Argentina Tenders Los Nihuiles Hydro Complex Privatization
Energy & Infrastructure
Key Facts
—The asset. The Los Nihuiles system comprises four plants and three reservoirs on the Atuel River in Mendoza, with roughly 290 MW of installed capacity.
—The structure. A 30-year generation concession from the national government is bundled with the sale of 100% of provincial operator HEMSA.
—The transition. HEMSA takes over from HINISA on 27 July 2026 and runs the system until the new concessionaire is in place.
—The process. Bids run through the Contrat.Ar platform and will be evaluated by a joint national-provincial commission with equal representation.
—The condition. The provincial share sale requires ratification by the Mendoza Legislature before it can close.
Argentina has opened a joint national-provincial tender to privatise the Los Nihuiles hydroelectric complex, putting roughly 290 MW of installed capacity and a 30-year concession on the block in one of the most significant energy-infrastructure offerings under the Milei administration.
What the Los Nihuiles privatisation actually covers
The tender bundles two awards that must go to the same bidder. The national government is granting a 30-year generation concession for the full cascade on the Atuel River in San Rafael, Mendoza.
Simultaneously, the Province of Mendoza is selling 100% of Hidroelectricidad Mendocina S.A. (HEMSA), the provincial company that holds the operating rights. The provincial share sale still requires ratification by the Mendoza Legislature.
The system includes the Nihuil I, II, III, and IV plants, three main reservoirs, and a compensating dam. Installed capacity is reported at roughly 290 MW, though the outgoing operator HINISA profiles the system at 265 MW depending on how the asset base is counted.
The transition timeline and who runs what
From 27 July 2026 through 31 December 2026, or until the new concessionaire takes possession, HEMSA is designated to operate the system as successor to Hidroeléctrica Nihuiles S.A. (HINISA).
HINISA, controlled by Pampa Energía, has run the complex under the previous concession framework. The transition gives bidders a clear operational bridge while the tender is evaluated and the legislative ratification plays out.
The tender will be processed through Contrat.Ar, the national procurement platform, and assessed by a joint commission with equal representation from the national government and Mendoza province.
Why the Los Nihuiles privatisation matters for Argentina’s energy map
Los Nihuiles is a baseload renewable asset in a country where hydropower provides roughly a fifth of electricity generation. A 30-year concession signals a long-term bet on Argentina’s regulatory stability under a government that has made privatisation a centrepiece of its economic programme.
The bundled structure, pairing a federal generation permit with a provincial asset sale, also tests the coordination between Buenos Aires and the provinces. Getting the Mendoza Legislature to ratify the share sale is not a formality, and the timeline leaves room for political friction.
For investors, the tender is a live gauge of appetite for Argentine infrastructure exposure. The Milei administration needs credible international bids to validate its narrative that Argentina is open for business after years of capital controls and regulatory unpredictability.
The wider privatisation push and the Futaleufú parallel
Los Nihuiles is not the only hydro asset in play. The transition period for the Futaleufú hydroelectric plant in Chubut was extended until 15 June 2026, and the potential future concession has already drawn interest from Grupo Neuss via Edison Energía.
The government has not yet defined the tender process or conditions for Futaleufú. That makes Los Nihuiles the first concrete test of whether the joint national-provincial model can actually deliver a signed concession and a closed share sale.
If the Los Nihuiles process moves smoothly from tender to ratification to financial close, it will set a template that can be replicated across Argentina’s ageing hydro fleet. If it stalls in the Mendoza Legislature or draws weak bids, the read-through for the broader privatisation agenda turns cautious.
What investors and expats should watch next
The immediate milestones are the publication of the full tender documents on Contrat.Ar and the composition of the evaluation commission. The names on the commission will signal how much weight Mendoza carries relative to Buenos Aires in the final award decision.
The legislative ratification vote in Mendoza is the political pinch point. Provincial lawmakers will face pressure from unions and local constituencies wary of privatisation, and the timing of the vote relative to the 2027 electoral cycle will matter.
For expats and businesses in Mendoza, a successful privatisation could mean more reliable generation and potential upgrades to the ageing infrastructure. A stalled process would leave the system in a prolonged transitional limbo with HEMSA as a temporary operator.
Frequently Asked Questions
What is the Los Nihuiles hydroelectric complex?
Los Nihuiles is a cascade of four hydroelectric plants, Nihuil I through IV, with three reservoirs and a compensating dam on the Atuel River in San Rafael, Mendoza province. The system has roughly 290 MW of installed capacity and has been operated under concession by HINISA, a Pampa Energía subsidiary.
Who can bid on the Los Nihuiles privatisation?
The tender is open through Argentina’s Contrat.Ar platform, and bidders must qualify for both the national generation concession and the provincial purchase of HEMSA shares. The two awards go to the same winner, and the provincial share sale requires subsequent ratification by the Mendoza Legislature.
How does the Los Nihuiles tender fit into Argentina’s broader energy privatisation?
It is the first major hydro privatisation to reach the formal tender stage under the Milei administration. A parallel process for the Futaleufú plant in Chubut is still in the pre-tender phase, making Los Nihuiles the benchmark for whether the joint national-provincial model can attract competitive bids and close.
In depth
LatAm Markets: Live Signals → — real-time movers, turnover leaders and FX across Latin America.
Read More from The Rio Times