energy · ocean · family: the solution exists but nobody can afford it
predictable power,prohibitive price
Tidal and riverine hydrokinetic turbines are too expensive for deployment despite reliable resource
Problem statement
Tidal and riverine currents are, in ARPA-E's description, highly reliable and forecastable renewable energy resources, typically co-located with demand centers. Yet hydrokinetic turbines (HKTs) that harvest energy from these flows remain too expensive for deployment. ARPA-E's stated aim for the program is to reduce their levelized cost of energy (LCOE) significantly. The problem, as the program describes it, is technical and environmental: significant technical and environmental barriers make current HKT systems prohibitively expensive, they operate in harsh environments, and lowering operation and maintenance costs is one of the routes the program names to a lower LCOE.
Why this matters
ARPA-E calls hydrokinetic energy an abundant energy source, and says HKTs are suited both to micro-grids that supply energy to remote communities without grid connections and to utility-scale grid-connected applications. The resource is highly reliable and forecastable. ARPA-E expected the SHARKS program to span three years with $38M in funded projects; the program describes the field's low technical readiness as calling for a system-level approach, and its aim as addressing industry-wide limitations to provide economical hydrokinetic power at micro-grid and utility scale.
What’s been tried and why it hasn’t worked
ARPA-E's account of why HKT designs have not converged centers on the multi-disciplinary nature of the design space. The system-level approach the program calls for spans hydrodynamics, structural dynamics, control systems, power electronics, grid connections, and performance optimization, while at the same time minimizing potential negative environmental effects and maximizing system reliability. The program says the challenging, multi-disciplinary nature of this design space means many systems haven't moved beyond the theoretical design phase, and that the technical and environmental challenges inhibiting the convergence of HKT designs require expertise from various scientific and engineering fields. The design methodologies the program encourages require a wide range of disciplines to work concurrently, as opposed to sequentially, during the concept design stage.
What would unlock progress
ARPA-E's SHARKS program calls for new holistic HKT designs and encourages three methodologies: control co-design (CCD), co-design (CD), and designing for operation and maintenance (DFO), all of which require a wide range of disciplines to work concurrently rather than sequentially during the concept design stage. The approaches to a lower LCOE the program names, among others, are increasing generation efficiency, increasing rotor area per unit of equivalent mass, lowering operation and maintenance costs, minimizing potential negative impacts on the surrounding environment, and maximizing system reliability. The teams it describes may include experts in hydrodynamics, mechanical design, materials, hydro-structural interactions, turbine and/or turbine array efficiency, system-level control solutions, power electronics, grid connection, numerical modeling, computer tools, and experimental validation.
Entry points for student teams
A team could develop and test a bio-inspired anti-fouling coating for turbine blades using accelerated lab-scale fouling protocols, or design a modular HKT concept optimized for rapid retrieval and maintenance in riverine settings. Ocean engineering, mechanical engineering, and marine biology students would find strong entry points.
Genes
Structural cousins: stuck the same way, in other fields
Sources
ARPA-E SHARKS (Submarine Hydrokinetic And Riverine Kilo-megawatt Systems) program description, U.S. Department of Energy, accessed 2026-02-16 go to source ↗
Working notes
Notes made while writing and checking this brief, shown as written. They use working shorthand.
Related to ocean-underwater-iot-energy (subsea energy challenges) and ocean-fiber-sensor-field-deployment (marine sensing in harsh conditions). The program page counts 11 projects in total and shows five of them; the page's data record (and each project's own page) gives their award amounts and statuses: Emrgy, Inc. (Atlanta, GA; $6,612,896; hydrokinetic arrays using reliable, low-cost dynamic components; listed as active), National Renewable Energy Laboratory (Golden, CO; $2,143,000; a computer tool for control co-design of hydrokinetic energy systems; listed as cancelled), University of Washington (Seattle, WA; $2,000,000; confinement-exploiting cross-flow turbine arrays; listed as alumni), University of Alaska Fairbanks (Fairbanks, AK; $5,306,426; a material- and cost-efficient modular riverine hydrokinetic energy system; listed as active), and Littoral Power Systems (New Bedford, MA; $2,179,837; control co-design of a cost-efficient hydrokinetic turbine system; listed as cancelled). The page also links a FOA FAQ PDF (DE-FOA-0002334).
