Sunlight in a tank

Steven Roman


Plant designers needed to store molten salts heated to over 600 degrees Celsius.


Austenitic Outokumpu Therma stainless steel was used to create plant’s hot nitrate storage tank with excellent temperature- and corrosion-resistance properties.


Steel grade: Outokumpu delivered 650 tonnes of Outokumpu Therma 347H stainless steel. Over 60 tonnes of Outokumpu’s Forta LDX 2101 went into their anchoring bolts.
Product form: quarto plate
Clean, abundant and costing absolutely nothing, solar power may one day prove to be the answer to the world’s energy puzzle. But perfecting utility-scale electricity production has always come up against a fundamental roadblock: when the sun goes down, the power dies. Designers of the Crescent Dunes Solar Energy Plant in Nevada have overcome that hurdle using a first-of-its-kind system that relies on molten salt to store heat, allowing the plant to stay in operation day and night, rain or shine.


Taking the heat

Like most plants built on the Concentrated Solar Power (CSP) model, Crescent Dunes consists of a field of tracking mirrors, or heliostats, that focus light onto a central receiver atop a concrete tower.

Rather than using the sunlight to boil water directly as other CSPs do, Crescent Dunes heats a mix of sodium and potassium nitrate to over 600 degrees Celsius and pumps it to an insulated thermal storage tank made of Outokumpu Therma stainless steel. Whenever electricity is needed, the salt is sent through a steam generation system, superheating water to turn a turbine.

For creating the plant’s hot nitrate storage tank, Outokumpu delivered 650 tonnes of Therma 347H quarto plate. Therma range is specifically designed for high temperatures. This grade’s superb corrosion resistance, given the harsh salts it would be exposed to, was also essential in ensuring that the plant can long fulfil its duty, supplying enough power for 75,000 homes.


Pivotal, in two ways

Stainless steel was also mission critical to the plant’s more than 10,000 heliostats. These must pivot on two planes as they track the path of the sun throughout the day, keeping the energy-rich rays directed toward the receiver.

Over 60 tonnes of Outokumpu’s Forta LDX 2101 went into their anchoring bolts, which have to function in an atmosphere of wildly fluctuating temperatures, sand, moisture and the corrosion that comes with them. This duplex stainless steel grade was chosen for its ability to withstand these tough conditions, making sure the sunlight never loses focus, nor does the drive toward clean, renewable energy.

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Energy and heavy industry

In energy and heavy industry, failure is simply not an option. When one single mishap can explode into a full-blown crisis, only stainless steel can deliver the assurance of control that you depend on.

Renewable energy

As communities around the world set ambitious goals to increase the role of renewable energy in power generation, it makes sense to partner with an organization committed to sustainability.


The Therma range contains heat-resisting stainless steels for use in applications with high service temperatures (≥550°C/1020°F). Ferritic stainless steels have resistance to sulfur containing hot gases and lower thermal expansion.


The Forta range contains duplex and other high strength stainless steels that enable thinner structures and weight reduction (measured in Rp0.2 > 400 MPa. PRE 16 to 43).

Quarto plate

For extra thickness or larger dimensions, Outokumpu hot-rolled plates – quarto or heavy plates – are the ideal solution. Because Outokumpu oversees production from melt to market, superior quality and on-time delivery are assured.


Stainless steel is a superb material for sustainable solutions as it is 100% recyclable, efficient and long-lasting. Our vision is to become the customers’ first choice in sustainable stainless steel.

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