Preventing Corrosion on Renewable Energy Projects

Corrosion is an issue that needs to be evaluated on every renewable energy initiative — solar, energy storage, and substation; managing it has become a critical consideration in project engineering and implementation. For example, a key material in photovoltaic arrays foundations and battery energy storage system foundations is steel, which tends to corrode over time, and is affected by the degree of corrosiveness of the soil surrounding it. However, it’s important to have steel piles last throughout the operational life of the projects they support. Therefore, the more corrosive the soil is at the site, the more precautions that need to be taken to protect the steel pile that comes in contact with that soil.

Overcoming the corrosion challenge

The renewable energy industry is running out of good soil and friendly landscapes for utility-scale renewable energy projects. Many prospective sites today have a level of corrosiveness that would have led developers to avoid them in the past. With many of the prime lands for utility-scale solar projects already in use, the growing demand to expand solar generation and other energy resources is leading developers to give less-than-ideal sites a closer look — making soil testing critical to address the corrosion challenge beforehand.

Soil tests provide the data for understanding the extent of the corrosion challenge at a potential utility-scale solar and renewable energy site, and allow for designing appropriate solutions to address it. Corrosion consultants are also brought in to provide steel corrosion reports and assist with project design. In fact, it’s now standard design procedure to have a corrosion report stamped by a corrosion specialist in place before beginning engineering and construction.

The steps to corrosion analysis and prevention  

The process to address and make accommodations for soil corrosion involves a series of steps:

• Geotechnical engineers conduct field and lab analysis of the soil and test its PH values and electrical resistivity. With this data, and working in conjunction with corrosion engineers, they look at geotechnical results and corrosion rates for bare steel and hot-dipped galvanized steel.

• The structural engineers then design steel foundations and piles to account for the soil corrosion rate, taking into consideration the corrosive steel properties at the end of the project life, when steel piles and foundations become smaller and weaker.

• In addition, if concrete is used for the foundations, which is the case for substations, it is critical to ensure that the concrete mix design is corrosion-resistant (the geotechnical report will spell this out). Concrete is porous, so all the metal bars need to be protected.

• To account for design requirements, as well as the loss of material from corrosion over time, uncoated steel foundations need to be larger to start with. Hot dip galvanization adds protection to resist long-term corrosion.

• In cases of high corrosion rates due to excessive moisture in the soil, caused by a high-water table or location near a body of water and resulting in highly acidic or alkaline conditions, cathodic protection systems or epoxy coating can be utilized.

• Once designs have been created, they go to the authority having jurisdiction who reviews the geotechnical report, the corrosion report, and the structural design.

While corrosion is typically associated with metal, the strategies discussed here are also applicable to other materials, including the plastic in junction boxes and the cable insulation and other materials exposed to moisture and harsh elements.

A procedural imperative

As the construction of alternative energy facilities and infrastructure continues to accelerate, it is imperative that owners and facilitators of these projects recognize and make accommodations for the inevitability of corrosion. In summary, here are some of the solutions that have proved effective:

• Additional steel – a larger section of steel pile may be used to account for the loss due to corrosion over time.
• Galvanization – a process that uses zinc as a protective coating over steel or iron.

Hot-dip galvanizing has provided steel corrosion protection for over 150 years, and at least half a century for structures used in the generation, transmission, and distribution of energy from traditional sources.

• Epoxy coatings – resins that cure and harden to protect against corrosion.
• Cathodic protection – an additional steel that acts as an anode while the protected metal is the cathode; the anode corrodes instead of the cathode.

With careful upfront analysis and the proper preventative measures, corrosion can be mitigated, ensuring that renewable energy infrastructure continues to deliver for years to come. It’s imperative that initiators and owners of these projects work with design and engineering professionals who understand the risks and the steps required to prevent them.

Stas Gorbis is Director of DG and EV at Blymyer Engineers, which offers full-service renewable energy engineering in multiple industries, including solar, wind, substation, energy storage, and EV charging.

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