Reconciliation 2026-09-30: Fact repair after reading the whole write-up against its one source. The ARPA-E page at https://arpa-e.energy.gov/programs-and-initiatives/view-all-programs/sharks was fetched on 2026-09-30. The address itself returns only an empty page shell (the site draws its text in the browser), so the program record the page renders was fetched from the site's own data endpoint (https://arpa-e.energy.gov/jsonapi/custom/node?filter[content_type]=program&filter[alias]=sharks) and read in full: the program description, the "innovation need" text, the impact blurbs, the two linked press items and the five project teasers shown on the page, which also displays a count of 11 projects in total. The page confirms the long title and the display title, the acronym on the Source line, that the resource is "highly reliable, forecastable, and typically co-located with demand centers," that HKTs suit both micro-grids for remote communities without grid connections and utility-scale applications, that "current HKTs are too expensive for deployment due to technical challenges and harsh operational environments," and that SHARKS "is expected to span three years with $38M in funded projects." Nearly everything else in the write-up was not on the page, so the following changes were made. (1) "One of the most predictable and reliable renewable energy sources available," "coastal demand centers" and "available 24/7 unlike wind or solar" are not in the source; the sentence now uses the page's words (highly reliable, forecastable, typically co-located with demand centers). "Far too expensive for commercial deployment" is now "too expensive for deployment," the page's phrase. (2) The LCOE figures of $0.30–0.50/kWh and "5–10 times higher than onshore wind" are not in the source and were removed; the sentence now gives the program's aim of reducing LCOE significantly. (3) Biofouling, corrosion, debris impacts and "extreme hydrodynamic loads" as the causes of cost are not in the source, which names "technical challenges and harsh operational environments" and "significant technical and environmental barriers"; the sentence now says that, and notes that lowering operation and maintenance costs is one route the program names. (4) The 120–150 GW resource estimate, "fully predictable years in advance," the claim that this would eliminate backup generation or storage, and the island-nation baseload sentence are not in the source and were removed; the paragraph now carries the page's description of hydrokinetic energy as abundant and suited to micro-grid and utility-scale use. (5) The $38M is confirmed, but "because the gap between resource quality and technology readiness represents a missed opportunity for grid diversity" is not the page's reason; the sentence now gives the page's own framing (low technical readiness calling for a system-level approach; aim of addressing industry-wide limitations). The page's later press item announces $35 million (November 2020) while the program text and the April 2020 press item say $38 million; the write-up keeps the program text's figure. (6) The whole "What's Been Tried" paragraph (wind-turbine-derived horizontal-axis designs, biofouling within months, saltwater corrosion, water being 800 times denser than air, heavy foundations, MeyGen and Verdant Power as demonstrations above grid parity, vertical-axis and oscillating-foil trade-offs) is not in the source; it now gives the page's account, which is that the multi-disciplinary nature of the design space means many systems "haven't moved beyond the theoretical design phase," that the challenges inhibiting convergence of designs call for expertise from various fields, and that the methodologies the program encourages require disciplines to work concurrently rather than sequentially. (7) Bio-inspired anti-fouling surfaces, corrosion-resistant composites and autonomous maintenance robots are not in the source; nor is the claim that control co-design "has shown promise in modeling studies but hasn't been implemented in hardware," nor mooring as part of it. The section now lists the three methodologies the program encourages (control co-design, co-design, designing for operation and maintenance), the LCOE approaches the page names (which it gives as a non-exhaustive list), and the disciplines it says teams may include. (8) In the Source Notes, the sentences calling MeyGen the world's largest operating tidal stream project and EMEC the primary testing facility are not in the source and were replaced by the page's project count, the five projects it shows, and their award amounts and statuses as the page's data record and the projects' own pages give them, plus the FAQ PDF link. The entry points were left as written; they are suggestions rather than claims. Could not be checked against this source because the page does not speak to them: everything removed under items (2), (4), (6) and (8). No title changed. Genome tags untouched. A second reader went over the repairs the same day, fetching the page, its data record, the five project records, the two press items, a 2022 Internet Archive copy of the older program page, and the linked FOA FAQ PDF (DE-FOA-0002334), none of which carry the removed figures or names; the second reader reworded items (6), (7) and (8) to the forms above so that they say no more than the source does, and left the rest standing.