Today’s consumer is more environmentally conscious than ever before. Forward-thinking companies, like Ocean Renewable Power Company (ORPC) and US Synthetic, are teaming up to develop new ways to capture and convert hydrokinetic energy from ocean waves and river currents into renewable, emission-free electricity.
ORPC’s RivGen® Power System was built in 2014 and deployed in the Kvichak River near the remote Alaskan village of Igiugig in 2015. Using the latest technology advancements, like diamond bearings from US Synthetic, the RivGen Power System is now supplying one-third of the village’s electrical needs, significantly offsetting diesel fuel use.
To meet the challenges of operating in a wet and dirty environment, renewable energy companies are relying on seal-less, corrosion-resistant diamond bearings to deliver on the promise of local, sustainable, clean continuous power.
“Engineers [in the renewable energy space] have to design systems that can survive the corrosive effects of seawater and withstand the intensity of waves….” Fast Company Magazine: Could Wave Power Be the Next Boom in Renewable Energy?, April 2019
The dirty water passing through a hydrokinetic system poses significant challenges to rotating equipment. Ocean waves and river currents generally carry significant amounts of damaging sediment (like sand, gravel, etc.), corrosive minerals (including salt), high amounts of fluid pressure caused by violent waves or powerful river currents, and even barnacles and mud that can compromise component life in any system. In most cases, frequent mechanical failure is common, due to eroded and contaminated rotating equipment–especially bearing seals. Traditional ball bearings running in these harsh environments must be replaced or repaired often, significantly increasing critical power outages and costly downtime.
Engineers have tried to overcome these challenges in the past, by adding redundant ball bearing stacks and/or encasing the bearings in large sealed sleeves for protection. These conventional methods work to a degree, but the power of ocean waves and river currents, combined with the eroding sediments within the water, still manage to break down these common counter measures. These methods of protecting traditional bearings also introduce complexity into the system and typically increase the overall size of the tool–increasing the cost, limiting the operating life, and significantly reducing the efficiency of this critical system.
ORPC and US Synthetic teamed up to develop a diamond-based bearing solution that completely overcomes the challenges of rotating equipment running in corrosive, abrasive ocean and river environments. By utilizing US Synthetic’s proprietary diamond technology, the ORPC RivGen Power System leverages:
- A seal-less, fluid-cooled diamond bearing that eliminates excess component weight and the need for contaminating lubricants and maintenance;
- A polycrystalline diamond material that can easily resist corrosive and damaging material flowing in the water;
- A sliding-element bearing that delivers a low coefficient of friction (0.01). After approximately 200 hours of use, diamond “wears in” and the coefficient of friction will perform similar to a polymer. At these low friction levels, diamond provides improved operating efficiency and eliminates excessive drag on the system’s rotating elements.
“We’re designing for a 20-year service life.” — Cian Marnagh, VP Engineering, ORPC
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