Renewable energy has been enduring its share of slings and arrows here in the US, but it looks like sunny skies are ahead once President-Elect Joe Biden takes office on January 20. He won’t have to start from scratch, either. For reasons best known only to itself, the US Department of Energy has been cutting loose with a firehose of clean power projects and programs of late, and among them is a new $35 million round of funding for hydrokinetic technology.
What Is This Hydrokinetic Technology Of Which You Speak?
If you haven’t heard much about hydrokinetic energy, that’s because there isn’t much to write home about, at least not compared to headline grabbers like the world’s biggest wind turbine or the latest solar cell breakthrough. Here, let’s have the Energy Department explain:
“Marine energy technologies are at an early stage of development due to the fundamental challenges of generating power from a dynamic, low-velocity, and high-density resource while withstanding corrosive marine environments. These challenges are intensified by high costs and lengthy permitting processes associated with in-water testing.”
What they mean is: hydrokinetic systems are similar to hydropower, but different.
Hydropower systems rely on dams that build up water pressure to run a turbine. In contrast, hydrokinetic systems rely on ambient water flow. Think of it like a wind turbine, only under water.
That could include the natural flow of rivers or tidal currents, as well as canals and other built infrastructure.
As an untapped domestic renewable energy resource, hydrokinetic tech has much to offer. Aside from producing electricity for remote communities, the Energy Department notes that hydrokinetic systems could be deployed for various marine-related uses including environmental surveillance, aquaculture, desalination, mining, and emergency response, and for powering watercraft.
So, what’s the problem? Among other issues related to building things in water (especially saltwater), that thing about dynamic means your generating station is at the mercy of shifting water levels and tides. The current state of technology is also cost-prohibitive.
On the plus side, tides are forecast-able, and so are river flows to some extent. That means a hydrokinetic system could be deployed to complement other forms of renewable energy, or it could kick in on daily or seasonal cycles. Add an energy storage element to the mix, and Bob’s your uncle.
More Renewable Energy From A Dynamic, Low-Velocity, & High-Density Resource
The Energy Department started taking a serious look at hydrokinetic tech back in April of 2010, when it kicked in $3 million to establish the Riversphere R&D center at Tulane University in Louisiana. However, the focus on power generation almost instantly took a back seat on the heels of the Deepwater oil spill disaster, and the school pivoted to coastal restoration and protection.
Things just kind of drifted along until last spring, when DOE reorganized its hydrokinetic efforts under a whole new R& D program, through its ARPA-E high-risk, high-reward funding office.
The program is called SHARKS, for Submarine Hydrokinetic And Riverine Kilo-megawatt Systems. The idea is to push the technology up a notch or three, by taking a holistic approach instead of doing things bit by bit.
That means taking cost into account as well as efficiency. To that end, the SHARKS team has identified remote use as one main area of focus, and utility-scale development as another.
11 More Renewable Energy Systems To Tap The Waters Of The US
SHARKS kicked off with $38 million in funding, and the new round adds another $35 million to the pot for 11 hydrokinetic projects.
On the remote-use side, one project of particular interest is the University of Alaska Fairbanks’s “Bladerunner” hydrokinetic system for rivers, which consists of a floating turbine tethered to an onshore generator.
Alaska is peppered with remote, far-flung, often inaccessible communities, making it ripe for off-grid renewable energy development. Solar power is already becoming a big thing in Alaska, and if all goes according to plan, hydrokinetic power could be next because Bladerunner sports a modular design.
More to the point, ARPA-E is excited by three breakthrough elements that cut costs:
- The highly material-efficient Bladerunner architecture increases swept area per equivalent mass by 130% over the base case
- The implementation of C-Motive’s novel electrostatic generator to efficiently convert low speed mechanical rotation into grid-voltage electricity
- The shore-based deployment and retrieval method enabled by the Bladerunner modular design
ARPA-E also highlights the remote-use RivGen hydrokinetic system developed by Ocean Renewable Power Company. That project first popped up on the CleanTechnica radar as a “futuristic water mill” back in 2015, and it seems that a lot of water has gone under the bridge since then. ARPA-E expects ORPC to develop a system that deploys arrays of interactive turbines to optimize performance.
The “social” turbine idea parallels a trend in the wind industry, where research has demonstrated that the performance in a wind farm can be improved if the turbines communicate with each other.
Another ARPA-E awardee that exploits turbine interaction is the University of Washington in Seattle. The school’s “Confinement-Exploiting Cross-Flow Turbine Array” project is based on the idea that turbines get a boost in power output and efficiency when they are placed close to each other.
That sounds simple enough, but the devil is in the details. “The University of Washington proposes a control co-design process that combines advances in turbine control strategies, hydrodynamic configurations and array geometry optimization to capitalize on the unsteady non-linear fluid dynamics,” ARPA-E explains, adding that “the team will focus on cross-flow current turbines, which are well-suited to achieving high confinement in river and tidal channels.”
Strange New Shapes For Underwater Energy
So far, the biggest project in the water is a three-turbine system called the RITE project located in New York City’s East River, which for the record is not really a river at all — it’s part of a tidal system.
The RITE project comes under the purview of a company called Verdant Power, which has developed underwater turbines that strongly resemble wind turbines.
The project got underway back in 2012.
In addition to Verdant Power’s riff on wind turbines, some new and unusual forms are taking shape.
The University of Virginia, for example, has come up with a system based on bio-inspired pairs of oscillating hydrofoils, and the nonprofit research institute SRI International is working on a kite-like system that leverages the pumping action that occurs when a kite is reeled in and payed out.
Ambient currents are not the only harvest-able resource offered by the waters of the Earth, and the Energy Department has also been investing in wave energy research.
The main area of focus on that score is the Pacific Northwest, on account of the superior energy density of its waves. Back in 2018 the Energy Department relaunched and rebranded existing wave energy facilities in the Pacific to include a focus on tidal and inland waters. They’ve been going at it hammer and tongs ever since, so stay tuned for more on that.
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Image: SHARKS hydrokinetic research via ARPA-E.
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