Dan Grech on what the ‘PLOTEC’ project means for the global energy transition
In the energy world, new technologies tend to follow a familiar path. There is the early excitement, then the long and quiet period where most ideas disappear, and then the slow return of interest once the right mix of engineering, economics, and political urgency aligns. Ocean Thermal Energy Conversion (OTEC) sits squarely in that final category.
OTEC is not new – it has been written about, researched, and prototyped for more than a century. What is new is the world we now find ourselves in: Island grids
remain among the most expensive in the world to run; offshore operators are under pressure to cut emissions and find alternatives to gas turbines; and climate resilience is no longer an abstract term but a real operational requirement in regions facing stronger and more frequent mega-storms. In that context, the recent installation of the PLOTEC prototype in the Atlantic Ocean marks an important moment for the marine energy sector.
A new type of demonstration
The platform, installed at the Oceanic Platform of the Canary Islands (PLOCAN) test site, is the latest in a line of attempts to bring OTEC out of the lab and into long term offshore operation. For decades, OTEC demonstrations were temporary and heavily constrained. Mini-OTEC and OTEC-1 in Hawaii, for example, were bold projects for their time, but they were never designed to sit offshore for months at a time and ride out whatever the ocean decided to throw at them. PLOTEC is different. It has been set up to answer a simple question that has not been answered properly before: can an OTEC structure survive, operate, and generate reliable data in real open-ocean conditions, including heavy weather?
That question matters because OTEC’s promise has never really been about producing the very first kilowatt hour, but rather reliability and economics. The ocean surface stays warm throughout the year in the tropics, and the deep ocean remains cold. Physics do not change with clouds or time of day, and seasonal changes are limited. That stability is the appeal. It is also why islands and offshore oil and gas operators have looked at OTEC on and off for decades. The challenge has always been proving that the system can operate safely at sea and proving that the cost can compete with diesel generation in the case of island grids, and with alternative offshore power solutions in the case of oil and gas.
The PLOTEC structure gives the sector a chance to collect data at a scale and duration that previous projects simply did not. The 1:5 scale hull and its station keeping system have been designed with Atlantic conditions in mind. Over the next months, it will experience a full range of sea states, which will allow engineers to compare real motion data from the platform and the cold water pipe with the predictions that have guided OTEC design for years. Understanding how accurate those numerical models are is crucial. It is the bridge between prototype and commercial design, and it is the point where most emerging marine technologies either gain confidence or stall.
Progress across the ecosystem
This work is not happening in isolation. Over the last ten years, other parts of the OTEC puzzle have matured. There has been progress in organic Rankine cycle systems, heat exchanger designs, and composite and polymer materials for large diameter pipes. There is also far more experience today in building and operating offshore infrastructure than existed when OTEC was first imagined. Floating wind, deepwater oil and gas, ocean monitoring systems, and subsea robotics have all pushed supply chains and contractors to become more capable in harsh environments. OTEC now enters a market that understands how to build and maintain offshore assets at scale.
The global energy context has shifted as well. Tropical island states are under pressure to strengthen energy security and reduce dependence on imported fuel. Some of these islands operate in regions where cyclones damage power lines and severely disrupt supply. A generating system that sits offshore and continues to operate through rough weather has a very different value proposition in those settings than it did twenty years ago. Meanwhile, offshore operators are increasingly required to cut emissions across their operations, including power generation on remote platforms. In deep water, where long tiebacks already face heating, flow assurance, and cost challenges, the idea of placing an independent, renewable power source close to the wellhead is no longer unrealistic.
Reducing uncertainty with data
What PLOTEC aims to provide the sector is data: evidence of survivability, structural response, and how a cold-water riser pipe behaves when waves, currents, and platform motion interact over time. Data like this reduces uncertainty – and reducing uncertainty is one of the biggest levers for lowering cost. It informs design margins, material choices, installation strategies, and maintenance planning, as well as determining how investors, governments, and insurers perceive risk.
This prototype will not answer every question, but it will help the industry to understand what a commercial scale design might look like, how often it would need maintenance, and what sort of weather windows it would require for installation and inspection. It will also help separate the parts of the system that need further innovation from the parts that are already mature enough to scale.
Meaningful steps
The wider renewables sector tends to move in waves, influenced by policy cycles, supply chain dynamics, and breakthrough moments. Floating wind had its moment when the first megawatt-class turbines proved they could operate offshore. Solar had its moment when costs dropped below grid parity. OTEC has been waiting for its own proof point. The PLOTEC project is not a final answer, but it is a meaningful step. It takes OTEC out of presentations and back into the water, where the real questions are answered.
For a technology that has long been defined by potential, that shift alone is important for the global discussion about what comes next in ocean energy.
Dan Grech is the Founder and CEO of Global OTEC Resources, a UK company developing ocean thermal energy systems for island grids and offshore operations. His work focuses on practical pathways for bringing emerging ocean energy technologies into commercial use.