Most of the major U.S. renewable energy advances seem to come from California, the land of solar power and Tesla cars.
However, it is Hawaii that has gone beyond the normal wind turbines and solar panels, though it has plenty of those as well, to create its own kind of hydropower called Ocean Thermal Energy Conversion (OTEC).
OTEC is the larger version of evacuated solar collector tubes: water is enclosed in an energy-collection container, the heat from the sun naturally warms the water, and the machinery pumps the heated water down below the cooler water underneath.
The heated water cools some, but rises back up because of its temperature, and cooler water is forced upward to begin the cycle again.
Hawaii is the first state to have one of these fully closed-cycle systems. The company that built it, Makai Ocean Engineering, touts the reliability of such technology.
70% of the sun’s rays fall on ocean water on Earth, and heat from sunlight is trapped in that water even at night. Makai claims it could be a constant source that is “capable of providing massive levels of energy.”
The single 150-kilowatt plant has the capacity to power about 120 homes. And even better, that power is dispatchable, meaning it can be ramped up or slowed down for peak electricity hours, and can be used to provide power when wind and solar energies are scarce.
The technology is still new, but has enough potential for the U.S. Navy to invest in it. This first plant cost about $5 million, so any outside funding will be a huge help.
The Navy itself has plans to produce at least 50% of its onshore energy from renewable sources in the next five years, and for a water-based organization, this kind of high-capacity hydropower could cover a big part of that goal.
According to Makai, one commercial-sized OTEC plant could replace about 1.3 million barrels of oil and cut almost half a million tons from carbon emissions per year.