Ocean Magic: OTEC and the Drive for 24/7 Renewable Energy
“It seems like magic really that you’ve got this” Peet Denny (Cool Hominids Podcast: Renewable Ocean Energy with Dan Grech)
The most recent episode of the Cool Hominids podcast features host Peet Denny and Dan Grech speaking about the history of, and modern-day process of OTEC or ‘Ocean Thermal Energy Conversion’. As Founder and CEO of Global OTEC Resources Ltd, Dan continues work, first started by Jacques Arsène D’Arsonval and his student Georges Claude, who first proposed using the temperature differences between surface and deep seawater to generate electricity, and even built the first model in 1930.
OTEC is a process for producing energy by using the temperature differential or ΔT (Delta T) between ocean surface waters and the deeper ocean waters. I’m sure you can picture this as much as I can — when swimming in the sea, you hit a cold spot and very quickly swim back the other way. The energy from the sun heats the surface water of the ocean, whereas the deeper water is much cooler, a ΔT of 77° Fahrenheit is needed. The warmer water is pumped through an evaporator containing a working fluid which powers a turbine to produce electricity. The vaporized fluid is then turned back to a liquid in a condenser cooled with cold ocean water pumped from deeper in the ocean. Condensed vapour is then returned to the boiler, completing a cycle that generates electricity on an ongoing basis.
Source: Global OTEC
A great advantage of using this method is that OTEC is a ‘baseload power’, meaning it is on all of the time. Looking at OTEC alongside other renewable energy sources, it benefits from being able to generate energy without the reliance on the sun shining like solar power, or the wind blowing for windmills, also reducing the need for energy storage. Other baseload power sources at the minute include nuclear and coal-fired power plants, and obviously coal is a huge environmental pollutant.
Making a bigger move away from coal and other fossil fuels is important in realising the Net Zero goal, with 40% of energy-related CO2 emissions still being due to the burning of fossil fuels for electricity generation and coal is responsible for over 0.3ºC of the 1ºC increase in global average temperatures, making it the single largest source of global temperature rises. Despite this, coal remains the largest source of electricity production globally.
Source: Our World in Data: Electricity Production by Source
What is the current working application of OTEC? For smaller islands like those around Mauritius, Maldives, the Caribbean and the Pacific Islands, who currently rely on expensive imported diesel to fuel the island, OTEC technologies could radically shift their access to affordably priced electricity. For these smaller islands, harnessing solar power would not be an option as replacing lush forests to install them would decrease the tourism influx that the locals and the economy so heavily rely on.
Global OTEC LTD is hoping to test their technology on São Tomé and Príncipe, nicknamed The Galapagos of Africa, replacing their old diesel generators with their upcoming technology to prove to the world just how advantageous this could be. The United States has also been testing this technology in the Natural Energy Laboratory of Hawaii Authority, which operated a 250 kilowatt (kW) demonstration OTEC plant for six years in the 1990s. It now has become operational and supplies electricity to the local electricity grid. In the podcast, Dan also suggests further applications like aquaculture, thermal desalination, hydrogen, lithium extraction and more.
What do you think? I would recommend you go out and research this technology and Dan Grech for Global OTEC LTD if you are interested in this. It is certainly something that felt too good to be true when I first heard the podcast, but now I think this could be the way forward. At some point, we will have to stop relying on our world’s pollutants as fuels and find a sustainable and successful way forward.
