New Sines Desalination Plant to Shield Alentejo from Drought

As Portugal braces for increasingly dry summers, the government has taken a decisive step to shore up water supplies for its largest industrial hub. The Ministry of Environment and Energy has just launched the first tender for the preliminary design and environmental studies of a seawater desalination plant at São Torpes, aimed at bolstering the Zona Industrial e Logística de Sines (ZILS) and easing pressure on traditional sources.

Key Points at a Glance

• Scope of work: Preliminary Technical Study and Environmental Impact Study (EIA)

• Initial output: 16 hm³/year, with potential to double to 32 hm³

• Investment estimate: €120 M, through a long-term industrial tariff

• Managing entity: Águas de Santo André (AdSA), part of Águas de Portugal

• Objective: Safeguard industry growth while relieving the rio Sado and barragem de Alqueva

A Strategic Pivot for Alentejo’s Thirstiest Region

The Alentejo has long battled water scarcity. With climate models foretelling hotter summers and more erratic rainfall, the reliance on the rio Sado and transfers from Alqueva—once sufficient—now teeters on the edge. By tapping the Atlantic at São Torpes, authorities hope to secure a predictable supply for energy, chemicals and green-hydrogen ventures operating within Sines. This modular approach echoes global best practices, offering flexibility to expand as demand rises.

What the Tender Actually Covers

Bidders will chart the route from sea to storage, specifying intake pipelines, pumping stations, buffer reservoirs and power requirements. Under Decree-Law no. 151-B/2013, the Environmental Impact Study must assess marine ecology, brine dispersion patterns and coastline erosion. Consultants will also draft tender documents for the future design, build and operate contract—laying the groundwork for construction in 2027 and commissioning by 2031.

Desalination vs. Conventional Sources

Current options:

• Pumping from Alqueva (~0.11 €/m³ in wet seasons, up to 0.25 €/m³ in drought)

• Abstractions from the rio Sado (contingent on river flows and ecological limits)

Desalination metrics:• Estimated cost: ~0.45 €/m³ at prevailing electricity rates• Energy recovery ratios up to 60%, building on lessons from Porto Santo’s 1980 facility• A steady baseline supply that doesn’t fluctuate with rainfall

Engineers argue a desalinated feedstock frees upstream allocations for agriculture and domestic use—critical in a region where field irrigation and industrial cooling vie for the same drops.

Financing the Future: Industry Foots the Bill

Unlike the Algarve plant backed by EU recovery funds, Sines will operate under a concession model. Anchor tenants—ranging from Galp’s refineries to emerging hydrogen consortia—will sign take-or-pay agreements under a negotiated industrial tariff. This shifts demand risk away from taxpayers and aligns costs directly with heavy users. €120 M is the headline figure, but the true metric is long-term rate stability for companies investing billions in low-carbon projects nearby.

Environmental Safeguards and Technological Innovation

Brine disposal has ignited concerns from local fishing associations and marine scientists. The tender mandates advanced dispersion systems—drawing on Spanish diffuser nozzles—and real-time salinity monitoring. On the power side, floating wind farms mooted off Sines could one day supply dedicated renewables to the plant, slashing carbon emissions and shielding operators from volatile grid prices.

Lessons Drawn from Algarve and Porto Santo

Portugal’s first mainland desalination in Albufeira, conceived under a 25-year PPP and financed with €108 M from the PRR, demonstrated the value of modularity: adding extra membranes without halting operations or re-seeking permits. Porto Santo’s decades-old unit pioneered energy-recovery turbines that now set industry benchmarks. Sines is poised to incorporate these insights, with an eye on EU Water Framework Directive targets and national water law.

Looking Ahead: Local Impacts and Next Steps

If the EIA clears in mid-2026, engineering firms will produce detailed schematics while public consultations address community questions—from brine plumes to visual impact along the Costa Vicentina. Santiago do Cacém and Grândola councils are already exploring small-scale potable withdrawals, though the official line stresses industrial security of supply as Phase 1’s priority. For residents, a more resilient regional water network could mean fewer summer restrictions and a revitalised agro-business sector upstream.

Portugal’s venture into large-scale desalination at Sines marks a milestone in adapting to climatic shifts and sustaining economic growth. With the right checks on environment, cost and technology, this plant could become a blueprint for other coastal zones facing the same parched future.