Mexico’s state-owned Federal Electricity Commission (CFE) is promoting the 476.4MW Agua Prieta II integrated solar combined cycle (ISCC) power plant in Sonora, Mexico. It will be Mexico’s first ISCC power plant including a 464.4MW combined-cycle power plant and a 12MW solar field.
Construction of the project began in March 2011 and commissioning is expected in 2015. The plant is estimated to offset approximately 391,270t of CO₂ emissions over an anticipated 25-year lifespan. The combined cycle power plant is estimated to cost approximately $350m, while the solar field is estimated to cost $49.35m. Abengoa Solar was chosen to develop the solar field.
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The project is supported by the Global Environment Facility (GEF) of the United Nations Development Programme.
Agua Prieta II integrated solar combined cycle power plant details
The 300MW Nuevo Pemex Cogeneration Power Plant, the largest of its kind in Mexico.
The ISCCP project will be located in the municipality of Agua Prieta, approximately 2km away from the US border.
The project is being developed in two phases. The first phase includes the design and construction of a solar collector field capable of producing a gross power output of 14MW. The solar field will cover an area of over 85,000m² and will comprise 104 solar collector assemblies (SCAs) manufactured by Abengoa Solar.
The second phase involves the design and construction of a natural gas-fuelled, combined cycle power plant, which is capable of producing up to 464.4MW of power. It will feature two industrial frame combustion turbines, a three-pressure reheat heat recovery steam generator (HRSG) and a steam turbine.
The combined cycle unit will use imported natural gas from the US, which will be supplied by a pipeline located 2km off the site. The unit will be interconnected with the solar field to form a hybrid concentrated solar power (CSP) plant.
Grey water from the Agua Prieta municipal sewage system, the only source of water available for the power plant, will be supplied through an 8in-diameter pipeline. A modular wastewater treatment plant will be installed to treat the grey water and produce boiler quality makeup water for the power plant and water for cleaning the solar trough components.
The project will also include the construction of two transmission lines and three substations, which will be undertaken by Abengoa.
Power generation and technology used at Agua Prieta II
The solar collector assemblies will be arranged in a loop of 26 rows containing four SCAs per loop. Each solar collector contains a linear parabolic-shaped reflector that will focus the Sun’s direct beam radiation onto a linear receiver, which will be filled with a heat transfer fluid (HTF).
The collectors will track the Sun’s movement, ensuring continuous reflection of sun light onto the linear receiver. The heated HTF will pass through a series of heat exchangers to generate high-pressure superheated steam, which will be combined with the saturated high pressure (HP) steam produced in the heat recovery steam generator of the CCPP.
The combined steam flow will be superheated by the energy in the gas turbine exhaust and flow into the HP steam turbine. Exhaust steam from the HP turbine will be again reheated by the gas turbine exhaust energy.
The steam turbine will operate in sliding-pressure mode. Inside, the main pressure at the turbine inlet will be high during the day and low during the night, based on the solar energy input. This will force the steam turbine to operate at part load condition, resulting in reduced steam turbine output.
Financing
The World Bank, through Global Environmental Facility (GEF), is funding the solar field under the United Nations Development Programme. CFE is financing the thermal plant, which accounts for 86% of the total cost.
Contractors involved
Abengoa Solar, Abener Energía and Teyma were awarded the contract for the design, construction and commissioning of the Agua Prieta II project in July 2011.
SENER and ELECNOR were contracted for the construction and commissioning of the combined cycle power plant.
Siemens was contracted to supply SPPA-E3000 low-voltage switchgear solution for the project. OCP was engaged to conduct earthworks and civil works for the power plant. IKM Testing México was engaged to conduct pre-operational cleaning services for the project.
