Duplex stainless steel used in a pioneering solar plant

22 APR 2013

Outokumpu provides high-performance stainless to the Crescent Dunes solar energy project in Tonopah, Nevada, USA. Tonopah Solar has commissioned a solar energy plant to provide some 100 megawatts of clean, renewable and sustainable energy. It uses large, circular field of mirrors, or heliostats, to reflect the sun’s energy onto a central receiving tower. The energy thus captured from the sun is used to power a conventional steam turbine generator to produce electricity.

The plant is built by a US-based Cobra Thermosolar Plants Inc., part of Spanish Group specializing in solar plants. The Crescent Dunes is the first project of its kind, designed by Cobra Thermosolar Plants and Solar Reserve, using a molten salt power tower and heliostat technology by Pratt & Whitney Rocketdyne. Not only does it include a steam turbine, but even the solar panels on the pedestal turn in two different ways. This will enable the panels to follow the sun and capture its energy more efficiently.

Previously Outokumpu has announced that it provided 650 tonnes of stainless quarto plate to Cobra’s subcontractor for the fabrication of a hot storage tank that enables the solar power plant to deliver electricity even when the sun is not shining.

Now Outokumpu will supply more than 60 tonnes of 70 mm hot-rolled black bar in LDX2101®, Outokumpu’s patented lean duplex grade, from Sheffield, UK. This material will be further machined to create zenithal anchor bolts, or the mounting bolts of the solar panels. These bolts will allow the solar panels to turn in two planes.

The overall challenge in this project results from its location, as these types of plant are usually located in a desert. Desert provides an abrasive and corrosive environment, due to the presence of sand and a high salt content. This is where properties of stainless steel and especially its abrasion/erosion and corrosion resistant come into play.

“After a successful start with the hot storage tank, where Outokumpu supplied our subcontractor quarto plate and where we have been satisfied with the material, when we started to look for suppliers for the zenithal anchor bolts, we contacted Outokumpu and requested an offer. As usual, the technical explanations and credibility of the technician contact at Outokumpu convinced us about the properties, capabilities and possibilities of the products and provided us all the information and arguments we needed to make the decision,” says José Manuel Suárez, Procurement and Subcontracting Director at Cobra Thermosolar Plants.

Outokumpu Sales Manager Jesús Gonzalez has been involved in both projects. “When Cobra contacted Outokumpu to request an offer on zenithal anchor bolts, we recommended the use of LDX 2101® because of its excellent corrosion and abrasion resistance. Besides, it is a good solution when machining is needed,” says Jesús Gonzalez. “Since this application is the first of its kind, there is a great potential for us in other similar kind of projects.”

“Moreover, this is a good example of how Outokumpu can offer a whole range of products for various uses and applications in one project,” says Stephen Jones, Product & Market Development Manager at Outokumpu Sheffield.

The deliveries of both quarto plate and hot-rolled black bar are under way. The solar plant will start operations in the beginning of 2014 to provide clean and renewable energy for customers in California and Nevada.