It’s easy to imagine sun and wind energy. We’ve seen the solar panelling on rooftops and wind turbines in vast fields. Yet, what happens when there’s not enough sunshine or wind to generate power? Those energy sources become obsolete, and people resort to traditional methods.
We’re not saying these aren’t solid energy sources, but they do have limitations hinged upon weather patterns and eco systems.
Ocean energy harvesting is bringing a new wave of renewable power. Pun intended.
For centuries, scientists have debated and experimented with waters generative abilities. Jacques-Arsène d’Arsonval idealized a closed-cycle ocean thermal energy conversion, while Monsieur Girard and Yoshui Masuda pioneered wave energy.
d’Arsonval believed you could harness the oceans energy through a simple heat exchanger, exploiting the warm surface water and cold depths. This heat transfer used ammonia to bolster a vapor that would pressurize a chamber connected to a generator. And voila, energy created.
Girard and Masuda hypothesized that using wave energy could produce a similar, if not greater, amount of energy. This application was used to operate machinery or power navigation lights for Japanese ships. In the 70s, Stephen Salter reinvented the wave generator and created the Salter Duck. Salter’s technology used the power of a pendulum activated by the waves moving in a back and forth motion.
Ocean energy is great in theory. It’s always constant, and it’s generative properties are rarely affected by weather patterns. Unfortunately, there hasn’t been much progress in the field since these early findings. And as a result, is years behind its counterparts.
Modern Ocean Energy Harvesting
Despite slowed growth, many scientists have continued developing osmotic power generators.
Here are some of our favorites.
British scientists, Dan Grech and Hayden Ashfield, capitalized on the d'Arsonval model and developed an ocean thermal energy converter that floats in the ocean. It is a closed-circuit generator, recycling the vapor from the heat chamber’s warm water into a fluid that is cooled by the deep ocean water. It’s then pumped back into the boiler to complete the cycle.
Their idea is rooted in the 60 million square kilometers of ocean surface water that absorbs approximately a quadrillion megajoules of energy a day. According to them, that’s equivalent to almost 170 billion barrels of oil a day.
Grech and Ashfield predict for every 2.5MW, 1.5MW is generated electricity. The “waste” energy is then used to power the generator, making this one of the most efficient models to date. Government reps in the Maldives have agreed to pilot this technology to power its resorts.
UC Berkeley scientist, Mohammad-Reza Alam, designed a wave-energy converter that lay along the ocean floor. Alam and his team were inspired by the properties of mud created by the compounding waves in particular areas. They developed a “carpet-like” model made of smooth rubber. As the rubber ebbs and flows with the waves, it would generate electricity through pumping.
Alam reported that this method of energy harvesting can generate up to twice the electricity an average American home generates in an hour. He also points out the contrasts in solar energy conversion - takes about 14x the square meters to generate similar power. The drastic difference in efficiency is hard to ignore.
Scientists from Australia and University of Michigan partnered together to develop a membrane inspired by living organisms that uses salt water for energy. They coupled properties of ion-selective, malleable materials, similar to cartilage, and boron nitride found in bones.
After testing this layered membrane in sodium chloride, the material remained strong and intact. This proved promising for materials faced with pressurization and salinity in the ocean for long periods of time.
The future of osmotic energy harvesting is an exciting frontier that will continue to evolve quickly. Our oceans could hold the key to cleaner, more stable renewable energy.