Paul Clough

Wave energy pioneer CorPower Ocean has partnered with a global heat treater and thermal specialist with locations in North America, Europe, and Asia.

The UK-headquartered Bodycote firm is now breaking into ocean energy thermal processing after helping Swedish developer CorPower optimize key components in its Wave Energy Converters (WECs).

The thermochemical treatment that they are using is Corr-I-Dur®, a combination of various low temperature thermochemical process steps, mainly gaseous nitrocarburizing and oxidizing. In the process, a boundary layer consisting of three zones is produced. The diffusion layer forms the transition to the substrate and consists of interstitially dissolved nitrogen and nitride precipitations which increase the hardness and the fatigue strength of the component. Towards the surface, it is followed by the compound layer, a carbonitride mainly of the hexagonal epsilon phase. The Fe3O4 iron oxide (magnetite) in the outer zone takes the effect of a passive layer comparable to the chromium-oxides on corrosion resistant steels. Due to the less metallic character of oxide and compound layer and the high hardness abrasion, adhesion and seizing wear can be distinctly reduced. Corr-I-Dur® has very little effect on distortion and dimensional changes of components compared to higher temperature case hardening processes.

CorPower’s high-efficiency WECs, inspired by the pumping principles of the human heart, offer five times more energy per ton of device compared to previously known technologies. Incorporating a series of unique features to boost storm survivability and power capture, the WECs also benefit from thermochemical treatment to protect against the harshest marine conditions.

"This thermochemical treatment," Thomas Lindahl, senior procurement and quality engineer, CorPower Ocean, "simultaneously improves corrosion resistance and wear properties by generating an iron nitride-oxide compound layer. Durability and robustness are of paramount importance in the wave energy sector, and effective protection of devices in the hostile ocean environment has always presented a major challenge to our industry. Corr-I-Dur® proved a particularly favorable solution being specifically designed for components subjected to a corrosive environment in combination with wear."

"We are pleased to be contributing to the marine renewable energy industry by making components last longer in extreme conditions," Paul Clough, president for northern and eastern Europe at Bodycote. "By using Corr-I-Dur®, CorPower was able to design mechanical components such as pistons, guides and linkages, that are suitable for the world’s harshest environments for metal. Our customers value Corr-I-Dur® for its ability to provide superior material properties such as wear and corrosion resistance, reducing maintenance costs and downtime for hard to access equipment. CorPower was looking to push the performance of their metal components through durability and corrosion resistance."

CorPower Ocean is aiming to bring reliable and competitive wave energy technology to the world, unlocking one of the largest untapped sources of renewable energy – harnessing the natural power of the oceans to help us tackle climate change and achieve a sustainable low-carbon future.

The firm is now increasing operations for its HiWave-5 demonstration project in northern Portugal to propel its wave technology to a bankable product offering by 2024 – proving the survivability, performance and economics of a grid-connected array of WECs. The 16MEUR project includes investment to build a wave energy hub in the Port of Viana do Castelo, involving R&D, Manufacturing and Servicing facilities for the long-term development of supply and service capacity for commercial wave energy farms.