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Grupo Dragon to commission 25.5 MW Unit 3 at Domo de San Pedro in Mexico

Domo de San Pedro - Aerial view of U3 together with Substation, SAGS, and Power House of U1&U2 (Source: Grupo Dragon)
Francisco Rojas 21 Apr 2016

Grupo Dragon will commission Unit 3 on the Domo de San Pedro Geothermal field next week; a year ahead of schedule thanks to the smart use of 2 back-pressure units to do well testing.

Grupo Dragon has recently announced that a 3rd unit has been completed and will be soon commissioned on the Domo de San Pedro geothermal field, located in Nayarit; the first private geothermal field in Mexico. The condensing unit with an installed capacity of 25.5 MW will be connected to the national grid on the last week of April 2016.

Construction of this power plant started in October 2014 being commissioned this last February of 2016, and it is currently under the final performance tests. The power plant construction as well as the manufacturing of the turbines and generators was made under a “turn-key” contract with a leading Japanese OEM.

This power plant will play a key role on the energy distribution in the region, providing stable, clean baseload, renewable energy from local geothermal sources.

As of now, two back-pressure units of 5 MW/each have been in operation but they will be shut down at the end of April and the all the steam flow will be redirected to the new condensing unit.

Why have these units been in operation?

Even when back pressure units (BPU´s) need almost twice of the specific steam consumption per MW compared with condensing units, they offer flexibility, operational and time advantages that the tailored large condensing type units cannot offer. These two factors allow project developers and utilities the possibility of a quick deployment to start electricity generation directly at the wellheads or even in a centralized arrangement. The size, simplicity and portability of these units, decreases installation and commissioning time and costs for about a third of that compared to standard condensed units, mainly because this units can be handled utilized in different projects without major adaptation.

This is the reason why in 2015 two 5 MW “second hand” back pressure units were brought, installed and commissioned at the Domo de San Pedro geothermal field. These units were manufactured originally in 1990 by ACEC in Belgium, were in service in other parts of Central America and were thoroughly serviced and upgraded in 2014 by Grupo Dragon. The overhaul required a deep cleaning of blades, rotor balancing, cooling system enhancements and replacement of the control equipment with a cutting edge digital control system with semi-automated features. The quick deployment of these two back pressure units helped Grupo Dragon test well behaviour and start comercial power generation more than one year ahead of expectations.

Out of the two BP Units, N°1 will be kept at the Domo de San Pedro Field as a backup unit for programmed shutdown maintenance works of the Unit 3 and N° 2 is available to be used in other geothermal projects worldwide.

Source: Grupo Dragon via email