Alto Maipo

Alto Maipo
Name	Alto Maipo
Location	Andes Mountains, Santiago, Chile / Mendoza Province
Status	Proposed/Under development
Owner	AES Corporation / Colbún (company) / Andes Iron
Type	Hydroelectric / Run-of-river / Pumped-storage
Capacity	~524 MW (planned)
Construction begin	2016 (initial) / delayed
Opening	projected 2021–2024 (delayed)

Alto Maipo Alto Maipo is a major Andean hydroelectric project in central Chile located in mountain catchments supplying the Maipo River. The project links Andes headwaters with transmission systems feeding the Santiago Metropolitan Region and was promoted by a consortium including AES Corporation and Colbún (company). It has been central to debates involving Chilean energy policy, environmental regulation, and community rights, engaging actors such as the Ministry of Energy (Chile), Superintendence of the Environment (Chile), and regional municipalities.

Overview

The project aims to exploit water resources in the Cordillera de los Andes basin using a long series of tunnels and underground facilities to provide about 524 MW to the SIC and later the National Electric System (Chile); proponents cite support from companies like AES Andes and Colbún. Planned works included intake structures in the Maipo River, underground powerhouses, access tunnels traversing geology near the San José Volcano and the Yerba Loca Nature Sanctuary, and high-voltage transmission lines linking to substations in Quilicura and Renca. The project intersects territories administered by the Metropolitan Region (Chile) and water authorities such as the Dirección General de Aguas.

History and Development

Initial feasibility and licensing processes involved studies submitted to the SEIA and reviews by the Superintendence of the Environment (Chile). The consortium negotiated permits amid prior precedent projects like Central Hidroeléctrica Alto Bío Bío and Ralco Hydroelectric Plant, prompting protracted consultation with municipalities including San José de Maipo and regional bodies such as the Regional Government of Santiago Metropolitan Region. Financial close and contracting involved international financiers and firms such as Banco Santander (Chile), BBVA Chile, engineering contractors like Salini Impregilo (now Webuild), and consultants with experience from projects like HidroAysén and Pangue.

Project Design and Technical Specifications

Design features include multiple diversion tunnels, several kilometers of pressure tunnels, surge tanks, and subterranean powerhouses intended to exploit high hydraulic head between Andean reservoirs analogous to designs at Itaipu Dam and Baker River reservoirs. Generation equipment specified Francis turbines manufactured by global suppliers such as Siemens or Voith Hydro in comparable projects. Transmission components were to integrate with 220 kV and 500 kV lines referencing standards applied in projects like Río Cuervo and substations modeled after Cardones-Polpaico. Geological and geotechnical assessments referenced regional studies by the Servicio Nacional de Geología y Minería.

Environmental and Social Impact

Assessments considered impacts on aquatic ecology of the Maipo River, glacial and snowpack-fed catchments near the Echaurren Glacier and San José Glacier, and downstream water users including urban consumers in Santiago and agricultural users in the Maipo Valley (Chile). Predicted effects invoked concerns similar to those raised during HidroAysén and Río Baker debates: altered streamflows, reduced baseflow in riparian zones, habitat fragmentation affecting species catalogued by the Chilean Forest Service (CONAF), and tourism impacts in areas like San José de Maipo and Embalse El Yeso. Social impact studies considered indigenous and local communities recognized in registers managed by the National Corporation for Indigenous Development (CONADI) and livelihoods tied to vineyards in Maipo Valley (DO).

Legal, Regulatory, and Financial Issues

Regulatory scrutiny involved permits under the SEIA and enforcement actions by the Superintendence of the Environment (Chile), with legal challenges brought before courts including the Supreme Court of Chile and administrative tribunals. Financial backers faced reputational and credit risks reflected in actions by institutional investors such as Pension Fund Administrators (AFP) and multilateral lenders historically active in Chile like the Inter-American Development Bank. Litigation and compliance issues echoed precedents from disputes over projects like Ralco Generating Station and regulatory decisions traced to frameworks set by the Ministry of Energy (Chile) and energy market rules enforced by the CNE.

Operation and Performance

Operational projections estimated annual generation comparable to mid-sized Andean hydro plants, contributing to seasonal peaking capacity and ancillary services to the SING/SIC grids. Performance metrics referenced reliability standards applied by the CDEC and later the Electric Coordinator of Chile. Planned operations included flow regulation to meet demand peaks in Santiago Metropolitan Region and support for intermittent renewables such as solar power in Chile and wind power in Chile by providing firming capacity analogous to pumped-storage projects like El Hierro experiments and large hydro plants such as Río Verde.

Controversies and Public Response

The project generated protests and public campaigns organized by environmental NGOs like Santiago Chile Sustentable, local advocacy groups in San José de Maipo, and national coalitions opposing large hydro projects similar to activism around HidroAysén. Media coverage in outlets such as El Mercurio, La Tercera, and international press highlighted conflicts over water rights adjudicated by the Dirección General de Aguas and enforcement interventions by the Superintendence of the Environment (Chile). Legal actions, technical audits by entities like the National Commission for Scientific and Technological Research (CONICYT)-affiliated researchers, and parliamentary inquiries in the Chilean Congress shaped public debate, influencing investor decisions by firms such as AES Corporation and negotiation outcomes with local governments and community leaders.

Category:Hydroelectric power stations in Chile