The Earth's Oceans Are A Potentially Huge Source Of Energy. Why Aren't We Harnessing Them?

As the search for ever-more sources of clean, renewable energy continues, it seems like there’s one resource we’ve forgotten to tap into. Not for nothing is Earth known as the “Blue Planet” – with more than 70 percent of the globe being covered by seas and oceans, is there no way we could harness the waves to produce our energy?

In fact, we could – and maybe one day, we will. Because it turns out that – with a lot of logistical legwork – the oceans have the potential to completely change the renewable energy game.

How much energy could the oceans provide?

It’s no secret that humans use an enormous amount of energy – more than 180,000 terawatt hours per year (TWh/year), at last count . Currently, a little more than 11,000 of those terawatt hours – around six percent – come from hydropower.

But it could be a lot more than that. “Sea waves are a very promising energy carrier among renewable power sources, since they are able to manifest an enormous amount of energy resources in almost all geographical regions,” explained Amadeu Leão Rodrigues, then a Professor in the Department of Electrical Engineering at NOVA University Lisbon, in a 2008 paper .

Of course, it’s far from evenly spread across the globe. Thanks to the Earth’s various climate systems and cycles, waves are more powerful within the northern and southern temperate zones – the latitudes roughly lining up with the UK, Alaska, and Hudson Bay in the north, and the southern tip of Chile and Argentina in the south. Waves are also (usually) far more powerful out in the open ocean than closer to shore, thanks to their longer wavelengths and larger sizes.

But ignoring all that for now, what’s the total amount of power we could harvest from world’s waves ? The answer, in short, is: a lot.

“The global theoretical energy from waves corresponds to 8x10 ⁶ TWh/year, which is about 100 times the total hydroelectricity generation of the whole planet,” Rodrigues continued. “To produce this energy using fossil fuels it would result an emission of 2 million [tonnes] of CO ₂ .”

For those keeping count, that’s about 45 times the amount we need as a species. Even counting only the waves off the coast of the US, wave power could potentially generate 2.64 trillion kilowatt hours of energy per year, according to the US Energy Information Administration – equal to more than three-fifths of the nation’s current annual electricity generation.

So, what’s stopping us from using this huge and abundant energy source? Well, as you may not be surprised to learn, it’s not that simple.

The difficulties with harnessing ocean power

Despite these big numbers, it’s highly unlikely that we could ever make the oceans a 100 percent efficient power source – experts more often put the figure at between 10 and 15 percent.

Now, that’s still a staggering amount of energy that we’re currently missing out on – but actually harvesting this power is intrinsically more difficult than with other renewable sources.

“Winds and currents, they go in one direction,” oceanographer Burke Hales told CNBC in 2022 . “It’s very easy to spin a turbine or a windmill when you’ve got linear movement. The waves really aren’t linear.”

Instead, “they’re oscillating,” explained Hales, a professor of oceanography at Oregon State University and chief scientist at PacWave, a Department of Energy-funded wave energy test site off the Coast of Oregon. “And so we have to be able to turn this oscillatory energy into some sort of catchable form.”

Were we to figure out the technical solutions, there would still be potential issues around the impact on marine ecosystems. Presumably, wave power would be harnessed via some heavy-duty machinery, perhaps fixed into the ocean bed, generating constant noise pollution – and, as with large offshore wind farms , it’s likely that would have some dramatic and unforeseen consequences for marine life.

“This is going to have to be something that we learn as we put systems in the water,” Jennifer Garson, Director of the Water Power Technologies Office at the US Department of Energy, told CNBC. “But we’re funding environmental monitoring, funding work to really understand the interaction of species with deployed systems.”

Could we ever harness the oceans’ energy?

These problems notwithstanding, is trying to harvest power from the waves even feasible? Or is it just wishful thinking?

Well, not only is it feasible enough for the US government to have invested 25 million dollars into wave energy research companies, but those companies are now testing a range of potential devices at PacWave that will hopefully make wave energy a reality.

“We’re building the sandbox, and anybody can come and bring their toys to test in the sandbox,” Hales told Popular Mechanics earlier this week. “An opaque and unprovable megawatt is less valuable to you than a verified 500 kilowatt. So we do that monitoring, we verify the power condition.”

Some of the companies on trial at PacWave have already proven their mettle in other arenas. CalWave Power Technologies, for example, is a California-based startup whose xWave device – a smaller version of the one they’re testing at PacWave – recently returned from a 10-month deployment off the coast of San Diego.

“The x800, our megawatt-class system, produces enough power to power about 3,000 households,” boasted Marcus Lehmann, co-founder and CEO of CalWave. Generating power by using internal dampeners to convert motion from waves into torque, the device works “like a wind turbine,” he told CNBC – albeit one located entirely underwater.

“The waves move the system up and down,” Lehmann explained. “And every time it moves down, we can generate power, and then the waves bring it back up. And […] that oscillating motion, we can turn into electricity[.]”

Other companies are building with specific end-users in mind. “The system that we’re deploying […] is a community-scale system,” said Balky Nair, CEO of Seattle-based Oscilla Power. “It’s designed for islands and small communities.”

Indeed, wave energy, even in its prototype stages, is expected by many observers to catch on in areas currently underserved by other power sources. For those living in remote islands, or off the grid, for example, renewable energy can be scarce, and other available power sources are expensive and highly polluting.

Oscilla’s device , the Triton WEC, is built in two parts: one section sits on the ocean surface and moves with the waves; the other – a large, ring-shaped structure – hangs below the surface and is meant to stay relatively steady. This difference in movement between the two sections creates force on the tendons that connect them, which three drivetrains then convert into power.

Other companies have focused on smaller, cheaper devices – ones that can sit atop piers or jetties, rather than be located far offshore. That’s not only useful from a USP perspective – it also counters one of the biggest and so far most obstinate stumbling blocks in the quest for renewable energy: the cost. Currently, wave power is at minimum around 10 times the price of fossil fuel energy – a price that will likely reduce with scale, but only if governments and investors choose to support it.

Still, with $369 billion earmarked for clean energy and climate change mitigation in the recent Inflation Reduction Act, maybe we finally have reason to be optimistic.

“[The ocean] is our biggest, best, and most flexible battery that we have,” Reenst Lesemann, CEO of C-Power, also trialing a device at PacWave, told Popular Mechanics.

“If you can’t tap that battery, it’s a power desert.”