Sediment — essential for fisheries and agriculture — could be reduced by 67-97%.

Thailand occupies an unusual position in Mekong hydropower politics: it’s simultaneously a downstream nation affected by Chinese dams and the primary financier and electricity buyer of Lao dams that affect Cambodia and Vietnam further downstream. This dual role makes it hard for Thailand to credibly oppose upstream dam construction while sponsoring similar projects downstream.

What Are the Environmental Impacts of Thai Dams?

The Pak Mun Dam in Ubon Ratchathani is Thailand’s most documented case of hydropower’s environmental costs. This 136 MW run-of-river dam on the Mun River, completed in 1994, affected over 250 fish species and reduced fish populations by an estimated 60-80% (World Bank / academic studies, documented). The 912 displaced families saw average annual earnings drop from 25,742 baht to 3,045 baht — an 8x reduction.

When the Thai government opened the dam’s gates as a trial from 2001 to 2002, 129 fish species returned and local earnings tripled. The gates have been seasonally opened since, but the debate over permanent opening continues.

Why No New Large Dams?

Pak Mun’s legacy shapes Thai water politics to this day. Combined with limited remaining dam-suitable sites in Thai territory and strong community opposition, the practical result is clear: Thailand isn’t building large new dams on its own rivers.

The AEDP 2024 confirms this. Its domestic hydro target is 2,918 MW of existing capacity plus just 99 MW of new development (Nation Thailand, 2024). Instead of new dams, the strategy focuses on:

• Modernizing existing facilities — ANDRITZ contracts for Srinagarind and Rajjaprabha turbine replacements
• Adding pumped storage — Converting existing reservoirs into energy storage
• Floating solar hybrids — Using reservoir surfaces for solar generation

This is a pragmatic pivot. The dams already exist. Making them more useful — as batteries, as solar platforms, as modernized generators — avoids the social and environmental costs of new construction while getting more value from past infrastructure investments.

What Does Thailand’s Hydropower Policy Look Like in 2026?

Thailand’s AEDP 2024 targets 73,286 MW of total renewable capacity by 2037. Hydropower’s share? A modest 2,918 MW of existing capacity plus 99 MW of new projects — less than 0.5% of the total renewable expansion target (Nation Thailand, 2024). Solar (24,412 MW) and wind (5,345 MW) dominate the plan.

But that 99 MW figure understates hydro’s actual policy footprint. The real investment goes into three areas:

1. Pumped storage — 2,472 MW of new capacity at 90 billion baht, the largest single category of EGAT infrastructure spending
2. Hydro-solar hybrids — 2,725 MW target by 2030, using dam reservoirs as solar platforms
3. Lao imports — Continued purchasing agreements for hydropower from at least four Thai-sponsored Lao projects

Add it up, and Thailand isn’t abandoning hydropower. It’s redefining it — from building new dams to maximizing existing infrastructure and importing from neighbors. The environmental politics make new domestic dams nearly impossible, but the engineering value of water storage for grid stability hasn’t diminished.

For residents, the policy impact is indirect. More pumped storage means better grid stability during the evening peak. More floating solar means higher renewable share in the mix. Neither will show up as a line item on your bill, but both reduce long-term exposure to natural gas price volatility — which is what drives those Ft charge adjustments every four months.

Frequently Asked Questions

Is Thailand building new hydropower dams?

No. The AEDP 2024 targets only 99 MW of new domestic hydropower — compared to 24,412 MW of solar (Nation Thailand, 2024). Thailand’s hydro strategy focuses on modernizing existing dams, adding pumped storage capacity (2,472 MW planned), and importing hydropower from Laos. Environmental opposition and limited suitable sites make new large dam construction politically and practically unfeasible.

How does pumped storage hydropower work?

Pumped storage works like a rechargeable battery using water. During off-peak hours, electricity pumps water from a lower reservoir to an upper one. During peak demand, the water flows back down through turbines to generate power. Thailand’s Lam Takhong facility operates at 1,000 MW — built 350 meters underground in Nakhon Ratchasima (EGAT, current). Round-trip efficiency is about 70-80%.

Why does Thailand import so much electricity from Laos?

Thailand imports approximately 15% of its electricity from Laos because Laos has abundant river resources that Thailand lacks (Stimson Center, 2024). Thai companies sponsor 4 in 10 Lao hydropower projects. The Xayaburi Dam alone sends 95% of its 1,285 MW output to EGAT. It’s cheaper than building new domestic gas plants, but creates dependency on cross-border supply chains and Mekong water politics.

Can small hydropower work for a Thai home?

For most Thai homes, no. Thailand’s terrain is too flat outside the northern and western highlands. Only 66 MW of small hydro is installed from an estimated 1,500 MW potential (EGAT, 2026). If you’re in a hilly area of Chiang Mai, Chiang Rai, or Kanchanaburi with a year-round stream, micro-hydro (5-100 kW) could work. For everyone else, rooftop solar is faster, cheaper, and simpler.

Is hydropower cheaper than solar in Thailand?

Not on raw generation cost. Global average hydropower costs USD 0.057/kWh versus USD 0.043/kWh for solar (IRENA, 2024). However, hydropower’s value lies in dispatchability — it generates on demand, unlike solar which only produces during daylight. EGAT’s planned pumped storage targets 2 THB/kWh (~USD 0.056/kWh), making it competitive as grid-scale energy storage.

Conclusion

Thailand’s hydropower story isn’t about building new dams. It’s about getting more from what already exists. The country’s 3,869 MW of domestic hydro capacity, combined with ~15% imported from Laos, provides about 18% of the electricity supply and — more importantly — the dispatchable generation that keeps the grid stable during peak demand.

The three biggest developments to watch:

• Pumped storage expansion — 2,472 MW of new capacity by 2037, funded by 90 billion baht. This is EGAT’s answer to storing excess solar energy.
• Floating solar hybrids — 2,725 MW target by 2030, using dam reservoirs for dual-purpose generation.
• Dam modernization — Srinagarind and Rajjaprabha turbine replacements, extending the productive life of 40-year-old infrastructure.

The Mekong dependency is the wildcard. China’s upstream dams and Laos’s expanding hydropower fleet provide Thailand with affordable electricity, but at the cost of ecological damage and supply unpredictability. How Thailand balances its role as both buyer and downstream stakeholder will shape the region’s energy landscape for decades.

For residents, hydropower doesn’t offer a direct household energy option the way solar does. But it plays a foundational role in grid stability and electricity pricing. More pumped storage means less reliance on expensive natural gas peaking plants — which ultimately affects the Ft charge on every electricity bill.