Taweelah: what scale did to the price of seawater

In August 2018 Saudi Arabia’s Rabigh 3 drew a low bid of SR1.99, about US$0.53 a cubic metre, a record at the time. Abu Dhabi awarded Taweelah five months later, at a tariff MEED put at US$0.49,¹ though neither EWEC nor the developer published a number.²

Nothing in the sea had changed, but the machine room, the procurement and the finance stack had. Plants were being decoupled from power stations and bid on their own, and in Abu Dhabi that followed the Barakah nuclear plant, which weakened the case for cogeneration.³

Taweelah is an independent water project. A single buyer runs a transparent tender against a long-term purchase agreement, and the winning consortium finances, builds and operates the plant.² ACWA Power holds 40 per cent, alongside TAQA and Mubadala. SEPCO III and Abengoa Agua built it for about US$907 million.⁴

The technical move is scale: spreading fixed costs across 909,218 cubic metres a day changes every line in the tariff.⁵ The other lever was energy. MEED attributed the low tariff at Taweelah to low-priced renewables,⁶ and the plant carries a photovoltaic field of more than 70 MWp.⁵

It was built and it performs. The first group entered commercial operation in mid-2022 and the second in April 2023, with full operation certified in March 2024.⁷ The plant passed 30 consecutive days of final performance tests. It desalinated 204 million imperial gallons in a day, about 2 per cent above planned capacity.⁵

The price signal travelled. Competitive procurement took seawater reverse-osmosis tariffs from above US$1.00 a cubic metre to below US$0.40.⁸ Sub-dollar water from the sea is the single most consequential number in the region’s water planning of the past decade.

The record everyone quotes was never built. Dubai took a bid of US$0.277 in September 2020, the lowest ever recorded.⁹ That developer could not reach financial close,¹⁰ the contract did not survive, and the site was re-let in 2023 at US$0.365.¹¹ No water has been produced at the record price.

Prices then rose across the board. Mirfa 2 and Shuweihat 4, bid in 2022, came in at US$0.483 and US$0.564, and the lowest bid for Abu Dhabi’s Saadiyat plant was US$0.731 in 2024. Part of the Saadiyat premium reflects a new electrical facility in its scope.¹² Bahrain’s first independent water project drew a lowest bid of US$0.73 in 2026.¹³ The larger cause is the cost of capital, not technical regression: MEED warned in 2022 that rising interest rates would push tariffs up.⁶ Where finance is so large a share of the levelised cost, the tariff reprices with the bond market.

Taweelah itself ran late. The 2019 announcement expected completion in October 2022.² Full commercial operation came in March 2024, a slip of about 17 months.⁷ Its capacity is also quoted three ways: 909,200 in the original release, 909,201 on the developer’s own page and 909,218 from the contractor at completion.²⁴⁵

Scale also concentrates risk: a plant this size is a single point of failure on a shore where storage is measured in days, which is the argument the Gulf’s strategic reserves are now answering.¹⁴ The 2019 deal announcement promised record energy use of less than 3 kWh a cubic metre, and the contractor reports consumption below expectations, but no measured figure has been published.¹⁵⁵

Financing and energy price decide the winning consortium more often than membrane choice does. A bid tariff struck in one interest-rate environment is not a forecast of the next one,⁶ and treating a record as a benchmark is how a procurement ends up unfinanceable.

For suppliers the technology margin has moved to the edges of the plant: energy recovery, intake and outfall works, digital operations and the brine. For governments the lesson is duller. Check that the lowest bidder can raise the money, and write the financial-close deadline into the award.