More than 5000 gearmotors for solar thermal plant in France

The Nord Drive System is being installed for a solar thermal plant. A total of 2,650 mirrors equipped with 5,300 gearmotors are being supplied.


Solar thermal installations built around a central tower have long been limited to mere tech demonstrations and R+D facilities, until now. In conjunction with Nord Drive System, Gemasolar, in the south of France, is now making the leap to full-scale production sites. In order to ensure precise and reliable operation of the plant's mobile heliostats that focus the sunlight, the vast array comprising of 2,650 mirrors is equipped with 5,300 robust gearmotors supplied by Nord Drive Systems.

The Gemasolar solar thermal plant in Andalusia stretches over an area of 185 hectares

The Gemasolar plant's basic set-up consists of a central tower with a receptor area at the top of the structure, a liquid circulation cycle including storage tanks and heat exchanger facilities for power generation via an adjacent turbine, and an array of mirror units that focus the rays of the sun onto the receiver. These mirrors are designed to turn and tilt, following the sun, in order to ensure that as much sunlight as possible is reflected onto the designated area on the tower - from dawn till dusk. Nord Drive Systems has supplied 5,300 gearmotors from their NordBloc.1 product line for the Gemasolar heliostats. In each of the 2,650 flat mirror units, two NordBloc.1 gearmotors enable highly accurate movements for two axes to track the path of the sun.

Keeping the heat in the can

The Gemasolar site extends over an area of 460 acres to accommodate the vast field of heliostats. Operated by Torresol, a joint venture between Spanish engineering giant SENER Ingeniería y Sistemas and Masdar, Abu Dhabi's state-owned future energy enterprise, Gemasolar is the first ever commercial-scale CSP (concentrated solar power) plant with central tower technology that implements a heat storage system based on molten salts. Liquefied nitrate salts are pumped up from a storage tank, run through the receiver section, and absorb the heat impact of the highly concentrated solar radiation in that tower segment. The temperature of the liquid that has passed through it usually exceeds 930 F. Once they leave the receptor, the molten salts flow through a heat exchanger where they cool down again, with the resulting water vapor driving a steam turbine that feeds a generator. The generated energy is supplied into the electrical grid. Most notably, though, the molten salts cycle at Gemasolar incorporates an innovative storage option. Whenever there is more heat energy available than the turbine is able to convert, the extra energy is stored by diverting some of the flow of molten salts before the liquid reaches the heat exchanger. Kept in a special tank, the hot medium can be used at a later time when insufficient solar radiation - or none at all - is available for standard operation of the plant. This solution enables the system to generate power from stored heat for up to 15 hours throughout long periods of cloudy skies or even darkness. The resulting total of 6,500 hours of productive operation per year makes this plant much more efficient than more conventional renewable energy facilities that are totally dependent on changing conditions.

Two robust geared motors for every heliostat enable high-precision movements for two axes

Always geared towards the sun

The sunlight concentration is achieved by 2,650 flat mirrors all continually pointing at the same receiver region on the installation's one central tower. Given the size, weight, and shape of these mirror units, each of them depends on a powerful, sturdy, and robust drive solution to ensure reliable tracking of the sun. Obviously, this is an application exposed to very rugged environmental conditions, so all equipment used here must be manufactured to withstand extreme application factors. Moreover, each heliostat has a flat surface of about 400 ft², which makes them markedly susceptible to strong, not to mention gale-force winds that naturally occur from time to time. Still, proper operation of the heliostats and the power plant as a whole is ensured in all but the most extreme weather conditions. The gearmotors working throughout the array of mirrors play an instrumental part in that. Torresol's heliostats are equipped with robust case size 5 geared motors. Compared to same size previous generations of the NordBloc housing solutions, these gearmotors are suitable for much greater forces than before. Mounting options are particularly user-friendly, allowing for cost-efficient, direct motor mounting, or an attachment of very short, space-saving lightweight motor adapters. These many product options were pivotal in the ease of gearmotor integration into the design of Torresol's heliostats. The gearmotors aluminum alloy housings provide robust, natural corrosion protection out of the box - without the need for a paint finish. Through the use of Finite Element Analysis Nord Drive Systems optimized the NORDBLOC.1 series design, these models are not only considerably lighter than their predecessors, but also one of the most reliable and durable gearboxes on the market. For gearmotors up to case size 6, the Unicase design enables the mounting of larger bearings - the units therefore withstand higher overhung loads, or last longer under a given load. 


- Edited by Chris Vavra, Control Engineering,

The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by Control Engineering subscribers. Vote now (if qualified)!
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
Maximize ROI with integrated control system approach; Microcontrollers vs. PLCs; Power quality; Accelerate and rewire IIoT; Traits for excellent engineers
HMI effectiveness; Distributed I/O; Engineers' Choice Award finalists; System Integrator advice; Inside Machines
Women in engineering; Engineering Leaders Under 40; PID benefits and drawbacks; Ladder logic; Cloud computing
Programmable logic controllers (PLCs) represent the logic (decision) part of the control loop of sense, decide, and actuate. As we know, PLCs aren’t the only option for making decisions in a control loop, but they are likely why you’re here.
This digital report explains how plant engineers and subject matter experts (SME) need support for time series data and its many challenges.
This article collection contains several articles on how advancements in vision system designs, computing power, algorithms, optics, and communications are making machine vision more cost effective than ever before.

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

Control room technology innovation; Practical approaches to corrosion protection; Pipeline regulator revises quality programs
Cloud, mobility, and remote operations; SCADA and contextual mobility; Custom UPS empowering a secure pipeline
Infrastructure for natural gas expansion; Artificial lift methods; Disruptive technology and fugitive gas emissions
Automation Engineer; Wood Group
System Integrator; Cross Integrated Systems Group
Jose S. Vasquez, Jr.
Fire & Life Safety Engineer; Technip USA Inc.
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me