Tag Archives: turnkey

Talinay Oriente 90MW EPC Wind Farm

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Although I don’t normally post stories about wind farms I’ve worked at I want to do an exception for Talinay, a project with whom I have a relationship almost emotional.

Located in Chile, in the Coquimbo province, near the Limarí river, it has been a project entirely developed by Vestas with internal founds and my first “hands on” EPC experience.

We’ve had the pleasure of optimizing the layout both in the preliminary phase, working together with the wind & site team, and in the constructive project. It was tough, because it is located in a mountainous area where impressive earthworks are needed.

It is a mix of V90 and V100 turbines of the 2MW platform, with an installed capacity of 90 MW.

Connected to the grid in March 2013, it has been constructed at an amazing, “china style” speed: with almost 400 peoples working together on site during the busiest period, it was a record for the foundation (5 per week, with two concrete plants on site working full time day and night) and the turbine installation (4 WTG per week).

The wind farm was completed in 6 months.

Almost all the big players of the sector have been involved: from the engineering side support was provided by IDOM, SISENER and ESTEYCO, while the main subcontractor was GES who worked with local and international subcontractors (among them, Hormigones Melón, Burger Gruas and CJR).

On the electrical side, it was one of the first (or maybe the first) PASS installed in Chile. The transformer was developed at lightning speed (155 days ex works), while the substation was made by ABB and Siemens.

Now is property of the Italian utility ENEL Green Power, who also signed a service agreement. Part of the money of the deal comes from a loan from Denmark’s Export Credit Agency (EKF). ENEL has an aggressive expansive approach in the Chilean market, where is developing several other wind farms (some of them with Vestas).

Below you will find several interesting pictures: two trucks pulling a tower section due to the high slope of the road, PASS switchgear and line trap, concrete plant and other interesting views of the wind farm.

Wind Farms construction contracts

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Wind farms can generally be broken down into 2 separate areas of construction:

  • Turbines: supply, installation and commissioning of wind turbines and towers
  • Balance of Plant (BoP) works: everything else needed except the turbines (foundations, substations, cabling, etc.)

Several option are available to the developers:

BoP contracts types

The first option is that the wind farm Special Purpose Vehicle signs separate contracts for BoP and Supply and Installation:

If two or more separate contracts are signed, the interface risk is taken by developer.

Warranties are backed by the balance sheet of each contractor, clearly only for the works undertaken. In exchange for this risk taken by the developer, substantial savings are possible and a broader range of participant to the tender is possible.

Moreover, the project management will be more complicated and sometimes it is difficult to attribute the source of a delay or to define de interface between obligations.

Another option is an EPC structure:

In this case, we will have a fixed price and fixed delivery date, with no interface risk and a single point of contact for the developer.

On the downside, the price will increase as the wrapping entity will add his margin for taking the risk. Moreover, they are more complex and time consuming with an heavy legal cost.

The third option is an unincorporated joint venture:

In this case the subcontractors will delivery a project without the requirement to form a separate legal entity. There is a single contract between the wind farm developer and the consortium of suppliers.

This structure has the same advantage of the EPC (fixed price and delivery date, reduced interface risk) but additionally there is a greater security thanks to the exposure to balance sheets of all the company in the consortium.

Disadvantages: increased price, heavy documentation costs and complex coordination work.

San Anton - a Wind Farm from cradle to completion

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San Anton is a small wind farm (4 WTGs) located in Lillo, Toledo (Spain).

I had the opportunity to follow this project from the beginning visiting the site very often. I collected several picture to show the main phases of a wind farm construction.

First of all a met mast is installed, and wind data is collected. If there is enought wind in the area and the investment is profitable, an authorizative project is developed and transmitted to the authorities. Normally this project is developed using existing information, that is without developing a new cartography or other field works.

When this project is approved and it start to become reality, than the first work on site is the geotechnical report, done to define the subsoil conditions trought several in situ and laboratory test: here in the picture a trial pit is open to see the materials in the subsoil

Trial pit

A trial pit opened using a backhoe

With this information and a document provided by the seller of the wind turbine with the load transmitted to the base (shear, moment and vertical loads), a preliminary (or sometimes directly a constructive project) of the foundation is developed.

Afterwards, a topographical survey is developed. This can be done using standard field topography, a flight or LIDAR (a laser system that can provide a very dense cloud of point).

The following picture show the first step of the construction phase: topsoil stripping, an operation that consist in the removal of the first layer of fertile vegetal terrain that will be stocked and piled separately and used at the end of the works to revegetate the site area.

Topsoil stripping

Topsoil stripping

The next step is what is called earthworks: the construction of embankments and cuts. For instance in the image below a crane pad is under construction. Several thousands of cubic meters can be moved during this operation.

Earthworks

Crane pad earthworks

In parallel, the foundation for the met mast is constructed. The mat foundation is smaller than a WTG foundations: it is around 7 x 7 meters. It has 3 pedestal where the met mast will be connected.

Met mast foundation

Met mast foundation

After, the circular holes for the turbine foundation are opened: here you can see the topographer checking the dimension and horizontality of the hole. Several days of work are necessary to open the hole, depending on the hardness of the excavated material.

Foundation hole

The internal roads are continuously washed with water, to avoid accumulation of dust in the air due to the traffic of heavy trucks and other machinery.

Roads watering

The following step is to pour the blinding concrete, to assembly the anchor cage and to position the steel reinforcement bars (rebars). More info here.

This is how it looks a completed foundation:

Meanwhile, the operation and maintenance building is built nearby. It will host the SCADA equipment and the medium voltage switchgear:

O&M Building